摘要
利用CO2轴流激光加工机对40Cr钢表面进行激光熔凝硬化处理。利用扫描电子显微镜、金相显微镜和显微硬度计研究了不同工艺下熔凝硬化层及基体的显微组织和硬度分布特征。实验表明:熔凝硬化层由熔化区、相变硬化区和热影响区组成;由表及里组织分别为极细隐晶马氏体+少量残余奥氏体、隐晶马氏体+碳化物+残余奥氏体、马氏体+回火屈氏体+铁素体。硬化层最高硬度约是基体的3倍;随着扫描速度的增加表层硬度先增加后减小,当扫描速度为2.5 m/m in时,表层硬度最大,为1097.9 HK。
The hardening of surface for 40Cr steel is melted by the axis flow CO2 laser. The hardness distribution character and microstructure of melting hardening layer and substrate in different processes are analyzed by scanning electron microscope and metalloscope and microhardmeter. The results of experiments show that the melting hardening layer consists of melting zone and hardening zone of phase transition and heat affected zone, The layer microstructures are respectively extremely small hidden - crystal martensite ＋ a few residual austenite, hidden - crystal martensite ＋ carbides ＋ residual austenite, martensite ＋ tempering troostite ＋ ferrite from surface to inside. The biggest hardeness of hardening layer is about 3 times as that of the substrate. The hardeness of surface increased first then decreased with the acelerating of scanning speed, The biggest hardeness of surface is 1097.9 HK when the scanning speed is 2.5 m/min.
出处
《热处理技术与装备》
2008年第3期25-28,共4页
Heat Treatment Technology and Equipment
关键词
激光熔凝
硬化层
扫描速度
硬度
laser melting
hardening layer
scanning speed
hardness
