Research and Application of Inconel 625 Surfacing Welding Process for Inner Cavity of AISI 4130 Valves in Deep-sea Oil and Gas Fields

In this paper, the Inconel 625 nickel-based alloy was deposited on the AISI 4130 medium carbon quenched and tempered steel ring-shaped mock-up by the pulse hot wire TIG surfacing repair process. The microstructure and mechanical properties of the surfacing layer and the base metal were characterized and tested systematically. The results show that the Inconel 625 surfacing layer with a lower Fe content is less affected by the base metal dilution, ensuring its good corrosion resistance. No network eutectic phase was found in the microstructure of the surfacing layer, and the average hardness was approximately 259 HV. In addition, the surfacing and post-weld heat treatment did not have an adverse effect on the microstructure and properties of the base metal, and the tensile and low-temperature impact properties of the AISI 4130 base metal were still within the specified range. Based on the surfacing process of this ring-shaped mock-up, a deep-sea oil and gas field combination valve was repaired. After inspection, the quality and performance of the surfacing layer met the acceptance requirements.