时效温度对304奥氏体不锈钢超塑性及显微组织的影响

Effect of Aging Temperature on Superplasticity and Microstructure of 304 Austenitic Stainless Steel

对304奥氏体不锈钢进行了室温拉伸和时效处理,完成了一次马氏体相变及逆相变,利用这种马氏体相变循环实现了304不锈钢的超塑性。结果表明：室温拉伸30%后304不锈钢在不同温度时效20 min的两次相变循环处理,其伸长率随时效温度增加先增加后略有下降。时效温度低于800℃时,钢未能实现超塑性;当时效温度为800～1000℃时钢均实现了超塑性。采用金相显微镜和扫描电镜对实现超塑性后时效处理的奥氏体态的显微组织进行了分析,发现随时效温度的升高,奥氏体晶粒尺寸增加,850℃后晶粒急剧长大。

The tensile at room temperature and aging treatment of 304 austenitic stainless steel were carried out. Primary martensitic transformation and inverse transformation were completed. The superplasticity of 304 stainless steel was achieved by using the martensitic transformation cycle. The results show that： the twice phase change cycles treatment of 304 stainless steel after room temperature tensile 30% and then aging at different temperatures for 20 min, the elongation increases firstly and then slightly decreases with the aging temperature increasing. When the aging temperature is less than 800 ℃, the superplasticity of the steel does not achieve. When the aging temperature is 800-1000 ℃, the superplasticity of the steel is achieved. The microstructure of austenite after superplasticity and then aging treatment was analyzed by metallographic examination and canning electron microscopy. It is found that the austenite grain size increases with the increase of aging temperature, and the grain grows rapidly after 850 ℃.