过时效温度对连续退火制备DP1180钢组织性能的影响

Effect of over-aging temperature on microstructure and properties of DP1180 steel under continuous annealing process

通过扫描电镜(SEM)、X射线衍射(XRD)和室温拉伸等技术对DP1180钢的微观结构和力学性能进行了表征。结果表明,冷轧退火后钢的微观组织主要由铁素体(F)、马氏体(M)和少量贝氏体组成。在230℃过时效处理时,马氏体主要呈板条状,铁素体呈多边形,粒状贝氏体含量较少。随着过时效温度的升高,板条状马氏体含量减少,粒状贝氏体增加,碳化物明显增加。随过时效温度的不断上升,抗拉强度降低,伸长率增加。过时效温度为270℃时,抗拉强度为1255.0 MPa,伸长率为11.39%,强塑积为14.29 GPa·%,综合力学性能最佳。DP1180钢的合理的过时效温度区间为230~306.8℃。

Microstructure and mechanical properties of the DP1180 steel were characterized by means of scanning electron microscopy(SEM), X-ray diffraction(XRD) and room temperature tensile techniques. The results show that microstructure of cold-rolled annealed steel is mainly composed of ferrite(F), martensite(M) and a small amount of bainite. When over-aged at 230 ℃, the martensite is mainly lath-like, the ferrite is polygonal, and the content of granular bainite is less. With the increase of over-aging temperature, the content of lath-like martensite decreases, granular bainite increases and carbides increase obviously. With the increase of over-aging temperature, the tensile strength decreases and the elongation increases. When the over-aging temperature is 270 ℃, the tensile strength is 1255.0 MPa, the elongation is 11.39%, and the product of strength and elongation is 14.29 GPa·%, and the comprehensive mechanical properties are the best. The reasonable over-aging temperature range of the DP1180 steel should be 230-306.8 ℃.