Optimization of welding application parameters of thin sheet blocks used in the new-generation ship hull

Abstract

The main material of merchant ships is steel. Generally, block sheets used in forming a ship hull are between 7 and 12 mm. On a 60 m ship, the hull consists of approximately 25–35 mega-blocks and 45–60 blocks. Welding operations cause expansion and shrinkage on the part due to regional temperature differences. The purpose of this study is determining the optimum welding parameter of panels with 48 × 1200 cm dimensions and 5 mm thickness. Because the thickness of the sheet metal used is very thin, the blocks to be welded are very large and the mega-blocks formed by welding are used in large numbers and include uncertainties such as optimal parameters in the process application and mechanical behavior on the weld. To reduce the number of experiments within the scope of the study, welding application conditions were determined by using Taguchi experimental design (L9). In the determined parameters, submerged arc welding was carried out on the panels in a horizontal position. Taking 10 × 48 cm sections as head–middle–end from each combined panel, visual control and radiographic testing (ISO 5580) was performed. Tensile (TS EN ISO 4136) and notch-impact (TS EN ISO 9016) mechanical tests were also conducted. By conducting statistical analysis (analysis of variance) of the selected parameters used in the Taguchi experimental design, percentage effects of each parameter on yield strength, tensile strength and notch-impact tests were obtained. The impact percentage of the highest current was determined; the results were 50.24% for yield strength, 51.43% for tensile strength and 57.53% for notched-impact test results. Data means were checked with design of experiment analysis. The best welding results were obtained at parameters of 650 A, 32 V and 150 cm/min.