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詞或詞組	中文	英文解釋中文解釋
Machine	機器	A mechanism that transmits power in the performance of a useful task. More than one machine in one place, either connected or performing separate functions, is termed machinery. 在執行有用任務時傳遞能量的機制。一個地方有一臺以上的連接或執行單獨的功能，稱為機器。
Machine screw	機械螺絲	A countersunk, slotted screw with machined threads such as are found on bolts. A relatively small screw, usually less than 20 mm in diameter, with the thread running along the whole length up to the head, intended to be screwed into threaded holes. If inserted through plain holes in assembled parts and held together by a nut, an undesirable contact surface of threads bearing against the surface of a hole results. 帶有機加工螺紋的沉頭開槽螺釘，如螺栓上的螺紋。一種相對較小的螺釘，直徑通常小于20毫米，螺紋沿整個長度一直延伸到頭部，用于擰入螺紋孔中。如果通過裝配零件上的平孔插入并用螺母固定在一起，則會導致螺紋與孔表面接觸不良。
Machine tool	機床工具	A powered machine, such as a borer, grinder, lathe, milling machine or planer, used for cutting and shaping metal, plastics, composites, etc. (machining). A machining centre is a CNC machine tool working about several axes, having a stock of tools and automatic tool changing ability, which is capable of diverse machining operations under automated control. 一種動力機器，如鉆孔機、磨床、車床、銑床或刨床，用于切割和成形金屬、塑料、復合材料等（機加工）。加工中心是圍繞多個軸工作的CNC機床，具有刀具庫存和自動換刀能力，能夠在自動化控制下進行各種加工操作。
Macrodeviation	宏觀偏差	Errors from–irregular surface departures from the design profile, often caused by lack of accuracy or stiffness of the machine system. 不規則表面偏離設計輪廓的誤差，通常是由于機器系統缺乏準確性或剛度造成的。
Magnetic materials	磁性材料	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. 相鄰原子的磁矩可以采用平行或反平行排列的材料。當磁矩采用平行排列時，會產生鐵磁性。當相鄰磁矩因反平行排列而抵消時，材料表現出反鐵磁性，沒有總磁矩。后者的實例包括氧化亞鐵和氧化錳。當相鄰磁矩采用反平行排列但大小不等時，就會出現鐵磁現象。磁矩對齊的鐵磁或鐵磁材料區域稱為磁疇，相鄰區域由磁疇壁分隔?？勾藕晚槾挪牧媳憩F出弱磁性形式，這是由外加磁場誘導的磁原子偶極子的獨立（非耦合）排列引起的。鐵磁性和鐵磁性材料可以在相對弱的磁場中獲得高磁化度。它們具有不同的磁滯特性，分為硬磁鐵和軟磁鐵。硬磁鐵在沒有外加磁場的情況下保持較大的磁化強度，用作永磁體。常規材料包括與鎢或鈷合金化的磁鋼。由稀土元素合金制成的稀土磁體產生明顯更強的磁場。其中最常見的是釤鈷和釹硼永磁體。它們的強度使其體積小，可用于多種應用，包括無繩工具、磁盤驅動器、耳機、玩具和汽車部件（如雨刷、風扇、洗衣機和車窗）的電機。軟磁體可以相對容易地磁化和退磁。當受到交變磁場時，由于磁滯引起的能量損失很小。常見材料包括鐵硅合金（稱為電工鋼）、鎳鐵合金（坡莫合金）、軟鐵氧體和非晶納米晶合金，最后一種可以通過熔釘以膠帶的形式生產。軟磁鐵用于增強電流產生的磁通量。
Magnetic test	磁性測試	Method used to test heat extraction rates of various quenchants. The test works by utilizing the change in magnetic properties of metals at their Curie point–the temperature above which metals lose their magnetism. 用于測試各種淬火劑的熱提取率的方法。該測試通過利用金屬在居里點（即金屬失去磁性的溫度）的磁性變化來進行。
Major diameter	螺紋大徑	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. 在直螺紋上，僅接觸外螺紋頂部或內螺紋根部的假想圓柱體的直徑。
Malleable cast iron	可鍛鑄鐵	A cast iron made by prolonged annealing of white cast iron in which decarburization or graphitization, or both, take place to eliminate some or all of the cementite. The graphite is in the form of temper carbon. If decarburization is the predominant reaction, the product will exhibit a light fracture surface, hence, “whiteheart malleable;” otherwise, the fracture surface will be dark, hence, “blackheart malleable.” Ferritic malleable has a predominantly ferritic matrix; pearlitic malleable may contain pearlitic, spheroidite or tempered martensite depending on heat treatment and desired hardness. 白口鑄鐵一種通過長時間退火制成的鑄鐵，脫碳，石墨化，或兩者都發生，以消除部分或全部滲碳體。石墨是回火碳的形式。如果脫碳是主要反應，產品將呈現出較輕的斷裂表面，“白心可鍛”。否則，斷裂表面將變暗，“黑心可鍛”。鐵素體可鍛性材料主要為鐵素體基體；根據熱處理和所需硬度，珠光體可鍛材料可能包含珠光體、球狀體或回火馬氏體。
Manometer	壓力計	An instrument used in the measurement of a pressure difference in a fluid (manometry). 用于測量流體壓力差（測壓）的儀器。
Maraging steels	馬氏體時效鋼	Very high-strength iron alloys named after ‘martensitic’ and ‘aging’. They contain nickel, chromium, cobalt, and molybdenum, and form martensite on air cooling with a strength of about 1 GPa. When reheated to about 500°C and aged for some hours, a room-temperature strength of some 2.4 GPa is reached. 以“馬氏體”和“時效”命名的超高強度鐵合金。它們含有鎳、鉻、鈷和鉬，在空氣冷卻下形成強度約為1GPa的馬氏體。當再加熱至約500°C并老化數小時時，室溫強度達到約2.4GPa。
Martempering	淬火	(1) A hardening procedure in which an austenitized ferrous workpiece is quenched into an appropriate medium whose temperature is maintained substantially at the Ms?of the workpiece, held in the medium until its temperature is uniform throughout–but not long enough to permit bainite to form–and then cooled in air. The treatment is frequently followed by tempering. (2) When the process is applied to carburized material, the controlling Ms?temperature is that of the case. This variation of the process is frequently called marquenching. （1）一種淬火工藝，將奧氏體化鐵質工件淬火到適當的介質中，該介質的溫度基本保持在工件的Ms，保持在該介質中直到其溫度在整個過程中均勻，但不足以形成貝氏體，然后在空氣中冷卻。處理后經常進行回火。（2） 當該工藝應用于滲碳材料時，控制Ms溫度與實際情況相同。這個過程的變化經常被稱為淬火。
Martensitic stainless steels	馬氏體不銹鋼	Martensitic stainless steels are hardenable magnetic stainless steels that contain 9–18% chromium, 0.06–1.25% carbon, and typically up to about 2.5% in total of manganese, silicon, nickel, and molybdenum. They can be heat-treated such that martensite is the prime microconstituent, and are usually available in the annealed or quenched-and-tempered condition. They have excellent strength and high hardness, and good corrosion resistance. Uses include cutlery, surgical instruments, rifle barrels, steam turbine tubing and blading, jet engine components, hand tools, machine parts, fasteners, valves, springs, bearings, pump shafts, nozzles, mining equipment, and wear-resistant parts. 馬氏體不銹鋼是一種可硬化的磁性不銹鋼，其鉻含量為9-18%，碳含量為0.06-1.25%，錳、硅、鎳和鉬的總含量通常高達約2.5%。它們可以進行熱處理，使馬氏體成為主要的微組分，通常可在退火或淬火回火條件下獲得。它們具有優異的強度和高硬度，以及良好的耐腐蝕性。用途包括餐具、外科器械、步槍槍管、蒸汽輪機管道和葉片、噴氣發動機部件、手動工具、機械零件、緊固件、閥門、彈簧、軸承、泵軸、噴嘴、采礦設備和耐磨零件。
Mass flow meter	質量流量計	An instrument, such as a Coriolis flow meter, which measures the mass flow rate of a fluid flowing through a pipe or other duct, rather than its volume flow rate. 一種儀器，例如科里奧利流量計，一種測量流經管道或其他管道的流體的質量流率而不是其體積流率的儀器。
Mass flow rate (?) (Unit kg/s)	質量流量（?）（單位kg/s）	The mass of a material, usually a fluid or powder, that flows across a surface or through a pipe or other duct per unit time. The corresponding mass flux (?″), with unit kg/s.m2, is the mass flow across a real surface or through a duct, divided by the surface or cross-sectional area A, i.e. ?″ = ?/A or ?″ = ρV where ρ is the material density and V is its velocity normal to the surface. 單位時間內流過表面或通過管道或其他管道的材料質量，通常是流體或粉末。相應的質量通量（?″），單位為kg/s.m2，是通過真實表面或通過管道的質量流量除以表面或橫截面積A，即?″=?/A或?″=ρV，其中ρ是材料密度，V是其垂直于表面的速度。
Material velocity	材料速度	The velocity of sound in a body (e.g., a bolt). A term used in the ultrasonic measurement of bolt stress or strain. 聲音在物體（例如螺栓）中的速度。用于螺栓應力或應變的超聲波測量的術語。
Materials science	材料科學	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. 研究金屬、陶瓷、玻璃、聚合物、復合材料、生物材料和半導體等固體物質的特性、行為和應用，涵蓋從原子到宏觀的所有范圍。起源于冶金學。
Materials selection	材料選擇	The process of selecting the most suitable material for a particular application. In the case of solid materials, it involves assessment of candidate materials in terms of their physical properties (density, elastic moduli, fracture toughness, yield strength, hardness, fatigue resistance, coefficient of thermal expansion, thermal conductivity, resistance to thermal shock, creep resistance, corrosion resistance, radiation resistance, etc), and such factors as the function of the final product, its shape, method of manufacture, required tolerances, number to be made, ease of inspection and quality control, cost, and design methodology employed. 為特定應用選擇最合適材料的過程。對于固體材料，它涉及根據其物理特性（密度、彈性模量、斷裂韌性、屈服強度、硬度、抗疲勞性、熱膨脹系數、導熱系數、抗熱沖擊性、抗蠕變性、耐腐蝕性、抗輻射性等）評估候選材料，以及諸如最終產品的功能、其形狀、制造方法、所需公差、制造數量、檢查和質量控制的容易程度、成本和采用的設計方法等因素。
Maximum allowable operating pressure (Unit Pa)	最大允許使用壓力（單位Pa）	The highest pressure at which any pressure system may be operated, usually 10 to 20% below the maximum allowable working pressure. 任何壓力系統可運行的最高壓力，通常比最大允許工作壓力低10%至20%。
Maximum allowable working pressure (Unit Pa)	最大允許工作壓力（單位Pa）	The pressure on which the design of a pressure system is based and the highest pressure at which relief valves should be set. The lowest-rated component in the system typically has a design safety factor of 4. 壓力系統設計所依據的壓力和應設置安全閥的最高壓力。系統中最低額定部件的設計安全系數通常為4。
Maximum continuous load	最大連續負載	(maximum continuous rating) (Unit kg/s) The maximum rate of steam output that a boiler can supply for a specified period, usually 24 hours. （最大連續額定功率）（單位為kg/s）鍋爐在規定時間內（通常為24小時）可供應的最大蒸汽輸出率。
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. （1）負載循環中具有最高代數值的負載。拉伸荷載視為正荷載，壓縮荷載視為負荷載。（2）用于確定結構構件的強度；失效前可承受的載荷是明顯的。
Maximum material condition	最大材料條件	(maximum metal condition) The situation where the volume of a manufactured component corresponds to the upper limit for all toleranced external dimensions, and to the lower limit for all internal dimensions. （最大金屬條件）制造部件的體積對應于所有公差外部尺寸的上限和所有內部尺寸的下限的情況。
Maximum stress (Smax)	最大應力（Smax）	The stress having the highest algebraic value in the stress cycle, tensile stress being considered positive and compressive stress negative. The nominal stress is used most commonly. 在應力循環中具有最高代數值的應力，拉應力被認為是正的，壓應力被認為是負的。名義應力是最常用的。
Maximum stress-intensity factor (Kmax)	最大應力強度因子（Kmax）	The maximum value of the stress-intensity factorin a fatigue cycle. 疲勞循環中應力強度因子的最大值。
Maximum-and-minimum thermometer	最高和最低溫度計	(minimum-maximum thermometer, Six’s thermometer) A liquid-in-glass instrument designed to register the maximum and minimum temperatures experienced over a given time period. （最低-最高溫度計，Six's溫度計）一種液體玻璃儀器，用于記錄給定時間段內經歷的最高和最低溫度。
Mean diameter (Unit m)	平均直徑（單位米）	The average of the inside and outside diameters for a helical spring or hollow circular cylinder or sphere 螺旋彈簧或空心圓柱體或球體的內徑和外徑的平均值
Mean stress (Unit Pa)	平均應力（單位 Pa）	The average of the maximum and minimum stresses for a material subjected to a stress cycle, as in a fatigue test. 承受應力循環的材料的最大和最小應力的平均值，如在疲勞試驗中。
Mean value	平均值	The average value of a number of data points. Computed by dividing the sum of all data by the number of data points. 多個數據點的平均值。通過將所有數據的總和除以數據點的數量來計算。
Mechanical alloying	機械合金化	Production of alloys from powders by consolidation, e.g. hotpressing or extrusion, followed by hot and/or cold working and final annealing. Materials such as dispersion-strengthened alloys, high-temperature aluminium alloys, and amorphous alloys can be made in this way. 通過固結（例如熱壓或擠壓）從粉末生產合金，然后進行熱和/或冷加工和最終退火。用這種方法可以制造彌散強化合金、高溫鋁合金和非晶合金等材料。
Mechanical efficiency (η)	機械效率（η）	1. In general for a machine, the ratio of output work to input work. 2. For a compressor, the ratio of indicated power to shaft power; for a reciprocating engine or an expander, the ratio of shaft power to indicated power. 1.一般而言，機器的輸出功與輸入功之比。2.對于壓縮機，指示功率與軸功率之比；對于往復式發動機或膨脹機，軸功率與指示功率之比。
Mechanical energy (Unit J)	機械能（單位J）	The sum of kinetic energy and potential energy for an object or a mechanical system, including the energy stored in springs, etc. 物體或機械系統的動能和勢能之和，包括儲存在彈簧等中的能量。
mechanical engineering	機械工業	That branch of engineering concerned with energy conversion, stress analysis, vibration, dynamics, and kinematics, especially applied to design (machine design, mechanical-engineering design). 與能量轉換、應力分析、振動、動力學和運動學有關的工程分支，尤其適用于設計（機器設計、機械工程設計）。
Mechanical metallurgy	機械冶金	The science and technology dealing with the behavior of metals when subjected to applied forces. 處理金屬在外力作用下的行為的科學技術。
Mechanical properties of solid materials	固體材料的力學性能	The strength and stiffness properties of solid materials such as fracture toughness, the moduli of elasticity, percent elongation, 固體材料的強度和剛度特性，例如斷裂韌性、彈性模量、伸長率、
Mechanical units	機械單位	The units of physical quantities, the dimensions of which includemass, length, and time. 物理量的單位，其量綱包括質量、長度和時間。
Mechanical vibration	機械振動	The motion of a particle or body which oscillates about a position of equilibrium. 圍繞平衡位置擺動的粒子或物體的運動。
Mechatronics	機電一體化	The integration of mechanical engineering, electrical engineering, electronic engineering, and software engineering. 機械工程、電氣工程、電子工程和軟件工程的集成。
Median fatigue life	中位疲勞壽命	The middle value when all of the observed fatigue life values of the individual specimens in a group tested under identical conditions are arranged in order of magnitude. When an even number of specimens are tested, the average of the two middlemost values is used. Use of the sample median rather than the arithmetic mean (that is, the average) is usually preferred. 當在相同條件下測試的一組中單個試樣的所有觀察疲勞壽命值按數量級排列時的中間值。當測試偶數個試樣時，使用兩個中間值的平均值。通常優選使用樣本中值而不是算術平均值（即平均值）。
Median fatigue strength at N cycles	N次循環的中位疲勞強度	An estimate of the stress level at which 50% of the population would survive N cycles. The estimate is derived from a particular point of the fatigue life distribution, because there is no test procedure by which a frequency distribution of fatigue strengths at Ncycles can be directly observed. 估計50%的量在N個周期內生存的壓力水平。該估計值來自疲勞壽命分布的一個特定點，因為沒有試驗程序可以直接觀察N次循環疲勞強度的頻率分布。
Melting point (Unit K or °C)	熔點（單位K或°C）	The temperature at which a solid material undergoes the phase change to a liquid at a specified pressure, usually 1 atm. Pure metals and eutectics have single-valued melting points, while alloys with other compositions melt over a range of temperature such that there is a well-defined start and end to the melting process, but there are states in between where solid and liquid are both present. 在特定壓力下，固體材料發生相變為液體的溫度，通常為1大氣壓。純金屬和共晶具有單值熔點，而具有其他成分的合金在一定溫度范圍內熔化，熔化過程有一個明確的起點和終點，但其間存在固態和液態并存的狀態。
Metallurgy	冶金	The study of the atomic, crystallographic, microstructural, mechanical, and physical properties of metallic elements and alloys and their applications. 研究金屬元素和合金的原子、晶體學、微觀結構、機械和物理特性及其應用。
Metre (m)	米（m）	The base unit of length in the SI system. It is equal to the distance travelled by light in vacuum in 1/299 792 458 seconds. SI系統中長度的基本單位。它等于光在真空中在1/299792458秒內傳播的距離。
Metric ton (tonne, t)	公制噸（噸，t）	An SI-accepted, but non-SI, unit of mass defined as 1 t = 103?kg. SI系統可接受但非國際單位制的質量單位，定義為1t=103kg。
Meyer hardness (Unit Pa)	邁耶硬度（單位Pa）	A material hardness similar to the Brinell hardness but based upon the projected area of the impression rather than the surface area. 與布氏硬度相似的材料硬度，但基于印模的投影面積而不是表面面積。
Microhardness	顯微硬度	The hardness of a material as determined by forcing an indenter such as a Vickers or Knoop indenter into the surface of a material under very light load; usually, the indentations are so small that they must be measured with a microscope. Capable of determining hardnesses of different microconstituents within a structure, or of measuring steep hardness gradients such as those encountered in case hardening. 通過在非常輕的載荷下將壓頭（如維氏或努氏壓頭）壓入材料表面來確定的材料硬度；通常壓痕很小，必須用顯微鏡測量。能夠確定結構內不同微組分的硬度，或測量陡峭的硬度梯度，如表面硬化中遇到的硬度梯度。
Microindentation hardness test	顯微壓痕硬度測試	Hardness test using a calibrated machine to force a diamond indenter of specific geometry, under a test load of 1 to 1000 gramforce, into the surface of the test material and to measure the diagonal or diagonals of the indentation optically. 使用校準機器進行硬度試驗，以在1至1000克力的試驗載荷下，將特定幾何形狀的金剛石壓頭壓入試驗材料表面，并光學測量壓痕的對角線。
Micrometer	千分尺	(micrometer gauge) A mechanical-contact device for the accurate measurement of the length, width, diameter, etc. of an object, the depth of a hole, the height of a step, etc. The usual arrangement is a spindle that is moved by rotation of a thimble, the distance then being read off a vernier scale. （千分尺）一種機械接觸裝置，用于精確測量物體的長度、寬度、直徑等、孔的深度、臺階的高度等。通常的布置是通過頂針的旋轉移動主軸，然后通過游標尺讀取距離。
Microscopic stresses	微觀應力	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. 與普通應變測量中的標距相比，從拉伸到壓縮的距離（大概接近晶粒尺寸）較小的殘余應力。它們無法通過解剖方法檢測到，但有時可以通過x射線衍射圖案中的線位移或線加寬來測量。
Microstrain	微應變	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. 與原子間距離相當的標距上的應變。這些是通過宏觀應變測量得到的平均應變。現有技術無法測量微應變。然而微應變分布的變化可以通過x射線衍射來測量。
Millimetre of mercury	毫米汞柱	A non-SI unit of pressure equal to the pressure exerted by a vertical column of mercury 1 mm high. Approximately equal to 133.3 Pa or 1 torr. 一種非SI壓力單位，等于1毫米高的垂直水銀柱施加的壓力。大約等于133.3Pa或1托。
Millimetre of water	毫米水柱	A non-SI unit of pressure equal to the pressure exerted by a vertical column of water 1 mm high. Approximately equal to 9.81 Pa. 一種非SI壓力單位，等于1毫米高的垂直水柱施加的壓力。大約等于9.81Pa。
Milling	銑削	A machining process, typically for metals and plastics, in which a multi-tooth rotary cutter removes material to produce flat or profiled surfaces, slots, grooves, etc. Milling is a machining process in which metal is removed by a rotating multiple-tooth cutter; each tooth removes a small amount of metal with each revolution of the spindle. Because both workpiece and cutter can be moved in more than one direction at the same time, surfaces having almost any orientation can be machined. 一種加工工藝，通常用于金屬和塑料，其中多齒旋轉刀具去除材料以產生平坦或異形表面、槽、槽等。金屬由旋轉多齒刀具去除；主軸每轉一圈，每個齒都會去除少量金屬。因為工件和刀具可以同時在多個方向上移動，所以幾乎可以加工任何方向的表面。
Minimum load (Pmin)	最小負載（Pmin）	In fatigue, the least algebraic value of applied load in a cycle. 在疲勞中，循環中施加載荷的最小代數值。
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. （最小金屬條件）制造部件的體積對應于所有公差外部尺寸的下限和所有內部尺寸的上限的情況。
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. 在疲勞中，循環中代數值最低的應力，拉應力被視為正應力，壓應力為負應力。
Minimum stress-intensity factor (Kmin)	最小應力強度因子（Kmin）	In fatigue, the minimum value of the stress-intensity factor in a cycle. This value corresponds to the minimum loadwhen the load ratio is 0 and is taken to be 0 when the load ratio is ≤0. 在疲勞中，一個循環中應力強度因子的最小值。該值對應于負載比為0時的最小負載，當負載比為≤0
Minor diameter	螺紋小徑	On a straight thread, the diameter of the imaginary cylinder which just touches the root of an external thread or the crest of an internal thread. 在直螺紋上，僅接觸外螺紋根部或內螺紋頂部的假想圓柱體的直徑。
Minute (min)	分鐘（min）	A non-SI unit of time. The conversion to SI is 1 min = 60 s. 非SI時間單位。轉換為1分鐘=60秒。
Mode of failure	故障模式	The various ways in which a material can fail when subjected to loading, surface damage, chemical attack, heating, cooling, or radiation, in either isolation or combination. The failure modes include fracture, fatigue, creep, corrosion, erosion, and embrittlement. 材料在受到載荷、表面損傷、化學侵蝕、加熱、冷卻或輻射時，可能發生失效的各種方式，無論是單獨還是組合。失效模式包括斷裂、疲勞、蠕變、腐蝕、侵蝕和脆化。
Modulus of elasticity (E)	彈性模量（E）	The measure of rigidity or stiffness of a metal; the ratio of stress, below the proportional limit, to the corresponding strain. In terms of the stress-strain diagram, the modulus of elasticity is the slope of the stress-strain curve in the range of linear proportionality of stress to strain. 金屬的剛度或剛度的量度；低于比例極限的應力與相應應變之比。根據應力應變圖，彈性模量是應力應變曲線在應力應變線性比例范圍內的斜率。
Modulus of resilience	回彈系數	The amount of energy stored in a material when loaded to its elastic limit. It is determined by measuring the area under the stress-strain curve up to the elastic limit. 當加載到其彈性極限時，材料中儲存的能量量。通過測量應力-應變曲線下直至彈性極限的面積來確定。
Modulus of rupture	斷裂模量	Nominal stress at fracture in a bend test or torsion test. In bending, modulus of rupture is the bending moment at fracture divided by the section modulus. In torsion, modulus of rupture is the torque at fracture divided by the polar section modulus. 彎曲試驗或扭轉試驗中的標稱斷裂應力。在彎曲中，斷裂模量是斷裂時的彎矩除以截面模量。在扭轉中，斷裂模量是斷裂時的扭矩除以極截面模量。
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. 一種斷裂準則，主要適用于脆性材料，根據該準則，當材料中某一點的應力落在單軸抗拉強度和單軸抗壓強度的莫爾圓所形成的包絡線之外時，就會發生斷裂。
Mohr–Coulomb yield criterion	Mohr–Coulomb屈服準則	A pressure-dependent yield criterion, according to which yielding occurs when the stress at a point in a material falls on the envelope created by the Mohr’s stress circles at yielding for various tests such as tension, shear, and compression that have different components of hydrostatic stress. 一種與壓力相關的屈服準則，根據該準則，當材料中某一點的應力落在屈服時的莫爾應力圓所形成的包絡線上時，即發生屈服，用于各種試驗，如具有不同靜水應力分量的拉伸、剪切和壓縮。
Mohs hardness test	莫氏硬度測試	A scratch hardness test for determining comparative hardness using 10 standard minerals—from talc (the softest) to diamond (the hardest). 刮擦硬度測試，用于使用從滑石（最軟）到鉆石（最硬）的10種標準礦物測定比較硬度。
Mohs scale	莫氏硬度	A scale of scratch hardness originally developed for minerals. 最初為礦物開發的劃痕硬度標尺。
Mole (mol)	摩爾（mol）	The base unit of the amount of substance in the SI system. It was previously defined as the amount of substance of a system that contains as many elementary entities as there are atoms in 0.012 kg of carbon-12. From 20 May 2019 it has been defined as the amount of substance containing exactly 6.022 140 76 × 1023?elementary entities. SI國際單位制中物質量的基本單位。此前，它被定義為一個系統中的物質量，該系統包含的基本實體數量與0.012千克碳-12中的原子數量相同。從2019年5月20日起，它已被定義為包含6.02214076×1023個基本實體的物質量。
Mole number (N)	摩爾數（N）	The number of moles in a given mass m of a substance, equal to m divided by the molar mass of the substance. 摩爾數物質給定質量m中的摩爾數，等于m除以物質的摩爾質量。
Monotron hardness test	摩諾硬度試驗	An obsolete method of determining indentation hardnessby measuring the load required to force a spherical penetrator into a metal to a specified depth. 一種已被淘汰的方法，通過測量將球形侵徹體壓入金屬至規定深度所需的載荷來確定壓痕硬度。
Morse taper	莫氏錐度	A self holding, standard taper largely used on drilling tools, drilling machine spindles, and some lathes. 一種自持式標準錐度，主要用于鉆孔工具、鉆床主軸和一些車床。
Multiple threaded screw	多螺紋螺釘	A screw with two or more threads cut around the periphery of the workpiece to provide an increased lead with a specified pitch. 一種螺釘，具有圍繞工件周邊切割的兩個或多個螺紋，以提供具有指定螺距的增加的導程。