Corrosion resistance of niobium-added slag-free self-shielded flux-cored welding overlay in neutral solution

ABSTRACT

The niobium-added iron-based slag-free self-shielded flux-cored wire was developed and the effect of niobium addition on the corrosion resistance in neutral pH solution was investigated. The carbides, including NbC carbides, primary (Cr, Fe)₇C₃, and eutectic (Cr, Fe)₃C carbides, remain intact after neutral corrosion, but the grain interface is corroded preferably for all the niobium-added welding overlays. The eutectic microstructure of 7.2 wt-% niobium-added welding overlay, which has more grain interface, leads to severe corrosion. When niobium addition reaches 14.4 wt-%, the welding overlay possesses the best corrosion resistance since more NbC carbides are formed, prophase austenite dendrite is precipitated, decreasing the grain interface, and chromium content is increased in the matrix of the hypoeutectic microstructure.

KEYWORDS:

• Welding overlay
• slag-free self-shielded flux-cored wire
• neutral corrosion resistance
• niobium addition

Acknowledgements

This work is supported by China Postdoctoral Science Foundation Funded Project (grant number 2016M601753), Natural Science Foundation of Jiangsu Province (grant number BK20201453), Major Projects of Natural Science Research in Colleges and Universities in Jiangsu (grant number 19KJA460009), and Graduate Research and Innovation Projects of Jiangsu Province (grant number KYCX21_3450).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Basic Research Program of Jiangsu Province [grant number BK20201453]; Graduate Research and Innovation Projects of Jiangsu Province [grant number KYCX21_3450]; Major Projects of Natural Science Research in Colleges and Universities in Jiangsu [grant number 19KJA460009]; Postdoctoral Science Foundation of Jiangsu Province [grant number 2016M601753].