Effect of metal powder additives on the microstructure and mechanical properties of resistance spot welds of low carbon steel.

Resistance spot welding (RSW) is a welding process used to join different types of steel based on the requirements of various applications. Heat and pressure are applied to create a weld nugget between metal sheets. This study examines the use of low-carbon steel in combination with metal powders, including nickel, chromium, tungsten, and vanadium. The welding process was performed under a specific range of welding currents and welding times based on preliminary experiments with and without cavities to investigate the effect of metal powders on the microstructure and mechanical properties of the welded material, such as hardness and tensile shear strength. The results indicate that adding powders altered the microstructure by forming a finer grain structure and a martensite phase. This, in turn, led to an increase in hardness by approximately 19%. Among the powders, nickel powder had a cluster-type structure that enhanced the hardness more than Cr/W, which was detected as stacked and stretched layers. However, the presence of a cavity had a negative effect on the joint strength. Interestingly, when metal powders were added without a cavity, the joint strength improved, especially in the case of Ni powder and Cr/W powders, and increased by 22% compared to the strength of the a-welded joint. [ABSTRACT FROM AUTHOR]