Underwater local dry wire-feed laser deposition of 10CrNi3MoV high-strength low-alloy steel

This study investigated the effects of process parameters on the formation quality of 10CrNi3MoV high-strength low-alloy steel fabricated by underwater local dry wire feed laser deposition. Under the optimal parameters, the influences of the water environment on the formation, microstructural characteristics, and microhardness were systematically analyzed. As the laser power increased from 0.5 to 3.5 kW, the wettability and spreadability of the underwater deposition layer improved, leading to the elimination of lack-of-fusion and undercut defects. When the deposition speed increased from 7 to 20 mm/s, the interaction time between the laser and the filler wire was reduced, resulting in intermittent deposition defects. With the wire feed rate increasing from 40 to 80 cm/min, the spreadability of the underwater deposition layer deteriorated, causing the occurrence of undercut defects. The optimal process window for underwater laser melting deposition was identified as a laser power between 2.3 and 2.9 kW, deposition speed between 7 and 12 mm/s, and wire feed rate between 40 and 50 cm/min. Under the optimal parameters, both underwater and land-based deposition layers exhibited favorable formation quality. Moreover, compared with the land-based deposition layer, the underwater deposition layer contained a higher fraction of lath martensite, resulting in superior microhardness.