Hastelloy C-276/316L激光異質(zhì)焊焊縫腐蝕性能Corrosion performance of laser welding on dissimilar materials Hastelloy C-276/316L

利用連續(xù)激光對(duì)Hastelloy C-276和316L進(jìn)行焊接，借助電化學(xué)腐蝕方法比較焊縫中心附近和母材在酸性、中性、堿性溶液中的腐蝕性能，并利用掃描電子顯微鏡和X線能量色散譜分析腐蝕形貌以及腐蝕表面元素成分。結(jié)果表明：在酸性環(huán)境中，抗腐蝕性由大到小的順序?yàn)镃-276的抗腐蝕性、焊縫、316L；在中性環(huán)境中，焊縫的抗腐蝕性和母材的相似；而在堿性環(huán)境中，焊縫的抗蝕性優(yōu)于316L的，而其腐蝕趨勢(shì)大于C-276的，但腐蝕速率小于C-276的；C-276中Mo元素較316L中的多，認(rèn)為焊縫中Mo元素主要來自C-276，而Mo元素在焊縫枝晶間、枝晶桿的含量差別是造成焊縫在酸性、中性溶液中枝晶間腐蝕的重要原因之一；在堿性溶液中焊縫發(fā)生點(diǎn)蝕，這與晶格缺陷有關(guān)。

By using continuous laser to weld Hastelloy C-276 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 C-276, 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 C-276 is the minimum. While the corrosion speed of weld and 316L has no obvious difference, and both of them are obviously less than C-276. 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.

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