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近年来,高温合金和钛合金的使用不断增加,尤其是在宇航飞行器及其发动机生产中。这些合金的特点是:流变抗力高,可塑性低。具有不均匀变形所引起机械性能各向异性的敏感性,难于机械加工及成本高昂,如采用普通热变形锻造时,机械加工的金属损耗达80%左右,如采用超塑性成形方法,就能改变锻件肥头大耳的落后状况。金属材料的超塑性是指金属在特定条件(晶粒细化,极低的变形速度及等温变形)下,具有更大的塑性。如低碳钢拉伸时延伸率只有30～40%,塑性好的有色金属也只有60～70%。但超塑性状态,一般认为塑性差的金属延伸率在100～200%范围内,塑性好的
In recent years, the use of superalloys and titanium alloys has been increasing, especially in the manufacture of spacecraft and its engines. These alloys are characterized by: high rheological resistance, low plasticity. With the anisotropy of the mechanical properties caused by the uneven deformation of the sensitivity is difficult to machine processing and high cost, such as the use of ordinary heat deformation forging, machining metal loss of about 80%, such as the use of superplastic forming methods, you can change Forging fat head and ears behind the situation. Metal superplasticity refers to the metal under certain conditions (grain refinement, low deformation rate and isothermal deformation), with greater plasticity. Such as low-carbon steel elongation of only 30 to 40% elongation, good plastic non-ferrous metals only 60 to 70%. But the superplastic state, generally considered poor ductility metal elongation in the range of 100 ~ 200%, good plasticity