脉冲电流作用下金属材料的相变行为

Electropulsing⁃induced phase transformation behavior in metal materials

针对α+β钛合金和奥氏体不锈钢两种重要金属材料,开展了电、热处理及相变定量统计实验,定量分析了电流对其相变的作用规律,探讨了电流的微观作用机理。结果表明,电流对钛合金α→β相变起降低相变温度和加速相变过程的促进作用,对不锈钢马氏体相变起抑制作用。通过相变定量统计,探明了电流参数对相变的影响规律:钛合金α→β相变温度随电流密度增大而显著降低,但几乎不受电流占空比影响,相变速度随电流密度增大而提高;不锈钢马氏体相变随电流密度增大而显著减少。基于电流对空位、位错等缺陷的“电子风”和焦耳热效应,揭示了电流对钛合金扩散型α→β相变和不锈钢应变诱导马氏体相变形核及长大阶段的作用机理。

For two typical metal materials ofα+βtitanium alloy and austenitic stainless steel,electropulsing treatment(EPT),tradi⁃tional heat treatment(THT)and quantitative statistics of phase transformation were conducted.The effect of current on the phase trans⁃formation was quantitatively analyzed and the microscopic mechanism of current was discussed.The results show that the electricity is a⁃ble to reduce the transformation temperature and accelerate the transformation process ofα→βtransformation in titanium alloy,and suppress the martensitic phase transformation in stainless steel.Moreover,the effects of elctropulsing parameters on the phase transfor⁃mations were quantitatively studied.In titanium alloy,with the increase of current density,theα→βphase transformation temperature is reduced but almost not be influenced by the pulse duty,and its transformation rate is enhanced.In austenitic stainless steel,the mar⁃tensitic phase transformation was reduced significantly with the increase of current density.The mechanism of current on the nucleation and growth stages of the diffusedα→βphase transition of titanium alloy and the strain⁃induced martensitic phase transformation of stainless steel were revealed based on the current⁃induced“electron wind”and Joule thermal effects on vacancy,dislocation and other defects.