热处理对40Mn钢带性能均匀性影响

Effect of Heat Treatment on Property Homogeneity of 40Mn Steel Strip

采用金相显微镜、洛氏和显微硬度计对影响40Mn钢带热处理性能均匀性的原因进行了分析,并探讨了影响淬回火试样显微组织和硬度的因素。结果表明,40Mn热轧钢带的带状组织级别越高,淬回火后屈氏体组织也越粗大。表面脱碳导致了 40Mn钢带淬火硬度不均,表面洛氏硬度随脱碳层的增加而急剧降低。40Mn热轧钢带淬火时受淬火保温温度影响大.860^和820T保温时硬度(HRC)分别为47. 8 ,43. 1。高的淬火加热温度能促进马氏体转变,回火组织更粗大、硬度更高。理论计算40Mn的Ac3点为795t,6m m厚度的钢带淬火所需最小保温时间约为 7min.

The reason of influence on heat treatment property homogeneity was analyzed by metallurgical microscope,testers of rockwell hardness and Microhardness in the 40Mn steel strip,and the influence factors were researched about microstructure and hardness of the samples after quenching and tempering.The results showed that the higher the grade of banded structure in the steel of 40Mn hot-rolling strip,the coarser the troostite structure after quenching and tempering.Surface decarburization brought about uneven quenching hardness,and surface rockwell hardness was reduced rapidly with surface decarburization increased in the 40Mn steel strip.Heat preservation temperature had greatly influences on the 40Mn hot-rolling strip during quenching,the hardness(HRC)under the preservation temperature of 860℃and 820℃:were 47.8 and 43.1 respectively.And martensitic transformation could be promoted by the high quenching heat temperature,moreover,with coarser tempering structure and higher hardness.The Ac3 temperature point of 40Mn is at 795℃ by theoretical calculation,and the minimum time of quenching preservation needs about 7min for 6mm thickness strip.