加热工艺对中锰钢残余奥氏体含量的影响

 研究了不同加热方式对0.2%C-5%Mn钢650℃临界退火后残余奥氏体含量的影响。采用透射电镜TEM、电子背散射EBSD等技术研究了碳化物析出和组织形貌，利用XRD技术测定了残余奥氏体体积分数。结果表明：较低温度下等温一段时间后加热到650℃，或直接快速加热到650℃进行临界退火，可获得较多残余奥氏体。因为快速加热既能抑制升温过程中组织的回复和再结晶，也能抑制粗大渗碳体颗粒的析出；在较低温度等温处理时可析出细小弥散的碳化物并在临界退火时迅速固溶，这些细小弥散的碳化物作为形核核心加速了奥氏体相变。

Effect of Heating Process on the Amount of Austenite Retained in Medium Mn Alloyed TRIP Steel

Effect of heating processes on the retained austenite of 0.2C-5Mn steel was investigated. The microstructure evolution during heating was characterized by transmission electronic microscopy and electron backscatter diffraction. The amount of retained austenite was measured by X-ray diffraction. The results show that heating with a high rate or with an interruption at low temperature leads to more austenite formed during the intercritical annealing and then more retained after quenching. An isothermal holding at low temperature results in extensive precipitation of transition carbide which can be completely dissolved during the intercritical annealing and acts as nucleation sites of austenite grains, leading to accelerated austenitization kinetics; whilst the high heating rate could suppress both precipitation of cementite and recovery of the matrix during heating, promoting austenitization before recrystallization.