Measurement and Prediction of Residual Stresses in Low Carbon Steel Pipes Welded Shielded Metal Arc Welding


Welding is carried out with a very complex thermal cycle, which results in irreversible elastic-plastic deformation, and residual stresses in and around fusion zone and heat-affected zone (HAZ). A residual stress due to welding arises from the differential heating of the pipes due to the weld heat source. However, due to the presence of residual stresses in and around the weld zone the strength and life of the component is also reduced. The objective of this work is to measure the welding residual stress in ASTM (A-106 Gr. b) steel pipes with 4" diameter and 6 mm thickness welded manually (SMAW) in three-pass butt joint where shielded metal arc welding process consists of heating, melting and solidification of parent metals and a filler material in localized fusion zone by a transient heat source to form a joint between the parent metals. The welding process will have accrued without preheating and heat treatment. This measuring of residual stress occurs by using hole-drilling strain gauge method according to (ASTM E-873) then the experimental results for residual stresses obtained from welded carbon steel pipes used to provide validation for finite element simulations. The welding process and welding residual stress distribution is calculated by Ansys Finite Element techniques. Theoretical considerations can be assessed by a mechanical model. The overall, there is good agreement between the predicated and measured distributions of residual stress, but the magnitude of predicted stress tend to greater in welding region.