Ti微合金化对耐火建筑钢组织和性能的影响

Effect of Ti microalloying on microstructure and properties of fire-resistant construction steel

采用低Mo及Ti的复合微合金化,设计3种试验钢配以合理的控轧控冷工艺,成功开发出低成本460 MPa级耐火钢。力学性能测试及显微组织分析结果表明,控轧控冷后水冷,试验钢板获得耐火钢的理想组织:粒状贝氏体和M/A岛。随Ti含量的增加,3种试验钢的平均晶粒尺寸递减。3种试验钢的室温屈服强度都大于460 MPa, 600℃保温3 h的高温屈服强度都大于307 MPa,具有良好的高温力学性能。在相变强化、析出强化、细晶强化及位错强化的共同作用下,不同Ti含量的试验钢获得了良好的高温力学性能。0.07%Ti含量试验钢的YS值(600℃屈服强度/室温屈服强度)为0.68,完全满足耐火钢的使用标准。

Three kinds of tested steels were designed with low Mo and Ti multi-microalloying, and reasonable thermo-mechanical control process(TMCP) was explored. The low cost 460 MPa grade fire-resistant steel was successfully developed. Through the test of mechanical properties and microstructure analysis, the results show that the ideal microstructure of fire-resistant steel is obtained, which is granular bainite and M/A island. With the increase of Ti content, the average grain size of the tested steel decreases. The room temperature yield strength of the three tested steels are all higher than 460 MPa, and the yield strength at high temperature of 600 ℃ for 3 h is higher than 307 MPa, which indicates that the three tested steels all have excellent mechanical properties at high temperature. Under the combined action of phase transformation strengthening, precipitation strengthening, fine grain strengthening and dislocation strengthening, the tested steels with different Ti contents obtain good high temperature mechanical properties. Among them, the YS value(600 ℃ yield strength/room temperature yield strength) of the tested steel with 0.07% Ti is 0.68, which fully meets the using standard of fire-resistant steel.