不銹鋼工程材料的選擇 外文翻譯

1、 unit 1 metals the use of metals has always been a key factor in the development of the social systems of man. of the roughly 100 basic elements of which all matter is composed, about half are classified as metals. the distinction between a metal and a nonmetal is not always clear-cut. the most basi

2、c definition centers around the type of bonding existing between the atoms of the element, and around the characteristics of certain of the electrons associated with these atoms. in a more practical way, however, a metal can be defined as an element which has a particular package of properties.metal

3、s are crystalline when in the solid state and, with few exceptions (e.g. mercury), are solid at ambient temperatures. they are good conductors of heat and electricity and are opaque to light. they usually have a comparatively high density. many metals are ductile-that is, their shape can be changed

4、permanently by the application of a force without breaking. the forces required to cause this deformation and those required to break or fracture a metal are comparatively high, although, the fracture forces is not nearly as high as would be expected from simple consideration of the forces required

5、to tear apart the atoms of the metal.one of the more significant of these characteristics from our point of view is that of crystallinity. a crystalline solid is one in which the constituent atoms are located in a regular three-dimensional array as if they were located at the corners of the squares

6、of a three-dimensional chessboard. the spacing of the atoms in the array is of the same order as the size of the atoms, the actual spacing being a characteristic of the particular metal. the directions of the axes of the array define the orientation of the crystal in space. the metals commonly used

7、in engineering practice are composed of a large number of such crystals, called grains. in the most general case, the crystals of the various grains are randomly oriented in space. the grains are everywhere in intimate contact with one another and joined together on an atomic scale. the region at wh

8、ich they join is known as a grain boundary.an absolutely pure metal (i.e. one composed of only one type of atom) has never been produced. engineers would not be particularly interested in such a metal even if it were to be produced, because it would be soft and weak. the metals used commercially ine

9、vitably contain small amounts of one or more foreign elements, either metallic or nonmetallic. these foreign elements may be detrimental, they may be beneficial, or they may have no influence at all on a particular property. if disadvantageous, the foreign elements tend to be known as impurities. if

10、 advantageous, they tend to be known as alloying elements. alloying elements are commonly added deliberately in substantial amounts in engineering materials. the result is known as an alloy.the distinction between the descriptors “metal” and “alloy” is not clear-cut. the term “metal” may be used to

11、encompass both a commercially pure metal and its alloys. perhaps it can be said that the more deliberately an alloying addition has been made and the larger the amount of the addition, the more likely it is that the product will specifically be called an alloy. in any event, the chemical composition

12、 of a metal or an alloy must be known and controlled within certain limits if consistent performance is to be achieved in service. thus chemical composition has to be taken into account when developing an understanding of the factors which determine the properties of metals and their alloys.of the 5

13、0 or so metallic elements, only a few are produced and used in large quantities in engineering practice. the most important by far is iron, on which are based the ubiquitous steels and cast irons (basically alloys of iron and carbon). they account for about 98% by weight of all metals produced. next

14、 in importance for structural uses (that is, for structures that are expected to carry loads) are aluminum, copper, nickel, and titanium. aluminum accounts for about 0.8% by weight of all metals produced, and copper about 0.7%, leaving only 0.5% for all other metals. as might be expected, the remain

15、ders are all used in rather special applications. for example, nickel alloys are used principally in corrosion-and heat-resistant applications, while titanium is used extensively in the aerospace industry because its alloys have good combinations of high strength and low density. both nickel and tit

16、anium are used in high-cost, high-quality applications, and, indeed, it is their high cost that tends to restrict their application.we cannot discuss these more esoteric properties here. suffice it to say that a whole complex of properties in addition to structural strength is required of an alloy b

17、efore it will be accepted into, and survive in, engineering practice. it may, for example, have to be strong and yet have reasonable corrosion resistance; it may have to be able to be fabricated by a particular process such as deep drawing, machining, or welding; it may have to be readily recyclable

18、; and its cost and availability may be of critical importance.翻譯如下： 第一單元 金屬 在人類社會(huì)的發(fā)展中，金屬的應(yīng)用起著關(guān)鍵性的作用。構(gòu)成物質(zhì)的大約100種基本元素中，大約有一半為金屬。金屬和非金屬之間的區(qū)別不是特別明顯。最基本的定義集中在元素原子間存在的連接形式和與這些原子相關(guān)聯(lián)的電子的某些特性。然而，在實(shí)際應(yīng)用中，可以將具有某些特性集合金屬定義為某種元素。除了少數(shù)例外金屬在常溫下是固態(tài)的。它們是熱和電的良導(dǎo)體，不透光。它們往往具有較高的密度。許多金屬具有延展性，也就是說，在不被破壞的情況下它們的形狀在外力的作用下可以發(fā)生變化

19、。引起永久變形所需的力和最終使金屬斷裂所需的力相當(dāng)大，盡管發(fā)生斷裂所需的力遠(yuǎn)沒有像所預(yù)期的撕開金屬原子所需的力那么大。從我們的觀點(diǎn)來看，在所有的特性中結(jié)晶性是最重要的。結(jié)晶體是這樣一種結(jié)構(gòu)，組成它的原子定位在規(guī)則的三維排列中，仿佛位于三維棋盤的方格的角上。原子間距隨著原子大小呈規(guī)律性變化，原子間距是金屬的一種特性。三維排列的軸線決定了晶體在空間中的方向。在工程實(shí)踐中應(yīng)用的金屬由大量的晶體組成，這些晶體稱之為晶粒。在大多數(shù)情況下，晶粒在空間中是自由排列的。在原子范圍內(nèi)，晶粒之間相互接觸緊密結(jié)合。晶粒之間連接區(qū)域被稱為晶界。絕對(duì)純凈的金屬從來也沒有被生產(chǎn)出來過。即使絕對(duì)純凈的金屬可以生產(chǎn)出來，工程

20、師們對(duì)它們也并不會(huì)特別感興趣，因?yàn)樗鼈兒苋彳洝⒋嗳?。?shí)際應(yīng)用中的金屬往往都包含著一定數(shù)量的一種或多種外來金屬或非金屬元素，這些外來元素可能是有害的也可能是有益的或者它們對(duì)某種特定的屬性沒有影響。如果是有害的，這些外來元素被認(rèn)為是雜質(zhì)。如果是有益的，它們被認(rèn)為是合金元素。在工程材料中往往被特意地加入一定數(shù)量的合金元素。得到的物質(zhì)被叫做合金。金屬和合金區(qū)別不大。金屬這個(gè)詞可以包括工業(yè)用純金屬和它的合金。也許可以這樣說，合金元素越故意的被添加，被添加的合金元素的量越大，那么生產(chǎn)出來的產(chǎn)品越傾向于被稱之為合金。不管怎樣，如果想使一種金屬或合金在使用中表現(xiàn)出穩(wěn)定一致的特性，在其中添加何種化學(xué)成分，它的量

21、多大都應(yīng)該在控制范圍之內(nèi)。因此，當(dāng)想了解決定金屬和合金性質(zhì)的因素時(shí)，應(yīng)充分考慮它們的化學(xué)組成。在50種左右的金屬元素里，工程實(shí)踐中只有少數(shù)金屬被大量生產(chǎn)和使用。到目前為止最重要的是鐵，以它為基礎(chǔ)構(gòu)成了處處可見的鋼和鑄鐵。（主要由鐵和碳構(gòu)成的合金）它們的重量占所有生產(chǎn)出來的金屬重量的98%。在結(jié)構(gòu)應(yīng)用（也就是說，可以承受載荷的結(jié)構(gòu)）中居于其次位置的是鋁、銅、鎳和鈦。在所有的金屬產(chǎn)量中，鋁占0.8，銅占0.7，剩下的占0.5。剩下的金屬用于相對(duì)特殊的用途。例如，鎳合金主要用于抗磨損和耐高溫的用途，由于鈦合金具有高強(qiáng)度和低密度的綜合特性，鈦被廣泛應(yīng)用于航空工業(yè)中。鎳合鈦有高成本和高質(zhì)量的使用特性，事

22、實(shí)上，它們高的成本限制了它們的應(yīng)用。我們不能在這里討論這些深?yuàn)W的特性。在合金材料被采用和應(yīng)用于工程實(shí)際之前，掌握其結(jié)構(gòu)強(qiáng)度和它的綜合性質(zhì)就夠了。舉例來說，它可以強(qiáng)度很高，并且有好的耐磨性；它可以被例如拉伸加工，機(jī)械加工，或焊接等特殊工藝來加工出來；它可以被循環(huán)利用；它的成本和實(shí)用性是首要的。reading material 1 stainless steel stainless steels do not rust in the atmosphere as most other steels do. the term "stainless" implies a resist

23、ance to staining, rusting, and pitting in the air, moist and polluted as it is, and generally defines a chromium content in excess of 11 % but less than 30%. and the fact that the stuff is "steel" means that the base is iron. stainless steels have room-temperature yield strengths that rang

24、e from 205 mpa (30 ksi) to more than 1725 mpa (250 ksi). operating temperatures around 750 c (1400 f) are reached. at the other extreme of temperature some stainless steels maintain their toughness down to temperatures approaching absolute zero.with specific restrictions in certain types, the stainl

25、ess steels can be shaped and fabricated in conventional ways. they can be produced and used in the as-cast condition; shapes can be produced by powder-metallurgy techniques; cast ingots can be rolled or forged (and this accounts for the greatest tonnage by far). the rolled product can be drawn, bent

26、, extruded, or spun. stainless steel can be further shaped by machining, and it can be joined by soldering, brazing, and welding. it can be used as an integral cladding on plain carbon or low-alloy steels.the generic term "stainless steel" covers scores of standard compositions as well as

27、variations bearing company trade names and special alloys made for particular applications. stainless steels vary in their composition from a fairly simple alloy of, essentially, iron with 11% chromium, to complex alloys that include 30% chromium, substantial quantities of nickel, and half a dozen o

28、ther effective elements. at the high-chromium, high-nickel end of the range they merge into other groups of heat-resisting alloys, and one has to be arbitrary about a cutoff point. if the alloy content is so high that the iron content is about half, however, the alloy falls outside the stainless fam

29、ily. even with these imposed restrictions on composition, the range is great, and naturally, the properties that affect fabrication and use vary enormously. it is obviously not enough to specify simply a "stainless steel.”classification the various specifying bodies categorize stainless steels

30、according to chemical composition and other properties. however, all the stainless steels, whatever specifications they conform to, can be conveniently classified into six major classes that represent three distinct types of alloy constitution, or structure. these classes are ferritic, martensitic,

31、austenitic, manganese-substituted austenitic, duplex austenitic ferritic, and precipitation-hardening. each class is briefly described below. ferrous stainless steels: this class is so named because the crystal structure of the steel is the same as that of iron at room temperature. the alloys in the

32、 class are magnetic at room temperature and up to their curie temperature (about 750 c; 1400 f). common alloys in the ferrous class contain between 11% and 29% chromium, no nickel, and very little carbon in the wrought condition. martensitic stainless steels: stainless steels of this class, which ne

33、cessarily contain more than 11 % chromium, have such a great hardenability that substantial thickness will harden during air cooling, and nothing more drastic than oil quenching is ever required. the hardness of the as-quenched martensitic stainless steel depends on its carbon content. however, the

34、development of mechanical properties through quenching and tempering is inevitably associated with increased susceptibility to corrosion. austenitic stainless steels: the traditional and familiar austenitic stainless steels have a composition that contains sufficient chromium to offer corrosion resi

35、stance, together with nickel to ensure austenite at room temperature and below. the basic austenitic composition is the familiar l8% chromium, 8% nickel alloy. both chromium and nickel contents can be increased to improve corrosion resistance, and additional elements (most commonly molybdenum) can b

36、e added to further enhance corrosion resistance. manganese-substituted austenitic stainless steels: the austenitic structure can be encouraged by elements other than nickel, and the substitution of manganese and nitrogen produces a c1ass that we believe is sufficiently different in its properties to

37、 be separated from the chromium-nickel austenitic class just described. the most important difference lies in the higher strength of the manganese-substituted alloys. duplex austenitic-ferrous stainless steels: the structure of these steels is a hybrid of the structures of ferrite and austenite; and

38、 the mechanical properties likewise combine qualities of each component steel type. the duplex steels combine desirable corrosion and mechanical properties, and their use is as a result increasing in both wrought and cast form. precipitation-hardening stainless steels: stainless steels can be design

39、ed so that their composition is amenable to precipitation hardening. this class cuts across two of the other c1asses, to give us martensitic and austenitic precipitation-hardening stainless steels. in this class we find stainless steels with the greatest useful strength as well as the highest useful

40、 operating temperature.properties in selection of stainless steels, three kinds of properties have to be considered: (1) physical properties: density, thermal conductivity, electrical resistivity, and so on; (2) mechanical properties: strength, ductility, hardness, creep resistance, fatigue, and so

41、on; and (3) corrosion-resistant properties. note that properties of stainless steels are substantially influenced by chemica1 composition and microstructure. hence specifications include chemical composition, or, more correctly, an analysis of the most important elements (traces of unreported elemen

42、ts also may be present) as well as a heat treatment that provides the optimum structure.applications since stainless steels were first used in cutlery industry, the number of applications has increased dramatically. the relative importance of the major fields of application for flat and long stainle

43、ss steel products is shown in table 1. chemical and power engineering is the largest market for both long and flat products. it began in about 1920 with the nitric acid industry. today, it includes an extremely diversified range of service conditions, including nuclear reactor vessels, heat exchange

44、rs, oil industry tubular, components for the chemical processing and pulp and paper industries, furnace parts, and boilers used in fossil fuel electric power plants. 翻譯如下閱讀材料1 不銹鋼 不銹鋼就像其他大多數(shù)的鋼在空氣中不會(huì)生銹，“不銹的”這個(gè)術(shù)語暗示了在空氣中抵抗污點(diǎn)，生銹和腐蝕，還具有抵抗潮濕和腐蝕。通常含鉻量大于11%且小于30%.實(shí)際上叫鋼的材料就是鐵。不銹鋼在室溫下的屈服強(qiáng)度的變化范圍是從205mpa（30ksi)

45、到1725mpa(250ksi).工作溫度可達(dá)到750°c（1400f)，一些不銹鋼能維持其韌性當(dāng)溫度達(dá)到絕對(duì)零度。由于特定的類型有特殊的限制，不銹鋼可以通過常規(guī)方法成型和制造。它們可以在鑄造狀態(tài)下制造和運(yùn)用。其成型可以通過粉冶金技術(shù)，鑄造錠可以軋或者鍛造（這是至今為止最大的噸位）。軋制產(chǎn)品可以取出，彎曲，擠壓或旋轉(zhuǎn)。不銹鋼可以被進(jìn)一步用機(jī)械加工塑造成型，它可以加入錫焊，銅焊和焊接。還可以用于普通鋼和低合金鋼的整體電鍍。一般術(shù)語上說的“不銹鋼”包括數(shù)十種標(biāo)準(zhǔn)組成部分，還包括變更軸承公司交易名稱和特殊合金的獨(dú)特應(yīng)用。不銹鋼的合成成分各不相同，本質(zhì)上，從單一的合金，如含11%鉻的鐵到含3

46、0%鉻和大量鎳的與五六種其他有效成分的復(fù)雜合金。高含量的鉻和鎳最后組成其他好的熱穩(wěn)定性的合金，并且分界點(diǎn)必定的任意的。然而，如果合金含量太高，鐵的含量達(dá)到一半左右，該合金就不再是不銹家族了。即使這加強(qiáng)成分的限制，但是范圍很大，很自然，其性能將很大影響制造和應(yīng)用。顯然，不能單純地指定某一“不銹鋼”。劃分多種指定機(jī)體種類的不銹鋼要根據(jù)它們的化學(xué)成分和其他性質(zhì)。但是，全部的不銹鋼，不論它們屬于哪種規(guī)格，都可以被分為六大類，代表著三種不同的合金憲法或結(jié)構(gòu)。這類別是鐵素體，馬氏體，奧氏體，錳代鉻奧氏體，奧氏體-鐵素體雙相和沉淀硬化型，每種類別簡(jiǎn)述如下：鐵素體不銹鋼:這種類被這樣命名是因?yàn)殇摰木w結(jié)構(gòu)在室

47、溫下和鐵的相同。該類里的合金在室溫到居里溫度(about750 c; 1400 f)間具有磁性。普通的合金在鐵素體類別里含有11%到29%的鉻元素，沒有鎳，在鍛造條件中含有極少的碳。 馬氏體不銹鋼：這種類別的不銹鋼，需要含量超過11%的鉻，在巨大的淬透性下和冷空氣下將大幅度變硬，有時(shí)候要在比油淬更激烈的情況下進(jìn)行。淬火馬氏體不銹鋼的硬度取決于它的碳含量。然而，機(jī)械性能通過淬火、回火而形成和增加金屬易感性的腐蝕有著必然的聯(lián)系。 奧氏體不銹鋼：傳統(tǒng)和熟悉的奧氏體不銹鋼成分中擁有充分的鉻同時(shí)含有鎳元素保證奧氏體在室溫下或更低溫度的抗腐蝕性，奧氏體基本的成分是熟悉的18%鉻和8%鎳的合金。增加鉻和鎳的

48、含量可以提高抗腐蝕性，額外的元素（大多是鉬)能進(jìn)一步加強(qiáng)抗腐蝕性。 錳代鉻奧氏體不銹鋼：奧氏體結(jié)構(gòu)被鼓勵(lì)通過描述和我們相信它充分的不同性能從鉻鎳奧氏體中分離出來，通過加進(jìn)其他元素如鎳、錳的替代物和氮的方法。最重要的區(qū)別在于高強(qiáng)度的錳代鉻合金。 奧氏體-鐵素體雙相不銹鋼： 這種結(jié)構(gòu)的鋼是鐵素體和奧氏體的混合體；機(jī)械性能也相似于組成的鋼的質(zhì)量的結(jié)合。雙重鋼結(jié)合想要的腐蝕性和機(jī)械性能，它們的用途使鍛造和鑄造形式更加困難。 沉淀硬化型不銹鋼：不銹鋼可以被設(shè)計(jì)使它們的成分服從沉淀硬化。這種類跨過其他兩種類別，給我們馬氏體和奧氏體沉淀硬化型不銹鋼。在這種類型我們發(fā)現(xiàn)不銹鋼有最多有用的強(qiáng)度和最高有用的操作溫

49、度。 性能 在選擇不銹鋼時(shí)，三種性能必須加以考慮：（1）物理性能：密度，導(dǎo)熱系數(shù)，電阻率等；（2)機(jī)械性能：強(qiáng)度，韌性，硬度，蠕變阻力，疲勞度等；（3）抗腐蝕性能：要認(rèn)識(shí)到化學(xué)成分和微觀結(jié)構(gòu)在本質(zhì)上影響不銹鋼的性能。因此規(guī)格包括化學(xué)構(gòu)成，或者更準(zhǔn)確地說，一種最重要的成分（沒被公布的成分的蹤跡會(huì)被呈現(xiàn)）的分析和熱療將提供最適宜的結(jié)構(gòu)。 應(yīng)用 自從不銹鋼第一次被應(yīng)用于餐具，刀劍工業(yè)，到現(xiàn)在應(yīng)用的數(shù)量戲劇性的增加。對(duì)單位和長(zhǎng)期不銹鋼商品的相對(duì)重要的主要應(yīng)用領(lǐng)域如表1所示?；瘜W(xué)和電力是單位和長(zhǎng)期不銹鋼商品的最大市場(chǎng)。它開始與約1920年的硝酸工業(yè)。如今，它包括極其多種多樣的服務(wù)條件，包括核反應(yīng)船舶，熱

50、交換器，石油工業(yè)管道，部分化學(xué)加工，紙漿和造紙工業(yè)，熔爐部件和化石燃料發(fā)電廠使用的鍋爐。 unit 2 selection of construction materials there is not a great difference between “this” steel and “that” steel; all are very similar in mechanical properties. selection must be made on factors such as hardenability, price, and availability, and not with

51、 the idea that “this” steel can do something no other can do because it contains 2 percent instead of 1 percent of a certain alloying element, or because it has a mysterious name. a tremendous range of properties is available in any steel after heat treatment; this is particularly true of alloy stee

52、ls.considerations in fabrication( the properties of the final part (hardness, strength, and machinability), rather than properties required by forging, govern the selection of material. the properties required for forging have very little relation to the final properties of the material; therefore,

53、not much can be done to improve its forgeability. higher-carbon steel is difficult to forge. large grain size is best if subsequent heat treatment will refine the grain size. low-carbon, nickel-chromium steels are just about as plastic at high temperature under a single 520-ft·lb(1 ft·lb=1

54、.35582j) blow as plain steels of similar carbon content. nickel decreases forgeability of medium-carbon steels, but has little effect on low-carbon steels. chromium seems to harden steel at forging temperatures, but vanadium has no discernible effect; neither has the method of manufacture any effect

55、 on high-carbon steel.formability the cold-formability of steel is a function of its tensile strength combined with ductility. the tensile strength and yield point must not be high or too much work will be required in bending ; likewise , the steel must have sufficient ductility to flow to the requi

56、red shape without cracking. the force required depends on the yield point, because deformation starts in the plastic range above the yield point of steel. work-hardening also occurs here, progressively stiffening ， the metal and causing difficulty, particularly in the low-carbon steels. it is quite

57、interesting in this connection to discover that deep draws can sometimes be made in one rapid operation that could not possibly be done leisurely in two or three. if a draw is half made and then stopped, it may be necessary to anneal before proceeding, that is , if the piece is given time to work-ha

58、rden. this may not be a scientific statement, but it is actually what seems to happen.internal stresses cold forming is done above the yield point in the work-hardening range, so internal stresses can be built up easily. evidence of this is the springback as the work leaves the forming operation and

59、 the warpage in any subsequent heat treatment. even a simple washer might, by virtue of( the internal stresses resulting from punching and then flattening , warp severely during heat treating. believed in the virtue of prayer. when doubt exists as to whether internal stresses will cause warpage, a piece can be checked by heating it to about 1100 and then letting i