HT20-40铸铁激光硬化组织特点的研究

Characteristic of laser hardened structures of HT20-40 cast iron

采用 CO2 激光器对 HT2 0 -4 0灰铸铁进行了熔一凝硬化处理 ,重点探讨了其组织特征及形成机理。结果表明 ,HT2 0 -4 0灰铸铁激光硬化带具有三层不同的显微组织 :(1 )与快速熔凝对应的白口化组织 -微细莱氏体 ;(2 )局部熔化区 ,具有铸态特点的岛状组织和马氏体 ,石墨部分消失 ;(3)相变区主要为隐晶马氏体 ,片状石墨基本保持原状。而且 ,通过适当的工艺控制 ,可使局部熔化区消失 ,仅存在熔 -凝区和相变区。

Hardening HT20-40 gray cast iron with CO 2 laser, the structures characteristics and forming principle of hardened layer were studied. The results reveal that the laser-hardened zone of HT20-40 gray cast iron is consisted of three layers:(1) melting-chilling layer with whitening structure-refined ledeburite; (2) localized melting layer-graphite part is melted, island structure has the characteristics of casting and martensite; (3) solid transformation layer-very fine martensite, the original pattern of lamellar graphite remains basically. Meanwhile, localized melting layer disappears by proper technology control, and there only exists melting-chilling layer and solid transformation layer.