不同等温温度下P92钢的组织演变

Microstructure evolution of P92 steel at different isothermal temperatures

采用膨胀法,测定了P92钢的组织转变温度,并将其奥氏体化后实施不同温度和时间的等温处理。通过OM和SEM表征分析了不同等温温度、不同时间下P92钢的组织演变规律,并利用维氏硬度计测定其硬度。结果表明,P92钢在370℃及以下等温1 h时,会发生马氏体转变,室温组织为马氏体;在400~430℃等温1 h时,会发生贝氏体转变;在520~620℃等温1 h时,过冷奥氏体相对稳定,在短时间内不发生转变。在650℃及以上等温足够长时间时(25 h),过冷奥氏体将发生共析分解,形成类珠光体组织;在680~770℃等温25 h时,会有先共析铁素体析出,且随着等温温度的升高,先共析相增多。随着等温温度的升高(160~770℃),P92钢硬度整体呈下降趋势,由516 HV降低至163 HV。

Microstructure transition temperatures of the P92 steel were determined by expansion method.After austenitizing,the steel was isothermal treated at different temperatures for different time.Microstructure evolution of the P92 steel isothermal treated at different temperatures for different time was analyzed by OM and SEM.Microhardness of the P92 steel under different states was measured by Vickers hardness tester.The results show that martensite transformation occurs at isothermal temperature of 370 C and below for 1 h,and microstructure of the P92 steel at room temperature is martensitic.Bainite transformation occurs at isothermal temperature of 400430 C for 1 h.When isothermal treated at 520-620 for 1 h,the supercooled austenite is relatively stable and doesn't change in a short time.When isothermal treated at 650 C and above for a long time(25 h),eutectoid decomposition of supercooled austenite occur,forming pearlitic structure.When isothermal treated at 680-770 C for 25 h,there is proeutectoid ferrite precipitation,and with the increase of temperature,the proeutectoid phase increases.With the increase of isothermal temperature(160-770℃),the hardness of the P92 steel shows an overall downward trend,and gradually decreases from 516 HV to 163 HV.