Effect of depth on the weldability of ferritic steels in simulated environments joined by wet welding

Influence of Heat Input on the Weldability of ASTM A131 DH36 Fillet Joints Welded by SMAW Underwater Wet Welding

“…To achieve uniform microstructures, using a high heat input single weld bed at a slow and constant welding speed is preferable, resulting in a microstructure of PF and LTM, which produces a non-brittle and uniform weld joint. Thus, the use of a high heat input at slow welding rates is preferred because the resulting microstructure increases the ductility of the welding joint, avoiding brittle behavior, which is consistent with the findings of prior studies on similar materials by Gao Wenbin et al [25], Gao Wenbin et al [29], Toumpis Athanasios et al [37], Li Hongliang et al [41], Di Xinjie et al [42], Macias Fernando et al [38], Kozlowska Aleksandra et al [43], Meng Fanxia et al [39], Zhang Hongmei et al [40], and Min-Seok Baek et al [48].…”

“…In contrast, at 1.5 kJ/mm (Figure 7e), the microstructure displays polygonal ferrite (PF) and lath-tempered martensite (LTM), which suggests that the high heat input and multiple welded beads temper the lath martensite (LM). This finding is in line with the results reported by Macias Fernando et al [38], Meng Fanxia et al [39], and Zhang Hongmei et al [40] on similar materials. The microstructures of the RCL HAZ display similar results between low and high heat inputs.…”

“…The microstructures of WM for low and high heat inputs are composed of grain boundary ferrite (GBF), AF, and PF. These microstructures resemble the results of prior studies on similar materials by Gao Wenbin et al [25], Gao Wenbin et al [29], Toumpis Athanasios et al [37], Li Hongliang et al [41], Di Xinjie et al [42], Macias Fernando et al [38], and Kozlowska Aleksandra et al [43].…”

“…The microstructures of the fillet T HAZ display a marked difference between low and high heat inputs. At 1.0 kJ/mm (Figure 7b), the microstructure is composed of polygonal ferrite (PF), upper bainite (UB), and retained austenite (RA), which resembles the results of prior studies on similar materials by Gao Wenbin et al [25], Toumpis Athanasios et al [37], and Macias Fernando et al [38]. In contrast, at 1.5 kJ/mm (Figure 7e), the microstructure displays polygonal ferrite (PF) and lath-tempered martensite (LTM), which suggests that the high heat input and multiple welded beads temper the lath martensite (LM).…”