Abstract
Taking S32101 duplex stainless steel as the research object, underwater laser wire filling welding technology was used for U-groove filling welding. The influence of different shielding gas compositions on the ferrite content, microstructure, mechanical properties and pitting corrosion resistance was studied by simulating a water depth of 15 m in the hyperbaric chamber. The results show that, under the same process parameters, the size and proportion of austenite in the weld when using pure nitrogen as the shielding gas are larger than those protected by other shielding gases. In a mixed shielding gas, the increase in nitrogen content has little effect on the strength and toughness of the weld. Regardless of the shielding gas used, the base metal was the weakest part of the weld. At the same time, intermetallic inclusions have an adverse effect on the impact toughness of the weld. The pitting corrosion resistance of the welds depends on the Cr2N content in the heat-affected zone. The precipitation and enrichment of Cr2N causes local chromium deficiency, which is the main factor for the weak pitting corrosion ability of the heat-affected zone. Pure nitrogen protection has a better corrosion resistance than other gas protection.
Highlights
Duplex stainless steel (DSS) has been widely developed in recent years because of its good corrosion resistance and economic benefits
Austenite in the BM are 721 banded along the rolling direction, whereas the ferrite and austenite in the weld metal (WM) and heat-affected zone (HAZ) are interlaced with different directions, C boundaries are increased, which
Of Cr, Mo and Ni in the weld 748 metal can be remelted at a high temperature, which can replace Fe atoms in the lattice and disturb the original lattice arrangement, 608As in and canBM
Summary
Duplex stainless steel (DSS) has been widely developed in recent years because of its good corrosion resistance and economic benefits. Underwater welding is mainly divided into three methods: underwater dry welding, underwater wet welding and underwater local dry welding [4,5,6,7] Underwater dry welding has good welding quality, but the welding process is complex, resulting in a significant increase in cost; the underwater wet welding device is simple, but it cannot guarantee the welding quality; local dry welding combines the advantages of the first two methods, which ensures the welding quality, and reduces the equipment cost It is very suitable for the construction [8] and maintenance of underwater nuclear power plants [4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
