摘要
13Cr4Ni马氏体不锈钢为水轮机转轮用材料,常用的热处理工艺为正火 + 两次高温回火,两次回火的目的是为了获得逆变奥氏体,在满足一定强度条件下具有良好的冲击性能。随着工况环境日益复杂,要求材料具有高的强度。本文采用950℃~1050℃正火 + 200℃低温回火处理工艺,目的是在满足低温冲击性能的同时获得高强度。利用OM、SEM、XRD等研究了不同正火温度加低温回火工艺对13Cr4Ni马氏体不锈钢高强度的影响规律。结果表明:热处理后13Cr4Ni马氏体不锈钢的室温组织为全马氏体组织,无明显析出相;经过950℃~1050℃正火 + 200℃回火后,−40℃的冲击断口形貌无明显差别,均为韧性断裂;随着正火温度的升高,晶粒逐渐变大,而位错密度逐渐降低;950℃正火 + 200℃回火试验钢的屈服强度和延伸率最高,三种工艺下的低温冲击功相差不大。
For 13Cr4Ni martensitic stainless steel, the traditional heat treatment process is normalizing and adding two high temperature tempering, the purpose of two tempering is to obtain stable inverter austenite, and then get good impact performance, so the two tempering temperatures are selected in the two-phase zone, which makes the tensile property be relatively low. Using 950˚C~1050˚C normalizing + 200˚C low temperature tempering process, the purpose is to obtain higher strength at the same time, keep the low temperature impact performance above 100 J. The influence of different normalizing temperature and low temperature tempering process on the high strength of 13Cr4Ni martensitic stainless steel was studied by OM, SEM and XRD. The results show that the microstructure of 13Cr4Ni stainless steel after heat treatment is full martensite structure without obvious precipitate at room temperature. After normalizing at 950˚C ~1050˚C and tempering at 200˚C, the impact fracture morphology of −40˚C has no obvious difference, and all of them are ductile fracture. With the increase of normalizing temperature, the grain size increases gradually, while the dislocation density decreases gradually. The yield strength and elongation of the steel tested by 950˚C normalizing + 200˚C tempering are the highest, and the low temperature impact work of the three processes has little difference. Therefore, the comprehensive mechanical properties of 950˚C normalizing + 200˚C tempering are better.
出处
《冶金工程》
CAS
2022年第4期321-327,共7页
Metallurgical Engineering
