材料期刊网

采用涂盐热腐蚀试验方法研究了M-38等四种镍基合金(二种铸造:M-38和K_3;二种板材:GH-30和GH-128)在900℃下的热腐蚀。用重量变化和渗透深度评价合金的热腐蚀抗力;用金相、X射线衍射、扫描电镜(配EDS分析)和电子探针分析鉴别腐蚀层结构和产物。结果说明:M-38和GH-30合金热腐蚀过程可分三个阶段—孕育期、扩展期和加速期;GH-128和K_3合金分二个阶段—孕育期和加速期。含有较高铝和钨的GH-128和K_3合金的热腐蚀受到酸性熔融控制,而M-38和GH-30合金受“沿晶界硫化—氧化—开裂—剥落过程”控制。晶粒细、成份均匀的热轧/板材渗透轻微;反之,晶粒粗、成份呈枝晶偏析的铸造合金渗透严重,必须采用失重和渗透深度来评价热腐蚀抗力。

The kineties on hot corrosion of four Ni-base superalloys, two sheets(GH-30 and GH-128 ) and two cast alloys ( M-38 and K_3 ) , were studied at900℃ by salt coat method. Results showed that hot corrosion process for the more resistant M-38 and GH-30 alloys can be divided into three stages—ineubation, extension and acceleration period, while that of the less resistant GH-128 and K_3 alloys can be divided into two stages—incubation and acceleration period. GH-128 and K_3 alloys have high Mo and W contents, so that hot corrosion is governed by acid fusion. The hot corrosion of M-38 and GH-30 alloys,on the other hand, is governed by a sulfidation—oxidation processes alonggrain boundaries. The penetration of the sheet having fine grain and homogenous composition is less serious than that of the cast alloys which are coarsegrained with a high extent of segregation. Both weight loss and depth of penetration must he employed for the evaluation of hot corrosion resistance of the latter alloys.