回火温度对F/B结构钢组织及性能的影响

 为研究回火温度对F/B结构钢力学性能的影响，利用力学性能测试、光学显微镜、透射电镜等方法，研究了回火温度对控轧＋弛豫＋控冷工艺生产的420 MPa级结构钢组织及力学性能的影响。研究结果表明，回火过程中F/B钢两相比例未发生变化，随着回火温度的升高，M-A岛发生了分解且F晶粒长大；同时，钢板的屈服强度上升明显，但抗拉强度变化较小，由此带来屈强比由0.80升至0.88，为回火过程中组织的回复、F晶粒长大、析出以及位错的相互作用综合影响的结果。结合去应力目的及满足屈强比技术条件的要求，推荐的回火工艺为：（400±10） ℃， （2×厚度）min。

Influence of tempering temperature on microstructure and mechanical properties of F/B structural steel

In order to study the influence of tempering temperature on mechanical properties of F/B steel,420 MPa struc-tural steel produced by Controlled Rolling,Relaxation and ACC processing was topics of research and studied by means of mechanical property test and microstructure observation with optical microscope and transmission electron microsco-py. The results show that there is no change in the proportion of ferrite and bainite during the tempering process. With the increases of tempering temperature,M-A island decomposes and grain of ferrite grows up. At the same time,yield strength increases obviously but the tensile strength increases slowly,thereby yield ratio rises from 0.80 to 0.88. Chang-es of properties are caused by recovery,grain growth,interaction between dislocation and precipitation. In order to re-lieve stresses and meet technical requirements,the recommended tempering process is(400 ± 10)℃,(2 × thickness) min.