灰铸铁激光表面处理硬化层的组织与性能

The Microstructure and Properties of the Hardening Layer on Grey Cast Iron by Laser Surface Treatment

测定了激光入射功率、扫描速度等工艺参数对灰铸铁表面硬化层深度、组织及显微硬度的影响 .实验结果表明 ,通过合理调配激光功率和扫描速度可实现微熔硬化处理和固态相变硬化处理 ,当功率一定时 ,随着扫描速度的增加 ,表面硬化区的深度、显微硬度逐渐降低 ;当扫描速度一定时 ,随着功率的提高 ,其硬化区深度及显微硬度均显著提高 ,金相分析结果表明 ,熔凝硬化区的组织为极细小初生晶 (M +A′)加莱氏体 (M +A′ +Fe3 C) ,固态相变区的组织为隐针马氏体、残余奥氏体和片状石墨 .磨损实验结果表明 ,激光处理后 ,试样的耐磨性较未处理的试样提高了 3倍 .

It is tested that the depth of laser hardening layer and its microstructure and microhardness varies with the power and scanning speed. The experimental result shows that micromelted solidified hardening and solid transformation hardening is obtained by regulating the power and scanning speed.Keeping the power constant,the depth of the hardening layer and its microhardness decrease gradually with increasing scanning speed;keeping the scanning speed constant,those of which increase obviously with the power increasing.Metallography analysis shows that the microstructure with very fine dendrites (M+A′) and ledeburite (M+A′+Fe 3C) is formed in the melted solidified hardening layer, and the microstructure with implicit acicular martensite,retained austenite and flake graphite (M+A′+G) is formed in the solid transformation hardening layer.The wear tests show that wear resistance of the gray cast iron after laser treatment is 3 times higher than those of the grey cast iron in the casting state.