Post Weld Quenching Impact on Microstructure and Mechanical Properties (Tensile, Impact, Hardness) of High Strength Low Alloy Steel

Shielded Metal Arc Welding (SMAW) is the most widely used welding technique in engineering industries. Compared to other arc welding techniques like TIG, SMAW is less heat-concentrating. However, welding thick jobs using SMAW can result in serious issues such as structural distortion due to non-uniform input heat distribution. High thermal stresses and distortions can degrade mechanical properties, similar to high input heat. Fast heat removal may prevent such defects, and different quenching media like sand, water, and oil were used to investigate variations in mechanical properties. High-strength low-alloy steel was selected due to its good weldability and easy availability, which makes it suitable for many industrial applications, such as in the space and defense industries. The tensile testing results showed that oil quenching was superior to other quenching techniques because oil-cooled joints had the highest tensile strength and ductility. However, water-cooled joints showed the highest yield strength, but oil-quenched joints had the highest welding efficiency. The hardness of water-cooled joints in the heat-affected zone and weld zone was greater due to rapid cooling in water. The impact energy of oil-cooled joints in the heat-affected zone was superior to that of other joints. Overall, the mechanical properties of oil-cooled joints were superior and showed better geometric configuration, such as minimal distortions.