热处理工艺对S31042奥氏体耐热钢显微组织和力学性能的影响

Effect of heat treatment on microstructure and mechanical properties of S31042 austenite heat resistant steel

研究S31042奥氏体耐热钢不同热处理工艺后的显微组织和力学性能。结果表明：随着时效温度由700℃上升到900℃,该钢的晶界M23C6型碳化物析出量增多,并逐渐呈现连续分布,冲击韧性显著降低,高温抗拉强度逐渐降低,屈服强度基本保持稳定,但900℃时效热处理后屈服强度略微增加;当时效温度由900℃上升到1000℃,该钢晶界碳化物析出量减少;高温抗拉强度变化不明显,屈服强度有所降低,冲击韧性提高;相比于拉伸过程中的低应变速率,在瞬时冲击高应变速率条件下,晶界M（23）C6相的聚集析出造成沿晶开裂倾向增加。

Microstructure and mechanical properties of S31042 austenite heat resistant steel after different heat treatments were studied by means of scanning electron microscopy（ SEM）,energy dispersive spectrometer（ EDS） analysis and MTS universal testing machine. The results show that with the increasing of aging temperature from 700 ℃ to 900 ℃,the precipitation amount of M_（23）C_6 carbides at grain boundaries increases,and gradually exhibits a continuous distribution,and the impact toughness of the steel decreases significantly,the tensile strength at high temperature of the steel decreases gradually,and the yield strength approximately remains stable,but the yield strength increases slightly after aging at 900 ℃ for 1 h. However,when the aging temperature increasing from 900 ℃ to 1000 ℃,the precipitation amount of the M_（23）C_6 carbides at grain boundaries decreases,the tensile strength at high temperature of the steel changes little,the yield strength decreases,and the impact toughness increases. Compared with the low strain rate in the tensile process,the aggregation precipitation of the M_（23）C_6 phases at grain boundary leads to an increase in the tendency of intergranular cracking under the condition of high instantaneous impact and high strain rate.