合金铸铁光束熔凝处理后的组织和硬度

采用自研的ＳＲ－Ⅱ型５ｋＷ聚焦光束加热设备对珠光体合金铸件进行了表面熔凝强化处理。借助扫描电镜、光学显微镜、显微硬度和表面硬度计研究了采用不同聚焦模式的光束熔凝处理的合金铸铁的表面硬度、显微硬度分布及光束热作用区的组织转变特点。结果表明，当采用单一模式的反光镜聚焦时，功率密度较低、热作用区的奥氏体发生了托氏体－索氏体转变；而采用透镜与反光镜配合的复式聚焦模式时，由于功率密度的提高，奥氏体转变为马氏

Microstructure and Hardness of Surface Melted Cast Alloy Iron with Light Beam

With the use of a SR II 5kW light beam heating equipment developed by ourselves, pearlite cast alloy iron is strengthened by surface melting with light beam. The surface hardness, microhardness distribution and structure transformation in the light beam surface melted zone with different focussing systems are investigated by SEM, optical microscope, microhardness and surface hardness tests. The results show that when using a reflector focusing system, the transformation from austenite into troostite sorbite occurs in the light beam surface melted zone due to low power density. But when employing combined focusing system with reflector and lens, austenite transforms into martensite in light beam surface melted zone. After light beam surface melting of cast alloy iron, the microstructure of surface is ledeburite, causing surface hardness above 50HRC. But microhardness distribution is related to the focusing systems.