【摘要】 研究了18-8型奥氏体不锈钢经低温不加载和加载热循环后的显微组织和低温机械性能,试验结果表明:(1)低温热循环后可形成ε和α′两种类型的马氏体。(2)在低温不加载热循环时,随着循环次数和等温时间的增加,奥氏体稳定性降低,马氏体转变量增加,引起低温屈服强度的升高和低温冲击韧性较大的降低,但对抗拉强度和塑性的影响不甚明显。(3)低温加载热循环时,奥氏体的稳定性显著降低,马氏体形成量更多,因而比不加载热循环具有更高的低温强度,而低温塑性有较大的降低。更多还原

【Abstract】 In this paper the microstructure and cryogenic mechanical properties of Type 18-8 austenitio stainless steel under crycgenic thermal cycle by unloading and loading were investigated. The experiment results showed that (1) both types of εand a’ martensite were formed under cryogenic thermal cycle. (2) In condition of cryogenic thermal cycle by unloading with increasing cycle time and isothermal time, the stability of austenite decreased and the amount of martensitic transformation increased also, which result in rising cryogenic yield strength and considerable reducing impact toughness. However, no remarkable change in tensile strength and ductility c ucrrcd. (3) In condition of cryogenic thermal cycle by loading, the stability of austenite was considerably reduced, and more amount of martensite was formed. Therefore, the strength was stronger and the ductility was lower than that under thermal cycle by unloading.更多还原