NUMERICAL-ANALYSIS OF GTA WELDING PROCESS WITH EMPHASIS ON POST-SOLIDIFICATION PHASE-TRANSFORMATION EFFECTS ON RESIDUAL-STRESSES

The objective of this work was to analyze the residual stress state in spot welds made in an MY-100 steel disk by an autogenous gas tungsten are (GTA) welding process. An uncoupled thermal-mechanical finite ele ment (FE) model was developed that took into account the effects of li quid-to-solid and solid-stale phase transformations. Effects of variat ions in mechanical properties due to solid-state phase transformations on residual stresses in the weld were studied. Extensive experimental testing was carried out to determine the mechanical properties of MY- 100 steel. The residual stresses in the disk with the spot weld were m easured by a neutron diffraction (ND) technique. The FE results are in good agreement with the ND measurements. The results show that the vo lumetric changes associated with the austenite to martensite phase tra nsformation in HY-100 steel significantly affect residual stresses in the weld fusion zone and the heat affected zone. (C) 1998 Elsevier Sci ence S.A. All rights reserved.