镍基合金油套管的析出相及对腐蚀性能的影响

Precipitated phase of nickel-based OCTG and its effect on corrosion performance

镍基合金油套管在凝固和热加工过程中极易产生析出相,使用SEM、TEM等方法分析了Inconel G3和Incoloy 028两种合金中析出相的形貌和结构,发现Incoloy 028合金富Cr、Mo析出相以σ相为主,而Inconel G3以MC和α(W-Mo)固溶体为主。对两种合金进行的晶间腐蚀和应力腐蚀开裂性能评估发现,晶界富Cr、Mo析出相严重降低了镍基合金油套管抗晶间腐蚀性能和在高温,高压,高含H2S、CO2介质中的抗应力腐蚀开裂(Stress CorrosionCracking)性能。

During the manufacturing processes of Ni-based OCTG such as solidification and heat treatment, detrimental precipitation rich in Cr and Mo is a frequently severe defect. In this paper, morphology and structure of precipitations formed in Inconel G3 and Incoloy 028 were analyzed with SEM and TEM. It was found that most precipitation rich in Cr and Mo was o＂ phase in Incoloy 028, while MC and or（ W- Mo） solid solution phase in Inconel G3. The present research also indicated that the resistance of the alloys to crevice corrosion and stress corrosion cracking （SCC） were significantly deteriorated in service environment containing high temperature, high pressure and high concentration of H2S and CO2 when the detrimental precipitation forms in the grain boundary.