Metallurgy and Mechanism of Underwater Wet Cutting Using Oxidizing and Exothermic Flux-Cored Wires

This paper considers the metallurgical processes of dissociation, ionization, oxidation, deoxidation, and dissolution of oxides during underwater wet cutting. A multiphase mechanism of underwater wet cutting consisting of working and idle cycles of the electrical process in a pulsating vapor gas bubble is proposed. A model of arc penetration into metal due to metal oxidation and stabilization of the arc by the inner walls of a narrow kerf is proposed. For underwater cutting of 10 KhSND, 304L steel, CuAl5, and AlMg4.5Mn0.7 alloy, we provide a principle of modeling the phase composition of the gas mixture based on high oxygen concentration, improving ionization, enthalpy, heat capacity, and thermal conductivity of plasma through the use of a mixture of KNO₃, FeCO₃ and aluminum. The method of improving the thermophysical properties and ionization of plasma due to the exothermic effect when introducing Fe₃O₄, MoO₂, WO₂ oxides and Al, Mg, Ti deoxidizers is proposed. Although a negative effect of refractory slag was revealed, it could be removed by using the method of reducing surface tension through the ionic dissolution of refractory oxides in Na₃AlF₆ cryolite. In underwater cutting of 10 KhSND and 304L, the steel welding current was 344-402 A with a voltage of 36-39 V; in cutting of CuAl5 and AlMg4.5Mn0.7 alloy, the welding current was 360-406; 240 A, with a voltage of 35-37; 38 V, respectively, with the optimal composition of flux-cored wire: 50-60% FeCO₃ and KNO₃, 20-30% aluminum, 20% Na₃AlF₆. Application of flux-cored wires of the KNO₃-FeCO₃-Na₃AlF₆-Al system allowed stable cutting of 10KhSND, AISI 304L steels, and CuAl5 bronze with kerf width up to 2.5-4.7 mm.