18.3Cr-11.0Mn-0.06Ni-0.19N超低Ni型双相不锈钢的热压缩行为及裂纹控制

Hot compression behavior and crack control of 18.3Cr-11.0Mn-0.06Ni-0.19N ultra-low nickel duplex stainless steel

采用物理模拟方法研究了18.3Cr-11.0Mn-0.06Ni-0.19N超低Ni型双相不锈钢在热压缩温度为1123~1423 K、应变速率为0.01~10 s^(-1)和50%变形量条件下的热压缩变形行为。结果表明:试验钢的热压缩软化以铁素体动态回复(DRV)为主,且伴随有少量的两相动态再结晶(DRX)发生,温度升高会促进铁素体发生DRV,有利于在应变速率为0.1 s^(-1)变形时部分奥氏体位错胞向DRX组织的转变。变形温度为1223 K时,随应变速率提高,应变逐渐向奥氏体相转移。再结晶临界应变主要发生在1123~1323 K/0.1~1 s^(-1)范围,应变速率与变形温度相比对其影响较大。确定了试验钢热变形方程和激活能(430.6 kJ/mol),结合热加工图和压缩裂纹特征确定了试验钢的最佳热加工参数范围为0.31~0.77 s^(-1)/1300~1390 K,失稳区主要集中在2.7~10 s^(-1)高应变速率区。高Mn添加导致低温变形时加工硬化率增加,促进了1123 K变形时楔形裂纹形成。

Hot compression deformation behavior of 18.3 Cr-11.0 Mn-0.06 Ni-0.19 N ultra-low nickel duplex stainless steel under conditions of hot compression temperature of 1123-1423 K, strain rate of 0.01-10 s^(-1)and 50% deformation was studied by physical simulation. The results show that the hot deformation softening of the experimental steel is mainly caused by ferrite dynamic recovery(DRV), accompanied by a small amount of two-phase dynamic recrystallization(DRX). The increase of deformation temperature will promote the occurrence of DRV in ferrite, which is conducive to the transformation of partial austenite dislocation cells to DRX microstructure at the strain rate of 0.1 s^(-1). When the deformation temperature is 1223 K, the strain gradually transfers to austenite phase with the increase of strain rate. The critical strain of dynamic recrystallization mainly occurs in the range of hot compression temperature of 1123-1323 K and strain rate of 0.1-1 s^(-1), and the strain rate has a great influence on it compared with the deformation temperature. The hot deformation equation and activation energy(430.6 kJ/mol) of the experimental steel are determined. By combining the hot working diagram with compression crack characteristics, the optimal hot working parameters of the experimental steel are determined to be the strain rate of 0.31-0.77 s^(-1)and deformation temperature of 1300-1390 K, and the instability zone is mainly concentrated in the high strain rate zone of 2.7-10 s^(-1). High Mn content leads to the increase of work hardening rate during low temperature deformation and promotes the formation of wedge crack during deformation at 1123 K.