Investigation of the welding area of grade A steel used in the shipbuilding industry

In this study, the most commonly used submerged arc welding method and gas welding method, used in welded joints of Grade A steel, were examined under current operating conditions of the industry, and it was observed that there were problems especially in joining sheets with thin (t ≤ 8 mm) wall thickness. The Grade A steel was welded by submerged and gas arc welding methods and additionally by plasma arc welding of Grade A steel. In the study, the welding regions of the samples obtained from all three welding methods were examined in both macro and micro dimensions mechanically and metallurgically. In the study, submerged arc welding method was welded bilaterally with parameters in the shipyard environment. The submerged arc welding method was made unilaterally by giving the root gap in the workshop environment. In one of the double-sided welded samples, it was observed that there was a gap error caused by plasma cutting in the center of the weld seam, which is frequently encountered in the shipyard environment. Tensile strengths were found as 455 MPa in 4 mm root spacing and single-sided submerged arc welding and 454 MPa in double-sided submerged arc welding. Synergic and robotic welding applied in gas welding method yielded tensile stronght of 439 MPa. As an alternative to these widely used methods in shipbuilding, plasma arc welding method, which is used on stainless materials especially in literature and applications, was used in welding Grade A steel and its tensile strength was found to be 471 MPa. It has been observed that automation welding methods will be more effective in eliminating defects and reducing repair costs in welded joints made in the shipyard environment, and in addition, the joints of Grade A steel created using plasma arc welding have much better mechanical and metallurgical properties compared to other methods.