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对具有不同原始组织的三个炉号的LZ50车轴钢进行了不同工艺的热处理,用金相方法分析了晶粒度的变化规律,比较了钢中微量元素Al、Ti含量与晶粒度的关系,结果表明:具有混晶组织的LZ50车轴钢加热到Ac1~Ac3之间时晶粒细化,但超过Ac3温度后即出现混晶,且不同钢中混晶倾向与原始状态的相同;钢中微量元素Al、Ti含量越高,混晶倾向越严重;高温固溶、低温析出预备热处理可以改变晶粒长大倾向,消除混晶组织.在此基础上对LZ50车轴钢的混晶原因进行了讨论.
The heat treatment of LZ50 axle steel with three heat numbers with different primary structure was carried out by different process. The variation of grain size was analyzed by metallographic method. The relationship between the content of Al and Ti in steel and the grain size was compared The results show that the grains of LZ50 steel with mixed grain structure are thinned when heated to between Ac1 and Ac3, but the mixed grains appear after the temperature of Ac3, and the tendency of mixed grains in different steels is the same as that of original steel. The higher the content of trace elements Al and Ti, the more serious the tendency of mixed crystal is. The high temperature solid solution and low temperature pre-precipitation heat treatment can change the tendency of grain growth and eliminate the mixed crystal structure.Based on the reason of the mixed crystal of LZ50 axle steel discuss.