终轧温度和冷却工艺对铁素体贝氏体双相钢组织和力学性能的影响

Effects of finish rolling temperature and cooling process on microstructures and mechanical properties of ferrite and bainite dual phases steel

利用Gleeble-2000D热模拟机、550 mm轧机、扫描电镜等研究了终轧温度和冷却工艺对铁素体贝氏体双相钢组织和性能的影响。首先,在水冷-空冷-水冷模式下研究终轧温度对显微组织和力学性能影响,结果表明:随终轧温度降低,基体组织带状加剧,且铁素体形态由多边形转变为沿轧制方向变形的椭圆形;当终轧温度低于800℃时,铁素体比例明显增加,贝氏体比例下降,抗拉强度下降。其次,在850℃的终轧温度下研究了冷却工艺对显微组织和力学性能的影响,结果表明:当终轧后冷却方式为水冷时,基体组织以准多边形铁素体和针状铁素体为主,伸长率较低;终轧后采用水冷-空冷-水冷方式冷却时,基体组织以块状铁素体和贝氏体为主,伸长率较高。

Gleeble-2000 D thermal simulation machine,550 mm rolling mill and SEM were adopted to investigate the effects of finish rolling temperature and cooling process on the microstructuress and mechanical properties of ferrite and bainite dual phases steel.The effects of finish rolling temperature on microstructure and mechanical properties under the process of water cooling-air cooling-water cooling were studied firstly.The results show that the band trend of microstructure is identified by reducing the finish rolling temperature,meanwhile,the shape of ferrite changes from polygonal to oval along rolling direction;when the finish rolling temperature is lower than 800℃,the proportion of ferrite increases and that of bainite decreases,and the tensile strength decreases accordingly.Secondly,the effects of cooling process on microstructures and mechanical properties with finish rolling temperature of 850℃were researched.The results show that the matrix microstructure is mainly quasi-ferrite and acicular ferrite after water cooling followed hot rolling immediately,which shows lower elongation.However,the matrix microstructure is mainly polygonal ferrite and bainite with cooling process of water cooling-air cooling-water cooling,which shows higher elongation.