穿水冷却对GCr15轴承钢组织和力学性能的影响

Effect of Through-Water Cooling on Microstructure and Mechanical Properties of GCr15 Bearing Steel

通过4种穿水冷却工艺生产φ20 mm热轧GCr15轴承钢棒材,研究了穿水冷却对热轧及球化退火、淬回火热处理后轴承钢组织和力学性能的影响.结果表明:终轧前后均采用穿水冷却,控制终轧温度在800～860℃,上冷床返红温度为620℃,能明显降低先共析碳化物及珠光体相变温度,减小热轧轴承钢中先共析碳化物厚度、连续度及珠光体片层、球团大小.退火及回火组织中碳化物厚度减小,均匀性增加,防止了粗大未溶网状碳化物的遗传.热轧及热处理后轴承钢抗拉强度及面缩率均增强.

Theφ20 mm hot-rolled GCr15 bearing steels were obtained through four kinds through-water cooling processes.The effects of through-water cooling on microstructure and mechanical properties of the hot-rolled bearing steels and heat-treated bearing steels after spheroidizing annealing and quenching-tempering processes,respectively were investigated.The results showed that when the through-water cooling was carried out both before and after finish rolling and the finish-rolling and re-reddening temperature was 800~860℃and 620℃,respectively,the temperature of phase transformation for the proeutectoid carbide and the pearlite went down,and the thickness and continuity of the proeutectoid carbide,the pearlite interlamellar spacing and the pearlitic colony size in the hot-rolled bearing steels were decreased.Accordingly,the thickness of carbide in the annealed and tempered microstructure was decreased while the homogeneity was enhanced.Moreover,the thick undissolved carbide networks were prevented.Eventually,the tensile strength and percentage of area reduction of the hot-rolled and heat-treated bearing steels were increased.