中温卷取工艺下热轧双相钢组织性能研究

对中温卷取工艺下的热轧双相钢组织性能进行了研究。结果表明,Cr、Mo成分体系的热轧双相钢采用3段式冷却后屈强比为0.6,显微组织为准多边形铁素体、岛状马氏体以及细小粒状贝氏体,具有较高的伸长率和扩孔性能。由于贝氏体的存在,缩小了双相钢多相组织之间的强度差,有利于提高其塑性变形过程中的协调变形能力及扩孔性能。通过对应力幅值为430MPa时双相钢的疲劳断口进行分析,断口具有显著的韧窝、二相粒子、疲劳辉纹、二次裂纹等特征,有利于提高其疲劳强度。

Study on the microstructure and properties of hot rolled dual phase steel under medium temperature coiling process

The microstructure and properties of hot rolled dual phase steel under the medium temperature coiling process were studied.The yield strength ratio of hot rolled dual phase steel with Cr and Mo composition system adopts three stage cooling was 0.6.The microstructure included quasi polygonal ferrite,island shaped martensite,and fine grained bainite,with high elongation and good hole expansion properties.Because of the existence of bainite,the strength difference between the multiphase structures of the experimental dual phase steel was reduced,which was beneficial to improve the coordinated deformation ability of the material during plastic deformation and improve the material's hole expansion performance.Through the analysis of the fatigue test of dual phase steel when the stress amplitude changes by 430 MPa,the fracture had the characteristics of obvious dimple,second phase particle,fatigue striation,secondary crack and other characteristics,which was conducive to improve the fatigue strength of the material.