模拟焊后热处理对大厚度15CrMoR钢板性能和组织的影响

The Effects of SPWHT on Mechanical Properties and Microstructure of Large Thickness 15CrMoR Steel Plate

通过长时间模拟焊后热处理试验,分析了焊后热处理对大厚度15CrMoR钢板性能和组织的影响,对实际生产具有一定的指导意义。试验结果表明:试验钢板经过模拟焊后热处理,获得的组织主要为贝氏体,钢中的固溶合金元素以碳化物形式析出,固溶强化作用减弱,经过长时间保温析出物数量不断增加,析出物颗粒尺寸逐渐增大,此时固溶强化效果不断减弱,组织内部析出物沿晶界聚集长大;抗拉强度和屈服强度均有不同程度下降,抗拉强度降幅30~40 MPa,屈服强度降幅40~50 MPa,断后伸长率明显上升,升幅在13%~27%范围内,冲击功呈现下降趋势,模拟焊后热处理温度越高,冲击功降幅越大。厚度≥80 mm的15CrMoR钢板模拟焊后热处理温度不宜超过690℃。

By means of long duration SPWHT test,the effects of PWHT on mechanical properties and microstructure of large thickness 15CrMoR steel plate are analysed,which has certain guidance significance for actual production.The test results show that after SPWHT,the microstructure of the steel plate is mainly composed of bainite,the solid solution alloy elements in the steel precipitate in the form of carbide,the solid solution strengthening effect deteriorates,the amount of precipitates continuouisly increases after long duration holding,the granular size of precipitates gradually increases with constant weakening of solid sloution strengthening,the precipatates in the microstructure assemble and grow along the grain boundary.The tensile strength and yield strength decrease to different extent,while the descending amplitude of tensile strength is between 30 MPa and 40 MPa,the descending amplitude of yield strength is between 40 MPa and 50 MPa,the elongation ratio increases significantly ranging between 13%and 27%,the impact absorbed energy values show descending trend with greater descending amplitude at higher SPWHT temperature.For 15CrMoR steel plate of thickness≥80 mm,the SPWHT temperature shall not be over 690℃.