材料成型級(jí)控制工程專業(yè)英語閱讀-在線瀏覽
2025-05-22 01:16本頁面
【正文】 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(jī)械性能將會(huì)改變。因此，提供給用戶的鋼應(yīng)保證其成分含量。用戶也會(huì)對鋼材的原始機(jī)械性能感興趣，因?yàn)槲春附拥牟糠值男阅苁窃夹阅?。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。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(huì)出現(xiàn)硅和錳。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。當(dāng)然，與鐵合金相比，非鐵合金的種類多且復(fù)雜。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?；谝陨咸攸c(diǎn)，近10年來鋁合金的產(chǎn)量幾乎翻了一番。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 systems and characteristic brittleness．鎂合金的密度比鋁合金的還低，因此，設(shè)計(jì)航空飛行器時(shí)大量的結(jié)構(gòu)件用鎂合金。相反，鎂合金是密排六方結(jié)構(gòu)，僅有3個(gè)滑移系，易脆斷（具有脆性）。一旦形成鈦合金，鈦的活性顯現(xiàn)出其優(yōu)點(diǎn)?！扳g化性”將在后面詳細(xì)討論。盡管密度要比Al、Mg高，鈦合金的顯著特點(diǎn)之一是在中等服役溫度下能保持其強(qiáng)度，因此航天中應(yīng)用多。然而，通過添加釩等合金，其高溫下bcc晶格結(jié)構(gòu)可以在室溫下保存。優(yōu)良的電導(dǎo)率使銅合金成為電線的首選材料。超級(jí)抗腐蝕性使其用于船舶及其它腐蝕性環(huán)境中。其顏色經(jīng)常用于建筑裝飾中。優(yōu)良的機(jī)械性能使其應(yīng)用上很具有競爭性。熱處理時(shí)添加2wt％的鈹元素，產(chǎn)生的CuBe沉淀相使其拉伸強(qiáng)度可超過1000MPaNickel alloys have much in mon with copper alloys．We have already used the CuNi system as the classic example of plete solid solubility. Monel is the name given to mercial alloys with NiCu ratios of roughly 2:1 by weight. These are good examples of solution hardening. Nickel is harder than copper, but Monel is harder than nickel. 鎳合金比銅合金更普通。比例接近2：1的Ni －Cu商業(yè)合金稱之為蒙乃爾合金。Ni比銅硬，但是蒙乃爾合金比Ni硬。由于熔點(diǎn)低不與鐵質(zhì)坩鍋和模具材料發(fā)生腐蝕反應(yīng)，鋅合金是模具鑄造的理想材料。鐵合金上鍍鋅層是重要的防腐蝕措施，該方法稱之為鍍鋅。2000年前羅馬人安裝在英國公共浴室的鉛管至今仍然在用。鉛合金用于電池鉛版(與鈣、銻混合)、焊料（與錫混合）、輻射屏蔽及進(jìn)行有效的組織控制。The refractory metals include molybdenum，niobium，tantalum，and tungsten．They are, even more than the superalloys, especially resistant to high temperatures. However, their general reactivity with oxygen requires the high temperature service to be in a controlled atmosphere or with protective coatings．難熔金屬包括鉬、鈮、鉭、鎢，它們不僅僅是超合金，還特別耐高溫。The precious metals include gold, iridium, osmium, palladium, platinum, rhodium，ruthenium，and silver. Excellent corrosion resistance bined with various inherent properties justify the many costly applications of these metals and alloys．Gold circuit in the electronics industry, various dental alloys, and platinum coatings for catalytic converters are a few of the better, known examples.貴重金屬包括金、銥、鋨、鈀、鉑、銠、釕和銀。金線用于電子工業(yè)、各種假牙合金，催化轉(zhuǎn)爐中的鉑金層是少數(shù)眾所周知的例子。isstructuralconsistingheatingAC3subsequentcooling.heatingAc1belowfullwilloccurtheispartialTheofsteelclosetheofequilibriumitsis+pearlite,pearlitecementite. 退火是一種結(jié)構(gòu)再結(jié)晶，由加熱到AC3以上并隨后緩慢冷卻組成。 a steel is heated above AC3 and then cooled in air, this will be the first step to change it to a state farther from the structural equilibrium. 如果一個(gè)鋼加熱到AC3以上,然后在空氣中冷卻,這將是改變它遠(yuǎn)離結(jié)構(gòu)平衡狀態(tài)的第一步。heatingthepoint,followedquickWithcooling,deposesferritecementiteAr1Withcoolingtheoccurslower再緩慢冷卻,奧氏體分解為鐵素體+滲碳體在Ar1。 AsAr1 pointlowered,ferritecementitebeesandfinedi
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