高铁用新型弹条用钢连续冷却转变曲线与热处理工艺

Continuous Cooling Transformation Curve and Heat Treatment Process of A New Type of Spring Steel Used for High Speed Railway

针对一种新研制的高速铁路弹条用钢,用Gleeble1500测定了弹簧钢的连续冷却转变曲线,采用金相显微镜观察不同冷速下的显微组织,测定不同冷速下钢的显微硬度。结果表明：当冷速在0.05～1℃/s时,组织为铁素体和珠光体;当冷速为2℃/s时,析出马氏体组织;冷速为5℃/s时,组织全部为马氏体组织;随冷却速度的进一步增大,马氏体逐渐细化,钢的显微硬度也逐渐增加。对该钢进行了正交热处理实验,通过对实验数据的分析,得出该钢的最佳热处理参数：淬火温度890℃,保温时间20min,回火温度410℃,回火保温时间50min。

A continuous cooling transformation curve of a newly developed spring steel for high speed elastic bar was tested by thermo mechanical simulator. The micmstructure at different cooling rates was observed by using optical microscope, and the microhardness of the steel at different cooling rates was measured by using the microhardness tester. The results show that the ferrite and pearlite precipitate firstly at the cooling rate of 0.05-2℃/s, martensite precipitates when the cooling rate reaches 2 ℃/s. When the cooling rate reaches 5 ℃/s, the microstructure is almost martensite. With the increase of the cooling rate, the microstructure gradually refines and the microhardness of the steel increases. The heat treatment process is optimized based on the analysis of the experimental data obtained by means of orthogonal heat treatment experiment. The optimum heat treatment is quenching at 890 ℃ for 20min in oil and tempering at 410℃ for 50min.