Residual Stress Distribution in Butt Welded Joints – Effect of the Weld Groove Shape

Abstract

The influence of the V-groove, X-groove and square butt edges, as well of the weld sequence on the residual stress distribution in butt welds is reported in this paper. Coupon plates with 400 x 180 x 11 mm size were prepared with square butt edges, V-groove and X-groove edges, stress relief heat treated and welded with two beads in each, using the gas metal arc welding process. Longitudinal and transverse residual stresses were measured in each coupon plate after the stress relief treatment and after each weld bead, following lines perpendicular to the weld direction and also along the central line of the weld. Residual stresses evaluation was conducted using an X-ray diffraction method. Residual stress distribution after the first weld bead is similar in the three types of weld grooves, nevertheless using weld X-groove longitudinal tensile residual stress tends to present the highest level in the weld metal and heat-affected zone. The execution of the second weld layer originates a small increase of the longitudinal residual stresses, but X-groove welds continue to present the highest level. The weld groove type seems to have a reduced effect on transverse residual stress distribution, though the second weld layer produces an increase in magnitude of the transverse residual stress in welds with X-groove and square butt edges.