马氏体沉淀硬化不锈钢0Cr15Ni5Cu3Nb热变形行为与热加工图研究

Study of Thermal Deformation Behavior and Processing Map of 0Cr15Ni5Cu3Nb Martensitic Precipitation-hardening Steel

采用Gleeble-1500D热模拟试验,研究了马氏体沉淀硬化不锈钢0Cr15Ni5Cu3Nb(15-5PH)在850~1250℃、0.001~1 s^(-1)条件下的热变形行为和微观组织演化机制。研究结果表明:材料变形过程存在加工硬化、动态软化和流变稳态的特征。利用Arrhenius型双曲正弦方程,建立了15-5PH热变形本构模型ε·=4.336×1018[sinh(0.011×σ)]^(5.817) exp(-519543/RT)。该模型预测值与试验值平均相对误差7.1%,能较好地描述15-5PH热变形行为。15-5PH在高应变速率条件下可能发生流变失稳现象。热变形过程,15-5PH可发生动态再结晶现象,动态再结晶晶粒尺寸和体积分数随着温度的升高或应变速率的降低而增加。

The hot deformation behaviors of martensitic precipitation-hardening steel 0Cr15Ni5Cu3Nb(15-5PH)at temperature of 850~1250℃and deformation rate of 0.001~1 s^(-1) were studied through Gleeble-1500D hot modeling test machine.The results show that the characteristics of work hardening,dynamic softening and rheological steady-state exist at material flow curve.A hyperbolic type constitutive modelε·=4.336×10^(18)[sinh(0.011×σ)]^(5.817) exp(-519543/RT)is established for the 15-5PH.The average relative error between predicted value and measured value is 7.1%,which indicates the accuracy of the constitutive model.The processing map indicates that flow instability may occur at higher strain rates.An obvious dynamic recrystallization phenomenon can take place in the thermal deformation process of 15-5PH.With increasing temperature or decreasing strain rate,the recrystallized grain size and volume fraction increase.