回火温度对LM_2钢B/M复相组织性能的影响

Influence of Tempering Temperature on the Properties of B/M Duplex Structure in Steel LM_2

研究了回火温度对新型冷模具钢-LM_2钢复相处理后的显微组织结构和性能的影响.结果表明,在一定等温淬火工艺下,回火对性能有明显影响,其中200℃回火后强韧性配合较好,示波单冲缺口冲击功大,疲劳裂纹扩展速率较低和疲劳门槛值较高.该工艺用于LM_2钢重载冷挤压模具可使寿命提高3～5倍以上.

This paper deals with the influcence of tempering temperature on the microstructure and properties after the treatment of duplex phase in steel LM_2.The results show that tempering has obvious effect on the properties under a certain austempering process,after austempering (1170℃-270℃-60min) and tempering (200℃) the strength-toughness is better,the notch impact energy larger,the fatigue crack propagation rate lower and fatigue threshold value △K_(1h) higher.The service life of heavy cold extrusion die made of steel LM_2 could be prolonged 3～5 times.