Improvement of mechanical properties in treated spot welded joint

Post Weld Impact Treatment (PWIT) is one of the treatment methods that is usually applied on weld region to reduce the level of residual stress originated from the welding process. During the spot weld process, the formation of stress is produced around the weld area and degrades the mechanical properties of the joint. This paper focused on the improvement of mechanical properties of the spot welding joint via Pneumatic Impact Treatment (PIT) process. This study uses the low-carbon steel with a welded single lap shear joint that has a constant thickness of 1.2 mm. All the welded samples were subjected to tensile-shear test, failure mode and hardness test. The tensile-shear load and fusion zone hardness of RSW joint after PIT was improved by 8% and 27%, respectively. The results indicated improvement in tensile-shear strength and hardness of treated samples as compared to the as-welded samples. From the observation done, the failure mode type was generally accepted as failure for spot-weld joint. The improvement of mechanical properties is envisaged as the result of the mechanical pulses produced by unique fluidic muscle conveyed to the surface of the RSW joint during PIT process.