Abstract: The precipitation behavior in double tempering between 100 ℃ and 600 ℃ of 4~6Cr-2~4W-2～4Mo-1.5~2.0V and Cr-W-Mo-V+0.05~0. 10N serious semi-high speed steel (HSS) quenched at 1050 ℃ has been studied,in which the morphology and composition of carbides are analyzed by Transmission and scanning electron microscopy,energy dispersive spectroscopy and electron energy loss spectroscopy,and the volume fraction of retained austenite are measured by X-ray diffraction method. The results indicated that the secondary hardening effect of steel was reinforced with addition of nitrogen,the precipitation of carbonitrides in tempering between 425 ℃ and 475 ℃ were attributed to nitrogen,and large amount of compound carbonitrides deposited and formed by tempering carbides at 550 ℃ touched to surface of nitride. The amount of retained austenite in semi-HSS + N tempered below 400 ℃ was 15%～17%,and decreased obviously with tempering temperature increasing and was less than 3% in steel tempered at 525 ℃.

Key words: Semi- High Speed Steel, Tempering, Nitrogen, Precipitation, Retained Austenite

摘要： 进行了Cr-W-Mo-V(%:46Cr-24W-24Mo-1.52.0V)系和Cr-W-Mo-V+N(0.05%0.10%)系半高速钢(Semi-HSS)1050℃淬火后分别在100~600℃两次回火沉淀析出行为的研究。采用透射电镜、扫描电镜及能谱仪和能量损失谱对碳化物形貌和成分进行分析,用X射线衍射法测定残余奥氏体的体积分数。结果表明,氮有增强钢的二次硬化的效果,氮促进碳氮化物在425~475℃回火析出,在550℃回火碳化物依附在氮化物表面而沉淀形成复合碳氮化物。Semi-HSS+N在淬火及400℃以下回火,残余奥氏体为15%~17%;随回火温度增加,残余奥氏体量急剧降低,在525℃回火残余奥氏体小于3%。

关键词: 半高速钢, 回火, 氮, 析出, 残余奥氏体