The Effect Of Nugget Sizes On Mechanical Properties In Resistance Spot Welding Of SPA-C Atmospheric Corrosion Resistant Steel Sheets Used In Rail Vehicles*

Abstract This publication presents an experimental study on the resistance spot welding of SPA-C steel sheets used in side wall and roof application of rail vehicles. SPA-C atmospheric corrosion resistant steel sheets with a thickness of 2.3 mm were joined by using resistance spot welding as lap joint. A timer and current controlled resistance spot welding machine with 120 kVA capacity and a pneumatic application mechanism with a single lever were used to join the specimens. Welding periods were chosen as 5, 10, 15, 20, 25 and 30 cycles (1 cycle = 0.02 s) and also welding currents were increased from 6 kA up to 14 kA by rising in steps of 0.5 kA. The electrode force was kept constant at 6 kN. The welding joints obtained were exposed to tensile peel and tensile shear tests and their nugget sizes were calculated by results of optical microscopy measurements. The effect of nugget sizes on tensile peel strength and tensile shear strength was researched by using related diagrams and the optimum welding currents and times were advised.