《材料科学英语》PPT课件.ppt

Hubei University of Automotive Hubei University of Automotive TechnologyTechnology Specialty English uu1 1、语法较为简单，多用被动语态，从句等。、语法较为简单，多用被动语态，从句等。 uu2 2、专有名词多，有规律可循（构词法）（读音较、专有名词多，有规律可循（构词法）（读音较 为复杂，无规律）为复杂，无规律） uu3 3、写作要求清晰明了、写作要求清晰明了 uu如何学习？如何学习？ uu（1 1）记忆常见科技词汇（构词法）记忆常见科技词汇（构词法） uu（2 2）多阅读科技文章，学习如何用英语表达。避）多阅读科技文章，学习如何用英语表达。避 免自创的新奇语句。免自创的新奇语句。 uu（3 3）课后练习翻译，写作（）课后练习翻译，写作（Practice makes Practice makes perfect.perfect.） Characteristics of Specialty English Chapter 1 Materials and Heat Treatment Reading and answer questions The new words you maybe meet: metallic 金属的 corrosion 腐蚀 ductile 延展 ball bearing 滚珠轴承 multiphase 多相 wrought 加工的，精细的 malleable 可锻的 有延展性的 Ferrous Alloys uuArbitrary Arbitrary 专横的，独断的，任意的专横的，独断的，任意的 uuSmelt Smelt 熔炼熔炼 ，精炼，精炼 uuIntricate Intricate 复杂的复杂的 ，精巧的，精巧的 uuCombination Combination 结合结合 ，合并，合并， 化合物化合物 Ferrous Alloys uuMore than 90% by weight of the metallic More than 90% by weight of the metallic materials used by human beings are materials used by human beings are ferrous ferrous alloysalloys. This represents an immense family of . This represents an immense family of engineering materials with a wide range of engineering materials with a wide range of microstructure and related properties. microstructure and related properties. Ferrous Alloys uuThe majority of engineering designs that The majority of engineering designs that require structural load support or power require structural load support or power transmission involve ferrous alloys. as a transmission involve ferrous alloys. as a practical matter, these alloys fall into two practical matter, these alloys fall into two broad categories based on the carbon in the broad categories based on the carbon in the alloy composition. alloy composition. Ferrous Alloys uuSteel generally contains between 0.05w and Steel generally contains between 0.05w and 2.0 w carbon. The cast irons generally contain 2.0 w carbon. The cast irons generally contain between 2.0w and 4.5 w carbon. between 2.0w and 4.5 w carbon. Within the steel category, we shall distinguish whether or not a significant amount of alloying elements other than carbon is used. 对于钢的区分，我们要弄清楚的是是否含有有效量的合金元素而不 是碳的含量。 Ferrous Alloys Ferrous Alloys uuA composition of 5 w total A composition of 5 w total noncarbonnoncarbon additions will serve as an arbitrary boundary additions will serve as an arbitrary boundary between low alloy and high alloy steels. between low alloy and high alloy steels. Ferrous Alloys uuThese alloy additions are chosen carefully These alloy additions are chosen carefully because they invariably bring with them because they invariably bring with them sharply increased material costs.sharply increased material costs. They are They are justified only by essential improvements in justified only by essential improvements in properties such as higher strength or improved properties such as higher strength or improved corrosion resistancecorrosion resistance questions uuHow do you distinguish steel from cast iron?How do you distinguish steel from cast iron? uuHow do you distinguish low alloy steel from How do you distinguish low alloy steel from high alloy steel?high alloy steel? 1.1.1 Iron and Steel The earth contains a large number of metals The earth contains a large number of metals which are useful to man. One of the most which are useful to man. One of the most important of these is iron. Modern industry important of these is iron. Modern industry needs considerable quantities of this metal, needs considerable quantities of this metal, either in the either in the form of iron or in the form of steel. 1.1.1 Iron and Steel A certain number of non-ferrous metals, certain number of non-ferrous metals, including including aluminum and zinc, are also important, but even today the majority of our of our engineering products are of iron or steel. engineering products are of iron or steel. Moreover, iron possesses magnetic properties, Moreover, iron possesses magnetic properties, which have made the development of electrical which have made the development of electrical power possible.power possible. 1.1.1 Iron and Steel The iron ore which we find on earth is not pure. The iron ore which we find on earth is not pure. It contains some impurities that must be It contains some impurities that must be removed by smelting. The process of smelting removed by smelting. The process of smelting consists of heating the ore in a blast furnace consists of heating the ore in a blast furnace with coke and limestone, and with coke and limestone, and reducingreducing it to it to metal. Blasts of hot air enter the furnace from metal. Blasts of hot air enter the furnace from the bottom and provide the oxygen that is the bottom and provide the oxygen that is necessary for the reduction of the ore. necessary for the reduction of the ore. 1.1.1 Iron and Steel The ore becomes molten, and its oxides combine The ore becomes molten, and its oxides combine with carbon from the coke. The non-metallic with carbon from the coke. The non-metallic constituents of the ore combine with the constituents of the ore combine with the limestone to form a liquid slag. This floats on limestone to form a liquid slag. This floats on top of the molten iron, and passed out of the top of the molten iron, and passed out of the furnace through a tap. The metal which furnace through a tap. The metal which remains is remains is pig ironpig iron. . 1.1.1 Iron and Steel uuWe can melt this down again in another We can melt this down again in another furnace-a cupola-with more coke and furnace-a cupola-with more coke and limestone, and tap it out into a ladle or directly limestone, and tap it out into a ladle or directly into molds. This is cast iron. into molds. This is cast iron. Cast ironCast iron does not does not have the strength of steel. It is brittle and may have the strength of steel. It is brittle and may fracture under tension. fracture under tension. 1.1.1 Iron and Steel uuBut it possesses certain properties that make it But it possesses certain properties that make it very useful in the manufacture of machinery . very useful in the manufacture of machinery . In the molten state it is very fluid, therefore, it In the molten state it is very fluid, therefore, it is easy to cast it into intricate shapes. Also it is is easy to cast it into intricate shapes. Also it is easy to machine it. Cast iron contains small easy to machine it. Cast iron contains small proportion of other substances. proportion of other substances. 1.1.1 Iron and Steel uuThese non-metallic constituents of cast iron These non-metallic constituents of cast iron include carbon, silicon and include carbon, silicon and sulphursulphur, and the , and the presence of these substances affects the presence of these substances affects the behavior of the metal. Iron which contains a behavior of the metal. Iron which contains a negligible quantity of carbon, for example, negligible quantity of carbon, for example, wrought iron behaves differently from iron wrought iron behaves differently from iron which contains a lot of carbon.which contains a lot of carbon. 1.1.1 Iron and Steel uuThe carbon in cast iron is present partly as free The carbon in cast iron is present partly as free graphite and partly as a chemical combination graphite and partly as a chemical combination of iron and carbon which is called of iron and carbon which is called cementitecementite. . This is a very hard substance, and it makes the This is a very hard substance, and it makes the iron hard too. iron hard too. 1.1.1 Iron and Steel uuHowever, iron can only hold about 1.5% of However, iron can only hold about 1.5% of cementitecementite. Any carbon content above that . Any carbon content above that percentage is present of the form of a flaky percentage is present of the form of a flaky graphite. graphite. 1.1.1 Iron and Steel uuSteel contains no free graphite, and its carbon Steel contains no free graphite, and its carbon content ranges from almost nothing to content ranges from almost nothing to 1.5%.We make wire and tubing from mild 1.5%.We make wire and tubing from mild steel with a very low carbon content, and steel with a very low carbon content, and drills and cutting tools from high carbon steel.drills and cutting tools from high carbon steel. questions uuHow is the steel made?How is the steel made? uuIf you want to have a high strength iron based If you want to have a high strength iron based material,whatmaterial,what should you do? should you do? uuWhat is the function of the coke when What is the function of the coke when producing pig iron?producing pig iron? uuWhat is the difference between the pig iron What is the difference between the pig iron and the cast iron?and the cast iron? 1.1.2 Carbon and low alloy steel uuThe majority of ferrous alloys belongs to this The majority of ferrous alloys belongs to this category . The reasons for this are category . The reasons for this are straightforward. They are moderately priced straightforward. They are moderately priced due to the absence of large amounts of alloying due to the absence of large amounts of alloying elements, and they are sufficiently ductile to be elements, and they are sufficiently ductile to be readily formed. The final product is strong and readily formed. The final product is strong and durable. durable. uuThese eminently practical materials find These eminently practical materials find application from application from ball bearingsball bearings to metal sheet to metal sheet formed into formed into automobile bodiesautomobile bodies .For example, .For example, the 10XX,11XX,12XX,15XX the 10XX,11XX,12XX,15XX etc.(AISIetc.(AISI standards, in which the first two numbers give standards, in which the first two numbers give a code designating the type of alloy additions a code designating the type of alloy additions and the last two or three numbers give the and the last two or three numbers give the carbon content in hundredths of a weight carbon content in hundredths of a weight percent). percent). 1.1.2 Carbon and Low Steel uuAs an As an example,theexample,the plain carbon steel with plain carbon steel with 0.40w carbon is a 1040 0.40w carbon is a 1040 steel,whereassteel,whereas a steel a steel with 1.45w Cr and 1.5w carbon is a 52150 with 1.45w Cr and 1.5w carbon is a 52150 steel.steel. 1.1.2 Carbon and Low Steel uuOne should keep in mind that chemical One should keep in mind that chemical compositions quoted in alloy designations are compositions quoted in alloy designations are approximate and will vary slightly from approximate and will vary slightly from product to product within acceptable limits of product to product within acceptable limits of industrial quality control.industrial quality control. 1.1.2 Carbon and Low Steel uuAn interesting class of alloys known as high An interesting class of alloys known as high strength low alloy (HSLA) steels has emerged strength low alloy (HSLA) steels has emerged in response to requirements for in response to requirements for weight weight reduction of vehicles. reduction of vehicles. 1.1.2 Carbon and Low Steel uuThe compositions of many commercial HSLA The compositions of many commercial HSLA steels are proprietary and specified by steels are proprietary and specified by mechanical properties rather than mechanical properties rather than composition.Butcomposition.But a typical example might a typical example might contain 0.2w carbon and about 1.0w or less of contain 0.2w carbon and about 1.0w or less of such elements as such elements as Mn,P,Si,Cr,Ni,orMn,P,Si,Cr,Ni,or Mo. Mo. 1.1.2 Carbon and Low Steel 1.1.2 Carbon and Low Steel uuThe high strength of HSLA steels is the result The high strength of HSLA steels is the result of optimal alloy selection and carefully of optimal alloy selection and carefully controlled processing such as hot rolling controlled processing such as hot rolling (deformation at temperatures sufficiently (deformation at temperatures sufficiently elevated to allow some stress relief)elevated to allow some stress relief) question uuWhat is the difference between the carbon What is the difference between the carbon steel and HSLA steel?steel and HSLA steel? uuWhy the HSLA steel is so popular?Why the HSLA steel is so popular? uuHow are the good properties of the HSLA How are the good properties of the HSLA steels obtained?steels obtained? vocabulary uDuctile 延展 uDurable 耐久的 uQuote 引用 援引 uEminently 杰出地 uRust 生锈 uPrecipitation 沉淀 沉积 uDislocation 位错 1.1.3High Alloy Steel uuAs mentioned above, alloy additions must be As mentioned above, alloy additions must be with care and justification because they are with care and justification because they are expensive. We shall now look at three cases in expensive. We shall now look at three cases in which engineering design requirements justify which engineering design requirements justify high alloy composition (i.e., total non-carbon high alloy composition (i.e., total non-carbon additions greater than 5 w). additions greater than 5 w). 1.1.3High Alloy Steel uuStainless steelsStainless steels require alloy additions to require alloy additions to prevent damage from a corrosive atmosphere. prevent damage from a corrosive atmosphere. Tool steels require alloy additions to obtain Tool steels require alloy additions to obtain sufficient hardness for machining applicationsufficient hardness for machining application 1.1.3High Alloy Steel uuSo it is called “ So it is called “ superalloyssuperalloys ” which require ” which require alloy additions to provide stability in high alloy additions to provide stability in high temperature applications such as turbine blades.temperature applications such as turbine blades. 1.1.3High Alloy Steel uuStainless steels are more resistant to rusting Stainless steels are more resistant to rusting and staining than carbon and low alloy steels, and staining than carbon and low alloy steels, due primarily to the presence of chromium due primarily to the presence of chromium addition. addition. 1.1.3High Alloy Steel uuThe amount of chromium is at least 4 w and The amount of chromium is at least 4 w and usually above 10 w. Levels as high as 30 w Cr usually above 10 w. Levels as high as 30 w Cr are sometimes used. The austenitic stainless are sometimes used. The austenitic stainless steels have the austenite structure retained at steels have the austenite structure retained at room temperature.room temperature. 1.1.3High Alloy Steel uuThe austenite has the The austenite has the fccfcc structure and is stable structure and is stable above 910above 910. This structure can occur at room . This structure can occur at room temperature when it is stabilized by an temperature when it is stabilized by an appropriate alloy addition such as nickel. appropriate alloy addition such as nickel. 1.1.3High Alloy Steel uuWithout the high nickel content, the bcc Without the high nickel content, the bcc structure is stable, as seen in the structure is stable, as seen in the ferriticferritic stainless stainless steels. For many applications not requiring the steels. For many applications not requiring the high corrosion resistance of austenitic stainless high corrosion resistance of austenitic stainless steels , these lower alloy (and less expensive) steels , these lower alloy (and less expensive) ferriticferritic stainless steels are quite serviceable. stainless steels are quite serviceable. 1.1.3High Alloy Steel uuA rapid quench heat treatment discussed later A rapid quench heat treatment discussed later allows the formation of a more complex body allows the formation of a more complex body centered tetragonal crystal structure called centered tetragonal crystal structure called martensitemartensite. This crystal structure yields high . This crystal structure yields high strength and strength and low ductilitylow ductility . . 1.1.3High Alloy Steel uuAs a result, these As a result, these martensiticmartensitic stainless steels are stainless steels are excellent for applications such as cutlery and excellent for applications such as cutlery and springs. springs. Precipitation hardeningPrecipitation hardening is another heat is another heat treatment.treatment. 1.1.3High Alloy Steel uuEssentially, it involves producing a multiphase Essentially, it involves producing a multiphase microstructure from a single phase one. The microstructure from a single phase one. The result is increased resistance to dislocation result is increased resistance to dislocation motion and, thereby, greater strength or hardness. motion and, thereby, greater strength or hardness. Precipitation hardening stainless steels can be Precipitation hardening stainless steels can be found in applications such as corrosion resistant found in applications such as corrosion resistant structural members.structural members. 1.1.3High Alloy Steel uuTool steels are used for cutting, forming or Tool steels are used for cutting, forming or otherwise shaping another material. Plain otherwise shaping another material. Plain carbon steel can also be tool steel. For shaping carbon steel can also be tool steel. For shaping operations that are not too demanding , such a operations that are not too demanding , such a material is adequate. material is adequate. 1.1.3High Alloy Steel uuIn fact, tool steels were historically of the In fact, tool steels were historically of the plain carbon variety until the mid-nineteenth plain carbon variety until the mid-nineteenth century. Now high alloy additions are century. Now high alloy additions are common. Their advantage is that they can common. Their advantage is that they can provide the necessary hardness with simple provide the necessary hardness with simple heat treatments and retain that hardness at heat treatments and retain that hardness at higher operating temperature. higher operating temperature. 1.1.3High