600 MPa级低合金高强钢的组织调控与工艺优化

为了开发并稳定600 MPa级低合金高强钢的生产工艺参数，利用连续退火模拟机对试验钢进行了连续退火试验，并通过扫描电镜和拉伸试验机研究了均热温度和过时效温度对试验钢显微组织和力学性能的影响。结果表明，随着均热温度的升高，试验钢的屈服强度和抗拉强度均逐渐减小，伸长率逐渐增大；随着过时效温度的升高，屈服强度逐渐增大，抗拉强度逐渐减小，伸长率则先增大后减小。试验钢在820 ℃均热、390 ℃过时效时，获得最优的力学性能，其中抗拉强度为627 MPa，屈服强度为493 MPa，总伸长率超过20%。此外，利用透射电镜观察到钢中存在大量的纳米尺度析出物，这些析出物对试验钢强度的提升有较大的贡献。

Microstructural control and process optimization of #br# 600 MPa grade low alloy high strength steel

 In order to develop and stabilize the technological parameters of 600 MPa low alloy high strength steel, continuous annealing experiments were carried out on the experimental steel by means of continuous annealing simulator. The effects of soaking temperature and over aging temperature on the microstructures and mechanical properties of the experimental steel were studied by means of scanning electron microscopy and tensile test machine. The results showed that with the increase of soaking temperature, the yield strength and tensile strength of the experimental steel decreased gradually, and the elongation increased gradually. With the increase of over aging temperature, the yield strength increased gradually, the tensile strength decreased gradually, and the elongation increased first and then decreased. The optimum mechanical properties were obtained when the steel was soaked at 820 ℃ and over aging at 390 ℃. The tensile strength was 627 MPa, the yield strength was 493 MPa and the total elongation was over 20%. In addition, a large number of nano scale precipitates were observed by transmission electron microscopy (TEM), which contributed greatly to the strength improvement of the experimental steel.