U76CrRE重轨钢热处理工艺优化及力学性能分析

通过在连续冷却的在线热处理工艺基础上进行工艺优化,研究了等温处理工艺对U76CrRE重轨钢微观组织和力学性能的影响。结果表明,相变前的冷却速度、等温温度和等温时间共同影响U76CrRE重轨钢的组织和力学性能。在相变前8 ℃/s的最佳冷却速度下,等温温度越低、等温时间越短,获得的珠光体越细小;U76CrRE重轨钢的抗拉强度随着等温温度的降低、等温时间的缩短而增大;560 ℃×30 s等温处理是U76CrRE重轨钢的最优热处理工艺,其综合力学性能最好,抗拉强度为1370 MPa,硬度为390 HBS,断后伸长率为9.33%,断面收缩率为41.32%,冲击吸收能量为4.4 J。

Optimization of heat treatment process and analysis of mechanical properties of U76CrRE heavy rail steel

Effect of isothermal treatment process on microstructure and mechanical properties of the U76CrRE heavy rail steel was studied by optimizing the process based on the on-line heat treatment with continuous cooling. The results show that the cooling rate before phase transformation, isothermal temperature and isothermal time jointly affect microstructure and mechanical properties of the U76CrRE heavy rail steel. At the optimum cooling rate of 8 ℃/s before phase transformation, the lower the isothermal temperature and the shorter the isothermal time, the finer the pearlite structure obtained. The tensile strength of the U76CrRE heavy rail steel increases with the decrease of isothermal temperature and isothermal time. Isothermal treatment at 560 ℃ for 30 s is the optimum heat treatment process for the U76CrRE heavy rail steel, under which the comprehensive mechanical properties are the best, the tensile strength is 1370 MPa, the hardness is 390 HBS, the elongation after fracture is 9.33%, the percentage reduction of area is 41.32%, and the impact absorbed energy is 4.4 J.