Microstructural, Mechanical, and Thermal Analysis of SS316L Weldment for Marine Engineering Application

SS316L steel is known as a marine-grade material, which is frequently used in shipbuilding structures and marine industries. In the present study, a shielded metal arc welding (SMAW) process was used for welding of SS316L steel plate by using electrode E316L-16 and E308L-16, welding currents of 70, 80 and 90 A and constant voltages of 24 V. The effect of process parameters on the microstructure and mechanical properties of the welded specimens in the fusion zone (FZ), heat-affected zone (HAZ) and at base has been analysed using scanning electron microscopy (SEM) and microhardness test. The results show that the mechanical properties of the SMAW welded sample are influenced by both electrode properties and applied current. The fusion zone hardness increases compared to the base material. The welded sample processed by using electrode E316L-16 and 80 A current exhibits the higher hardness i.e., 223 HV due to a combination of lower heat input, higher welding speed, and the presence of a fine grain structure compared to other welded sample. A tensile result shows that the Ultimate tensile strength (UTS) of the SMAW welded sample varies from 190 to 262 N/mm2 compared to a base material, i.e., 565 N/mm2. This drop in tensile strength in the welded joints is attributed to HAZ softening stemming from the formation of coarse-grained microstructures. Furthermore, thermal analysis utilizing ANSYS software was employed to assess the influence of heat input at different welding arc times and to map temperature distribution across various plate regions. The results indicate that reducing welding time leads to lower temperatures in the electrode samples, consistent with simulation outcomes. Additionally, variations in microstructure were evident across distinct plate regions. The impact of heat input on microstructural behaviour was further comprehensively examined.