Cr13Ni4Mo钢逆转变奥氏体的形成及其对性能的影响

采用XRD、扫描电镜、EBSD、拉伸性能测试等手段研究了Cr13Ni4Mo钢逆转变奥氏体的形成规律、形成机制与力学性能。结果表明，Cr13Ni4Mo钢经550～730℃一次回火后并没有逆转变奥氏体产生；经630℃一次回火+530～630℃二次回火时，随二次回火温度的升高，逆转变奥氏体含量呈先增加后减少的趋势，其抗拉强度、伸长率和强塑积也相应地先增加后减少。当二次回火温度为590℃时，逆转变奥氏体的含量达到峰值，综合力学性能最佳。二次回火温度为550℃时，逆转变奥氏体主要以切变机制在马氏体板条内部形成，随着二次回火温度升高，逆转变奥氏体逐渐以扩散机制形成为主。

Formation of reversed austenite and its effect on properties of Cr13Ni4Mo steel

Formation law, mechanism of reversed austenite and mechanical properties of Cr13Ni4Mo steel were studied by means of XRD, SEM, EBSD and tensile test. The results show that no reversed austeniteis formed in the Cr13Ni4Mo steel after first tempering at 550-730 ℃. When first tempering at 630 ℃ and second tempering at 530-630 ℃, the content of reversed austenite in the steel increases firstly and then decreases with the increase of the second tempering temperature, and the tensile strength, elongation and product of strength and elongation also increase first and then decrease correspondingly. When the second tempering temperature approaches 590 ℃, the content of reversed austenite reaches the peak and the comprehensive mechanical properties are the best. The reversed austenite is mainly formed in the martensite lath with shear mechanism when the second tempering temperature is 550 ℃, and with the increase of second tempering temperature, the formation of reversed austenite is gradually dominated by diffusion mechanism.