THE EFFECT OF WELDING METHODS ON THE MECHANICAL AND MICROSTRUCTURE OF HIGH-CARBON STEEL

High-carbon steel, with a carbon content of 0.6% to 1.5%, is widely used in critical applications like cutting tools, springs, and high-performance bearings due to its strength, hardness and wear resistance. However, joining high carbon steel is challenging due to its susceptibility to cracking, brittleness, microstructural alteration in the heat affected zone. The impact of welding parameters, particularly current levels, on the mechanical and microstructural properties of high-carbon steel remains underexplored. This research explores the mechanical properties and microstructure of high-carbon steel welded using Shielded Metal Arc Welding (SMAW) and Gas Metal Arc Welding (GMAW) at varying current levels. SMAW was found to produce superior mechanical properties, with SMAW 140A achieving the highest ultimate tensile strength (495 MPa) and elongation (15%). In contrast, GMAW 120A had lower tensile strength (424 MPa) and elongation (10.5%). Higher current levels in GMAW, particularly GMAW 140A, resulted in coarser grain structures and reduced mechanical performance, with a UTS of 317 MPa and elongation of 7.5%. Hardness testing revealed increased hardness in the weld zones of all samples, attributed to the formation of martensite and other hard phases such as pearlite and bainitic ferrite. Microstructural analysis via optical microscopy and SEM showed ferrite, pearlite, martensite, and bainitic ferrite, with SMAW samples displaying a lath martensitic structure and GMAW samples showing bainitic ferrite. These findings suggest that SMAW produces better mechanical properties and microstructural stability, making it more suitable for high-carbon steel applications requiring strength and durability.