材料成型級(jí)控制工程專業(yè)英語(yǔ)閱讀-文庫(kù)吧資料
2025-04-10 01:16本頁(yè)面
【正文】 伸長(zhǎng)率，且包括本構(gòu)RELA蒸發(fā)散的超塑性流動(dòng)的詳細(xì)的表征。31As the phenomenon of superplasticity moves from the laboratory into the industrial arena, as in the case of a number of engineering metals, the need for quality and process control during superplastic forming bees increasingly important. This calls for laboratory characterization of superplastic metals which can reflect their behavior in actual forming applications. Such requirements are not limited to determining tensile elongations under optimum superplastic conditions, but include detailed characterization of the constitutive relations for superplastic flow, since a reasonably accurate control of the pressurization cycle during forming is required. This provides a significant challenge to the materials engineer because of the plexity associated with microstructural changes occurring simultaneously during forming.超塑性的現(xiàn)象從實(shí)驗(yàn)室轉(zhuǎn)移到工業(yè)領(lǐng)域，如在許多工程金屬中，這種需求在超塑性質(zhì)量和過(guò)程控制成形變得越來(lái)越重要。coolingatroomcoolingandbelowsteelaofa如果冷卻速度很高,和過(guò)冷度大幅的提高，滲碳體和鐵素體沒(méi)有發(fā)生,不會(huì)有固溶體的分解并且?jiàn)W氏體(r 固溶體)將轉(zhuǎn)變成馬氏體(airon碳過(guò)飽和固溶體)。(hypereutectoidhypoeutectoidstructuretheafterAC3butAc1,metalheatingprocedureheatisInpleteinofsolid(supersaturatedintowillsolid(andsolidofnobetheretakedoesandofthesubstantialundercoolingandiscoolingIfandmoremoremixturetheisthe隨著冷卻速率增加,轉(zhuǎn)換發(fā)生在更低的溫度。temperatures. 淬火是加熱到臨界點(diǎn)以上,Ac3,隨后快速冷卻。attransformationrate,increasing.at+intoausteniteslowcooling.byAc3,criticalaboveis This type of heat treatment is called normalizing and is an intermediate stage between the second group procedure (annealing) and the thirdgroup procedure (hardening). 這種類型的熱處理被稱為正火,且為第二組之間的中間階段過(guò)程(退火)和第三種過(guò)程(硬化)。加熱到Ac1以上但低于AC3,完全再結(jié)晶將不會(huì)發(fā)生并且該過(guò)程被稱為局部退火,退火鋼的狀態(tài)接近于結(jié)構(gòu)平衡狀態(tài)，其結(jié)構(gòu)是珠光體+鐵素體,珠光體或珠光體+滲碳體。+orferrite,pearlitestructureandstructuralstatetoisannealedstateannealing.calledprocedureandnotrecrystallizationAc3,butaboveWithslowandaboveofrecrystallizationa優(yōu)秀的防腐性能以及其他各種性能使這些金屬及其合金應(yīng)用非常昂貴。然而，它們一般與氧反應(yīng)，高溫服役時(shí)需控制氣氛，或帶有保護(hù)層。鉛的毒性限制了其設(shè)計(jì)應(yīng)用和合金處理。鉛的高密度、高成形性和低熔點(diǎn)使其具有多種用途。Lead alloys are durable and versatile materials. The lead pipes installed by the Romans at the public baths in Bath, England, nearly 2000 years ago are still in use. Lead’s high density and deformability bined with a low melting point adds to its versatility．Lead alloys find use in battery grids (alloyed with calcium or antimony), solders (alloyed with tin), radiation shielding，and sound control structures. The toxicity of lead restricts design applications and the handling of its alloys.鉛合金是耐用的多功能材料。其(鋅合金)應(yīng)用于典型的汽車結(jié)構(gòu)零件及硬度高的零件。Nickel exhibits excellent corrosion resistance and high temperature strength. Zinc alloys are ideally suited for die castings due to their low melting point and lack of corrosion reaction with steel crucibles and dies. Automobile parts and hardware are typical structural applications. Zinc coatings on ferrous alloys are important means of corrosion protection. This method is termed as galvanization鎳有優(yōu)良的腐蝕性和高溫強(qiáng)度。這是很好的固溶硬化的例子。Cu－Ni合金已是典型的完全固溶例子。High purity copper is an exceptionally soft material. The addition of 2 wt％ beryllium followed by a heal treatment to produce CuBe precipitates is sufficient to push the tensile strength beyond l000 MPa．純銅非常軟。銅合金的廣泛應(yīng)用使其描述詞語(yǔ)選擇時(shí)經(jīng)?；煜he fcc structure contributes to their generally high ductility and formability. Their coloration is frequently used for architectural appearance. Widespread uses of copper alloy through history have led to a somewhat confusing collection of descriptive terms．The mechanical properties of these alloys rival the steels in their variability.Fcc晶格結(jié)構(gòu)使其具有高延展性和成形性。優(yōu)良的熱導(dǎo)率使其應(yīng)用于散熱器和熱交換器上。Copper alloys possess a number of superior properties. Their
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