For the long-term service of X65/Incoloy 825 bimetallic composite pipe girth welds in the H2S environment, the corrosion damage behavior were investigated. Characterizations of welded joint were conducted by OM, SEM, XRD and EDS. And the pitting corrosion’s 3D surface morphology of welded joint in NACE-B solution saturated with H2S was investigated. The results show that composition segregation occurs in the welding process, and the Laves phase appear between dendrites, which leads to the decrease of corrosion resistance. The maximum depth of the corrosion pit is 2.46μm after 30 days, 4.54μm after 60 days, and 10.94μm after 180 days. The cell automata (CA) model of corrosion damage was established based on the MATLAB program, and the basic elements of the CA model were determined. Through the simulation of the electrochemical reaction and diffusion process, the influence of different parameters of the pitting corrosion morphology was determined. The simulation results were compared with experimental data, which is available for the prediction of morphology and size of the corrosion pits on the sample surface after 300 days. The results will be beneficial for long-term service of bimetallic composite pipe.

中文翻译：

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X65/Incoloy 825焊接双金属复合管在H2S环境中的腐蚀损伤行为

针对 X65/Incoloy 825 双金属复合管环焊缝在 H2S 环境下的长期服役，研究了腐蚀损伤行为。焊接接头的表征通过 OM、SEM、XRD 和 EDS 进行。并研究了焊接接头在 H2S 饱和的 NACE-B 溶液中点腐蚀的 3D 表面形貌。结果表明，焊接过程中发生成分偏析，枝晶间出现Laves相，导致耐蚀性下降。30天后腐蚀坑的最大深度为2.46μm，60天后为4.54μm，180天后为10.94μm。基于MATLAB程序建立腐蚀损伤元胞自动机（CA）模型，确定CA模型的基本要素。通过对电化学反应和扩散过程的模拟，确定了不同参数对点蚀形貌的影响。将模拟结果与实验数据进行对比，可用于预测300天后样品表面腐蚀坑的形态和大小。研究结果将有利于双金属复合管的长期使用。