Hastelloy C­276/316L激光异质焊焊缝腐蚀性能

摘要

By using continuous laser to weld Hastelloy C­276 and 316L and method of electrochemical corrosion, the corrosion resistances of the weld and base material in acid, neutral and alkaline solution were studied, continuously. The corrosion morphology and the composition of the corrosion surface were analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that, in the acidic environment, the sequence of corrosion resistance from high to low are C­276, weld, 316L. In the neutral environment, there is little difference between corrosion resistance of the weld and base materials. In the alkaline environment, the corrosion tendency of 316L is the largest, corrosion tendency of the weld follows, the corrosion tendency of C­276 is the minimum. While the corrosion speed of weld and 316L has no obvious difference, and both of them are obviously less than C­276. In the acidic and neutral solution,the intergranular corrosion is found in the weld. The mass fraction of Mo in the intergranular is about 4%larger than that in the grain. This shows that the segregation of Mo element has a great influence on intergranular corrosion. In the alkaline solution, pitting corrosion is found in the weld and it is associated with lattice defects.%利用连续激光对Hastelloy C­276和316L进行焊接，借助电化学腐蚀方法比较焊缝中心附近和母材在酸性、中性、碱性溶液中的腐蚀性能，并利用扫描电子显微镜和X线能量色散谱分析腐蚀形貌以及腐蚀表面元素成分。结果表明：在酸性环境中，抗腐蚀性由大到小的顺序为C­276的抗腐蚀性、焊缝、316L；在中性环境中，焊缝的抗腐蚀性和母材的相似；而在碱性环境中，焊缝的抗蚀性优于316L的，而其腐蚀趋势大于C­276的，但腐蚀速率小于C­276的；C­276中Mo元素较316L中的多，认为焊缝中Mo元素主要来自C­276，而Mo元素在焊缝枝晶间、枝晶杆的含量差别是造成焊缝在酸性、中性溶液中枝晶间腐蚀的重要原因之一；在碱性溶液中焊缝发生点蚀，这与晶格缺陷有关。