冷却工艺对特厚多相组织高强低合金钢板组织与性能的影响

Effect of final cooling temperature on microstructure and properties of super heavy multi-phase HSLA steel plate

采用轧后弛豫控制相变的组织调控技术开发了一种60 mm厚460 MPa级别铁素体/贝氏体(F/B)双相钢;在工业化条件下,研究了不同终冷温度对F/B双相组织和力学性能的影响规律。结果表明:在相同开冷温度和冷却速度下,降低终冷温度能够显著细化F/B双相中的铁素体晶粒,促使贝氏体由粒状贝氏体向板条贝氏体过渡,减小钢板心部M/A岛的尺寸,提高贝氏体中大角度晶界密度,从而提高钢的强度,降低屈强比,并能够大幅降低特厚F/B双相钢韧脆转变温度。

A ferrite / bainite（F / B） dual-phase low carbon steel with thickness of 60 mm and strength of 460 MPa was developed by controlled rolling-relaxation-ACC（Accelerated Controlled Cooling） process in industrialized condition.The effects of final cooling temperature on microstructure and mechanical properties of the F / B dual-phase steel were studied.The results indicate that decreasing final cooling temperature can significantly refine the ferrite grain and M / A constituent of the steel,promotes the transformation of bainite from granular bainite to lath bainite,and increeses the high angle boundary density.Correspondingly,the yield strength and tensile strength of the steel are enhanced,and meanwhile the ductile-brittle transition temperature and yield ratio decrease and the toughness improves.