M38合金激光辐照层的结构及其抗热腐蚀性能

铸造镍基合金M38经过功率密度为2.3×10~4W/cm~2、连续CO_2激光束作用0.2秒处理后,形成了0.6毫米厚树枝胞状晶的表层;大量的TIC被固溶;γ’相及M23C6相重新以更细小的颗粒析出在晶内或晶界上,晶粒的平均直径由0.2—0.3mm减少到～0.01mm;熔区晶粒内的含铬量略有增加;经900℃下的坩锅熔盐法试验,激光处理层较未激光处理层表现出良好的抗热腐蚀性能,特别是显著地减少了沿晶腐蚀.

STRUCTURE AND HOT-CORROSION RESISTANCE PROPERTIES OF M38 SUPERALLOY IN LASER-IRRADIATED ZONES

The structure and the hot-corrosion resiance of cast nickel-base superalloy M38 irradiated by CO_2 laser beam of 1.3kW output have been examinated by microscopy, SEM, EMPA, X—ray diffraction analysis and potential measurements in contrast with those unirradiated. The hot corrosion tests were carried out in the crucible with saltmixture of 75% Na_2SO_4 and 25% NaCl at 900℃ for 15hr, 35hr, 55hr, 80hrand 95.5h, respectively. The results show that the remelted-solidifying surface layer irradiated by laser besm may be regarded as an integrated effective coat due to its much better corrosion resistance(particularly, no obvious grain boundary penetraion corrosion) and the firm bonding between the irradiated urface layer and the base material.