Influence of Groove Design on the Mechanical Properties of AISI 1018 Mild Steel Welded Joints

Abstract

The influence of groove design on mechanical properties of AISI 1018 mild steel welded joint was studied. An 8 mm thick mild steel plate was marked out and cut to dimension of 120 × 75 × 8 mm using a portable cutting machine. Groove preparation was done for the single-V and single-beveled grooves. After proper alignment of the edges, the work pieces were welded using the Shielded Metal Arc Welding (SMAW) method with a Direct Current (D.C.) welding machine with voltage and current of 220 V and 100 A respectively. Specifically, gauge-12 (2.5 mm) stick electrodes were used for the root run while many passes (hot pass, filling and capping) were undertaken with gauge-10 (3.25 mm) electrodes because of the volume of filler metal required to fill the single-V and single beveled joints. The mechanical properties of the butt, single beveled and singe V joints were evaluated. The results showed that microstructural changes occurred in the specimens due to heat in the fusion and heat-affected zones with the appearance of ferrite, pearlite, martensite and bainite phases with grain boundaries, which confirm recrystallization. The heat-affected zone single V-joint exhibited the highest tensile strength of 442.41 MPa while fusion zone single V-joint exhibited the highest hardness of 358.9 HV. In fusion zone, the butt-joint specimen exhibited impact energy of 65.2 J/mm² compared to 62.37 J/mm² and 48.81 J/mm² exhibited by the single V and single beveled joints respectively. However, the heat-affected zone single V-joint exhibited the highest impact energy of 73.22 J/mm².