Ash, carbon, and other incombustible solids, often due to impurities in the fuel, that build up on any surfaces exposed to products of combustion. They can lead to corrosion, reduced heat transfer and so higher flue-gas temperatures and reduced efficiency.
|Turning angle (θ)||轉向角（θ）||
The change in direction experienced by a gas flow passing through an oblique shock wave or Prandtl–Meyer expansion fan.
Residual stresses that vary from tension to compression in a distance (presumably approximating the grain size) that is small compared with the gage length in ordinary strain measurements. They are not detectable by dissection methods, but can sometimes be measured from line shift or line broadening in an x-ray diffraction pattern.
Treatment carried out after quenching to transform retained austenite into martensite, involving cooling and holding at a temperature below ambient.
(turboset) The combination of a steam or gas turbine and an electrical generator with a single shaft or connected coaxial shafts.
|Bond strength (Unit Pa)||結合強度（單位Pa）||
The tensile, compressive or shear stress at which joints fail, e.g. by fracture or excessive deformation.
A non-intrusive pyrometer based on the principle that the sound speed in a gas is proportional to the square root of its absolute temperature.
The process whereby a fluid permeates a porous solid, or a gas is dissolved by a liquid.
Any of several tests to obtain shear strength of a metal. Common tests used on mill products include the double-shear test, single-shear test, the blanking shear test (also known as the punching shear test) and the torsion test.
The middle value when all observed values in a sample are arranged in order of magnitude. If an even number of samples are tested, the average of the two middlemost values is used. It is a point estimate of the population median, or 50% point.
Tension (tensile stress) created in the bolt by assembly preloads and=or such things as thermal expansion, service loads, etc.
A methodology which integrates all disciplines and specialty groups into a team effort, forming a structured development process that proceeds from concept to production to operation.
Literally ‘not elastic’, but in practice used for materials that display timedependent recovery on unloading.
|Strength of materials||材料強度||
A confusing name for what is really stress analysis, reflecting older engineering design based upon elasticity and ‘theories of strength’ for different materials, without regard to cracks.
The shape of a cross section of an object, such as an aerofoil or cam.
A conical or cylindrical plug, in which there are transverse holes, in a valve, such as a plug valve. Flow through the holes occurs when the plug is rotated.
The units of physical quantities, the dimensions of which includemass, length, and time.
Fine, apparently amorphous carbon particles formed in white cast iron and certain steels during prolonged annealing. Also called temper carbon.
1. A process of high-speed multiple scratching of surfaces by a wheel formed from hard grits and a binder which are progressively exposed as the binder wears away. It is a process of micromachining employed particularly in accurate finishing operations on hard materials. 2. A form of comminution.
The average value of a number of data points. Computed by dividing the sum of all data by the number of data points.
A humidifier that functions by spraying fine droplets of water into an airstream.
A process in which molten metal, particularly alloys of aluminium, magnesium, copper, and zinc, is forced under pressure (10 to 200 MPa) into a reusable hardened-steel mould machined into a die.
A coherent derived SI unit defined as the plane angle subtended at the centre of a circle by an arc having a length equal to the radius. Thus 2π radians are equivalent to 360° and 1 rad ≈ 57.3°.
|Residual strength (Unit N)||剩余強度（單位：N）||
The strength of a damaged body containing defects induced by microcracking, thermal shock, etc.
A test machine, first proposed by Gerhard Junker, for testing the vibration resistance of fasteners.
A machine used to cut an external thread on a rod, tube, bolt blank, etc. or an internal thread in a hole, tube, nut blank, etc.
A load on a component which is distributed over a very small area, idealized as the line load of a wedge or knife edge, and the point load of a cone.
(fracture stress) (Unit Pa) The stress at which a material breaks. It is not absolute for a given material, as it depends on the laws of fracture mechanics and is size-dependent.
The prevention of transmission of vibration from one component of a system to another part of the same system, such as a building or other structure. Isolation may be achieved using dampers (vibration damping) or by active feedback-control methods. Mechanical vibration is often attenuated by means of components immersed in oil such as in dashpots (viscous damping). Vibration suppression can be achieved (a) using dampers and absorbers tuned to a particular frequency to suppress vibratory forces in structures and other systems (passive suppression) or (b) by the measurement of vibration at key locations in a structure and the application of? cancellation forces (active suppression).
|Effective crack size (ae)||有效裂紋尺寸（ae）||
The physical crack size augmented for the effects of cracking plastic deformation. Sometimes the effective crack size is calculated from a measured value of a physical crack size plus a calculated value of a plastic-zone adjustment. A preferred method for calculation of effective crack size compares compliance from the secant of a load-deflection trace with the elastic compliance from a calibration for the type of specimen.
The maximum stress which a material is capable of sustaining without any permanent strain (deformation) remaining on complete release of the stress.
A pump for exhausting air and non-condensable gases from a vessel to be maintained at sub-atmospheric pressure. The pirani and thermal-conductivity gauges are vacuum gauges used to measure the absolute pressure within a vacuum system (vacuum level), usually expressed in torr or Pa.
A solid solution of one or more elements in body-centered cubic iron. Unless otherwise designated (for instance, as chromium ferrite), the solute is generally assumed to be carbon. On some equilibrium diagrams, there are two ferrite regions separated by an austenite area. The lower area is alpha ferrite; the upper, delta ferrite. If there is no designation, alpha ferrite is assumed.
一種或多種元素在體心立方鐵中的固溶體。除非另有說明（例如，鐵酸鉻），否則通常假定溶質為碳。在一些平衡圖上，有兩個鐵素體區域被一個奧氏體區域隔開。下部區域為α鐵素體；上部，δ鐵氧體。如果沒有指定，則假定為 α 鐵氧體。
|Torsional shaft vibration||扭軸振動||
The rapid back-and-forth angular twisting along a rotating unbalanced shaft which reaches maxima at critical rotation speeds. Shaft eccentricity, unbalanced mass distribution, oscillatory torque, misalignment, etc. all influence torsional vibration.
A non-SI unit of pressure commonly used in vacuum systems; defined by 760 torr = 1 atm so that 1 torr = 133.322 368 4 Pa, and approximately equivalent to the pressure corresponding to 1 mm of mercury.
Quenching with aqueous solutions of 5 to 10% sodium hydroxide (NaOH).
Threads with relatively large separation between corresponding points on the threads.
The absolute value of the slope of a stress-relaxation curve at a given time.
A compound of iron and carbon, known chemically as iron carbide and having the approximate chemical formula Fe3C. It is characterized by an orthorhombic crystal structure. When it occurs as a phase in steel, the chemical composition will be altered by the presence of manganese and other carbide-forming elements.
A scale of scratch hardness originally developed for minerals.
A type of fracture appearance, typical of plane-stress fractures, in which the plane of metal separation is inclined at an angle (usually about 45°) to the axis of the applied stress.
Hardening of carbon steel in an oil bath. Oils are categorized as conventional, fast, martempering, or hot quenching.
|Engineering strain (e)||工程應變（e）||
A term sometimes used for average linear strain or conventional strain in order to differentiate it from true strain. In tension testing it is calculated by dividing the change in the gage length by the original gage length.
(Ea, U) (Unit kJ/mol) The minimum energy for a chemical reaction to occur or for processes such as diffusion to take place in crystals.
A type of compression spring, similar to a coil spring, but made of strip shaped into waves around the circumference.
The plastic deformation of a metal, by rolling (cold rolling), drawing, forging (cold forging), etc. at a temperature well below its recrystallization temperature, which results not only in permanent shape change but also increase in strength and loss of ductility owing to work-hardening.
|Crack-extension force (G)||裂紋擴展力（G）||
The elastic energy per unit of new separation area that would be made available at the front of an ideal crack in an elastic solid during a virtual increment of forward crack extension.
The deformation or strain remaining in a previously stressed body after release of load.
|Hydrogen-induced delayed cracking||氫致延遲開裂||
A term sometimes used to identify a form of hydrogen embrittlement in which a metal appears to fracture spontaneously under a steady stress less than the yield stress. There is usually a delay between the application of stress (or exposure of the stressed metal to hydrogen) and the onset of cracking. Also referred to as static fatigue.
|Length of engagement||嚙合長度||
It is the axial measurement within which the external and internal threads have theoretical contact.
The rate of material removal or dimensional change due to wear per unit of exposure parameter—for example, quantity of material removed(mass, volume, thickness) in unit distance of sliding or unit time.
|Workspace (Unit m3)||工作空間（單位m3）||
(working-space volume) The volume around the base frame of a robot, defined by the reach of the robot. The robot can thus only perform tasks within this volume.
|Swift cup test||斯威夫特杯測試||
A simulative cupping test in which circular blanks of various diameters are clamped in a die ring and deep drawn into cups by a flat-bottomed cylindrical punch.
|Natural unit system (n.u. system)||自然單位制（n.u.制）||
A non-SI system of units, based on fundamental constants, used in high-energy and particle physics. The n.u. of speed is the speed of light in a vacuum, c0?= 299 792 458 m/s.
For testing machines, a force applied to a test piece that is measured in units such as pound-force, newton, or kilogram-force.
A mode of failure of composite materials, including radial-ply tyres, in which the layers separate due to repeated cyclic loading, impact, or weak bonding.
On a straight thread, the diameter of the imaginary cylinder that just touches the crest of an external thread or the root of an internal thread.
|Root diameter (Unit m)||根部直徑（單位：m）||
The diameter of the circle passing through the roots of teeth in gear teeth or screw threads.
Hot forging of brass and bronze alloys.
The original length of the portion of a specimen over which strain, change of length, or other characteristics are determined.
Any deviation from an original size, shape, or contour that occurs because of the application of stress or the release of residual stress.
An imprecise term used to denote the last anneal given to a nonferrous alloy prior to shipment.
The permanent (inelastic) distortion of a material under applied stress that strains the material beyond its elastic limit.
A block having a 90° V-shaped recess; used in a workshop to hold round workpieces.
|Thermal energy (heat energy) (Unit J)||熱能（單位：J）||
The sensible and latent forms of internal energy.
On an engineering drawing, where the end point of one dimension is the starting point for the next. Parallel dimensioning is preferred as chain dimensioning can lead to the accumulation of tolerances.
|Celsius temperature scale||攝氏溫標||
(centigrade temperature scale) A relative, non-SI, temperature scale now defined in terms of the Kelvin absolute temperature scale as °C = K ? 273.15, where °C is the symbol for degrees Celsius. The scale was previously called the centigrade scale, with two fixed points: the melting point of ice (the ice point) as 0°C, and the boiling point of water (the steam point) as 100°C.
|Horizontal batch furnace||臥式間歇爐||
A versatile batch-type furnace that can give light or deep case depths, and because the parts are not exposed to air, horizontal batch furnaces can give surfaces almost entirely free of oxides.
|Minimum material condition||最小材料條件||
(minimum metal condition) The situation where the volume of a manufactured component corresponds to the lower limit of all toleranced external dimensions and to the upper limit for all internal dimensions.
1. Heat generated by internal-combustion engines, gas turbines, electrical generators, electrical equipment, and industrial processes that is not used directly but is expelled to the environment, often in hot flue or exhaust gases. 2. Heat generated from waste
1. A cup-shaped vane with a central dividing ridge attached to the periphery of the runner of an impulse water turbine such as a Pelton turbine. 2. A rotor blade in a compressor or turbine.
Quenching in a fine vapor or mist.
(Cal, kg-cal, kilogram-calorie, large calorie) An obsolete (i.e. non-SI) unit of energy equal to 1 000 cal.
The improvement of fracture toughness of a material by stress-induced transformation of the microstructure.
(balance drum, dummy piston) A disc attached to the shaft of a turbine or compressor, to one side of which high or low pressure is applied to counteract the axial thrust produced by the pressure change across the machine. A form of thrust bearing.
|Austenitic stainless steels||奧氏體不銹鋼||
Austenitic stainless steels are non-magnetic. They contain significant additions of chromium (16–30%), but have the austenite (FCC) crystal structure, stabilized by the addition of nickel in the composition range 6–20%. Carbon content ranges from about 0.03 to 0.15%. The ‘18–8’ stainless steels containing approximately 18% chromium and 8% nickel are typical of the class. Austenitic stainless steels have high strength and corrosion resistance even at elevated temperatures, good ductility, good low-temperature properties, and good weldability. Used for aircraft and transport equipment, cutlery, chemical and food-processing equipment, surgical instruments, and cryogenic vessels.
A temper of nonferrous alloys and some ferrous alloys characterized by tensile strength about mid-way between that of dead soft and full hard tempers.
The intended size of a component. The actual size will depend on manufacturing tolerances.
An air- or electric-powered wrench in which multiple blows from tiny hammers are used to produce output torque to tighten fasteners. A pneumatically-or electrically-powered socket wrench used to tighten or loosen nuts through the application of torque in a rapid series of impulses.
Aging under conditions of time and temperature greater than those required to obtain maximum change in a certain property, so that the property is altered in the direction of the initial value.
Any of various manual or automatic devices that are able to initiate, regulate, or stop the flow of a fluid through a conduit or from a closed container.
A ductile fracture in which a crystal (or a polycrystalline mass)has separated by sliding or tearing under the action of shear stresses. Contrast with cleavage fracture.
The study of the properties, behaviour, and application of solid substances such as metals, ceramics, glasses, polymers, composites, biomaterials, and semiconductors, at all scales from the atomic to the macroscopic. The topic has its origins in metallurgy.
A clip made of a material such as spring steel which grips an inserted part.
(relief angle) (Unit °) The angle between the underneath or flank of a cutting tool and the machined surface.
Materials in which the magnetic moment of adjacent atoms can adopt either parallel or antiparallel alignment. Ferromagnetism occurs when the magnetic moments adopt parallel alignment. When adjacent magnetic moments cancel due to antiparallel alignment, the material exhibits antiferromagnetism and has no overall magnetic moment. Examples of the latter include ferrous oxide and manganese oxide. The phenomenon of ferrimagnetism occurs when adjacent magnetic moments adopt antiparallel alignment but have unequal magnitude. The region of ferromagnetic or ferrimagnetic material in which the magnetic moments are aligned is known as a magnetic domain and adjacent regions are separated by domain walls. Diamagnetic and paramagnetic materials exhibit weak forms of magnetism that results from independent (uncoupled) alignment of magnetic atomic dipoles induced by an applied magnetic field. Ferromagnetic and ferrimagnetic materials can acquire high degrees of magnetization in relatively weak magnetic fields. They have different hysteresis characteristics and are classified as either hard magnets or soft magnets. Hard magnets retain large magnetization in the absence of an applied magnetic field and are used as permanent magnets. Conventional materials include magnet steels alloyed with tungsten or cobalt. Rare-earth magnets made from alloys of rare-earth elements produce significantly stronger magnetic fields. The most common of these are samarium-cobalt and neodymiumiron-boron permanent magnets. Their strength allows them to be small and used in numerous applications, including cordless tools, disk drives, headphones, toys, and motors for automotive components such as wipers, fans, washers, and windows. Soft magnets may be magnetized and demagnetized relatively easily. When subjected to an alternating magnetic? field the energy loss due to hysteresis is small. Common materials include iron-silicon alloys (known as electrical steels), nickel-iron alloys (permalloy), soft ferrites, and amorphous nanocrystalline alloys, the last of which can be produced in the form of tape by meltspinning. Soft magnets are used to enhance the magnetic flux produced by an electric current.
The stroke in a reciprocating compressor or engine during which the working fluid is compressed.
Materials having a high coefficient of friction which, when coupled with a long life, may be employed as brake linings or the facing of the plates of a clutch.
That stress level which will create a permanent deformation of 0.2% or 0.5% or some other small, preselected, amount in a body.? Approximately equal to the elastic and proportional limits of the material; a little higher than the proof strength of a bolt. The stress at which a material exhibits a specified deviation from proportionality of stress and strain. An offset of 0.2% is used for many metals.
1. Any of various tests in which different hard indenters are forced into the surface of a solid under different loads to give permanent impressions, the pressure to cause which being called the hardness. The Brinell test employs a spherical indenter; the Vickers test a square-based pyramid. The relation between indentation hardness H and uniaxial yield stress Y is approximately H = (2.5 ~ 3.0)Y. Originally hardnesses were given in kg/mm2 but now are often given in Pa. 2. The tests for scratch and file hardness relate either to one material being able to mark another (Mohs hardness scale for minerals), or to the size of groove produced by a rigid indenter slid under load across a surface. 3. Rebound hardness concerns the height of rebound of a dropped indenter, or an indenter at the end of a pivoted arm, having struck a surface.
|Radial wave equation||徑向波動方程||
A differential equation describing the transmission of a wave in a system with radial symmetry.
Raising the strength and hardness of an alloy by heating a supersaturated solid solution at a relatively low temperature to induce precipitation of a finely dispersed second phase. Also known as aging or precipitation hardening. Hardening by aging, usually after rapid cooling or cold working.
?(1) The ratio of the change in dimension, resulting from a given load increment, to the magnitude of the dimension immediately prior to applying the load increment. (2) In a body subjected to axial force, the natural logarithm of the ratio of the gage length at the moment of observation to the original gage length. Also known as natural strain. Compare with engineering strain.
(compression–ignition engine) A piston engine operating on the Diesel cycle in which the air is compressed to a temperature above the autoignition temperature of the fuel and combustion is initiated as the fuel is injected into the hot air. Diesel engines operate at higher compression ratios (typically in the range 12 to 24) than petrol engines. Although named after Rudolf Diesel, the inventor, Diesel engine is often spelled with a lower case d, contrary to normal practice.
|Screw area (Unit m2)||螺絲面積（單位m2）||
The area of a circle described by the tips of a propeller.
The manufacture of hollow polymer objects (e.g. bottles) by expanding, with internal air pressure, a tube sealed at one end (parison) against the walls of a cavity mould.
A temper of nonferrous alloys and some ferrous alloys characterized by tensile strength and hardness about two-thirds of the way from full hard to extra spring temper.
|Effective radius of nut, bolt head, or threads||螺母、螺栓頭或螺紋的有效半徑||
Distance between the geometric center of the part and the circle of points through which the resultant contact forces between mating parts passes. Must be determined by integration.
Imparting resistance to oxidation to an iron or steel surface by heating in aluminum powder at 800 to 1000 °C (1470 to 1830 °F).
A manual wrench which incorporates a gage or measuring apparatus of some sort to measure and display the amount of torque being delivered to the nut or bolt. All wrenches produce torque. Only a torque wrench tells how much torque. A socket wrench or ring spanner that can be set to allow a specific torque to be applied to a nut or bolt head.
The phenomenon of permanently absorbed or lost energy that occurs during any cycle of loading or unloading when a material is subjected to repeated loading.
A metal bar designed to act as an elastic spring when torque is applied.
It is the depth below the surfaces, as revealed in microstructural sections of joined metals, which is melted during welding.
The stress state at a point in a component subjected to combination of axial, bending, torsional loadings etc., acting along all reference axes.
The cross-sectional shape of the threads, defining thread angle, root, and crest profiles, etc. Thread length Length of that portion of the fastener which contains threads cut or rolled to full depth.
The underfaces of the nut and the bolt head should be exactly perpendicular to the thread or shank axes. If the angle between the face and the axis is, for example, 868 or 948, the fastener is said to have an angularity of 48 (sometimes called Perpendicularity).
(hot-dip galvanizing) A process of coating an iron, steel, or aluminium object with a thin layer of zinc by passing it through a bath of molten zinc at a temperature of about 460°C.
|Energy losses (Unit kJ)||能量損失（單位kJ）||
A commonly-used misnomer in view of the conservation-ofenergy principle, but used to mean energy converted into forms that are not used in a process, for example thermal energy from a heat engine dissipated to the surroundings, or produced by friction in a machine, or by surface drag.
The nut thickness shall be the overall distance measured parallel to the axis of nut, from the top of the nut to the bearing surface, and shall include the thickness of the washer face where provided.
The simultaneous extrusion through the same die of two or more materials in combination.
|Maximum load (Pmax)||最大負載（Pmax）||
(1) The load having the highest algebraic value in the load cycle. Tensile loads are considered positive and compressive loads negative. (2)Used to determine the strength of a structural member; the load that can be borne before failure is apparent.
Mechanical property value above which at least 90% of the population of values is expected to fall, with a confidence of 95%.
|Radiosity (J) (Unit W/m2)||輻射度（J）（單位W/m2）||
The total radiation leaving a given surface per unit area, including emitted, reflected, and transmitted radiation.
|Ferritic stainless steels||鐵素體不銹鋼||
Ferritic stainless steels have the ferrite (BCC) crystal structure and contain 10–28% chromium and typically 0.1–0.35% carbon (all in wt%). They are magnetic and can be hardened by cold working. They have good to moderate mechanical properties, good oxidation and corrosion resistance at elevated temperatures, and susceptibility to embrittlement at temperatures between 400 and 540°C. Used for turbine parts, hightemperature valves, automotive exhaust components, and nuclear reactor core components.
This bolt has been so named because of its use in stove building. It is made in a number of different forms, either with a round button, or flat countersunk head, the head having a slot for a screwdriver and the threaded end being provided with a square or hexagon nut.
|Specific weight (γ) (Unit N/m3)||比重（γ）（單位：N/m3）||
The weight per unit volume of a substance: if W is the weight of a volume of the substance, ρ is its density, and g is the acceleration due to gravity, γ = W/ = ρg.
An unbalanced force, such as an impact, applied at one location in a body sets the material there into vibration that is transmitted to adjacent elements and ultimately to all parts of the body in the form of stress waves or wave packets.
|Available head (Unit m)||可用水頭（單位米）||
In a hydroelectric power system, the difference between the vertical height of the water level in the supply reservoir above the turbine inlet less the head loss due to friction and fittings in the duct leading to the turbine.
A subcritical annealing treatment applied to cold-worked low- or medium-carbon steel. Finish annealing, which is a compromise treatment, lowers residual stresses, thereby minimizing the risk of distortion in machining while retaining most of the benefits to machinability contributed by cold working. Compare with final annealing.
1. National and international agreements for design, manufacture, materials, performance, practices, requirements, strength, etc. which ensure common results wherever an item is made and wherever used. 2. The manufacture of components so that interchangeability of parts during assembly of new, or repair of old, items is possible without ‘fitting’.
For a pure substance, the curve of saturation pressure plotted vs saturation temperature.
Combined thickness of all the things clamped together by the bolt and nut, including washers, gaskets, and joint members.
|Lead of thread||螺紋導程||
On a single threaded screw, the distance the screw or nut advances in one complete revolution.
(1) Permanently damaging a metal or alloy by heating to cause either incipient melting or intergranular oxidation. See overheating, grain-boundary liquation. (2) In grinding, getting the work hot enough to cause discoloration or to change the microstructure by tempering or hardening.
The strain over a gage length comparable to interatomic distances. These are the strains being averaged by the macrostrain measurement. Microstrain is not measurable by currently existing techniques. Variance of the microstrain distribution can, however, be measured by x-ray diffraction.
1. (stroke length) (Unit m) The linear distance between top dead centre and bottom dead centre of a piston in a reciprocating engine or mechanism. 2. The movement of a piston or plunger in a reciprocating machine to execute a particular function; for example, the exhaust stroke of an engine in which the exhaust gases are expelled from a cylinder.
A highly ductile (but anisotropic) type of iron containing elongated slag fibres that resulted from the method of manufacture in which excess carbon in pig iron was burnt and worked out. The yield strength is some 200 MPa, tensile strength 320 MPa, and reduction of area on a 50-mm gauge length up to 35%. Now replaced by steel.
A solid disc, or a circular ring with spokes radiating from a central hub, either attached to an axle around which it revolves or which revolves with a rotating axle.
|Equation, long form||方程，長格式||
An equation which relates the torque applied to a bolt to the preload created in it, and involves fastener geometry and the coefficient of friction between mating surfaces. A theoretical equation based on rigid body mechanics and the assumption that the geometry of the fastener is perfectly described by blueprint dimensions.
A gradual, often linear, reduction in cross section or shape. A shaft or hole that gets gradually smaller toward one end.
|Critical load (Unit N)||臨界負荷（單位N）||
1. The applied load that causes propagation of an existing crack of known length, and hence fracture of a component or structure. 2. The applied load that results in buckling of a column of given end fixity.
|British thermal unit (BTU, Btu)||英熱單位（BTU，Btu）||
An obsolete (non-SI) imperial unit of energy defined as the energy required to raise the temperature of one pound of pure water at 68°F by 1°F. The conversion to SI is 1 Btu = 1.055 056 × 103?J.
|Wind pressure (Unit Pa)||風壓（單位Pa）||
The dynamic pressure associated with the wind. The static pressure of the wind is the atmospheric pressure.
An engineering drawing that shows how parts are assembled to produce a component or a complete machine. It may include sections to show internal features, dimensions that are critical for assembly, manufacturing information, and part numbers.
An increase in the average size of the grains in polycrystalline metal, usually as a result of heating at elevated temperature.
Use of a carburizing process to convert a low-carbon ferrous alloy to one of uniform and higher carbon content throughout the section.
The projecting elements on gears, cutting tools, etc.
|Tear strength (Unit N/m)||撕裂強度（單位：N/m）||
The tensile force divided by the sheet thickness required to tear a pre-split sheet material at a specified rate. Particularly used for plastics, rubber, fabrics, and elastomers. Since the units are not those of stress but equivalent to J/m2, the units of toughness, the term ‘strength’ is strictly incorrect.
Alloying element expanding the γ-phase field in the corresponding phase diagram, which manifests itself in a decrease of the A3?temperature and an increase of the A4?temperature in binary alloys Fe–M as well as in a decrease of A1?temperature in ternary alloys Fe–C–M (M is an alloying element). The solubility of austenite-stabilizers in ferrite is much lower than in austenite. Under the influence of austenite-stabilizers, austenite can become thermodynamically stable down to room temperature.
The cooling of a surface exposed to very high external gas temperature which causes the surface material to sublime, melt or decompose. The chemical process absorbs heat while the mass flow of material away from the surface blocks the heat flux from the hot gas.
|Secondary stresses (Unit Pa)||二次應力（單位Pa）||
Stresses different from those induced by the major loading but nevertheless resulting from the major loads; for example, the hoop stresses that occur around the circumference of barrelled compression testpieces and forgings.
In an alloy system exhibiting a eutectic, any alloy whose composition has an excess of alloying element compared with the eutectic composition, and whose equilibrium microstructure contains some eutectic structure.
The helix produced in a cylindrical component, such as a shaft, wire, tensioned cable, or rope, when one end is rotated relative to the other. Measured either as the number of turns per unit length, or by the helix angle (twist angle).
An annular disc of metal, rubber, plastic, ceramic, etc., placed between two surfaces in contact either to spread the load (for example, between a surface and a tightened nut or a bolt head), to provide a seal, or to separate or align components.
The differently sized grits of hard materials such as emery employed for grinding, polishing, etc. The abrasive grade is determined by the grit size (grit number) originally related to the hole sizes in wire sieves.
That branch of engineering concerned with energy conversion, stress analysis, vibration, dynamics, and kinematics, especially applied to design (machine design, mechanical-engineering design).
The intensity of the internally distributed forces or components of forces that resist a change in the volume or shape of a material that is or has been subjected to external forces. Stress is expressed in force per unit area and is calculated on the basis of the original dimensions of the cross section of the specimen. Stress can be either direct (tension or compression)or shear. 1. Stress ‘at a point’ (i.e. over a volume of material that is very small compared with that of the component or structure) is the load per unit area for every face of an infinitesimal cube surrounding the point. 2. In fluid flow the stress tensor σij is the sum of an isotropic part ?pδij, δij being the Kronecker delta, having the same form as the stress tensor for a fluid at rest, p being the static pressure, and the non-isotropic, deviatoric stress tensor dij which is due entirely to the fluid motion.
內部分布力或力分量的強度，這些力或力的分量抵抗正在或已經受到外力的材料的體積或形狀的變化。應力以單位面積的力表示，并根據試樣橫截面的原始尺寸計算。應力可以是直接（拉伸或壓縮）或剪切。1.“在一點”的應力（即在與組件或結構相比非常小的材料體積上）是圍繞該點的無限小立方體的每個面的單位面積載荷。2. 在流體流動中，應力張量σij是各向同性部分-pδij的總和，δij是Kroneckerδ，具有與靜止流體的應力張量相同的形式，p是靜壓，非各向同性, 偏應力張量 dij 完全由流體運動引起。
(1) Before finishing to final dimensions, repeatedly heating a ferrous or nonferrous part to or slightly above its normal operating temperature and then cooling to room temperature to ensure dimensional stability in service. (2) Transforming retained austenite in quenched hardenable steels, usually by cold treatment. (3) Heating a solution-treated stabilized grade of austenitic stainless steel to 870 to 900 °C (1600 to 1650 °F) to precipitate all carbon as TiC, NbC, or TaC so that sensitization is avoided on subsequent exposure to elevated temperature.
The hypothetical collection of all possible test specimens that could be prepared in the specified way from the material under consideration. Also known as universe.
The manner in which tensile, compressive, and shear stresses are distributed within a loaded body, indicated by loci of constant stress.
A device for measuring temperature, consisting of lengths of two dissimilar metals or alloys that are electrically joined at one end and connected to a voltage-measuring instrument at the other end. When one junction is hotter than the other, a thermal electromotive force is produced that is roughly proportional to the difference in temperature between the hot and cold junctions.
|International Bureau of Weights and Measures||國際度量衡局IBWM||
(BIPM, Bureau International des Poids et Mesures) The intergovernmental organization which has the mandate to provide the basis for a single, coherent system of measurements, traceable to the International System of Units.
Wholly leak-free joints are impossible, at least if the contained fluid is a gas, so it has been proposed that the design of a gasketed joint should start with the selection of an ‘‘acceptable’’ leak rate. The designer would dimension bolts and joint members so that the actual leak rate would never exceed this. Three standard levels of tightness have been proposed as well.
The bolt length shall be the distance measured parallel to the axis of the product from the bearing surface of the head to the extreme end of the bolt including point.
|True stress (σ) (Unit Pa)||真應力（σ）（單位Pa）||
The value obtained by dividing the load applied to a member at a given instant by the cross-sectional area over which it acts. Compare with engineering stress. The applied load on a test specimen divided by the current cross-section area over which it acts. σ = s expε where s is the engineering stress given by the applied load divided by the original cross-section area over which it acts, and ε is the true strain.
A steel containing sufficient carbon and other alloying elements to harden fully during cooling in air or other gaseous mediums from a temperature above its transformation range. The terms should be restricted to steels that are capable of being hardened by cooling in air in fairly large sections, about 2 in. (50 mm) or more in diameter. Same as self-hardening steel.
The sum of the free and combined carbon (including carbon in solution) in a ferrous alloy.
The property of a material by virtue of which deformation caused by stress disappears on removal of the stress. A perfectly elastic body completely recovers its original shape and dimensions after release of stress.
|Crack size (a)||裂紋尺寸（a）||
A lineal measure of a principal planar dimension of a crack. This measure is commonly used in the calculation of quantities descriptive of the stress and displacement fields. In practice, the value of crack size is obtained from procedures for measurement of physical crack size, original crack size, or effective crack size, as appropriate to the situation under consideration.
|Torque reaction (Unit N.m)||扭矩反作用力（單位：N.m）||
The torque needed to counteract an applied torque. For example, in a helicopter with a single main rotor, the tendency of the fuselage to rotate in the opposite direction to the rotor.
A pressure gauge used to measure gauge pressure in a line, boiler, cylinder, or other device operating with steam.
A self holding, standard taper largely used on drilling tools, drilling machine spindles, and some lathes.
Two links connected together to form a kinematic pair, in which the contacting surfaces are screw threads, so that their relative motion consists of rotation and sliding.
|Relative humidity (?)||相對濕度（ψ）||
The ratio or percentage of the actual mass of moisture in a given volume of air at a given temperature to the maximum possible mass of moisture at the same temperature.
(rotary-vane compressor, vane compressor) A rotary compressor in which gas is compressed as the spaces between spring-loaded sliding vanes held in an offset rotor reduce as the rotor revolves within a cylindrical housing.
A turbomachine used for torque amplification consisting of an impeller, a turbine, and a reaction member. Applications include motor-vehicle transmissions.
(Joule cycle) An air standard cycle that is the ideal cycle for a gasturbine engine. As shown on the diagram of pressure (p) ?s specific volume (?), it consists of four internally reversible processes: isentropic compression in a compressor (1–2), isobaric heat addition in a combustor (2–3), isentropic expansion in a turbine (3–4) and isobaric heat rejection. The cycle can be extended to include regeneration, reheating, and intercooling.
The system that transmits power and torque from a power source; for example a shaft, belts and pulleys, or a gear train. In the case of a motor vehicle, it includes the gearbox, clutch, propeller shaft, differential and final drive shafts.
The condition of a system or working fluid according to its properties.
|Linear (tensile or compressive) strain||線性（拉伸或壓縮）應變||
The change per unit length due to force in an original linear dimension. An increase in length is considered positive.
The part of the total carbon in steel or cast iron that is present as other than free carbon.
An organization that fabricates raw steel into a fastener meeting specified standards.
The temperature scale based on the freezing point of water (0oC) and the boiling point of water (100oC). The interval between these points is divided into 100 degrees. The scale was devised by Anders Celsius.
|X-ray thickness gauge||X射線厚度計||
A device comprising an X-ray source and a detector used to determine the thickness of material in sheet or plate form, including metals, paper, plastics, rubber, and ceramics.
|Plane-stress fracture toughness (Kc)||平面應力斷裂韌性（Kc）||
In linear-elastic fracture mechanics, the value of the crack-extension resistance at the instability condition determined from the tangency between the R-curve and the critical crack-extension force curve of the specimen.
|Compression pressure (Unit Pa)||壓縮壓力（單位Pa）||
The pressure produced in a cylinder of a piston engine by compression of air in the absence of fuel.
|Minimum stress (Smin)||最小應力（Smin）||
In fatigue, the stress having the lowest algebraic value in the cycle, tensile stress being considered positive and compressive stress negative.
|Coefficient of restitution (e)||回彈系數（e）||
The ratio of the relative velocity of two colliding bodies after collision to that before. In perfectly elastic collisions e = 1; when all the impact energy is dissipated, e = 0.
|Net weight (Unit N)||凈重（單位：N）||
The difference between the gross weight of any container including its contents and the tare weight of the empty container.
Ability of a plastic part to retain the precise shape in which it was molded, fabricated, or cast.
The part of the total carbon in steel or cast iron that is present in elemental form as graphite or temper carbon. Contrast with combined carbon.
A nut having two opposite protruding wings to permit hand tightening.
A row of notches or tooth-like projections on an edge or surface. On an engineering drawing, serrations on the surface of a circular component are shown over about 60° of arc.
A generic term denoting a treatment, consisting of heating to and holding at a suitable temperature followed by cooling at a suitable rate, used primarily to soften metallic materials, but also to simultaneously produce desired changes in other properties or in microstructure.
An instrument for measuring changes in length over a given gage length caused by application or removal of a force. Commonly used in tension testing of metal specimens. Any instrument which measures the change in length of a part as the part is loaded.
A reaction that proceeds without benefit of thermal fluctuations; that is, thermal activation is not required. In contrast, a reaction that occurs at constant temperature is an isothermal transformation; thermal activation is necessary in this case and the reaction proceeds as a function of time.
|Pin expansion test||插頭膨脹試驗||
A test for determining the ability of a tube to be expanded or for revealing the presence of cracks or other longitudinal weaknesses in it, made by forcing a tapered pin into the open end of the tube, similar to flare test.
A hollow rivet that enables a connexion to be made from one side only of an assembly.
An SI unit prefix indicating a multiplier of 0.01; thus centimetre is a unit of length equal to one one-hundredth of a metre or 10 mm.
|Autonomous energy system||自主能源系統||
(stand-alone energy system) A sole source of electricity, usually small-scale, for applications remote from a grid, especially with energy storage in the system. Hydroelectric, photovoltaic, wind-power and other renewable systems are well suited to stand-alone applications.
Any type of compressor, including piston and rotary-screw types, that delivers a fixed volume of gas at high pressure per unit time. A positive-displacement pump delivers a fixed volume of fluid, usually a liquid, per unit time.
|Pressure (p) (Unit Pa)||壓力（p）（單位Pa）||
In thermodynamics and fluid mechanics, the compressive force exerted by the fluid per unit area. The pressure exerted by a fluid on a surface acts normal to the surface.
A threaded bolt having a square or rectangular end which fits into the T slot of a machine table for clamping workpieces.
|Tooth lock washers||帶齒鎖緊墊圈||
These washers serve to lock fasteners, such as bolts and nuts, to the component parts of an assembly, or increase the friction between the fasteners and the assembly. They are designated in a manner similar to helical spring lock washers, and are available in carbon steel.
|Acceleration due to gravity||重力加速度||
(acceleration of free fall, gravitational acceleration, g) (Unit m/s2) The acceleration of a freely-falling body in a vacuum, with a mean value at sea level of approximately 9.81 m/s2.
The digitization and processing of optical images/patterns by computer in order to recognize parts, orientation, etc. in manufacturing.
A measure of the mass leak rate from a gasketed joint.
A type of motor-vehicle suspension in which one end of a torsion bar is rigidly fixed to the chassis while the other carries a lever to which are attached the components that carry a wheel. In a torsion-beam suspension, a beam connects the wheels on either side of the vehicle.
The motion of a particle or body which oscillates about a position of equilibrium.
The stress at failure. Also known as breaking stress.
Fatigue damage initiated in a surface damaged by rubbing against another body.
Fracture of a metal during quenching from elevated temperature. Most frequently observed in hardened carbon steel, alloy steel, or tool steel parts of high hardness and low toughness. Cracks often emanate from fillets, holes, corners, or other stress raisers and result from high stresses due to the volume changes accompanying transformation to martensite.
|Mohr–Coulomb fracture criterion||Mohr–Coulomb斷裂準則||
A fracture criterion, primarily for brittle materials, according to which failure occurs when the stress at a point in a material falls outside the envelope created by the Mohr’s circles for uniaxial tensile strength and uniaxial compressive strength.
|Total combustion air (Unit kg/s)||總燃燒空氣（單位：kg/s）||
1. The combination of the stoichiometric flow of air required for combustion together with any excess air. 2. The flow of fresh air into a boiler plus any flue gas recirculated.
A furnace used for heat treating materials that progress continuously through the furnace, entering one door and being discharged from another. See belt furnac, direct-fired tunnel-type furnac, rotary retort furnace, shaker-hearth furnace.
|Bias pressure (Unit Pa)||偏壓（單位Pa）||
In a fluidic device controlled by pressure difference, the magnitude of that difference.
The coating on a fastener is said to provide galvanic protection if it is more anodic than the fastener and will, therefore, be destroyed instead of the fastener. Zinc plate (galvanizing) provides galvanic protection to steel fasteners, for example.
|Degradation of energy||能源退化||
Conversion of energy into forms of lower usefulness due to irreversibilities in energy transfer and conversion processes. The increase in entropy can be regarded as a measure of the degradation of energy.
1. Energy derived from materials such as purpose-grown energy crops, including sugar cane, maize, wheat, and rice, as well as wood, straw, and animal waste, including sewage, manure, and animal litter. 2. A term sometimes used to cover biomass and biofuels together.
A failure that occurs in a riveted or bolted joint when the transverse load divided by the bearing area results in a stress that leads to permanent plastic deformation.
The flaring out of the rim of a drilled hole to form a truncated conical depression to receive a screw having a conical head, thus giving a flush fitting.
Decarburization with sufficient carbon loss to show only clearly defined ferrite grains under metallographic examination.
That temperature range between liquidus and solidus temperatures in which molten and solid constituents coexist.
(temporal frequency, f) (Unit Hz) The number of cycles per second in an oscillation or the repetition rate for a cyclic process.
A cylindrical head on a screw or bolt. For driving, it may be slotted, or hexagonally recessed.
A measure of plane angle such that 1° is 1/360 of a complete revolution and equal to π/180 rad.
A valve that limits the maximum pressure in a pressure vessel or fluid-power system to a specified level.
|Fastener with waisted shank||帶腰柄的緊固件||
Finished fastener with a shank diameter of ds < d2. |
A nut having six sides and shaped like a hexagon.
Hardening caused by the precipitation of a constituent from a supersaturated solid solution.
The difference between the actual value and the desired value of a controlled variable.
A distinct pattern of intersecting sets of parallel lines, usually producing a set of V-shaped lines, sometimes observed when viewing brittle fracture surfaces at high magnification in an electron microscope. Wallner lines are attributed to interaction between a shock wave and a brittle crack front propagating at high velocity. Sometimes Wallner lines are misinterpreted as fatigue striations.
A joint which is primarily subjected to loads acting more or less parallel to the axes of the bolts.
A thin fissure-like defect in a component or structure across which material continuity is lost and which reduces the strength of the body.
The slow decrease in stress level within a part (e.g., a bolt) which is heavily loaded under constant deflection conditions. A ‘‘cousin’’ to creep, which is a slow change in geometry under constant stress conditions. The time-dependent decrease in stress in a solid under constant strain at constant temperature due to creep. The stress-relaxation behavior of a metal is usually shown in a stress-relaxation curve.
|Shear modulus (G)||剪切模量（G）||
The ratio of shear stress to the corresponding shear strain for shear stresses below the proportional limit of the material. Values of shear modulus are usually determined by torsion testing. Also known as modulus of rigidity.
An imprecise term used to cover a variety of quenching procedures in which a quenching medium is maintained at a prescribed temperature above 70 °C (160 °F)
A device containing a non-return valve screwed into a lubrication point through which grease may be introduced, for example into a bearing.
|Pitch-circle diameter (Unit m)||節圓直徑（單位：m）||
The diameter of the circle (the pitch circle) centred on a component’s axis, around which holes or bolts are equally spaced.
The science and engineering of sound; its production, propagation, control, interaction with materials, etc.
(defect tolerance) A design philosophy that takes into account initial imperfections, crack-growth rates and conditions at final fracture, and uses fracture mechanics to demonstrate that cracks should not grow to their critical length within the design life (or at least should be capable of ready detection).
|Absolute value error||絕對值誤差||
The magnitude of the error dlsregarding the algebraic sign, or, for a vectorial error, disregarding its function.
The particular value of a characteristic determined as a result of a test or measurement.
A geared wrench which multiplies input torque and provides a read-out of output torque. In effect, a combination of a Torque wrench and a Torque multiplier.
Errors from–irregular surface departures from the design profile, often caused by lack of accuracy or stiffness of the machine system.
1. A type of combustion chamber in which solid, liquid, or gaseous fuels are burned to supply hot gases to a boiler or other process plant. Examples include the firebox, boiler furnace (steam-generating furnace), hot-air furnace, oil-fired furnace, updraught furnace, and water-cooled furnace. 2. A chamber, sometimes having a controlled atmosphere or under vacuum (vacuum furnace), for heating and melting materials. Examples include the blast furnace, direct- and indirect-arc furnaces, the induction furnace (high-frequency furnace), muffle furnace, reverberatory furnace, and solar furnace.
An instrument used to quantify the roughness of a surface. For a contact profilometer, a diamond stylus sweeps across the surface along a series of parallel lines. Noncontact profilometers use optical techniques to map the surface irregularities.
A general term for the embrittlement, cracking, blistering, and hydride formation that can occur when hydrogen is present in some metals.
The distance along the strain coordinate between the initial portion of a stress-strain curve and a line parallel to the initial portion that intersects the stress-strain curve at a value of stress (commonly 0.2%) that is used as a measure of the yield strength. Used for materials that have no obvious yield point.
Wear in which chemical or electrochemical reaction with the environment is significant.
A condition of brittleness that causes transcrystalline fracture in the coarse grain structure that results from prolonged annealing of thin sheets of low-carbon steel previously rolled at a temperature below about 705 °C (1300 °F). The fracture usually occurs at about 45° to the direction of rolling.
|Standard deviation (σ)||標準偏差（σ）||
A statistical term used to quantify the Scatter in a set of data points. If the standard deviation is small, most of the data points are ‘‘nearly equal.’’ A large deviation means less agreement. The most usual measure of the dispersion of observed values or results expressed as the positive square root of the variance. The square root of variance, a measure of the spread of data about the mean value.
A calibration constant used in ultrasonic measurement of bolt stress or strain. Accounts for the effects of thermal expansion and the temperature-induced change in the velocity of sound.
The smallest segment of the stress-time function that is repeated periodically.
Strain gages arranged to indicate, at a single position, strain in three different directions.
A device used to measure the motion of a vibrating surface, typically using a contactless laser-based technique.
For testing machines, the ratio, expressed as a percentage, of the error to the correct value of the applied load.
|Coefficient of thermal expansion||熱膨脹系數||
(1) Change in unit of length (or volume) accompanying a unit change of temperature, at a specified temperature. (2) The linear or volume expansion of a given material per degree rise of temperature, expressed at an arbitrary base temperature or as a more complicated equation applicable to a wide range.
（1） 單位長度（或體積）隨溫度單位變化的變化。（2） 給定材料每上升一度的線性或體積膨脹，在任意基礎溫度下表示，或作為適用于寬范圍的更復雜方程表示。
|Finished hexagon bolts||精制六角螺栓||
A washer faced or chamfered bearing surface with a close body tolerance.
The maximum load on a notched tensile-test specimen divided by the minimum cross-sectional area (the area at the root of the notch). Also known as notch tensile strength.
A small hole in the wall of a pipe or pressure vessel to which is attached a tube, the other end of which is connected to one side of a pressure transducer.
For two gears in contact, the ratio of the number of teeth on the driving gear to that on the driven gear.
|Proof strength? (Unit Pa)||驗證強度（單位Pa）||
(proof stress, Rp, Rp,) The yield strength (offset yield strength) at some fixed value of the permanent strain given by the intersection of a line offset from, but parallel to, the elastic loading line and the engineering stress-engineering strain curve. The offset is arbitrary but is usually 0.1, 0.2, or 0.5% permanent strain (the proof strain). Used for materials which do not exhibit a sharply defined yield point. The notation Rp0.2?or Rp0.2?is employed for the 0.2% proof stress.
Sometimes used to describe the general rotation of the nut (or bolt head) as the fastener is tightened. More often used to define a particular tightening procedure in which a fastener is first tightened with a preselected torque, and is then tightened further by giving the nut an additional, measured, turn such as ‘‘three flats’’ (180°).
The SI base unit of time equal to 9 192 631 770 times the period of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.
The distance that a chosen measurement point on a cracked specimen displaces normal to the crack plane as the crack grows.
(1) A reaction in which there is an increase in valence resulting from a loss of electrons. (2) A corrosion reaction in which the corroded metal forms an oxide; usually applied to reaction with a gas containing elemental oxygen, such as air.
Fracture in crystalline materials where the path of cracking is predominantly across grains.
The rate of doing work or of producing or consuming energy. The unit of power is the watt, W, where 1 W = 1 N m/s.
A nut attached loosely or rigidly to a sheet member that is too thin to thread and which engages with a cap screw.
This may occur during fastener manufacturing at the cutting or forging operations and are located on the top of the head or on the raised periphery of indented head bolts.
A positive-displacement rotary compressor in which gas is progressively compressed by two intermeshing, counter-rotating, helical screws.
|Concentrated solar power plant (CSP plant)||聚光太陽能發電廠（CSP發電廠）||
A power plant in which solar radiation is concentrated using mirrors or lenses, typically using parabolic trough mirrors which focus solar radiation on to receiver tubes along the trough’s focal line. In an alternative arrangement molten salt, heated by solar receivers mounted on a tower, is circulated through a steam generator.
In tribology, a severe form of wear characterized by the formation of extensive grooves and scratches in the direction of sliding.
Checking or testing an instrument to ensure conformance with a specification.
There are three broad classes of materials that have a sponge-like structure containing many small closed or open (interlinked) pores or cells. Natural cellular materials include bone, cork, sponge, and wood, and have numerous well-known uses. Wide ranges of cellular plastics are produced using blowing or foaming agents, such as air, ammonium carbonate, sodium bicarbonate, etc., to create pores during the processing of thermoplastic or thermosetting polymers. Rigid foams have moderate compressive strength and can be moulded and machined.
An industrial oven for burning, baking, or drying.
|Radiation pressure (Unit μPa)||輻射壓力（單位：μPa）||
The pressure exerted on a surface exposed to any form of electromagnetic radiation. If the radiation is absorbed, it is equal to the power-flux density divided by the speed of light.
|Collapse load (Unit N)||毀壞荷載（單位N）||
The applied load at which a structure becomes a mechanism owing to the formation of sufficient plastic hinges for collapse to occur.
The tendency of a material to cleave or split along definite crystallographic planes.
That portion of the threads which are not cut or rolled full depth, but which provide the transition between full-depth threads and the body or head. Officially called thread washout or vanish, although the term run-out is more popular. (Run-out is officially reserved for rotational eccentricity, as defined by total indicator readings or the like.)
|Size dimension (Unit m)||尺寸范圍（單位：米）||
The specified value of a diameter, length, width, etc. of a feature required to specify the finished form of a component or assembly.
A natural ‘‘battery’’ formed when two metals having different electrical potentials (an Anode and a Cathode) are connected together in the presence of a liquid (the Electrolyte).
Linear strain in a plane perpendicular to the loading axis of a specimen.
A dowel, key, or pin that prevents a pulley from turning on its shaft.
A method of surface hardening in which molten nitrogen-bearing, fused-salt baths containing both cyanides and cyanates are exposed to parts at subcritical temperatures.
Cooling below the temperature at which an equilibrium phase transformation can take place, without actually obtaining the transformation.
A mechanism for handling bulk materials in which a rotating helicoidal screw moves the material axially forward. Similar to a screw conveyor, but required to discharge material at a controlled rate very accurately. It operates with the screw completely full.
The greatest stress a material is capable of developing without a deviation from straight-line proportionality between stress and strain.
A measure of the internal shear properties of fluids, expressed as the tangential force per unit area at either of two horizontal planes separated by one unit thickness of a given fluid, one of the planes being fixed and the other moving with unit velocity.
(1) In heat treatment, reheating hardened steel or hardened cast iron to some temperature below the eutectoid temperature for the purpose of decreasing hardness and increasing toughness. The process also is sometimes applied to normalized steel. (2) In tool steels, temper is sometimes used, but inadvisedly, to denote the carbon content. (3) In nonferrous alloys and in some ferrous alloys (steels that cannot be hardened by heat treatment), the hardness and strength produced by mechanical or thermal treatment, or both, and characterized by a certain structure, mechanical properties, or reduction in area during cold working.
(1) The temperature or pressure at which a change in crystal structure, phase or physical properties occurs. Same as transformation temperature. (2) In an equilibrium diagram, that specific value of composition, temperature and pressure, or combinations thereof, at which the phases of a heterogeneous system are in equilibrium.
（1） 晶體結構、相或物理性質發生變化的溫度或壓力。與轉變溫度相同。（2） 在平衡圖中，指組成、溫度和壓力或其組合的特定值，在該值下，多相體系的相處于平衡狀態。
An instrument that records vibrations in a system over time.
A process occurring in hot working of metals in which a fine subgrain structure forms within the elongated grains due to annihilation of dislocations due to easy cross slip and climb. It results in a lowering of the flow stress. Dynamic recovery, as opposed to dynamic recrystallization that occurs in hot working, occurs in metals of high stacking fault energy such as aluminum, αiron, and most bcc metals.
A factor of proportionality representing the amount of substance diffusing across a unit area through a unit concentration gradient in unit time.
The temperature at which a substance changes phase (or state) from liquid to solid. The freezing point for most substances increases as pressure increases. The reverse process, from solid to liquid, is melting; melting point is the same as freezing point.
Cracking or fracturing that occurs between the grains or crystals in a polycrystalline aggregate. Also called intercrystalline cracking.
1. In an engineering drawing, a line of symmetry. 2. An imaginary line along a pipe, duct, or shaft that defines an axis of symmetry. 3. An imaginary straight line parallel to the intended direction of a surface located such that the areas above and below the line and the real wavy (rough) surface cancel out.
The ratio of the transmitted force to the disturbing force for a system subjected to a vibratory disturbance. The ratio may also be defined in terms of displacements, velocities, or accelerations.
A furnace used for liquid carburizing of parts by heating molten salt baths with the use of electrodes submerged in the ceramic lining.
(double-slider coupling) A device for connecting a pair of misaligned parallel shafts, on the end of each of which are flanges having diametral tenons (tongues) that engage with matching slots spaced at 90° in an intermediate disc. As the coupling rotates, the disc compensates for shaft offset by sliding along each tenon in turn. Low-friction surfaces are requisite and the disc is often made of a polymer. An alternative arrangement has the slots in the flanges and the tenons on the disc.
|Absolute temperature (Unit K)||絕對溫度（單位K）||
A temperature T measured relative to absolute zero, 0 K or ?273.15°C, the lowest temperature achievable at which molecular motion vanishes so that a body would have zero heat energy. The kelvin is equal in magnitude to the degree Celsius (°C). The kelvin temperature scale (kelvin absolute temperature scale) is an absolute or thermodynamic temperature scale derived from the Celsius scale: T(K) = T(°C) + 273.15. The Rankine absolute scale is derived from the Fahrenheit scale such that T(R) = T(°F) + 459.67, i.e. a scale relative to 0 R or ?459.67°F where R is the Rankine degree symbol and °F is the Fahrenheit symbol.
A substance such as ethylene glycol added to the cooling system of a watercooled engine to lower the freezing point of the cooling water and also inhibit the formation of rust and other deposits.
A summary value calculated from the observed values in a sample.
Mechanical property value above which at least 99% of the population of values is expected to fall, with a confidence of 95%. Also called A-allowable.
A coil of electrically-conducting wire wrapped around a metal core, typically iron, to produce a magnetic field and hence a force on the core when an electric current passes through the coil. Solenoids are widely used to produce linear movement to actuate valves (solenoid valves) and other devices.
The ratio of the offset yield stress to the extension at the offset point (plastics).
An instrument used to measure surface tension.
A gearbox in which the pairs of gears giving different speed ratios are constantly in mesh, different ratios being obtained by? connecting or disconnecting the relevant gear to the driving shaft.
1. A starting workpiece for forging and similar operations, such as a length of wire or rod to make a bolt blank on which a thread can be rolled or cut. 2. (geepound) An obsolete imperial (non-SI) unit of mass, being the mass which under an acceleration of one foot per second squared gives a force of one pound-force. The conversion to SI is 1 slug = 14.593 902 94 kg. 3. A large-scale flow structure which occurs in the transition from laminar to turbulent flow in a pipe.
A method for determining the range of alternating (fluctuating)stresses a material can withstand without failing.