机械工程英语(Part1Unit 2 )(精品).ppt

Unit 2 Heat Treatment of Metals 金属的热处理New Words：1.embrace vt.接受，信奉 2.metallurgy n.冶金术，冶金学 3.extraction n.抽出物，采出物 4.abrasion n.磨损，擦伤 5.interior a.内的，内部的 6.molybdenum n.钼 7.tungsten n.钨 8.vanadium n.钒 9.simplify vt.简化，精简 10.diagram n.图表，简图 11.eutectoid n.共析的 a.共析体 12.transition n.转变，变迁 13.decomposition n.化分解 14.austenite n.冶奥氏体 15.ferrite n.冶铁素体 16.solubility n.溶解度，溶解性 17.cementite n.冶渗碳体 18.intermetallic a.金属间化合的 19.polish vt.磨光，抛光 20.etching n.蚀刻，浸蚀 21.nitric a.（含）氮的 nitric acid 硝酸 22.lamellar a.片状的，层状的 23.hypoeutectoid a.冶亚共析的 24.pearlite n.冶珠光体 25.equilibrium n.平衡 26.reverse vt.颠倒，使变得相反 27.preliminary a.预备的，初步的 28.exterior a.外部的 29.interior a.内部的 30.eliminate vt.消除 31.warp vt.使翘起，弄弯 32.hardenability n.淬透性，淬硬性 33.appreciable a.可看到（或感觉到）的可看到（或感觉到）的 34.anneal vt.冶冶退火退火 35.brine n.盐水，海水盐水，海水 36.martensite n.冶马氏体 37.constituent a.组成的，形成的 38.precipitation n.化沉淀作用 39.agglomeration n.化附聚作用 40.coalescence n.化聚结 41.substantial a.物质的，实际上的 42.refine v.精炼，精制 43.crystalline a.结晶的 44.relieve v.减轻，（使）解除 45.readily ad.容易地 46.uniformity n.一致性，均匀性 47.normalizing n.正火，常化 48.spheroidizing n.球化处理 49.carburizing n.渗碳处理 50.affinity n.共鸣，吸引 51.diffuse a.散开的，扩散的 52.carbonaceous a.碳质的，含碳的 53.charcoal n.木炭 54.coke n.焦炭 55.core n.芯子，铁心 56.cyanide n.化氰化物 57.nicarbing n.气体表面硬化法（碳氮共渗）58.ammonia n.化氨 59.immerse vt.沉浸 60.fused a.熔化的 61.sodium n.化钠 62.nitride n.化氮化物 63.spray n.浪花，飞沫 64.alkali n.化碱The understanding of heat treatment is embraced by the broader study of metallurgy.对冶金学加以广泛研究已使人们对热处对冶金学加以广泛研究已使人们对热处理加深了理解。理加深了理解。Metallurgy is the physics,chemistry and engineering related to metals from one extraction to the final product.冶金学是物理、化学及与从采矿冶炼到冶金学是物理、化学及与从采矿冶炼到最终产品的金属相关的工程学最终产品的金属相关的工程学。According to the procedure used,steel can be hardened to resist cutting action and abrasion,or it can be softened to permit machining.根据工艺规程，可使钢硬化以抵抗切削作用和根据工艺规程，可使钢硬化以抵抗切削作用和耐磨损，或使之变软，以便于切削加工。耐磨损，或使之变软，以便于切削加工。With the proper heat treatment internal stresses may be removed,grain size reduced,toughness increased,or a hard surfaced produced on a ductile interior.采用合适的热处理，可以消除零件的内应力，采用合适的热处理，可以消除零件的内应力，细化晶粒，增加韧性，或使材料表面坚硬而内细化晶粒，增加韧性，或使材料表面坚硬而内部产生塑性。部产生塑性。The key transition described in this diagram is the decomposition of singlephase austenite to the twophase ferrite plus carbide structure as temperature drops.此图中此图中描述的主要转变是当温度下降时，描述的主要转变是当温度下降时，单相奥氏体分解为两相铁素体加碳化物结单相奥氏体分解为两相铁素体加碳化物结构。构。Control of this reaction,which arises due to the drastically different carbon solubilities of austenite and ferrite,enables a wide range of properties to be achieved through heat treatment.由于碳在奥氏体和铁素体中的溶解度差异由于碳在奥氏体和铁素体中的溶解度差异很大而产生这种转变，控制这种转变，通过很大而产生这种转变，控制这种转变，通过热处理，就可能获得较大范围的性能。热处理，就可能获得较大范围的性能。Speciments prepared by polishing and etching in a weak solution of nitric acid and alcohol reveal the lamellar structure of alternating plates that forms on slow cooling.准备试样的方法是先将试样抛光准备试样的方法是先将试样抛光,然后用然后用稀硝酸和酒精溶液浸蚀稀硝酸和酒精溶液浸蚀,使之显示出交变板使之显示出交变板层状结构层状结构,这是在缓慢冷却过程中形成的这是在缓慢冷却过程中形成的.weak solution of nitric acid and alcohol 稀硝酸和酒精溶液稀硝酸和酒精溶液 the lamellar structure of alternating plates 交变板层状结构交变板层状结构 Hypereutectoid steels are steels that contain greater than the eutectoid amount of carbon.过共析钢是含有高于共析钢含碳量的钢。过共析钢是含有高于共析钢含碳量的钢。proeutectoid n.先共析体先共析体 eutectoid a.共析的共析的 n.共析体共析体 hypoeutectoid steel 亚共析钢亚共析钢 hypereutectoid steel 过共析钢过共析钢 As before,any remaining austenite transforms to pearlite upon slow cooling through this temperature.如上所述，在此温度任何残留的奥氏体都会通如上所述，在此温度任何残留的奥氏体都会通过缓慢冷却转变成为珠光体。过缓慢冷却转变成为珠光体。It should be remembered that the transitions that have been described by the phase diagrams are for equilibrium conditions,which can be approximated by slow cooling.应当记住状态图所描述的这种转变是处于平衡状应当记住状态图所描述的这种转变是处于平衡状态的，通过缓慢冷却才能接近这个状态。态的，通过缓慢冷却才能接近这个状态。However,when alloys are cooling rapidly,entirely different results may be obtained,because sufficient time is not provided for the normal phase reactions to occur.然而，当合金快速冷却时，由于不再对正常相变然而，当合金快速冷却时，由于不再对正常相变提供充足的时间，就可能得到完全不同的结果。提供充足的时间，就可能得到完全不同的结果。phase reactions 相变相变 Hardening 淬火淬火 Hardening is the process of heating a piece of steel to a temperature within or above its critical range and then cooling it rapidly.淬火是将钢加热到临界温度范围之内或以上的淬火是将钢加热到临界温度范围之内或以上的某一温度，然后快速冷却的工艺过程。某一温度，然后快速冷却的工艺过程。If the carbon content of the steels known,the proper temperature to which the steel should be heated may be obtained by reference to the iron-iron carbide phase diagram.如果已知钢的含碳量，钢应当加热的合适温度如果已知钢的含碳量，钢应当加热的合适温度就可通过参考铁就可通过参考铁-铁碳合金状态图查到。铁碳合金状态图查到。However,if the composition of the steel is unknown,a little preliminary experimentation may be necessary to determine the range.然而，如果不知道钢的成分，为了决定其温度然而，如果不知道钢的成分，为了决定其温度范围，有必要做一些初步试验。范围，有必要做一些初步试验。A good procedure to follow is to heat-quench a number of small speciments of the steel at various temperatures and observe the results,either by hardness testing or by microscopic examination.以下提及的好方法之一是在各种温度下加热淬冷以下提及的好方法之一是在各种温度下加热淬冷一些小的钢试件，既可用硬度试验也可用金相检一些小的钢试件，既可用硬度试验也可用金相检查观察其结果。查观察其结果。hardness testing 硬度试验硬度试验 Even after the correct temperature has been reached,the piece should be held at that temperature for a sufficient period of time to permit its thickest section to attain a uniform temperature.甚至在达到了正确的温度之后，工件也应在此甚至在达到了正确的温度之后，工件也应在此温度保温有效的时间，以使其最厚的截面获得均温度保温有效的时间，以使其最厚的截面获得均匀一致的温度。匀一致的温度。The hardness obtained from a given treatment depends on the quenching rate,the carbon content,and the work size.从给定的热处理工艺中获得的硬度取决于淬火从给定的热处理工艺中获得的硬度取决于淬火速率、含碳量和工件尺寸。速率、含碳量和工件尺寸。In alloy steels the kind and amount of alloying element influences only the hardenability(the ability of the workpiece to be hardened to depths)of the steel and does not affect the hardness except in unhardened or partially hardened steels.在合金钢中，除了非淬硬钢和局部淬硬钢之外，在合金钢中，除了非淬硬钢和局部淬硬钢之外，合金元素的种类和数量仅仅影响钢的淬透性（工合金元素的种类和数量仅仅影响钢的淬透性（工件可淬硬的深度），而不影响硬度。件可淬硬的深度），而不影响硬度。hardenability 淬透性淬透性 unhardened steels 非淬硬钢非淬硬钢 partially hardened steels 局部淬硬钢局部淬硬钢Tempering 回火回火 By tempering or drawing，the hardnessand brittleness may be reduced to the desired point for service conditions.通过回火，可以降低硬度和脆性，通过回火，可以降低硬度和脆性，满足使用要求。满足使用要求。drawing n.回火回火 Although this process softens steel,it differs considerably from annealingin that the process lends itself to close control of the physical properties and in most cases does not soften the steel to the extent that annealing would.尽管回火工艺使钢变软，但它与退火尽管回火工艺使钢变软，但它与退火有很大不同，回火工艺适用于完全控制有很大不同，回火工艺适用于完全控制钢的物理性能，在大多数情况下，钢不钢的物理性能，在大多数情况下，钢不会软化到退火所达到的程度。会软化到退火所达到的程度。The final structure obtained from tempering a fully hardened steel is called tempered martensite.完全硬化钢从回火中所获得的最终完全硬化钢从回火中所获得的最终结构称为回火马氏体。结构称为回火马氏体。fully hardened steel 完全硬化钢完全硬化钢 tempered martensite 回火马氏体回火马氏体 The tempering operation may be describedas one of precipitation and agglomeration or coalescence of cementite.回火操作可以用渗碳体的沉淀和结聚来回火操作可以用渗碳体的沉淀和结聚来加以描述。加以描述。precipitation n.沉淀作用沉淀作用 agglomeration n.附聚作用附聚作用 coalescence n.聚结聚结1.Two special processes using interruptedquenching are a form of tempering.用于分级淬火的两个特殊过程也是一种用于分级淬火的两个特殊过程也是一种回火形式。回火形式。interrupted quenching 分级淬火，断续冷却分级淬火，断续冷却 2.In both，the hardened steel is quenched in a salt bath held at a selected lower temperature before being allowed to cool.在这两个过程中，在钢取出冷却之前，先将在这两个过程中，在钢取出冷却之前，先将硬钢放在选定的较低温度的盐浴中淬火。硬钢放在选定的较低温度的盐浴中淬火。Annealing 退火退火This process is known as full annealingbecause it wipes out all trace of previous structure,refines the crystalline structure,and softens the metal.此工艺过程称为完全退火，因为它清除了此工艺过程称为完全退火，因为它清除了以前结构的所有痕迹，细化了结晶结构，并以前结构的所有痕迹，细化了结晶结构，并且软化了金属。且软化了金属。Normalizing and Spheroidizing 正火和球化处理正火和球化处理 Spheroidizing is a process of producingA structure in which the cementite is in a Spheroidal distribution.球化处理是产生渗碳体呈球状分布结构的球化处理是产生渗碳体呈球状分布结构的一种工艺过程。一种工艺过程。If a steel is heated slowly to a temperature just below the critical range and held there for a prolonged period of time,this structure will be obtained.如果缓慢加热钢至稍低于临界范围的如果缓慢加热钢至稍低于临界范围的温度，并作长时间的保温，就会获得这温度，并作长时间的保温，就会获得这种结构。种结构。Surface hardening 表面硬化表面硬化 The oldest known method of producing a hard surface on steel is case hardening or carburizing.众所周知使钢产生坚硬表面的最古老的方法是众所周知使钢产生坚硬表面的最古老的方法是表面硬化和渗碳处理。表面硬化和渗碳处理。Iron at temperatures close to and above its critical temperature has an affinity for carbon.接近或超过临界温度的铁有一种对碳的亲合性。接近或超过临界温度的铁有一种对碳的亲合性。Pack carburizing consists of placing the parts to be treated in a closed container with some carbonaceous material such as charcoal or coke.固体渗碳包括将需要处理的零件和一些如木炭固体渗碳包括将需要处理的零件和一些如木炭或焦炭类的碳质材料一起放进密闭的容器里。或焦炭类的碳质材料一起放进密闭的容器里。pack carburizing 固体渗碳固体渗碳 Steel for carburizing is usually a low-carbon steel of about 0.15%carbon that would not in itself respond appreciably to heat treatment.进行渗碳处理的钢通常是含碳量约为进行渗碳处理的钢通常是含碳量约为0.15%的的低碳钢，而低碳钢本身明显不符合热处理要求。低碳钢，而低碳钢本身明显不符合热处理要求。Because there is some grain growth in the steel during the prolonged carburizing treatment,the work should be heated to the critical temperature of the core and then cooled,thus refining the core structure.因为在长时间的渗碳处理过程中，钢中有一些因为在长时间的渗碳处理过程中，钢中有一些晶粒在生长，应当加热工件至芯部的临界温度，晶粒在生长，应当加热工件至芯部的临界温度，然后冷却，这样就能细化芯部结构。然后冷却，这样就能细化芯部结构。The steel should then be reheated to a point above the transformation range of the case(AC1)and quenched to produce a hard,fine structure.接着应当重新加热钢件至渗碳层转变范围接着应当重新加热钢件至渗碳层转变范围(AC1)以上的某一温度，并淬冷，产生一种既坚以上的某一温度，并淬冷，产生一种既坚硬又细化的结构。硬又细化的结构。Carbonitriding 碳氮共渗碳氮共渗 Carbonitriding,sometimes known as dry cyaniding or nicarbing,is a case-hardening process in which the steel is held at a temperature above the critical range in a gaseous atmosphere from which it absorbs carbon and nitrogen.碳氮共渗，有时称为干氰化或气体表面硬化，碳氮共渗，有时称为干氰化或气体表面硬化，是一种表面硬化工艺。在此工艺中，钢在气态气是一种表面硬化工艺。在此工艺中，钢在气态气体中保温在临界范围以上的某一温度，从气体中体中保温在临界范围以上的某一温度，从气体中吸收碳和氮。吸收碳和氮。Cyaniding 氰化氰化 Cyaniding,or liquid carbonitriding as it is sometimes called,is also a process that combines the absorption of carbon and nitrogen to obtain surface hardness in low-carbon steels that do not respond to ordinary heat treatment.氰化，有时称为液体碳氮共渗，也是一种应用氰化，有时称为液体碳氮共渗，也是一种应用于不适应普通热处理的低碳钢，使之通过碳氮共于不适应普通热处理的低碳钢，使之通过碳氮共渗获得表面硬度的工艺。渗获得表面硬度的工艺。Nitriding 氮化氮化 Nitriding is somewhat similar to ordinary case hardening,but it uses a different material and treatment to create the hard surface constituents.氮化与普通的表面淬硬处理有些类似，但它使氮化与普通的表面淬硬处理有些类似，但它使用不同的材料和处理工艺产生坚硬的表面层。用不同的材料和处理工艺产生坚硬的表面层。Nitrogen from the gas is introduced into the steel,forming very hard nitrides that are finely dispersed through the surface metal.氨气中的氮传入钢中，形成很硬的氮化物，氮氨气中的氮传入钢中，形成很硬的氮化物，氮化物密布遍及金属表面。化物密布遍及金属表面。It is recommended that these steels be machined and heat-treated before nitriding,because there is no scale or further work necessary after this process.建议在氮化之前对这些钢进行加工和热处理，建议在氮化之前对这些钢进行加工和热处理，因为在此工艺之后无氧化皮形成，无法完成必要因为在此工艺之后无氧化皮形成，无法完成必要的进一步的善后工作。的进一步的善后工作。