普通碳素鋼畢業(yè)論文外文翻譯

1、外文資料翻譯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、普通碳素鋼任何煉鋼方法都能煉出只含有0.05% (甚至更少)碳的鋼。由于只有少量的 碳，鋼的性能接近于純鐵，具有很高塑形和很低的強(qiáng)度。從便于成形和使用的角 度看，高塑性和低強(qiáng)度是變形所需要的，然而，從產(chǎn)品設(shè)計角度來

38、說，需要比這 種低碳鋼更高的強(qiáng)度。增加強(qiáng)度最適用的方法是在鋼中增加或保留一些碳。然而, 必須明口，強(qiáng)度的增加只有在損失塑性的情況下才能實現(xiàn)，因此，最終總是在塑 性和強(qiáng)度之間形成某種折衷。因為成分控制和增碳過程有一定的難度，高碳高強(qiáng) 度鋼的成本比低碳鋼高。最常用的普通碳素鋼 因為成木低，實際使用的大多數(shù)是普通碳素鋼，它們 由鐵和碳組成，普通碳素鋼的碳含量可分為低碳、中碳、高碳三類。除了用來控 制硫和猛元素以外，其他元素只有很少而被認(rèn)為是雜質(zhì)，有時它們對材料的性能 可能有較小的影響。低碳鋼含碳大約0.06%0.25%的鋼稱為低碳鋼，他們很難通過熱處理淬 硬，因為碳的含量太低，很難形成硬的馬氏體結(jié)構(gòu)

39、，從而使熱處理相對不起作用。 大量的低碳鋼被做成薄板材、帶材、棒材、板材、管材和線材等結(jié)構(gòu)。很多這類 材料最后通過冷加工來提高硬度、強(qiáng)度和表面質(zhì)量。含碳小于等于20%的鋼可以 經(jīng)受較大的塑性流動，經(jīng)常用作深拉成形零件或可用表面硬化材料的塑性心部。 低碳鋼容易銅焊、熔焊和鍛造。中碳鋼 中碳鋼(0.25%0.5%)含有足夠的碳，可以通過熱處理得到所需強(qiáng) 度、硬度、切削加工性和其他特性。此類普通鋼的硬度不能顯著提高到滿意的作 為切削刀具，但承載能力可提高很多，同時保留足夠的塑性和良好的韌性。大多 數(shù)鋼在熱軋狀態(tài)提供，經(jīng)常需進(jìn)行切削加工。它能焊接，但比低碳鋼難得多，因 為焊接熱量在局部區(qū)域引起了組織結(jié)

40、構(gòu)的變化。高碳鋼 高碳鋼含有0.5%1.6%的碳，這類鋼稱為工具和模具鋼，硬度是 這類鋼所需的主要性能。因為組織轉(zhuǎn)變快，淬透性低這種鋼幾乎都是用水淬火。 即使用這種激烈的處理方式，并有變形和開裂的危險，這種鋼很少能完成淬透, 淬碩層厚度不超過1英寸。實際上，在同樣強(qiáng)度下，熱處理淬硬的普通碳素鋼的 塑性比合金鋼的低，但即使如此，因其成本低，仍常使用碳素鋼。二、合金鋼普通碳素鋼可用于許多場合，也是最便宜的鋼種，因此使用最多，但它們對 某些工作要求不能完全滿足。這是可通過加入一些元素形成合金的方式來提高鋼 的某一項或兒項性能。即使是普通碳素鋼，也是鐵、碳和鐳的合金，但合金鋼中 除了這些元素外，其他元

41、素含量大于普通碳素結(jié)構(gòu)鋼的雜質(zhì)含量，如錨含量要大 于 1.5%。合金元素影響淬透性人們對淬透性的興趣是間接的。淬透性通常與完全淬 火時碩化深度的能力有關(guān)系。然而，隨著等溫曲線右移，即使在完全硬化時，材 料性能也能顯著改變。在熱軋或鍛打后，材料通常采用空冷。所有合金通常使等 溫曲線右移，空冷時得到比普通鋼細(xì)的珠光體。這種細(xì)珠光體有較高的硬度和強(qiáng) 度，可能會降低塑性，對切削加工性也有影響。可悍性 總的來說，合金元素對可悍性產(chǎn)生壞影響，這也是影響淬透性的一 種反應(yīng)，焊接區(qū)快冷時，合金會使焊接區(qū)形成硬的、韌性差的結(jié)構(gòu)，經(jīng)常導(dǎo)致開 裂和變形。晶粒尺寸和韌性 在奧氏體階段，銀對防止晶粒長犬有特別優(yōu)異的作用

42、。對 淬透性而言，對性能影響大的晶粒細(xì)化過程就只是次要影響。細(xì)晶粒結(jié)構(gòu)會使淬 透性變差，但對韌性影響很大。對硬度和強(qiáng)度相等的兩種鋼，細(xì)晶粒的鋼塑性較 好，反映在圖表中就是韌性高，但這種高韌性，對切削加工形式有害的。耐腐蝕能力 總的來說，大多數(shù)純金屬耐腐蝕能力相對較好，含有雜質(zhì)或少 量合金元素吋會降低其耐腐蝕能力。對鋼而言，碳會顯著降低其耐腐蝕能力。銅 和磷含量少時對減輕腐蝕有利，鎳在含量大約5%時對減輕腐蝕也是有利的，珞 在含量大于10%時特別有益，會產(chǎn)生一種稱為不銹鋼的合金鋼。許多工具鋼，因 其鎘含量高而實際上也是不銹鋼，雖然設(shè)計中沒做這種要求。三、低合金結(jié)構(gòu)鋼市場上已有多種多樣的低合金結(jié)構(gòu)

43、鋼，他們是屈服強(qiáng)度比普通碳鋼高的低成 本結(jié)構(gòu)材料。外加少量的一些合金元素不需經(jīng)過熱處理就可以提高熱軋鋼的屈服 強(qiáng)度，比普通碳鋼高30%40%。在高應(yīng)力條件下，可減少橫截面尺寸25%30%, 同時增加成木15%50%,這取決于合金元素的量和種類。四、低合金aisi鋼高性能高成本 低合金aisi （美國鋼鐵協(xié)會）鋼中的合金元素主要用于提 高淬透性，他們比普碳鋼貴得多，通常只在必須是使用，用于熱處理硬化和回火 條件下。與普碳鋼相比，屈服強(qiáng)度高30%40%,抗拉強(qiáng)度高10%20%。同樣 的拉伸強(qiáng)度和硬度時面積可減少30%40%,沖擊強(qiáng)度大約提高兩倍。通常需熱處理 低合金aisi鋼的總合金元素含量小于8

44、%,雖然工業(yè)上大多 數(shù)重要鋼的合金元素的含量少于5%o碳含量可從很低變到很高，但大多數(shù)為中 碳鋼，可用最小成本進(jìn)行熱處理來有效改善性能，這種鋼廣泛用于汽車、機(jī)床、 飛機(jī)，特別隨時用于制造承受高應(yīng)力且磨損大的運動零件。五、不銹鋼大量使用且最重要的高合金鋼是一組抗化學(xué)腐蝕能力極高的高輅鋼。這類港 的大多數(shù)在高溫下好的的力學(xué)性能，這類鋼最早稱為不銹鋼，隨著在高溫下使用 的增加，它們經(jīng)常也稱為耐熱耐腐蝕鋼。馬氏體不銹鋼 在鋼中加入少量銘，或在一些高珞鋼中加入硅或鋁，這種鋼 稱為馬氏體鋼，其屮含銘4%到6%的鋼最常用。鐵素體不銹鋼 含輅量達(dá)30%或更多時，鐵碳平衡相圖的奧氏體區(qū)縮小，鋼 失去了用通常熱處

45、理方法硬化的能力。這種鋼稱為鐵素體鋼，特別適用于由高耐 腐蝕性要求的冷加工產(chǎn)品。奧氏體不銹鋼高輅鋼再加上8%以上的銀或鎳與鎰，相圖的鐵素體區(qū)就會 縮小。最典型的鋼含18%和8%鐮，稱為奧氏體不銹鋼。他們不能用通常鋼的熱 處理方法硬化，但可附加少量的其他元素通過固溶強(qiáng)化使它們碩化。六、大量的工具（與切削刀具不同）和模具用普通鋼或低合金鋼制造，這只是因 為他們價格便宜，但這些材料有很多缺點。它們的淬透性差，硬度高而塑性低, 溫度升高時不能很好的保持硬度。¥孟鋼鋼工具模具鋼是油淬硬化鋼，在熱處理是很少變形或開裂。為提高淬 透性，鋼屮含有0.85%到1.00%的碳和1.5%1.75%的猛，并

46、有少量鈕、饑、鋁 來提高硬度和韌性。鋸鋼 高鉆工具模具鋼通常在油中淬硬，但有一些鉛鋼淬透性好，在空冷時 就能淬硬。有一組高輅鋼加油許多鴨、（有時還有鉆）其提高起高溫硬度，它 們成為高速鋼。生命列車the train of life1. 不久以it，我續(xù)了一本 書。書中把人生比作一 次彖行。2. 人生一世，就好比是一次培車嵌行，要經(jīng)易無 數(shù)次上車、下車；肘常 有事故發(fā)生；有時是意 外驚喜，有時卻是刻骨 銘心的悲傷3. 陣生人世，我們就坐上 了生命列車。我們以為 我們最先見到的那兩個 人我們的父母，會 衣人生嵌途:中一直陪佯 著我們。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. 很遺憾，事賣并非如此。 他們會衣m個車誌下 車，留下我們，孤獨無 助。他們的愛、他們的 情、他們不可唇代的陪 徉，再也i無從尋找。5. 盡管如此還會有其他 人上車。他們當(dāng)中的一 些人將對我們有著特殊 的意義。6. 他們之中有我們的兄弟 蛆妹，有我們的親朋好 發(fā)。我們還將會體驗千古不朽的愛悄坎事。7. 坐同一班車的人多中,有的經(jīng)松嵌行。有的卻帶著誅誅的

49、悲曩還有的確列車上s處弄忙，1時準(zhǔn)備幫助有需要的 9. 很多人下車后，其他嵌直對他們的回憶歷久號新但赴也有一些人，當(dāng)他們富開座住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時，卻沒有人案覺。10. 有對候，對你來說情 竦義重的嵌佯卻坐到了 另一節(jié)車術(shù)。你只得遠(yuǎn) kept in the mind of the other passengers for long;some, to the opposite, leave their seats without being noticed.頭。此，盡量使蔽途猶球彷徨。find the merits of theirs.富他，繼續(xù)你的彖程。11. 多然，癥彖途:中，你也可以搖搖晃晃地穿過自 己的車廂，去別的車術(shù) 找他12. 可惜，你再也！無廉坐 衣他身務(wù)，因為這個住 置已經(jīng)讓別人給占13. 沒關(guān)糸。彖逾克滿挑戰(zhàn)、夢想、希望、離別就是不能回愉快吧!14. 善待彖途:上遇.見的 所有嵌彖，找出人們身 上的閃光點。15. 永遠(yuǎn)詢住，農(nóng)禁一段彖程中，有人會猶掾彷因為我們ii己也會lo.sometimes, the