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 stee l plate are investigated by means of a fully three dimensional finite eleme nt analysis. Temperature field and stress-strain field decoupling is assume d to be essential in order to perform an efficient finite element analysis. Moreover, ad hoc constitutive elastoviscoplastic equations have been adapt ed in order to overcome the unreliable behaviour of rate independent (plast ic) constitutive models. Evolution of temperature and stress during the wel ding process has been numerically simulated as a function of the motion of the travelling laser beam. The results obtained showed also the three dimen sional character of stress field due to the typical keyhole form of the mol ten material under the laser beam, and the relative sound contribution of t he stress component along the thickness to the triaxial state of stress, of ten neglected in previous calculations. (C) 1999 Elsevier Science S.A. All rights reserved.