Welding Time Effect of Welding Joints in Micro Alloyed and TRIP 800 Steels in Resistance Spot Welding

This paper presents an analysis of resistance spot welds between micro alloyed steel sheets having 1 mm thickness and TRIP 800 (transformation-induced plasticity) steel sheets having 1.5 mm. TRIP 800 steel and micro alloyed steel sheets are used in automobile chassis and automobile body parts, respectively. In this study, resistance spot-welding method was used for joining steel pairs to be lap joint. A time and current controlled resistance spot welding machine having 120 kVA capacity, and pneumatic application mechanism were used in the experiments. Specimens prepared for spot welding operations were joined with different welding time ranging from 5 to 30 periods (1 period = 0.02 s) and different weld currents, ranging from 8.5 to 16.5 kA in 0.5 kA steps. The electrode force was kept constant at 6 kN. Tensile-peel tests were applied to the welded specimens. The effect of welding time parameter on tensile-peel properties was analyzed. The highest tensile-peel load was obtained using 15 periods

Effect of Welding Current on Tensile-Peel Loading of Welding Joints in TRIP 800 and Micro-Alloyed Steels in Resistance Spot Welding

In this paper, an analysis of electric resistance spot welding between micro-alloyed steel sheets having 1 mm thickness and TRIP 800 (transformation induced plasticity) steel sheets having 1.5 mm thickness was made. Couples of steel sheets are used in automobile industry. Steel pairs were joined by using resistance spot welding as overlap joint. A timer and current controlled resistance spot welding machine had pneumatic application mechanism and 120 kVA capacity. Preparation of specimens by spot welding was performed using different cycles ranging from 5 to 30 cycle and welding currents ranging from 8.5 to 16.5 kA by rise of 0.5 kA. The electrode force was kept constant at 6 kN. The prepared welding specimens were exposed to tensile-peel tests and the obtained results were supported by diagrams. Finally, appropriate welding parameters were advised to the users

Resistance spot weldability of Fe-15.4Mn-2.1Al-1.2C twinning induced plasticity steel

Welding of twinning induced plasticity steels contains problems due to high manganese constituent. Low manganese and high carbon included twinning induced plasticity steels have not studied throughly in the literature. In this study, resistance spot weldability of Fe-15.4Mn-2.1Al-1.2C twinning induced plasticity steel was investigated. According to the results, interfacial, partial interfacial and pull-out type failure modes were obtained in tensile-shear tests. The maximum tensile-shear load was measured as 17.7 kN with 125 J ? ??1 heat input rate separated with pull-out failure. Although the heat affected zone was narrow, it formed the weakest region of the joint. Cleavage facets which is a sign of brittle fracture were detected on the fracture surface that formed in heat affected zone. A sudden increase in hardness supports the brittleness of the heat affected zone. Also, grain coarsening reduced strength of the heat affected zone. A narrow partially melted zone was identified between heat affected zone and weld nugget. According to electron back scatter diffraction phase distribution analysis, formation of manganese carbides was detected in the heat affected zone. © 2023 Wiley-VCH GmbH.The authors would like to thank ASAŞ Aluminium Company, Turkey, for utilizing SEM/EDS/EBSD devices