Multi-wire SAW of 640 MPa Arctic shipbuilding steel plates

Extensive industrial use of thick high-strength steel plates in Arctic shipbuilding calls for submerged arc welding (SAW) processes with higher deposition rates. One of the most effective ways of increasing the deposition rate is to increase the number of welding wires. Although SAW processes with up to six wires exist, their use is not widespread and two- or three-wire modifications, which are the focus of this paper, are the most common approaches. This paper presents a case study of the development of a welding procedure for welding of high-strength steel shipbuilding plates using a three-wire SAW process. Welding parameters and conditions were evaluated with the aim of achieving a high-quality weld. Optimal parameters for 12-mm plate thickness were found to be: Св-08ГСМТ wire (similar to Mn4Ni1Mo) of 3.2 mm in diameter, single-pass welding, welding flux 48AF-56, I = 840 A, U = 37 V, Q = 5.4 kJ/mm. Optimal parameters were also found for 16-mm plate for two pass welding. Testing of the weld joint included a static tensile strength test, an impact energy test at different temperatures, a bending test, a low-cycle fatigue strength test, microstructure examination and a hardness test. The tests showed satisfactory results that indicate that the developed welding technique is applicable for Arctic shipbuilding applications. The paper provides improved understanding of the welding technique selection process for Arctic shipbuilding as well as providing industrially valuable information about the developed welding technique.