A novel approach to prediction of welding residual stress and distortion

A rigorous, accurate, and general methodology is presented to predict welding residual stress and distortion. The presented theory has two key advantages over existing experimental and numerical approaches: (1) there is an explicit relationship and dependency between input parameters and output values; and (2) it may be readily adapted to consider the effect of new and future processes, materials, and geometries. Formal definitions are provided and general formulae are derived for the two key attributes of the residual stress distribution: the material yield temperatures, and the tendon force. The yield temperatures are material properties which describe the respective boundaries of the plastic strain zone during heating and cooling. The tendon force corresponds to the net driving force for distortion. Practical engineering equations for each output value are presented as the combination of a minimal expression, based on idealized treatment, and correction factors to account for real life aspects not included in the ideal model. The idealized treatment corresponds to instantaneous line heating of an infinite thin section with constant material properties. Secondary phenomena considered expressly in this work include the following: incomplete uniaxial thermal constraint (i.e., the effect of welding procedure), temperature-dependent thermal and mechanical properties (i.e., the effect of material), and limited rigidity of a real cross-section with finite size and arbitrary shape (i.e., the effect of geometry). This work brings fresh insights to a century-old problem. The new contribution to knowledge includes both an improved theoretical understanding and also a practical consideration of how to apply this understanding to real-world, non-ideal problems of immediate and significant industrial relevance. This paper received the 2022 Henry Granjon award in Category C: Design and structural integrity and is based on work related to the author’s doctoral thesis.