等温变形0Cr14Mn21NiN无磁不锈钢的晶间腐蚀敏感性

通过Thermal-Calc热力学软件对0Cr14Mn21NiN无磁不锈钢中碳化物析出的平衡相区进行了计算,并通过时效处理试验进行了验证。通过不同参数的等温变形试验对实际的非平衡态碳化物析出行为进行了研究。通过双环电化学动电位再活化法(DL-EPR)对等温变形试样的晶间腐蚀敏感性进行了测试和对比。结果表明:热力学计算的平衡态Cr₂₃C₆碳化物析出温度范围为512~847 ℃,而通过时效试验验证的实际析出温度范围为720~940 ℃,表明二者之间存在约200 ℃的误差。当总变形量不超过20%时,等温变形非平衡态Cr₂₃C₆碳化物析出下限温度进一步降低至625 ℃,等温变形过程对晶界Cr₂₃C₆碳化物形核和长大过程均有加速作用。DL-EPR电化学方法结果表明等温变形后由于碳化物析出速度的加快,0Cr14Mn21NiN无磁不锈钢的晶间腐蚀敏感性显著增加。

Intergranular corrosion susceptibility of isothermally deformed 0Cr14Mn21NiN non-magnetic stainless steel

The equilibrium phase regions of carbide precipitation in the 0Cr14Mn21NiN non-magnetic stainless steel (NMSS) were calculated by Thermal-Calc software, and the result was verified by aging treatment experiment. The real non-equilibrium carbide precipitation behavior was researched after isothermal deformation (ITD) experiment with different parameters. The intergranular corrosion (IGC) susceptibility of ITD specimens was tested and compared by double loop electrochemical potential-dynamic reactivation (DL-EPR) method. The results show that the Thermal-Calc calculated equilibrium Cr₂₃C₆ precipitation temperature region is from 512 ℃ to 847 ℃, while the real region obtained from the aging experiment is from 720 ℃ to 940 ℃, indicating a distinction of approximately 200 ℃. When the total deformation is less than 20%, the lower temperature limit of non-equilibrium carbide precipitation of ITD specimens is descended to 625 ℃, and both the carbide nucleation and growth are accelerated after the ITD process. The DL-EPR results show that the IGC susceptibility of the 0Cr14Mn21NiN non-magnetic stainless steel is obviously increased after the ITD process due to the accelerated carbide precipitation.