不同激光器熔凝处理40Cr钢硬化层的显微组织及深度

Microstructure and Depth of Harden Layer of 40Cr Steel Melting Treated with Different Lasers

分别采用轴流和横流CO2激光器对40Cr钢进行熔凝硬化处理,利用扫描电镜和显微硬度计分析了不同工艺参数下熔凝硬化层的显微组织及深度。结果表明:两种激光器熔凝处理后的硬化层均由相变硬化区和过渡区组成;两个区的显微组织分别为混合马氏体+残余奥氏体和回火马氏体+残余奥氏体+铁素体+珠光体+碳化物;经过两种激光器处理后的硬化层深度都随着能量密度的增加而增大;横流CO2激光器处理后的硬化层深度比轴流CO2激光器处理后的更深。

The surface of 40Cr steel was treated by melting hardening with the axial flow CO2 laser and the transversal flow CO2 laser respectively. The microstructure and depth of melting hardened layers was analyzed by means of scanning electron microscope and microhardeness sclerometer. The results show that the melting hardened layer treated by axis flow and transversal flow CO2 laser both consisted of hardening zone and transient zone. The microstructure of the two zones was mixed martensite ＋ retained austenite, and tempered martensite ＋ retained austenite -F ferrite ＋ pearlite ＋ carbide. The depth of the hardened layer treated by these two lasers both increased with the increase of energy density. The depth of hardened layer treated by transversal flow CO2 laser was deeper than that treated by the axis flow CO2 laser.