热处理对镍基合金G3耐蚀性能的影响

Effects of Heat Treatment on the Corrosion Resistance of the Ni-Based G3 Alloy

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。

The effect of the solution and aging treatment on the microstructure and precipitated phase of the G3 steel was investigated by TEM and SEM. And then, the effect of the microstructure change and precipitated phase on the corrosion resistance of G3 steel was analyzed by the corrosion test in high temperature and high pressure environment containing H2S/CO2. The results indicate that the solution treatment temperature should not exceed 1150 ℃ in order to avoid the much bigger grains. The carbide M23C6 precipitated in grain boundaries is increased, and the plate-like carbide M6C is formed inside grains with the aging temperature increasing. The formation of precipitated phase of chrome carbide leads to the severe pitting corrosion of the Ni-based alloy because a poor chromium area has been formed in intergranular sites so that the corrosion resistance of G3 alloys is reduced .