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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 60 mm thick, 460 MPa grade ferritic / bainitic (F / B) duplex steel was developed by means of microstructure control of post-rolling relaxation-controlled phase transformation. Under industrial conditions, F / B dual phase microstructure and mechanical properties of the law. The results show that the reduction of the final cooling temperature can remarkably refine the ferrite grains in the F / B dual phase at the same opening and cooling temperatures and promote the transition from granular bainite to lath bainite , Reducing the size of the M / A island in the heart of the steel plate and increasing the large-angle grain boundary density in the bainite, thereby increasing the strength of the steel, reducing the yield ratio, and greatly reducing the ductile-brittle transition of the ultra-thick F / B duplex steel temperature.