| 词或词组 | 中文 | 英文解释中文解释 |
|---|---|---|
| Machine | 机器 |
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. 在执行有用任务时传递能量的机制。一个地方有一台以上的连接或执行单独的功能，称为机器。 |
| Machine screw | 机械螺丝 |
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. 带有机加工螺纹的沉头开槽螺钉，如螺栓上的螺纹。一种相对较小的螺钉，直径通常小于20毫米，螺纹沿整个长度一直延伸到头部，用于拧入螺纹孔中。如果通过装配零件上的平孔插入并用螺母固定在一起，则会导致螺纹与孔表面接触不良。 |
| Machine tool | 机床工具 |
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. 一种动力机器，如钻孔机、磨床、车床、铣床或刨床，用于切割和成形金属、塑料、复合材料等（机加工）。加工中心是围绕多个轴工作的CNC机床，具有刀具库存和自动换刀能力，能够在自动化控制下进行各种加工操作。 |
| Macrodeviation | 宏观偏差 |
Errors from–irregular surface departures from the design profile, often caused by lack of accuracy or stiffness of the machine system. 不规则表面偏离设计轮廓的误差，通常是由于机器系统缺乏准确性或刚度造成的。 |
| 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. 相邻原子的磁矩可以采用平行或反平行排列的材料。当磁矩采用平行排列时，会产生铁磁性。当相邻磁矩因反平行排列而抵消时，材料表现出反铁磁性，没有总磁矩。后者的实例包括氧化亚铁和氧化锰。当相邻磁矩采用反平行排列但大小不等时，就会出现铁磁现象。磁矩对齐的铁磁或铁磁材料区域称为磁畴，相邻区域由磁畴壁分隔。抗磁和顺磁材料表现出弱磁性形式，这是由外加磁场诱导的磁原子偶极子的独立（非耦合）排列引起的。铁磁性和铁磁性材料可以在相对弱的磁场中获得高磁化度。它们具有不同的磁滞特性，分为硬磁铁和软磁铁。硬磁铁在没有外加磁场的情况下保持较大的磁化强度，用作永磁体。常规材料包括与钨或钴合金化的磁钢。由稀土元素合金制成的稀土磁体产生明显更强的磁场。其中最常见的是钐钴和钕硼永磁体。它们的强度使其体积小，可用于多种应用，包括无绳工具、磁盘驱动器、耳机、玩具和汽车部件（如雨刷、风扇、洗衣机和车窗）的电机。软磁体可以相对容易地磁化和退磁。当受到交变磁场时，由于磁滞引起的能量损失很小。常见材料包括铁硅合金（称为电工钢）、镍铁合金（坡莫合金）、软铁氧体和非晶纳米晶合金，最后一种可以通过熔钉以胶带的形式生产。软磁铁用于增强电流产生的磁通量。 |
| Magnetic test | 磁性测试 |
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. 用于测试各种淬火剂的热提取率的方法。该测试通过利用金属在居里点（即金属失去磁性的温度）的磁性变化来进行。 |
| Major diameter | 螺纹大径 |
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. 在直螺纹上，仅接触外螺纹顶部或内螺纹根部的假想圆柱体的直径。 |
| Malleable cast iron | 可锻铸铁 |
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. 白口铸铁一种通过长时间退火制成的铸铁，脱碳，石墨化，或两者都发生，以消除部分或全部渗碳体。石墨是回火碳的形式。如果脱碳是主要反应，产品将呈现出较轻的断裂表面，“白心可锻”。否则，断裂表面将变暗，“黑心可锻”。铁素体可锻性材料主要为铁素体基体；根据热处理和所需硬度，珠光体可锻材料可能包含珠光体、球状体或回火马氏体。 |
| Manometer | 压力计 |
An instrument used in the measurement of a pressure difference in a fluid (manometry). 用于测量流体压力差（测压）的仪器。 |
| Maraging steels | 马氏体时效钢 |
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“马氏体”和“时效”命名的超高强度铁合金。它们含有镍、铬、钴和钼，在空气冷却下形成强度约为1GPa的马氏体。当再加热至约500°C并老化数小时时，室温强度达到约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）一种淬火工艺，将奥氏体化铁质工件淬火到适当的介质中，该介质的温度基本保持在工件的Ms，保持在该介质中直到其温度在整个过程中均匀，但不足以形成贝氏体，然后在空气中冷却。处理后经常进行回火。（2） 当该工艺应用于渗碳材料时，控制Ms温度与实际情况相同。这个过程的变化经常被称为淬火。 |
| Martensitic stainless steels | 马氏体不锈钢 |
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. 马氏体不锈钢是一种可硬化的磁性不锈钢，其铬含量为9-18%，碳含量为0.06-1.25%，锰、硅、镍和钼的总含量通常高达约2.5%。它们可以进行热处理，使马氏体成为主要的微组分，通常可在退火或淬火回火条件下获得。它们具有优异的强度和高硬度，以及良好的耐腐蚀性。用途包括餐具、外科器械、步枪枪管、蒸汽轮机管道和叶片、喷气发动机部件、手动工具、机械零件、紧固件、阀门、弹簧、轴承、泵轴、喷嘴、采矿设备和耐磨零件。 |
| Mass flow meter | 质量流量计 |
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. 一种仪器，例如科里奥利流量计，一种测量流经管道或其他管道的流体的质量流率而不是其体积流率的仪器。 |
| Mass flow rate (ṁ) (Unit kg/s) | 质量流量（ṁ）（单位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 (ṁ″), 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. ṁ″ = ṁ/A or ṁ″ = ρV where ρ is the material density and V is its velocity normal to the surface. 单位时间内流过表面或通过管道或其他管道的材料质量，通常是流体或粉末。相应的质量通量（ṁ″），单位为kg/s.m²，是通过真实表面或通过管道的质量流量除以表面或横截面积A，即ṁ″=ṁ/A或ṁ″=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. 声音在物体（例如螺栓）中的速度。用于螺栓应力或应变的超声波测量的术语。 |
| Materials science | 材料科学 |
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. 研究金属、陶瓷、玻璃、聚合物、复合材料、生物材料和半导体等固体物质的特性、行为和应用，涵盖从原子到宏观的所有范围。起源于冶金学。 |
| Materials selection | 材料选择 |
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. 为特定应用选择最合适材料的过程。对于固体材料，它涉及根据其物理特性（密度、弹性模量、断裂韧性、屈服强度、硬度、抗疲劳性、热膨胀系数、导热系数、抗热冲击性、抗蠕变性、耐腐蚀性、抗辐射性等）评估候选材料，以及诸如最终产品的功能、其形状、制造方法、所需公差、制造数量、检查和质量控制的容易程度、成本和采用的设计方法等因素。 |
| Maximum allowable operating pressure (Unit Pa) | 最大允许使用压力（单位Pa） |
The highest pressure at which any pressure system may be operated, usually 10 to 20% below the maximum allowable working pressure. 任何压力系统可运行的最高压力，通常比最大允许工作压力低10%至20%。 |
| Maximum allowable working pressure (Unit Pa) | 最大允许工作压力（单位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. 压力系统设计所依据的压力和应设置安全阀的最高压力。系统中最低额定部件的设计安全系数通常为4。 |
| Maximum continuous load | 最大连续负载 |
(maximum continuous rating) (Unit kg/s) The maximum rate of steam output that a boiler can supply for a specified period, usually 24 hours. （最大连续额定功率）（单位为kg/s）锅炉在规定时间内（通常为24小时）可供应的最大蒸汽输出率。 |
| Maximum load (Pmax) | 最大负载（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）负载循环中具有最高代数值的负载。拉伸荷载视为正荷载，压缩荷载视为负荷载。（2）用于确定结构构件的强度；失效前可承受的载荷是明显的。 |
| Maximum material condition | 最大材料条件 |
(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. （最大金属条件）制造部件的体积对应于所有公差外部尺寸的上限和所有内部尺寸的下限的情况。 |
| Maximum stress (Smax) | 最大应力（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. 在应力循环中具有最高代数值的应力，拉应力被认为是正的，压应力被认为是负的。名义应力是最常用的。 |
| Maximum stress-intensity factor (Kmax) | 最大应力强度因子（Kmax） |
The maximum value of the stress-intensity factorin a fatigue cycle. 疲劳循环中应力强度因子的最大值。 |
| Maximum-and-minimum thermometer | 最高和最低温度计 |
(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-最高温度计，Six's温度计）一种液体玻璃仪器，用于记录给定时间段内经历的最高和最低温度。 |
| Mean diameter (Unit m) | 平均直径（单位米） |
The average of the inside and outside diameters for a helical spring or hollow circular cylinder or sphere 螺旋弹簧或空心圆柱体或球体的内径和外径的平均值 |
| Mean stress (Unit Pa) | 平均应力（单位 Pa） |
The average of the maximum and minimum stresses for a material subjected to a stress cycle, as in a fatigue test. 承受应力循环的材料的最大和最小应力的平均值，如在疲劳试验中。 |
| 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. 多个数据点的平均值。通过将所有数据的总和除以数据点的数量来计算。 |
| Mechanical alloying | 机械合金化 |
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. 通过固结（例如热压或挤压）从粉末生产合金，然后进行热和/或冷加工和最终退火。用这种方法可以制造弥散强化合金、高温铝合金和非晶合金等材料。 |
| Mechanical efficiency (η) | 机械效率（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，机器的输出功与输入功之比。2.对于压缩机，指示功率与轴功率之比；对于往复式发动机或膨胀机，轴功率与指示功率之比。 |
| Mechanical energy (Unit J) | 机械能（单位J） |
The sum of kinetic energy and potential energy for an object or a mechanical system, including the energy stored in springs, etc. 物体或机械系统的动能和势能之和，包括储存在弹簧等中的能量。 |
| mechanical engineering | 机械工业 |
That branch of engineering concerned with energy conversion, stress analysis, vibration, dynamics, and kinematics, especially applied to design (machine design, mechanical-engineering design). 与能量转换、应力分析、振动、动力学和运动学有关的工程分支，尤其适用于设计（机器设计、机械工程设计）。 |
| Mechanical metallurgy | 机械冶金 |
The science and technology dealing with the behavior of metals when subjected to applied forces. 处理金属在外力作用下的行为的科学技术。 |
| Mechanical properties of solid materials | 固体材料的力学性能 |
The strength and stiffness properties of solid materials such as fracture toughness, the moduli of elasticity, percent elongation, 固体材料的强度和刚度特性，例如断裂韧性、弹性模量、伸长率、 |
| Mechanical units | 机械单位 |
The units of physical quantities, the dimensions of which includemass, length, and time. 物理量的单位，其量纲包括质量、长度和时间。 |
| Mechanical vibration | 机械振动 |
The motion of a particle or body which oscillates about a position of equilibrium. 围绕平衡位置摆动的粒子或物体的运动。 |
| Mechatronics | 机电一体化 |
The integration of mechanical engineering, electrical engineering, electronic engineering, and software engineering. 机械工程、电气工程、电子工程和软件工程的集成。 |
| Median fatigue life | 中位疲劳寿命 |
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. 当在相同条件下测试的一组中单个试样的所有观察疲劳寿命值按数量级排列时的中间值。当测试偶数个试样时，使用两个中间值的平均值。通常优选使用样本中值而不是算术平均值（即平均值）。 |
| Median fatigue strength at N cycles | N次循环的中位疲劳强度 |
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. 估计50%的量在N个周期内生存的压力水平。该估计值来自疲劳寿命分布的一个特定点，因为没有试验程序可以直接观察N次循环疲劳强度的频率分布。 |
| Melting point (Unit K or °C) | 熔点（单位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. 在特定压力下，固体材料发生相变为液体的温度，通常为1大气压。纯金属和共晶具有单值熔点，而具有其他成分的合金在一定温度范围内熔化，熔化过程有一个明确的起点和终点，但其间存在固态和液态并存的状态。 |
| Metallurgy | 冶金 |
The study of the atomic, crystallographic, microstructural, mechanical, and physical properties of metallic elements and alloys and their applications. 研究金属元素和合金的原子、晶体学、微观结构、机械和物理特性及其应用。 |
| 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系统中长度的基本单位。它等于光在真空中在1/299792458秒内传播的距离。 |
| Metric ton (tonne, t) | 公制吨（吨，t） |
An SI-accepted, but non-SI, unit of mass defined as 1 t = 103 kg. SI系统可接受但非国际单位制的质量单位，定义为1t=103kg。 |
| Meyer hardness (Unit Pa) | 迈耶硬度（单位Pa） |
A material hardness similar to the Brinell hardness but based upon the projected area of the impression rather than the surface area. 与布氏硬度相似的材料硬度，但基于印模的投影面积而不是表面面积。 |
| Microhardness | 显微硬度 |
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. 通过在非常轻的载荷下将压头（如维氏或努氏压头）压入材料表面来确定的材料硬度；通常压痕很小，必须用显微镜测量。能够确定结构内不同微组分的硬度，或测量陡峭的硬度梯度，如表面硬化中遇到的硬度梯度。 |
| Microindentation hardness test | 显微压痕硬度测试 |
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. 使用校准机器进行硬度试验，以在1至1000克力的试验载荷下，将特定几何形状的金刚石压头压入试验材料表面，并光学测量压痕的对角线。 |
| 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）一种机械接触装置，用于精确测量物体的长度、宽度、直径等、孔的深度、台阶的高度等。通常的布置是通过顶针的旋转移动主轴，然后通过游标尺读取距离。 |
| Microscopic stresses | 微观应力 |
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. 与普通应变测量中的标距相比，从拉伸到压缩的距离（大概接近晶粒尺寸）较小的残余应力。它们无法通过解剖方法检测到，但有时可以通过x射线衍射图案中的线位移或线加宽来测量。 |
| Microstrain | 微应变 |
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. 与原子间距离相当的标距上的应变。这些是通过宏观应变测量得到的平均应变。现有技术无法测量微应变。然而微应变分布的变化可以通过x射线衍射来测量。 |
| 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. 一种非SI压力单位，等于1毫米高的垂直水银柱施加的压力。大约等于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. 一种非SI压力单位，等于1毫米高的垂直水柱施加的压力。大约等于9.81Pa。 |
| Milling | 铣削 |
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. 一种加工工艺，通常用于金属和塑料，其中多齿旋转刀具去除材料以产生平坦或异形表面、槽、槽等。金属由旋转多齿刀具去除；主轴每转一圈，每个齿都会去除少量金属。因为工件和刀具可以同时在多个方向上移动，所以几乎可以加工任何方向的表面。 |
| Minimum load (Pmin) | 最小负载（Pmin） |
In fatigue, the least algebraic value of applied load in a cycle. 在疲劳中，循环中施加载荷的最小代数值。 |
| Minimum material condition | 最小材料条件 |
(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. （最小金属条件）制造部件的体积对应于所有公差外部尺寸的下限和所有内部尺寸的上限的情况。 |
| Minimum stress (Smin) | 最小应力（Smin） |
In fatigue, the stress having the lowest algebraic value in the cycle, tensile stress being considered positive and compressive stress negative. 在疲劳中，循环中代数值最低的应力，拉应力被视为正应力，压应力为负应力。 |
| Minimum stress-intensity factor (Kmin) | 最小应力强度因子（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. 在疲劳中，一个循环中应力强度因子的最小值。该值对应于负载比为0时的最小负载，当负载比为≤0 |
| Minor diameter | 螺纹小径 |
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. 在直螺纹上，仅接触外螺纹根部或内螺纹顶部的假想圆柱体的直径。 |
| Minute (min) | 分钟（min） |
A non-SI unit of time. The conversion to SI is 1 min = 60 s. 非SI时间单位。转换为1分钟=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. 材料在受到载荷、表面损伤、化学侵蚀、加热、冷却或辐射时，可能发生失效的各种方式，无论是单独还是组合。失效模式包括断裂、疲劳、蠕变、腐蚀、侵蚀和脆化。 |
| Modulus of elasticity (E) | 弹性模量（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. 金属的刚度或刚度的量度；低于比例极限的应力与相应应变之比。根据应力应变图，弹性模量是应力应变曲线在应力应变线性比例范围内的斜率。 |
| Modulus of resilience | 回弹系数 |
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. 当加载到其弹性极限时，材料中储存的能量量。通过测量应力-应变曲线下直至弹性极限的面积来确定。 |
| Modulus of rupture | 断裂模量 |
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. 弯曲试验或扭转试验中的标称断裂应力。在弯曲中，断裂模量是断裂时的弯矩除以截面模量。在扭转中，断裂模量是断裂时的扭矩除以极截面模量。 |
| Mohr–Coulomb fracture criterion | Mohr–Coulomb断裂准则 |
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. 一种断裂准则，主要适用于脆性材料，根据该准则，当材料中某一点的应力落在单轴抗拉强度和单轴抗压强度的莫尔圆所形成的包络线之外时，就会发生断裂。 |
| Mohr–Coulomb yield criterion | Mohr–Coulomb屈服准则 |
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. 一种与压力相关的屈服准则，根据该准则，当材料中某一点的应力落在屈服时的莫尔应力圆所形成的包络线上时，即发生屈服，用于各种试验，如具有不同静水应力分量的拉伸、剪切和压缩。 |
| Mohs hardness test | 莫氏硬度测试 |
A scratch hardness test for determining comparative hardness using 10 standard minerals—from talc (the softest) to diamond (the hardest). 刮擦硬度测试，用于使用从滑石（最软）到钻石（最硬）的10种标准矿物测定比较硬度。 |
| Mohs scale | 莫氏硬度 |
A scale of scratch hardness originally developed for minerals. 最初为矿物开发的划痕硬度标尺。 |
| Mole (mol) | 摩尔（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国际单位制中物质量的基本单位。此前，它被定义为一个系统中的物质量，该系统包含的基本实体数量与0.012千克碳-12中的原子数量相同。从2019年5月20日起，它已被定义为包含6.02214076×1023个基本实体的物质量。 |
| Mole number (N) | 摩尔数（N） |
The number of moles in a given mass m of a substance, equal to m divided by the molar mass of the substance. 摩尔数物质给定质量m中的摩尔数，等于m除以物质的摩尔质量。 |
| Monotron hardness test | 摩诺硬度试验 |
An obsolete method of determining indentation hardnessby measuring the load required to force a spherical penetrator into a metal to a specified depth. 一种已被淘汰的方法，通过测量将球形侵彻体压入金属至规定深度所需的载荷来确定压痕硬度。 |
| Morse taper | 莫氏锥度 |
A self holding, standard taper largely used on drilling tools, drilling machine spindles, and some lathes. 一种自持式标准锥度，主要用于钻孔工具、钻床主轴和一些车床。 |
| Multiple threaded screw | 多螺纹螺钉 |
A screw with two or more threads cut around the periphery of the workpiece to provide an increased lead with a specified pitch. 一种螺钉，具有围绕工件周边切割的两个或多个螺纹，以提供具有指定螺距的增加的导程。 |