Experimental investigation of effect of residual stress on mechanical properties in welded joints

In this study, effect of residual stress on mechanical properties of welded joints was investigated. For this purpose Fe37 grade structural steel plates (50x10 mm and 70x10 mm) were used. In the lower plates (70x10 mm), different prestress (91 N/mm2, 148 N/mm2, 194 N/mm2 and 222 N/mm2) were created by horizontal tensile device. The upper plate (50x10 mm) was placed on the prestressed lower plate and then it was welded by means of corner weld. Having completed welding procedure, prestress in the lower plate was relieved. By this way, in the welded joints, various residual stress were created. Effects of residual stress on mechanical properties of welded joints were determined by tensile/shearing test. Also residual stress in the welded joints were analysed by Photoelasticity technique and measured via Vishay PALC3 programme. Yield stress and strain decreased with increasing residual stress in the welded joints. The highest yield stress and strain were determined for the welded joint which was not subjected to prestress. However, minimum mechanical properties were observed for joint prestressed with 222 N/mm2.