High chromium nickel-based fillers are used in nuclear dissimilar joints or repairs. Due to the risks of ductility dip cracking of Alloy 52 M weld surfacing, a nickel-based filler with a high niobium and molybdenum content (Alloy 52MSS) is expected to enhance the stability of grain boundary and improve the resistance to stress corrosion cracking. In this study, Alloy 52 M and Alloy 52MSS were used in weld surfacing on A508 steel. The results showed that Nb concentrated in the interdendritic region, and Mo gathered around Nb-rich carbide grains. The hardness profile presented similar trends for both filler metals. In potentiodynamic testing, the corrosion potential was increased while the corrosion current density was lowered for 52MSS.

Further cyclic polarization testing indicated that 52MSS had the capability to increase the protection potential and reduce the pitting phenomenon. The morphology of 52 M welding surfacing after testing showed a feature of interdendritic corrosion, while the characteristic of 52MSS′ showed a behavior in general corrosion. The Mo addition resulted in the formation of a metastable oxide scale that improved the alloy's corrosion resistance in the trans-passivity region. The 52MSS had a more remarkable ability to prevent the outer surface of weld surfacing from interdendritic corrosion.

高铬镍基填料用于核异种接头或维修。由于52 M合金堆焊焊缝具有延性开裂的风险，因此，铌和钼含量较高的镍基填料（Alloy 52MSS）有望增强晶界的稳定性并提高抗应力腐蚀开裂的能力。在这项研究中，合金52 M和合金52MSS被用于A508钢的焊缝堆焊。结果表明，Nb集中在枝晶间区域，Mo聚集在富Nb的碳化物晶粒周围。两种填充金属的硬度分布都呈现出相似的趋势。在电位动力学测试中，对于52MSS，腐蚀电位增加而腐蚀电流密度降低。

进一步的循环极化测试表明52MSS具有增加保护电位和减少点蚀现象的能力。试验后的52 M堆焊堆焊层的形态表现出枝晶间腐蚀的特征，而52MSS'的特征表现出一般腐蚀的行为。钼的添加导致形成亚稳态氧化皮，从而改善了合金在反钝化区的耐蚀性。52MSS具有更出色的防止焊缝外表面树突腐蚀的能力。