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针对国产商用镍基耐蚀合金G3,采用TEM、SEM等方法研究固溶时效对合金微观组织及析出相的影响;进而利用高温高压釜的挂片试验,分析组织变化以及析出相对材料在H2S/CO2共存的井下水中耐蚀性能的影响。结果表明,该镍基合金的固溶温度应低于1150℃,以避免合金晶粒过大。随时效温度的提高,晶界析出的M23C6碳化物增多,并在晶内形成M6C片状碳化物。析出相的形成导致镍基合金的点蚀加剧,由于碳化铬在晶界上析出而导致的贫铬是引发点蚀的主要原因。
According to the domestic commercial nickel base corrosion resistant alloy G3, the effects of solution aging on the microstructure and precipitated phase of the alloy were investigated by TEM, SEM and other coupons. Then the coupons of high temperature autoclave were used to analyze the microstructure changes and the relative materials precipitated in H2S / Effect of coexistence of CO2 on corrosion resistance of downhole water. The results show that the solution temperature of the nickel-based alloy should be lower than 1150 ℃ to avoid excessive grain size. With the increase of aging temperature, M23C6 carbide precipitated in the grain boundary increased, and M6C flake carbides formed in the grain. The formation of precipitated phase leads to the increase of pitting corrosion of the nickel-base alloy. The main cause of pitting corrosion is chromium-depleted, which is caused by the precipitation of chromium carbide on the grain boundaries.