750 MPa级高强度磁轭钢板性能和强化机理研究

Study on Properties and Strengthening Mechanisms of 750 MPa High Strength Rim Steel Sheet

磁轭钢板性能是水轮机机组平衡与稳定性的保障。基于某钢厂试制750MPa级高强度磁轭钢板的工艺路线分析,开展解剖试验,对磁轭钢板的化学成分、磁感性能和力学性能进行测试分析,进而得出磁轭钢板的强化机理。研究表明:1)控轧控冷技术的应用和Nb、Ti复合合金化对细化晶粒的贡献及工艺参数的相互匹配,是磁轭钢板生产工艺技术的关键;2)试制的磁轭钢板的化学成分、磁感性能和力学性能指标均处于标准值范围内;3)磁轭钢板的微观组织为贝氏体加碳化物,Nb、Ti等微量元素的添加对金相组织的细化非常有利;4)磁轭钢板的强化机理为组织强化与析出强化,其中组织强化占主导地位。

The performance of the rim steel sheet is the guarantee of balance and stability of the hydraulic turbine unit.Based on the technological route analysis of 750 MPa high strength rim steel sheet trial produced in a steel plant,the dissection test is carried out to test and analyze the chemical composition,the magnetic inductive properties and the mechanical properties of the rim steel sheet,and then the strengthening mechanism of the rim steel sheet is obtained.The results show that:1)the application of controlled rolling and controlled cooling technology,the contribution of Nb and Ti composite alloying to the grain refinement and the matching of their process parameters are the key to the production technology of the rim steel sheet;(2)the chemical composition,the magnetic inductive properties and the mechanical properties of the trial produced rim steel sheet are all within the standard range;3)the microstructure of the rim steel sheet is bainite with carbide,and the addition of trace elements including Nb and Ti is very beneficial to the refinement of metallographic structure;4)the strengthening mechanism of rim steel sheet is the structural strengthening and the precipitation strengthening,in which the structural strengthening is dominant.