Laser filling welding repair process for U-shaped groove of S32101 duplex stainless steel

In this paper, cracks were removed by beveling, and repairs were performed using groove-filling welding techniques. An experimental investigation of laser wire-filling welding repair of S32101 duplex stainless steel in an air environment was conducted. The welding procedure and related parameters may serve as a reference for underwater welding studies. To prevent damage to the welding auxiliary equipment caused by excessive laser power input, comparative experiments were performed with three filling repairs and four filling repairs under a process window of 5000 ~ 6000 W laser power. The cross-sections, microstructure, mechanical properties, and corrosion resistance of the welds were thoroughly analyzed. During the experiments, optical microscopy and scanning electron microscopy were used to examine the effects of heat input during welding on microstructural transformations. Additionally, by comparing the tensile properties and microhardness of welds at different laser power levels, the specific influence of process parameters on the mechanical properties and corrosion resistance of the welds was further elucidated, thereby optimizing the stability and reliability of the repair process. The results showed that the welds repaired with three filling repairs exhibited issues such as porosity and poor metallurgical fusion, whereas the cross-sections of the welds repaired with four filling repairs showed no porosity defects, and the tensile specimens fractured at the base metal. Preheating and reheating of the interpass welding promoted the precipitation of austenite in the welds, and the austenite content was slightly higher than that of ferrite, with the average hardness being slightly lower than that of the base metal. The higher Ni and Mo content in the welds contributed to superior corrosion resistance compared to the base metal. The welds repaired with four filling repairs met the quality standards for repairs conducted in an air environment.