Influence Of Welding Parameters and Titanium Powder Addition on Nugget Diameter and Mechanical Properties of Dissimilar Advanced High-Strength Steel Resistance Spot Welded Joints

Abstract

Resistance Spot Welding (RSW) is a widely used joining method employed in automotive manufacturing for Advanced High-Strength Steels (AHSS) because of its high production efficiency and suitability for joining lightweight structures. The effects of welding current, welding time and titanium powder addition on weld nugget diameter, tensile shear strength, and microstructural characteristics of dissimilar AHSS spot welds were systematically investigated. A Taguchi (L9) design was employed to evaluate the effects of the welding parameters. The joints were further examined using optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) and The experimental results were statistically analyzed using ANOVA. The results indicated that the welding current exhibited the strongest influence parameter on the fusion zone diameter, and the titanium powder was the most important parameter effecting the tensile shear strength. Microstructural the sound fusion zone was formed without any visible defects including cracks, porosity and incomplete fusion. The analysis of the elemental composition performed using EDS showed there was no significant change in the elemental composition across the weld zone, and XRD analysis confirmed the coexistence of body-centered cubic (BCC) and face-centered cubic (FCC) phases without the formation of new crystalline phases throughout of RSW process. Overall, the study revealed that while the microstructure and crystal structure remained stable, the mechanical performance of the welded joints were improved by the right choice of welding parameters and the use of the titanium powder. These findings demonstrate the potential of this approach for producing reliable dissimilar AHSS welded joints for engineering applications, particularly in the automotive industry.