低碳Si-Mn系TRIP钢的热处理工艺对组织的影响

Effect of Heat Treatment Technology on Microstructure of Low Carbon Si-Mn TRIP Steel

低碳Si Mn系TRIP钢有着复杂的显微组织 ,主要由多边形铁素体 (F) +无碳贝氏体 (B) +残留奥氏体(AR)组成。本试验采用了彩色金相法 ,并结合X ray衍射、SEM和TEM等手段研究了低碳Si Mn系TRIP钢显微组织与工艺的关系 ,发现随着两相区退火温度的升高 ,最终显微组织中铁素体基体体积分数变小 ,并且贝氏体量增多 ,残留奥氏体的稳定性呈起伏式变化 ;在贝氏体转变区的等温温度过高或过低 ,均使最终显微组织中残留奥氏体体积分数减少 ;在贝氏体转变区等温时 ,所形成贝氏体表现出粒状的特征。

Si Mn TRIP steel has a multi phase microstructure,which is mainly composed of ferrite,bainite and retained austenite.The relationship between heat treatment process and microstructure of the steel was investigated by means of tint etching method,together with X ray diffraction,SEM and TEM method in this paper.The results show that in the intercritical phase regions,with the annealing temperature rising,the volume percentage of the ferrite matrix reduces,the bainite increases and the stability of retained austenite fluctuates.In the bainite transformation range,if isothermal temperature is either over high or over low,the volume percentage of the retained austenite will be reduced and the bainite is provided with granular morphology.