The effect of variation of the electric current on physical and mechanical properties in A36 steel welding

Abstract

The research objective was to determine the effect of current on microstructure, hardness values, and tensile strength of A36 steel before (raw material) and after welding using SMAW using electrodes E7016 diameter 3.2 mm. The research adopted an experimental method and utilized Olympus Metallurgical Microscope, Micro Vickers Hardness Tester, and Universal Testing Machine for data analysis. The results revealed that welding caused a change in the microstructure of the weld area into Grain boundary Ferrite (GF), Widmanstatten Ferrite (WF), and Acicular Ferrite (AF). The hardness test showed that higher current leads to greater hardness values. The specimens with a current of 130 Ampere had a hardness level of 181.39 VHN, which was higher than specimens with 120 Ampere (176.21 VHN) and 110 Ampere (159.56 VHN). The raw material had a hardness value of 125.4 VHN. The welding resulted in a difference in tensile stress, with specimens using 130 Ampere having the highest tensile strength level of 520.20 MPa, followed by 120 Ampere with 504.61 MPa, and 110 Ampere with 483.03 MPa. The research concludes that varying the electric current during welding affects the microstructure, tensile strength, and hardness value of Steel ASTM A36.