等温处理对15-5PH不锈钢马氏体相变的影响

Effect of isothermal treatment on martensitic transformation of 15-5PH stainless steel

采用DIL805A膨胀仪测定15-5PH不锈钢马氏体相变点,通过透射电镜和金相显微镜观察了等温处理后的组织。结果表明,等温温度的提高会导致马氏体相变点升高,在700~800℃之间等温时,Ms点变化更为明显;等温处理后基体中出现了第二相NbC,且随等温温度的升高,NbC的数量和尺寸都有所增加。随等温时间延长,Ms点先下降后升高,等温30 min时达到最低值,而Mf点的变化不明显。

The martensitic transformation point of 15-5PH stainless steel was tested on DIL805A dilatometer, and the microstructure of the isothermal treated steel was observed by metallurgical microscope and transmission electron microscope .The results show that the martensitic transformation point increases as the isothermal treatment temperature increases .The change of Ms is particularly noticeable when the isothermal treatment temperature is 700-800 ℃.The second phase NbC precipitates from martensitic after isothermal treatment , the quantity and size of NbC increases slightly as isothermal treatment temperature increases .As the isothermal treatment holding time increases , the Ms point first decreases and then increases , and reaches a minimum value when holding time is 30 min, however the Mf point does not significantly change .