Effect of Water Depth and Flow Velocity on Microstructure, Tensile Strength and Hardness in Underwater Wet Welding

Abstract

Wet underwater welding is a welding process carried out under water. The depth and water flow velocity greatly affect the welding results. Thus, a further research needs to be done about the effect of the depth and water flow velocity of underwater wet welding. The research aimed to determine the effect of depth and velocity of water flow on underwater wet welding on physical and mechanical properties. The welding process is carried out by using SMAW method at a depth of 2.5 m and 5 m with variations in water flow velocity of 0, 1, and 2 m/s. Land welding is performed as a comparison. X-ray radiography, micro-structure, tensile strength, and Vickers hardness test were performed to determine the type of welding defects. Radiographic test results indicate an incomplete penetration defect (I), spatter (S), porosity (P), undercut (U), concavity (V), and irregular surface (Z). The results of the micro-structure test show that the grain size is fine and coarse as the depth and velocity of the water flow increase. Tensile strength and micro-hardness testing increase along with an increasing depth and velocity of water flow.