【正文】 材料成型級控制工程專業(yè)英語閱讀 Plain Carbon Steel 普通碳鋼Hotrolled steel delivered （供給）by steelmaking works as rolled sections(bars, beams，sheets．tubes，etc) is the most wildly used material for manufacture of various machines，machine tools, building structures，consumer goods，etc．Delivered steel should have the properties as specified by State Standards（國家標(biāo)準）．鋼鐵制造車間供給的熱軋鋼主要為棒材、柱材、板材、管材等，熱軋鋼是制造各種機械、機器工具、建筑結(jié)構(gòu)和消費品中應(yīng)用最廣泛的材料。所供給的鋼應(yīng)具有國家標(biāo)準規(guī)定的各種性能。 In the RSSU．Plain carbon steels are classified into three groups：A, B and C，depending on their application. 在RSSU中，普通碳鋼根據(jù)其用途分為A、B、C三類。A: If a steel is to be used for making products without hot working (welding, Forging．Etc.). Its structure and properties in the final product will be the same as delivered from the rolling mill．In that case the user requests for a steel of warranted（保證） mechanical properties，while the chemical position is not guaranteed（保證、擔(dān)保）．A:如果鋼在制造產(chǎn)品的過程中沒有進行熱加工（焊接、鍛造等），則最終產(chǎn)品的組織和性能將與軋廠提供的相同。這種情況下，用戶只需要求材料應(yīng)有的機械性能，而不必保證其成分。B: If a steel is to be subjected to hot working(forging，stamping，etc)，its initial structure and mechanical properties will be that case the position of the steel will be of prime importance for the user，since it determines the conditions of hot working and the final mechanical properties of steel products．Now a steel of warranted position is delivered to the user. （鍛造、沖壓等），則其初始組織和機械性能將會改變。此時/在這種情況下，鋼的成分對用戶來講是最重要的，因為它(成分)決定了熱加工的條件，鋼制品的最終機械性能。因此，提供給用戶的鋼應(yīng)保證其成分含量。C: If a steel is to be welded．the user wants to know the position of the steel．since it determines the properties of the metal in the zone subjected to thermal effect of weld（焊接熱影響區(qū)）．The user is also interested in the initial mechanical properties of the metal，since these properties will remain the same in portions not subjected to welding．In that case the metal is delivered with warranted position and mechanical properties.C．如果鋼要進行焊接，則用戶需要知道鋼的成分，因為成分決定鋼焊接時熱影響區(qū)的性能。用戶也會對鋼材的原始機械性能感興趣，因為未焊接的部分的性能是原始性能。這種情況下，供給用戶的鋼應(yīng)具有規(guī)定的成分和機械性能。Generalpurpose plain steels are not alloyed．Some alloying elements may sometimes be present in them occasionally and their content（含量） is limited．非特殊用途/一般用途的普通鋼不是合金鋼。一些合金元素偶爾會出現(xiàn)，其含量受限制。The presence of silicon and manganese may be due to the steel—making process(the necessity of deoxidation脫氧)．Surphur（硫）and phosphorus（磷） are harmful impurities（雜質(zhì)） in steel and their content should be minimized as it may affect the quality of steel． 在鋼冶煉過程中由于脫氧的需要，會出現(xiàn)硅和錳。硫、磷是鋼中有害的雜質(zhì)，應(yīng)盡可能減少其含量，它們會影響鋼的質(zhì)量。The principal element whose content is responsible for the properties of steels is carbon 影響鋼性能最主要的元素是碳。 AlloysAlthough ferrous alloys ale used in the majority of metallic applications in current engineering designs，non—ferrous alloys play a large and indispensable role in our technology. As pared to ferrous alloys，the list of non—ferrous alloys is，of course，long and plex．We shall briefly list the major families of non—ferrous alloys and their key attributes．盡管現(xiàn)代工業(yè)設(shè)計中，鐵合金是主要應(yīng)用的金屬，但是非鐵合金在當(dāng)前科技中也起著很大并不可替代的作用。當(dāng)然，與鐵合金相比，非鐵合金的種類多且復(fù)雜。我們將簡要介紹幾種非鐵合金及其主要特征。Aluminum alloys are best known for low density and corrosion resistance. Electrical conductivity，easy of fabrication，and appearance are also attractive features．Because of these，the world production of aluminum roughly doubled in one recent 10 year period．Ore reserves for aluminum are large (representing 8％of the earth’s crust) and aluminum can be easily recycled鋁合金以其低密度和腐蝕抗力而聞名。電導(dǎo)率、易加工以及好的外觀也是其具有吸引力的特征?；谝陨咸攸c，近10年來鋁合金的產(chǎn)量幾乎翻了一番。鋁礦石的產(chǎn)量很大（占地殼的8％），并且鋁是可以回收的。Magnesium alloys have even lower density than aluminum and，as a result，appear in numerous structural applications such as aerospace designs．Aluminum is a fcc material and therefore has numerous (12) slip systems, leading to good ductility．By contrast．magnesium is hcp with only three slip sys