Influence of Nb Content on IGC Resistance of Strip Cladding Metal of Alloy 625
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摘要: 研究了不同Nb含量对625合金带极堆焊金属的组织转变及耐晶间腐蚀性能的影响。结果表明,Nb含量的增加导致堆焊层耐腐蚀性能显著下降。Nb含量较低时,合金中析出相以MC为主,Laves相很少,具有较好的耐腐蚀性能。Nb含量增加后,在枝晶间产生强烈偏析,促进合金中富Nb、Mo、Si的Laves相的析出和长大。块状形态的Laves相本身贫铬并造成枝晶间区域较大的成分差异,导致析出相附近成为晶间腐蚀的薄弱区,明显加快合金的腐蚀速率。Abstract: The effects of Nb content on microstructure and intergranular corrosion resistance( IGC) of 625 strip surfacing metal were analysed.Resultsshow that the increase of Nb content critically decreases the IGC resistance of alloy. When Nb content is at a low level,the precipitates are mainly Nb C and few Laves phase,so a high corrosion resistance is exhibited. With the increase of Nb content,severe dendritic segregation occurs and segregation and growth of Laves phase enriched with Nb,Mo and Si are promoted. The blocky Laves phase causes Chromium depleted zone and inhomogeneity of chemical composition around interdendritic regions,where is a priority for IGC,thus the corrosion rate is sharply increased.
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Keywords:
- Nb /
- alloy 625 /
- strip cladding /
- IGC
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