SS400 steel, categorized as a form of structural carbon steel, finds frequent application in both the construction and industrial domains. It is a common choice in a variety of construction ventures, such as buildings, bridges, and other structures, primarily due to its favorable mechanical attributes. Notably, SS400 steel is distinguished by its substantial tensile strength, rendering it well-suited for construction scenarios that require robust structural integrity. Additionally, SS400 steel showcases commendable weldability characteristics, simplifying its incorporation into diverse welding configurations.
Based on the findings obtained from conducted research, it has been established that 90% of material failures stem from fatigue-induced stress. One of the contributing factors leading to a decline in the rate of fatigue crack propagation is the presence of flaws within the welded joint. Consequently, a meticulous control of the welding environment becomes imperative to minimize imperfections in welding SS400 metal. This investigation highlights variations in the rates of fatigue crack propagation within welded joints, attributable to diverse environmental conditions during welding. These conditions encompass disparities in welding depth and water flow velocity in underwater welding processes. The parameters examined in the experiment involve welding depths of 2.5 m and 5 m, along with water flow speeds of 0 m/s, 1 m/s, and 2 m/s.
The research findings suggest that augmenting the depth of the underwater welding environment will lead to an escalation in the fatigue crack propagation rate. Elevated water flow velocities can hinder the formation of a shielding gas layer, reducing its effectiveness. Conversely, the attributes associated with intergranular fatigue crack propagation and ductile fracture patterns are more likely to manifest at lower water flow velocities, primarily due to the minimal influence of hydrogen during the welding process.
