Forming, Microstructure and Properties of 10CrNi3MoV High-Strength Steel by Underwater Laser Melting Deposition

China has independently developed 10CrNi3MoV high-strength steel, which has become a crucial structural material for manufacturing submarine pressure hulls due to its high strength, excellent toughness, superior explosion resistance, and outstanding corrosion resistance. In this study, the response surface method was used to investigate the effects of laser power, scanning speed, and wire feeding speed on the dilution rate and deposition angle of the underwater single-pass deposition layer. Then the optimized underwater single-pass deposition process parameters were obtained. Based on this, the influence of the water environment on the formation, microstructure, and microhardness of the single-pass deposition layer was investigated. Compared with that in air, the faster cooling rate in the underwater laser melting deposition process leads to a larger deposition angle and a slower dilution rate in the underwater deposition layer. Additionally, the microstructure of the underwater deposition layer is finer, which results in a higher microhardness.