高铬铸钢激光熔凝组织与性能研究

为提高锅炉燃烧器喷嘴的表面性能,采用5kW横流CO2激光加工系统对高铬铸钢表面进行熔凝处理,并进行显微组织分析和硬度测试.研究结果表明:铸态高铬铸钢晶粒较粗大、组织不均匀,原始组织以奥氏体为基体,还存在大量网状断续共晶碳化物、莱氏体.经激光凝熔后,显微组织明显细化,其试样剖面组织分为激光熔凝区(细小奥氏体 少量细小未熔碳化物)、激光相变区(奥氏体 少量晶界碳化物)、过渡区和母材4个区域.熔凝区和相变硬化区的淬硬深度依工艺参数不同.可达0.2～0.3mm.由于形成了奥氏体组织,高铬铸钢表面硬度增加不明显,硬度最大值出现在相变硬化区.

Investigation on Laser Remelting and Property of High Chromium Cast Steel

In order to improve surface properties of the burning spraying nozzles of boilers, using a 5kW continuous wave CO2 laser to perform the laser remelting treatment experiment on specimen of high chromium cast steel, the microstrncture and the hardness of the specimen were measured. The results show that as cast structure of high chromium cast steel is coarsely and non-homogeneous, is mainly austenite, ledeburite and carbides. After laser remelting, the section is divided into remelted zone consisted of austenite and carbides, quenched zone composed of austenite and carbides . heat affected zone and base metal. The region and the hardness of various zones are related to the laser processing parameters. The hardening depth of melted zone and quenched zone may be up to 1mm-2mm. The hardening effect is not obvious after laser remelting treatment because the formation of austenite in remelting zone.