Transient finite element analysis of deep penetration laser welding process in a singlepass butt-welded thick steel plate

The laser welding residual stresses and strains in a rectangular thick steel plate are investigated by means of a fully three dimensional finite element analysis. Temperature field and stress-strain field decoupling is assumed to be essential in order to perform an efficient finite element analysis. Moreover, ad hoc constitutive elastoviscoplastic equations have been adapted in order to overcome the unreliable behaviour of rate independent (plastic) constitutive models. Evolution of temperature and stress during the welding process has been numerically simulated as a function of the motion of the travelling laser beam. The results obtained showed also the three dimensional character of stress field due to the typical keyhole form of the molten material under the laser beam, and the relative sound contribution of the stress component along the thickness to the triaxial state of stress, often neglected in previous calculations. (C) 1999 Elsevier Science S.A. All rights reserved.