普通碳素钢毕业论文外文翻译

1、外文资料翻译plain carbon steelany steel-making process is capable of producing a product that has 0.05% or less carbon. with this small amount of carbon, the properties approach of pure iron with maximum ductility and minimum strength. maximum ductility is desirable from the standpoint of ease in deformat

2、ion processing and service use. minimum strength is desirable for deformation processing. however, higher strengths than that obtainable with this low carbon are desirable from the standpoint of product design. the most practical means of increasing the strength is by the addition or retention of so

3、me carbon. however, it should be fully understood that any increase of strength over that pure iron can be obtained only at the expense of some loss of ductility, and the final choice is always a compromise of some degree. because of the difficulty of composition control or the additional operation

4、of increasing carbon content, the cost of higher carbon, higher strength steel is greater than of low carbon.plain carbon steels most used. because of their low cost, the majority of steels used are plain carbon steels. these consist of iron combined with carbon concentrated in there ranges classed

5、as low carbon,medium carbon, and high carbon. with the exception of manganese used to control sulphur, other elements are present only in small enough quantities to be considered as impurities, though in some cases they may have minor effect on properties of the materiallow carbon. steel with approx

6、imately 6 to 25 points of carbon (0.06% 0.25%)are rated as low carbon steels and are rarely hardened by heat treatment because the low carbon content permits so little formation of hard magnesite that the process is relatively ineffective. enormous tonnages of these low carbon steels are processed i

7、n such structural shapes as sheet, strip,rod,plate,pipe,and wire. a large portion of the material is cold worked in its final processing to improve its hardness, strength, and surface-finish qualities.the grades containing 20 points or less of carbon are susceptible to considerable plastic flow and

8、are frequently used as deep-drawn products or may be used as a ductile core for casehardened material. the low lain carbon steels are reality brazed, welded, and forged.medium carbon. the medium carbon steels (0.25%0.5%)contain sufficient carbon that they may be heat treated for desirable strength,

9、hardness, machinability, or other properties. the hardness of plain carbon steels in this range cannot be increased sufficiently for the material to serve satisfactorily as cutting tools,but the load-carrying capacity of the steels can be raised considerably, while still retaining sufficient ductili

10、ty for good toughness. the majority of the steel is furnished in the hot-rolled condition and is often machined for final finishing. it can be welded,but is more difficult to join by this method than the low carbon steel because of structural changes caused by welding heat in localized areas.high ca

11、rbon. high carbon steel contains from 50 to 160 points of carbon (0.8%1.6%) this group of steels is classed as tool and die steel, in which hardness is the principal property desired. because of the fast reaction time and resulting low hardenability, and its associated danger of distortion or cracki

12、ng, it is seldom possible to develop fully of heat-treat-hardened plain carbon steel is low compared to that of alloy steels with the same strength, but, even so, carbon steel is frequently used because of its lower cost.alloy steelsalthough plain carbon steels work well for many uses and are the ch

13、eapest steels and therefore the most used, they cannot completely fulfill the requirements for some work. individual or groups of properties can be improved by addition of various elements in the form of alloys. even plain carbon steels are alloys of at least iron, carbon, and manganese, but the ter

14、m alloy steel refers to steels containing elements other than these in controlled quantities greater than impurity concentration or, in the case of manganese, greater than 1.5%.alloys affect hardenability< interest in hardenability is indirect. hardenability is usually thought of most in connecti

15、on with depthhanlening ability in a full hardening operation. however, with the isothermal transformation curves shifted to the right, the properties forging operations, the materially usually air cools. any alloy generally shifts the transformation curves to the right, which with air cooling result

16、s in finer pearlite than would be formed in a plain carbon steel. this finer pearlite has higher hardness and strength, which has an effect on machinability and may lower ductility.weldability. the generally bad influence of alloys on weldability is a further reflection of the influence on hardenabi

17、lity. with alloys present is a further reflection of the influence on hardenability. with alloys present during the rapid cooling taking place in the welding area, hard, nonductile structures are formed in the steel and frequently lead to cracking and distortion.grain size and toughness. nickel in p

18、articular has a very beneficial effect by retarding grain growth in the austenite range. as with hardenability, it is the secondary effects of grain refinement that are noted in properties- a finer grain structure may actually have less hardenability, but it has its most pronounced effect on toughne

19、ss; for two steels with equivalent in the chart as improved toughness. this improved toughness, however, may be detrimental to machinability.corrosion resistance. most pure metals have relatively good corrosion resistance, which is generally lowered by impurities or small amounts of intentional allo

20、ys. in steel, carbon in particular lowers the corrosion resistance very seriously. in small percentages, copper and phosphorus are beneficial in reducing corrosion. nickel becomes effective in percentages of about %, and chromium is extremely effective in percentages greater than %,which leads to a

21、separate class of alloy steels called stainless steels. many tool steels,while not designed for the purpose, are in effect stainless steels because of the high percentage of chromium present.low alloy structural steelscertain low alloy steels sold under various trade names have been developed to pro

22、vide a low cost structural material with higher yield strengh than plain carbon steel. the addition of small amount of some alloying elements can raise the yield strength of hot-rolled sections without heat treatment to 30%40% greater than that of plain carbon steels. designing to higher working str

23、esses may reduce the required section size by 25%30% at an increased cost of 15%50%,depending upon the amount and the kind of alloy.the low alloy structural steels are sold almost entirely in the form of hot -rolled structural shapes. these materials have good weldability, ductility, better impact s

24、trength than that of plain carbon steel, and good corrosion resistance, particularly to atmospheric exposure. many building codes are based on the more conservative use of plain carbon steels, and the use of alloy structural steel often has no economic advantage in these cases.low alloy aisi steelsi

25、mproved properties at higher cost. the low alloy american iron and steel institute (aisi) steels are alloyed primarily for improved hardenability. they are more costly than plain carbon steels, and their use can generally be justified only when needed in the heat-treat-hardened and tempered conditio

26、n. compared to plain carbon steels, they can have 30%40% higher yield strength and 10%20% higher tensile strength. at equivalent tensile strengths and hardnesses, they can have 30%40% higher reduction of area and approximately twice the impact strength.usually heat treated. the low alloy aisi steels

27、 are those containing less than approximately 8% total alloying elements, although most commercially important steels contain less than 5%. the carbon content may very form very low to very high, but for most steels it is in the medium range that effective heat treatment may be employed for property

28、 improvement at minimum costs. the steels are used widely in automobile, machine tool, and aircraft construction, especially for the manufacture of moving parts that are subject to high stress and wear.stainless steelstonnage-wise, the most important of the higher alloy steels are a group of these s

29、teels have much better mechanical properties at high temperatures. this group was first called stainless steel. with the emphasis on high temperature use, they are frequently referred to as heat and corrosion-resistant steels.martensitic stainless steel with lower amounts of chromium or with silicon

30、 or aluminium added to some higher chromium steels, the material responds to heat treatment much as any low alloy steal. the gamma-to-alpha transformation in iron occurs normally, and the steel may be hardened by heat treatment similar to that used on plain carbon or low alloy steels. steels of this

31、 class are called martensitic, and the most used ones have 4%to 6% chromium.ferritic stainless steel with large amounts of chromium, as great as 30% or more,the austenite region of the iron-carbon equilibrium diagram is suppressed, and the steel loses its ability to be hardened by normal steel heat-

32、treating procedures. steels of this type are called ferritic and are particularly useful when high corrosion resistance is necessary in cold-worked products.austenitic stainless steel with high chromium and the addition of 8% or more of nickel or combinations of nickel and manganese, the ferrite reg

33、ion of the diagram is suppressed. these steels, the most typical of which contains 18%chromium and 8% nickel, are referred to as austenitic stainless steels. they are not hardenable by normal steel heat-treating procedures, but the addition of small amounts of other elements makes some of them harde

34、nable by a solutioprecipitation reaction.tool and die steelsthe greatest tonnage of tools (other than cutting tools) and dies are made from plain carbon or low alloy steels. this is true only because of the low cost these materials as their use has a number of disadvantages. they have low harden-abi

35、lity, low ductility associated with high hardness, and do not hold their hardness well at elevated temperature.manganese steels. manganese tool and die steels are oil hardening and have a reduced tendency to deform or crack during heat treatment. they contain from 85 100 points of carbon, 1.5%1.75%

36、of manganese to improve hardenability, and small amounts of chromium, vanadium, and molybdenum to improve hardness and toughness qualities.chromium steels* high chromium tool and die steels are usually quenched in oil for hardening, but some have sufficient hardenability to develop hardness with an

37、air quench. one group of the high chromium steels, called high speed steel, has substantial additions of tungsten, vanadium,and sometimes cobalt to improve the hardness in the red heat range.一、普通碳素钢任何炼钢方法都能炼出只含有0.05% (甚至更少)碳的钢。由于只有少量的 碳，钢的性能接近于纯铁，具有很高塑形和很低的强度。从便于成形和使用的角 度看，高塑性和低强度是变形所需要的，然而，从产品设计角度来

38、说，需要比这 种低碳钢更高的强度。增加强度最适用的方法是在钢中增加或保留一些碳。然而, 必须明口，强度的增加只有在损失塑性的情况下才能实现，因此，最终总是在塑 性和强度之间形成某种折衷。因为成分控制和增碳过程有一定的难度，高碳高强 度钢的成本比低碳钢高。最常用的普通碳素钢 因为成木低，实际使用的大多数是普通碳素钢，它们 由铁和碳组成，普通碳素钢的碳含量可分为低碳、中碳、高碳三类。除了用来控 制硫和猛元素以外，其他元素只有很少而被认为是杂质，有时它们对材料的性能 可能有较小的影响。低碳钢含碳大约0.06%0.25%的钢称为低碳钢，他们很难通过热处理淬 硬，因为碳的含量太低，很难形成硬的马氏体结构

39、，从而使热处理相对不起作用。 大量的低碳钢被做成薄板材、带材、棒材、板材、管材和线材等结构。很多这类 材料最后通过冷加工來提高硬度、强度和表面质量。含碳小于等于20%的钢可以 经受较大的塑性流动，经常用作深拉成形零件或可用表面硬化材料的塑性心部。 低碳钢容易铜焊、熔焊和锻造。中碳钢 中碳钢(0.25%0.5%)含有足够的碳，可以通过热处理得到所需强 度、硬度、切削加工性和其他特性。此类普通钢的硬度不能显著提高到满意的作 为切削刀具，但承载能力可提高很多，同时保留足够的塑性和良好的韧性。大多 数钢在热轧状态提供，经常需进行切削加工。它能焊接，但比低碳钢难得多，因 为焊接热量在局部区域引起了组织结

40、构的变化。高碳钢 高碳钢含有0.5%1.6%的碳，这类钢称为工具和模具钢，硬度是 这类钢所需的主要性能。因为组织转变快，淬透性低这种钢几乎都是用水淬火。 即使用这种激烈的处理方式，并有变形和开裂的危险，这种钢很少能完成淬透, 淬硕层厚度不超过1英寸。实际上，在同样强度下，热处理淬硬的普通碳素钢的 塑性比合金钢的低，但即使如此，因其成本低，仍常使用碳素钢。二、合金钢普通碳素钢可用于许多场合，也是最便宜的钢种，因此使用最多，但它们对 某些工作要求不能完全满足。这是可通过加入一些元素形成合金的方式来提高钢 的某一项或儿项性能。即使是普通碳素钢，也是铁、碳和镭的合金，但合金钢中 除了这些元素外，其他元

41、素含量大于普通碳素结构钢的杂质含量，如锚含量要大 于 1.5%。合金元素影响淬透性人们对淬透性的兴趣是间接的。淬透性通常与完全淬 火时硕化深度的能力有关系。然而，随着等温曲线右移，即使在完全硬化时，材 料性能也能显著改变。在热轧或锻打后，材料通常采用空冷。所有合金通常使等 温曲线右移，空冷时得到比普通钢细的珠光体。这种细珠光体有较高的硬度和强 度，可能会降低塑性，对切削加工性也有影响。可悍性 总的来说，合金元素对可悍性产生坏影响，这也是影响淬透性的一 种反应，焊接区快冷时，合金会使焊接区形成硬的、韧性差的结构，经常导致开 裂和变形。晶粒尺寸和韧性 在奥氏体阶段，银对防止晶粒长犬有特别优异的作用

42、。对 淬透性而言，对性能影响大的晶粒细化过程就只是次要影响。细晶粒结构会使淬 透性变差，但对韧性影响很大。对硬度和强度相等的两种钢，细晶粒的钢塑性较 好，反映在图表中就是韧性高，但这种高韧性，对切削加工形式有害的。耐腐蚀能力 总的来说，大多数纯金属耐腐蚀能力相对较好，含有杂质或少 量合金元素吋会降低其耐腐蚀能力。对钢而言，碳会显著降低其耐腐蚀能力。铜 和磷含量少时对减轻腐蚀有利，鎳在含量大约5%时对减轻腐蚀也是有利的，珞 在含量大于10%时特别有益，会产生一种称为不锈钢的合金钢。许多工具钢，因 其镉含量高而实际上也是不锈钢，虽然设计中没做这种要求。三、低合金结构钢市场上已有多种多样的低合金结构

43、钢，他们是屈服强度比普通碳钢高的低成 本结构材料。外加少量的一些合金元素不需经过热处理就可以提高热轧钢的屈服 强度，比普通碳钢高30%40%。在高应力条件下，可减少横截面尺寸25%30%, 同时增加成木15%50%,这取决于合金元素的量和种类。四、低合金aisi钢高性能高成本 低合金aisi （美国钢铁协会）钢中的合金元素主要用于提 高淬透性，他们比普碳钢贵得多，通常只在必须是使用，用于热处理硬化和回火 条件下。与普碳钢相比，屈服强度高30%40%,抗拉强度高10%20%。同样 的拉伸强度和硬度时面积可减少30%40%,冲击强度大约提高两倍。通常需热处理 低合金aisi钢的总合金元素含量小于8

44、%,虽然工业上大多 数重要钢的合金元素的含量少于5%o碳含量可从很低变到很高，但大多数为中 碳钢，可用最小成本进行热处理来有效改善性能，这种钢广泛用于汽车、机床、 飞机，特别随时用于制造承受高应力且磨损大的运动零件。五、不锈钢大量使用且最重要的高合金钢是一组抗化学腐蚀能力极高的高辂钢。这类港 的大多数在高温下好的的力学性能，这类钢最早称为不锈钢，随着在高温下使用 的增加，它们经常也称为耐热耐腐蚀钢。马氏体不锈钢 在钢中加入少量銘，或在一些高珞钢中加入硅或铝，这种钢 称为马氏体钢，其屮含銘4%到6%的钢最常用。铁素体不锈钢 含辂量达30%或更多时，铁碳平衡相图的奥氏体区缩小，钢 失去了用通常热处

45、理方法硬化的能力。这种钢称为铁素体钢，特别适用于由高耐 腐蚀性要求的冷加工产品。奥氏体不锈钢高辂钢再加上8%以上的银或鎳与镒，相图的铁素体区就会 缩小。最典型的钢含18%和8%镰，称为奥氏体不锈钢。他们不能用通常钢的热 处理方法硬化，但可附加少量的其他元素通过固溶强化使它们硕化。六、大量的工具（与切削刀具不同）和模具用普通钢或低合金钢制造，这只是因 为他们价格便宜，但这些材料有很多缺点。它们的淬透性差，硬度高而塑性低, 温度升高时不能很好的保持硬度。¥孟钢钢工具模具钢是油淬硬化钢，在热处理是很少变形或开裂。为提高淬 透性，钢屮含有0.85%到1.00%的碳和1.5%1.75%的猛，并

46、有少量钮、饥、鋁 来提高硬度和韧性。锯钢 高钻工具模具钢通常在油中淬硬，但有一些铅钢淬透性好，在空冷时 就能淬硬。有一组高辂钢加油许多鸭、（有时还有钻）其提高起高温硬度，它 们成为高速钢。生命列车the train of life1. 不久以it，我续了一本 书。书中把人生比作一 次彖行。2. 人生一世，就好比是一次培车嵌行，要经易无 数次上车、下车；肘常 有事故发生；有时是意 外惊喜，有时却是刻骨 铭心的悲伤3. 阵生人世，我们就坐上 了生命列车。我们以为 我们最先见到的那两个 人我们的父母，会 衣人生嵌途:中一直陪佯 着我们。1. not long ago, i read a book,

47、in which a maits life was compared to a journey.2. the life of a man is just like a hitchhikings during which many times we go up and down. now and then things will happen accidently, some of which are to be unexpected excitement, while some heart-breaking sorrows.3. when first embraced the world, w

48、e are already on the train of life. we take it for granted that the first two persons，our parents whom we are encountered4. 很遗憾，事卖并非如此。 他们会衣m个车誌下 车，留下我们，孤独无 助。他们的爱、他们的 情、他们不可唇代的陪 徉，再也i无从寻找。5. 尽管如此还会有其他 人上车。他们当中的一 些人将对我们有着特殊 的意义。6. 他们之中有我们的兄弟 蛆妹，有我们的亲朋好 发。我们还将会体验千古不朽的爱悄坎事。7. 坐同一班车的人多中,有的经松嵌行。有的却带着诛诛的

49、悲曩还有的確列车上s处弄忙，1时准备帮助有需要的 9. 很多人下车后，其他嵌直对他们的回忆历久號新但赴也有一些人，当他们富开座住with, will accompany us all the way.4. sadly, things do not go on as we thought.our parents will get off the train at a certain station, leaving us, bereft and helpless.thlove and emotion to us and their irreplaceable company can be fou

50、nd in nowhere5. however, there will be somebody else who will get on the train. some of them will have special meaning to us6. some of them may be our siblings，relatives and friends, and we will also expereince the imperishable love.7. some of our travelling companions are quite light-hearted on the

51、 way.8. while some m町 bear immense sorrow.still some，back and forth, are ready to hold out their hands for others who need help.9 some people alight off the train, yet they are still时，却没有人案觉。10. 有对候，对你来说情 竦义重的嵌佯却坐到了 另一节车術。你只得远 kept in the mind of the other passengers for long;some, to the opposite, leave their seats without being noticed.头。此，尽量使蔽途犹球彷徨。find the merits of theirs.富他，继续你的彖程。11. 多然，症彖途:中，你也可以摇摇晃晃地穿过自 己的车厢，去别的车術 找他12. 可惜，你再也！无廉坐 衣他身务，因为这个住 置已经让别人给占13. 没关糸。彖逾克满挑战、梦想、希望、离别就是不能回愉快吧!14. 善待彖途:上遇.见的 所有嵌彖，找出人们身 上的闪光点。15. 永远询住，農禁一段彖程中，有人会犹掾彷因为我们ii己也会lo.sometimes, the