GCr15轴承钢高温变形后控冷工艺的研究

轴承钢棒材轧后温度较高导致的网状碳化物析出严重影响我国高质量轴承钢生产.在热模拟试验机上对GCr15轴承钢进行了试验研究,分析了不同控冷工艺参数对GCr15轴承钢二次碳化物的析出和珠光体转变的影响.研究表明,GCr15轴承钢经980℃高温变形后快速冷却,随着冷却速度的增加,晶界处二次碳化物由半网状分布、短棒状分布到最后弥散析出,珠光体球团直径和片层间距减小,并有退化珠光体生成.轴承钢中退化珠光体组织的出现,是由于其热变形后快速冷却,抑制了先共析碳化物在冷却过程中的过早析出造成的.较合理的冷却工艺是GCr15轴承钢高温变形后快速冷却到700℃,再以3℃/s的冷却速度进行冷却.

Controlled cooling of GCr15 bearing steel after high temperature deformation

Thermal simulation was conducted by thermo-mechanical simulators on GCr15 bearing steel. The mechanism for different cooling processes on the precipitation of proeutectoid secondary carbide and the transformation of pearlite was analyzed. The results show that the secondary carbide converts from half network,rodshaped distribution to dispersive precipitation,the diameter of pearlite nodule and the pearlitic lamellar spacing decrease,the degenerated pearlite appears along with the increase of cooling rates for GCr15 bearing steel after high temperature deformation at 980 ℃. The optimal process is the cooling rate of 3 ℃ /s for GCr15 bearing steel,and then the rapid cooling to 700 ℃ after high temperature deformation. The appearance of degenerated pearlite is due to the controlled cooling after hot deformation and therefore suppressing the proeutectoid carbide precipitation during cooling.