機(jī)械工程英語(yǔ)第二版翻譯

1、 .111/111第一單元Types of Materials 材料的類型Materials may be grouped in several ways. Scientists often classify materials by their state: solid, liquid, or gas. They also separate them into organic (once living) and inorganic (never living) materials.材料可以按多種方法分類?？茖W(xué)家常根據(jù)狀態(tài)將材料分為：固體、液體或氣體。他們也把材料分為有機(jī)材料(曾經(jīng)有生命的)和

2、無(wú)機(jī)材料(從未有生命的)。For industrial purposes, materials are divided into engineering materials or nonengineering materials. Engineering materials are those used in manufacture and become parts of products.就工業(yè)效用而言，材料被分為工程材料和非工程材料。那些用于加工制造并成為產(chǎn)品組成部分的就是工程材料。Nonengineering materials are the chemicals, fuels, lub

3、ricants, and other materials used in the manufacturing process, which do not become part of the product.非工程材料則是化學(xué)品、燃料、潤(rùn)滑劑以與其它用于加工制造過(guò)程但不成為產(chǎn)品組成部分的材料。Engineering materials may be further subdivided into: Metal Ceramics Composite Polymers, etc.工程材料還能進(jìn)一步細(xì)分為：金屬材料瓷材料復(fù)合材料 聚合材料，等等。Metals and Metal Alloys 金屬和

4、金屬合金Metals are elements that generally have good electrical and thermal conductivity. Many metals have high strength, high stiffness, and have good ductility.金屬就是通常具有良好導(dǎo)電性和導(dǎo)熱性的元素。許多金屬具有高強(qiáng)度、高硬度以與良好的延展性。Some metals, such as iron, cobalt and nickel, are magnetic. At low temperatures, some metals and in

5、termetallic compounds become superconductors.某些金屬能被磁化，例如鐵、鈷和鎳。在極低的溫度下，某些金屬和金屬化合物能轉(zhuǎn)變成超導(dǎo)體。What is the difference between an alloy and a pure metal? Pure metals are elements which come from a particular area of the periodic table. Examples of pure metals include copper in electrical wires and aluminum

6、in cooking foil and beverage cans.合金與純金屬的區(qū)別是什么？純金屬是在元素周期表中占據(jù)特定位置的元素。例如電線中的銅和制造烹飪箔與飲料罐的鋁。Alloys contain more than one metallic element. Their properties can be changed by changing the elements present in the alloy. Examples of metal alloys include stainless steel which is an alloy of iron, nickel, an

7、d chromium; and gold jewelry which usually contains an alloy of gold and nickel.合金包含不止一種金屬元素。合金的性質(zhì)能通過(guò)改變其中存在的元素而改變。金屬合金的例子有：不銹鋼是一種鐵、鎳、鉻的合金，以與金飾品通常含有金鎳合金。Why are metals and alloys used? Many metals and alloys have high densities and are used in applications which require a high mass-to-volume ratio.為什

8、么要使用金屬和合金？許多金屬和合金具有高密度，因此被用在需要較高質(zhì)量體積比的場(chǎng)合。Some metal alloys, such as those based on aluminum, have low densities and are used in aerospace applications for fuel economy. Many alloys also have high fracture toughness, which means they can withstand impact and are durable.某些金屬合金，例如鋁基合金，其密度低，可用于航空航天以節(jié)約燃

9、料。許多合金還具有高斷裂韌性，這意味著它們能經(jīng)得起沖擊并且是耐用的。What are some important properties of metals?Density is defined as a materials mass divided by its volume. Most metals have relatively high densities, especially compared to polymers.金屬有哪些重要特性？密度定義為材料的質(zhì)量與其體積之比。大多數(shù)金屬密度相對(duì)較高，尤其是和聚合物相比較而言。Materials with high densities o

10、ften contain atoms with high atomic numbers, such as gold or lead. However, some metals such as aluminum or magnesium have low densities, and are used in applications that require other metallic properties but also require low weight.高密度材料通常由較大原子序數(shù)原子構(gòu)成，例如金和鉛。然而，諸如鋁和鎂之類的一些金屬則具有低密度，并被用于既需要金屬特性又要求重量輕的場(chǎng)

11、合。Fracture toughness can be described as a materials ability to avoid fracture, especially when a flaw is introduced. Metals can generally contain nicks and dents without weakening very much, and are impact resistant. A football player counts on this when he trusts that his facemask wont shatter.斷裂韌

12、性可以描述為材料防止斷裂特別是出現(xiàn)缺陷時(shí)不斷裂的能力。金屬一般能在有缺口和凹痕的情況下不顯著削弱，并且能抵抗沖擊。橄欖球運(yùn)動(dòng)員據(jù)此相信他的面罩不會(huì)裂成碎片。Plastic deformation is the ability of bend or deform before breaking. As engineers, we usually design materials so that they dont deform under normal conditions. You dont want your car to lean to the east after a strong we

13、st wind.塑性變形就是在斷裂前彎曲或變形的能力。作為工程師，設(shè)計(jì)時(shí)通常要使材料在正常條件下不變形。沒(méi)有人愿意一陣強(qiáng)烈的西風(fēng)過(guò)后自己的汽車向東傾斜。However, sometimes we can take advantage of plastic deformation. The crumple zones in a car absorb energy by undergoing plastic deformation before they break.然而，有時(shí)我們也能利用塑性變形。汽車上壓皺的區(qū)域在它們斷裂前通過(guò)經(jīng)歷塑性變形來(lái)吸收能量。The atomic bonding of

14、metals also affects their properties. In metals, the outer valence electrons are shared among all atoms, and are free to travel everywhere. Since electrons conduct heat and electricity, metals make good cooking pans and electrical wires.金屬的原子連結(jié)對(duì)它們的特性也有影響。在金屬部，原子的外層階電子由所有原子共享并能到處自由移動(dòng)。由于電子能導(dǎo)熱和導(dǎo)電，所以用金屬

15、可以制造好的烹飪鍋和電線。It is impossible to see through metals, since these valence electrons absorb any photons of light which reach the metal. No photons pass through.因?yàn)檫@些階電子吸收到達(dá)金屬的光子，所以透過(guò)金屬不可能看得見。沒(méi)有光子能通過(guò)金屬。Alloys are compounds consisting of more than one metal. Adding other metals can affect the density, st

16、rength, fracture toughness, plastic deformation, electrical conductivity and environmental degradation.合金是由一種以上金屬組成的混合物。加一些其它金屬能影響密度、強(qiáng)度、斷裂韌性、塑性變形、導(dǎo)電性以與環(huán)境侵蝕。For example, adding a small amount of iron to aluminum will make it stronger. Also, adding some chromium to steel will slow the rusting process,

17、 but will make it more brittle.例如，往鋁里加少量鐵可使其更強(qiáng)。同樣，在鋼里加一些鉻能減緩它的生銹過(guò)程，但也將使它更脆。Ceramics and Glasses瓷和玻璃A ceramic is often broadly defined as any inorganic nonmetallic material By this definition, ceramic materials would also include glasses; however, many materials scientists add the stipulation that “c

18、eramic” must also be crystalline.瓷通常被概括地定義為無(wú)機(jī)的非金屬材料。照此定義，瓷材料也應(yīng)包括玻璃；然而許多材料科學(xué)家添加了“瓷”必須同時(shí)是晶體物組成的約定。A glass is an inorganic nonmetallic material that does not have a crystalline structure. Such materials are said to be amorphous.玻璃是沒(méi)有晶體狀結(jié)構(gòu)的無(wú)機(jī)非金屬材料。這種材料被稱為非結(jié)晶質(zhì)材料。Properties of Ceramics and GlassesSome of

19、the useful properties of ceramics and glasses include high melting temperature, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance.瓷和玻璃的特性高熔點(diǎn)、低密度、高強(qiáng)度、高剛度、高硬度、高耐磨性和抗腐蝕性是瓷和玻璃的一些有用特性。Many ceramics are good electrical and thermal insulators. Some ceramics have spe

20、cial properties: some ceramics are magnetic materials; some are piezoelectric materials; and a few special ceramics are superconductors at very low temperatures. Ceramics and glasses have one major drawback: they are brittle.許多瓷都是電和熱的良絕緣體。某些瓷還具有一些特殊性能：有些是磁性材料，有些是壓電材料，還有些特殊瓷在極低溫度下是超導(dǎo)體。瓷和玻璃都有一個(gè)主要的缺點(diǎn)：它

21、們?nèi)菀灼扑椤eramics are not typically formed from the melt. This is because most ceramics will crack extensively (i.e. form a powder) upon cooling from the liquid state.瓷一般不是由熔化形成的。因?yàn)榇蠖鄶?shù)瓷在從液態(tài)冷卻時(shí)將會(huì)完全破碎(即形成粉末)。Hence, all the simple and efficient manufacturing techniques used for glass production such as ca

22、sting and blowing, which involve the molten state, cannot be used for the production of crystalline ceramics. Instead, “sintering” or “firing” is the process typically used.因此，所有用于玻璃生產(chǎn)的簡(jiǎn)單有效的諸如澆鑄和吹制這些涉與熔化的技術(shù)都不能用于由晶體物組成的瓷的生產(chǎn)。作為替代，一般采用“燒結(jié)”或“焙燒”工藝。In sintering, ceramic powders are processed into compact

23、ed shapes and then heated to temperatures just below the melting point. At such temperatures, the powders react internally to remove porosity and fully dense articles can be obtained.在燒結(jié)過(guò)程中，瓷粉末先擠壓成型然后加熱到略低于熔點(diǎn)溫度。在這樣的溫度下，粉末部起反應(yīng)去除孔隙并得到十分致密的物品。An optical fiber contains three layers: a core made of highl

24、y pure glass with a high refractive index for the light to travel, a middle layer of glass with a lower refractive index known as the cladding which protects the core glass from scratches and other surface imperfections, and an out polymer jacket to protect the fiber from damage.光導(dǎo)纖維有三層：核心由高折射指數(shù)高純光傳

25、輸玻璃制成，中間層為低折射指數(shù)玻璃，是保護(hù)核心玻璃表面不被擦傷和完整性不被破壞的所謂覆層，外層是聚合物護(hù)套，用于保護(hù)光導(dǎo)纖維不受損。In order for the core glass to have a higher refractive index than the cladding, the core glass is doped with a small, controlled amount of an impurity, or dopant, which causes light to travel slower, but does not absorb the light.為了使

26、核心玻璃有比覆層大的折射指數(shù)，在其中摻入微小的、可控?cái)?shù)量的能減緩光速而不會(huì)吸收光線的雜質(zhì)或攙雜劑。Because the refractive index of the core glass is greater than that of the cladding, light traveling in the core glass will remain in the core glass due to total internal reflection as long as the light strikes the core/cladding interface at an angle

27、greater than the critical angle.由于核心玻璃的折射指數(shù)比覆層大，只要在全反射過(guò)程中光線照射核心/覆層分界面的角度比臨界角大，在核心玻璃中傳送的光線將仍保留在核心玻璃中。The total internal reflection phenomenon, as well as the high purity of the core glass, enables light to travel long distances with little loss of intensity.全反射現(xiàn)象與核心玻璃的高純度一樣，使光線幾乎無(wú)強(qiáng)度損耗傳遞長(zhǎng)距離成為可能。Compos

28、ites 復(fù)合材料Composites are formed from two or more types of materials. Examples include polymer/ceramic and metal/ceramic composites. Composites are used because overall properties of the composites are superior to those of the individual components.復(fù)合材料由兩種或更多材料構(gòu)成。例子有聚合物/瓷和金屬/瓷復(fù)合材料。之所以使用復(fù)合材料是因?yàn)槠淙嫘阅軆?yōu)于組

29、成部分單獨(dú)的性能。For example: polymer/ceramic composites have a greater modulus than the polymer component, but arent as brittle as ceramics.Two types of composites are: fiber-reinforced composites and particle-reinforced composites.例如：聚合物/瓷復(fù)合材料具有比聚合物成分更大的模量，但又不像瓷那樣易碎。復(fù)合材料有兩種：纖維加強(qiáng)型復(fù)合材料和微粒加強(qiáng)型復(fù)合材料。Fiber-reinf

30、orced CompositesReinforcing fibers can be made of metals, ceramics, glasses, or polymers that have been turned into graphite and known as carbon fibers. Fibers increase the modulus of the matrix material.纖維加強(qiáng)型復(fù)合材料加強(qiáng)纖維可以是金屬、瓷、玻璃或是已變成石墨的被稱為碳纖維的聚合物。纖維能加強(qiáng)基材的模量。The strong covalent bonds along the fibers

31、length give them a very high modulus in this direction because to break or extend the fiber the bonds must also be broken or moved.沿著纖維長(zhǎng)度有很強(qiáng)結(jié)合力的共價(jià)結(jié)合在這個(gè)方向上給予復(fù)合材料很高的模量，因?yàn)橐獡p壞或拉伸纖維就必須破壞或移除這種結(jié)合。Fibers are difficult to process into composites, making fiber-reinforced composites relatively expensive.把纖維放入復(fù)

32、合材料較困難，這使得制造纖維加強(qiáng)型復(fù)合材料相對(duì)昂貴。Fiber-reinforced composites are used in some of the most advanced, and therefore most expensive sports equipment, such as a time-trial racing bicycle frame which consists of carbon fibers in a thermoset polymer matrix.纖維加強(qiáng)型復(fù)合材料用于某些最先進(jìn)也是最昂貴的運(yùn)動(dòng)設(shè)備，例如計(jì)時(shí)賽競(jìng)賽用自行車骨架就是用含碳纖維的熱固塑料基材制成

33、的。Body parts of race cars and some automobiles are composites made of glass fibers (or fiberglass) in a thermoset matrix.競(jìng)賽用汽車和某些機(jī)動(dòng)車的車體部件是由含玻璃纖維(或玻璃絲)的熱固塑料基材制成的。Fibers have a very high modulus along their axis, but have a low modulus perpendicular to their axis. Fiber composite manufacturers often r

34、otate layers of fibers to avoid directional variations in the modulus.纖維在沿著其軸向有很高的模量，但垂直于其軸向的模量卻較低。纖維復(fù)合材料的制造者往往旋轉(zhuǎn)纖維層以防模量產(chǎn)生方向變化。Particle-reinforced compositesParticles used for reinforcing include ceramics and glasses such as small mineral particles, metal particles such as aluminum, and amorphous ma

35、terials, including polymers and carbon black.微粒加強(qiáng)型復(fù)合材料用于加強(qiáng)的微粒包含了瓷和玻璃之類的礦物微粒，鋁之類的金屬微粒以與包括聚合物和碳黑的非結(jié)晶質(zhì)微粒。Particles are used to increase the modulus of the matrix, to decrease the permeability of the matrix, to decrease the ductility of the matrix. An example of particle-reinforced composites is an auto

36、mobile tire which has carbon black particles in a matrix of polyisobutylene elastomeric polymer.微粒用于增加基材的模量、減少基材的滲透性和延展性。微粒加強(qiáng)型復(fù)合材料的一個(gè)例子是機(jī)動(dòng)車胎，它就是在聚異丁烯人造橡膠聚合物基材中加入了碳黑微粒。Polymers 聚合材料A polymer has a repeating structure, usually based on a carbon backbone. The repeating structure results in large chainl

37、ike molecules. Polymers are useful because they are lightweight, corrosion resistant, easy to process at low temperatures and generally inexpensive.聚合物具有一般是基于碳鏈的重復(fù)結(jié)構(gòu)。這種重復(fù)結(jié)構(gòu)產(chǎn)生鏈狀大分子。由于重量輕、耐腐蝕、容易在較低溫度下加工并且通常較便宜，聚合物是很有用的。Some important characteristics of polymers include their size (or molecular weight)

38、, softening and melting points, crystallinity, and structure. The mechanical properties of polymers generally include low strength and high toughness. Their strength is often improved using reinforced composite structures.聚合材料具有一些重要特性，包括尺寸(或分子量)、軟化與熔化點(diǎn)、結(jié)晶度和結(jié)構(gòu)。聚合材料的機(jī)械性能一般表現(xiàn)為低強(qiáng)度和高韌性。它們的強(qiáng)度通?？刹捎眉訌?qiáng)復(fù)合結(jié)構(gòu)來(lái)改

39、善。Important Characteristics of PolymersSize. Single polymer molecules typically have molecular weights between 10,000 and 1,000,000g/molthat can be more than 2,000 repeating units depending on the polymer structure!聚合材料的重要特性尺寸：?jiǎn)蝹€(gè)聚合物分子一般分子量為10,000到1,000,000g/mol之間，具體取決于聚合物的結(jié)構(gòu)這可以比2,000個(gè)重復(fù)單元還多。The mech

40、anical properties of a polymer are significantly affected by the molecular weight, with better engineering properties at higher molecular weights.聚合物的分子量極影響其機(jī)械性能，分子量越大，工程性能也越好。Thermal transitions. The softening point (glass transition temperature) and the melting point of a polymer will determine wh

41、ich it will be suitable for applications. These temperatures usually determine the upper limit for which a polymer can be used.熱轉(zhuǎn)換性：聚合物的軟化點(diǎn)(玻璃狀轉(zhuǎn)化溫度)和熔化點(diǎn)決定了它是否適合應(yīng)用。這些溫度通常決定聚合物能否使用的上限。For example, many industrially important polymers have glass transition temperatures near the boiling point of water (

42、100, 212), and they are most useful for room temperature applications. Some specially engineered polymers can withstand temperatures as high as 300(572).例如，許多工業(yè)上的重要聚合物其玻璃狀轉(zhuǎn)化溫度接近水的沸點(diǎn)(100, 212)，它們被廣泛用于室溫下。而某些特別制造的聚合物能經(jīng)受住高達(dá)300(572)的溫度。Crystallinity. Polymers can be crystalline or amorphous, but they us

43、ually have a combination of crystalline and amorphous structures (semi-crystalline).結(jié)晶度：聚合物可以是晶體狀的或非結(jié)晶質(zhì)的，但它們通常是晶體狀和非結(jié)晶質(zhì)結(jié)構(gòu)的結(jié)合物(半晶體)。Interchain interactions. The polymer chains can be free to slide past one another (thermo-plastic) or they can be connected to each other with crosslinks (thermoset or e

44、lastomer). Thermo-plastics can be reformed and recycled, while thermosets and elastomers are not reworkable.原子鏈間的相互作用：聚合物的原子鏈可以自由地彼此滑動(dòng)(熱可塑性)或通過(guò)交鍵互相連接(熱固性或彈性)。熱可塑性材料可以重新形成和循環(huán)使用，而熱固性與彈性材料則是不能再使用的。Intrachain structure. The chemical structure of the chains also has a tremendous effect on the properties.

45、 Depending on the structure the polymer may be hydrophilic or hydrophobic (likes or hates water), stiff or flexible, crystalline or amorphous, reactive or unreactive.鏈結(jié)構(gòu)：原子鏈的化學(xué)結(jié)構(gòu)對(duì)性能也有很大影響。根據(jù)各自的結(jié)構(gòu)不同，聚合物可以是親水的或憎水的(喜歡或討厭水)、硬的或軟的、晶體狀的或非結(jié)晶質(zhì)的、易起反應(yīng)的或不易起反應(yīng)的。第二單元The understanding of heat treatment is embrace

46、d by the broader study of metallurgy. Metallurgy is the physics, chemistry, and engineering related to metals from ore extraction to the final product.對(duì)熱處理的理解包含于對(duì)冶金學(xué)較廣泛的研究。冶金學(xué)是物理學(xué)、化學(xué)和涉與金屬?gòu)牡V石提煉到最后產(chǎn)物的工程學(xué)。Heat treatment is the operation of heating and cooling a metal in its solid state to change its ph

47、ysical properties. According to the procedure used, steel can be hardened to resist cutting action and abrasion, or it can be softened to permit machining.熱處理是將金屬在固態(tài)加熱和冷卻以改變其物理性能的操作。按所采用的步驟，鋼可以通過(guò)硬化來(lái)抵抗切削和磨損，也可以通過(guò)軟化來(lái)允許機(jī)加工。With the proper heat treatment internal stresses may be removed, grain size redu

48、ced, toughness increased, or a hard surface produced on a ductile interior. The analysis of the steel must be known because small percentages of certain elements, notably carbon, greatly affect the physical properties.使用合適的熱處理可以去除應(yīng)力、細(xì)化晶粒、增加韌性或在柔軟材料上覆蓋堅(jiān)硬的表面。因?yàn)槟承┰?尤其是碳)的微小百分比極影響物理性能，所以必須知道對(duì)鋼的分析。Alloy

49、 steel owe their properties to the presence of one or more elements other than carbon, namely nickel, chromium, manganese, molybdenum, tungsten, silicon, vanadium, and copper. Because of their improved physical properties they are used commercially in many ways not possible with carbon steels.合金鋼的性質(zhì)

50、取決于其所含有的除碳以外的一種或多種元素，如鎳、鉻、錳、鉬、鎢、硅、釩和銅。由于合金鋼改善的物理性能，它們被大量使用在許多碳鋼不適用的地方。The following discussion applies principally to the heat treatment of ordinary commercial steels known as plain carbon steels. With this process the rate of cooling is the controlling factor, rapid cooling from above the critical

51、range results in hard structure, whereas very slow cooling produces the opposite effect.下列討論主要針對(duì)被稱為普通碳鋼的工業(yè)用鋼而言。熱處理時(shí)冷卻速率是控制要素，從高于臨界溫度快速冷卻導(dǎo)致堅(jiān)硬的組織結(jié)構(gòu)，而緩慢冷卻則產(chǎn)生相反效果。A Simplified Iron-carbon Diagram簡(jiǎn)化鐵碳狀態(tài)圖If we focus only on the materials normally known as steels, a simplified diagram is often used.如果只把注意力

52、集中于一般所說(shuō)的鋼上，經(jīng)常要用到簡(jiǎn)化鐵碳狀態(tài)圖。Those portions of the iron-carbon diagram near the delta region and those above 2% carbon content are of little importance to the engineer and are deleted. A simplified diagram, such as the one in Fig.2.1, focuses on the eutectoid region and is quite useful in understanding t

53、he properties and processing of steel.鐵碳狀態(tài)圖中靠近三角區(qū)和含碳量高于2%的那些部分對(duì)工程師而言不重要，因此將它們刪除。如圖2.1所示的簡(jiǎn)化鐵碳狀態(tài)圖將焦點(diǎn)集中在共析區(qū)，這對(duì)理解鋼的性能和處理是十分有用的。The key transition described in this diagram is the decomposition of single-phase austenite() to the two-phase ferrite plus carbide structure as temperature drops.在此圖中描述的關(guān)鍵轉(zhuǎn)變是單相

54、奧氏體() 隨著溫度下降分解成兩相鐵素體加滲碳體組織結(jié)構(gòu)。Control of this reaction, which arises due to the drastically different carbon solubility of austenite and ferrite, enables a wide range of properties to be achieved through heat treatment.控制這一由于奧氏體和鐵素體的碳溶解性完全不同而產(chǎn)生的反應(yīng)，使得通過(guò)熱處理能獲得很大圍的特性。To begin to understand these process

55、es, consider a steel of the eutectoid composition, 0.77% carbon, being slow cooled along line x-x in Fig.2.1. At the upper temperatures, only austenite is present, the 0.77% carbon being dissolved in solid solution with the iron. When the steel cools to 727(1341), several changes occur simultaneousl

56、y.為了理解這些過(guò)程，考慮含碳量為0.77%的共析鋼，沿著圖2.1的x-x線慢慢冷卻。在較高溫度時(shí)，只存在奧氏體，0.77%的碳溶解在鐵里形成固溶體。當(dāng)鋼冷卻到727 (1341)時(shí)，將同時(shí)發(fā)生若干變化。The iron wants to change from the FCC austenite structure to the BCC ferrite structure, but the ferrite can only contain 0.02% carbon in solid solution.鐵需要從面心立方體奧氏體結(jié)構(gòu)轉(zhuǎn)變?yōu)轶w心立方體鐵素體結(jié)構(gòu)，但是鐵素體只能容納固溶體狀態(tài)的0.0

57、2%的碳。The rejected carbon forms the carbon-rich cementite intermetallic with composition Fe3C. In essence, the net reaction at the eutectoid is austenite 0.77%Cferrite 0.02%C+cementite 6.67%C.被析出的碳與金屬化合物Fe3C形成富碳的滲碳體。本質(zhì)上，共析體的基本反應(yīng)是奧氏體0.77%的碳鐵素體0.02%的碳+滲碳體6.67%的碳。Since this chemical separation of the ca

58、rbon component occurs entirely in the solid state, the resulting structure is a fine mechanical mixture of ferrite and cementite. Specimens 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.由

59、于這種碳成分的化學(xué)分離完全發(fā)生在固態(tài)中，產(chǎn)生的組織結(jié)構(gòu)是一種細(xì)致的鐵素體與滲碳體的機(jī)械混合物。通過(guò)打磨并在弱硝酸酒精溶液中蝕刻制備的樣本顯示出由緩慢冷卻形成的交互層狀的薄片結(jié)構(gòu)。This structure is composed of two distinct phases, but has its own set of characteristic properties and goes by the name pearlite, because of its resemblance to mother- of- pearl at low magnification.這種結(jié)構(gòu)由兩種截然不同

60、的狀態(tài)組成，但它本身具有一系列特性，且因與低倍數(shù)放大時(shí)的珠母層有類同之處而被稱為珠光體。Steels having less than the eutectoid amount of carbon (less than 0.77%) are known as hypo-eutectoid steels. Consider now the transformation of such a material represented by cooling along line y-y in Fig.2.1.含碳量少于共析體(低于0.77%)的鋼稱為亞共析鋼?，F(xiàn)在來(lái)看這種材料沿著圖2.1中y-y 線冷