Method for predicting risk of cracking during weld repair of heat resistant cast steels

Arnaud Duchosal , Frederic Deschaux-Beaume (1, 2) , Cyril Bordreuil (1, 2) , Gilles Fras (1, 2) , Philippe Lours (3)

1 AS - Assemblages Soudés
2 LMGC - Laboratoire de Mécanique et Génie Civil
3 CROMeP - Centre de Recherche Outillages, Matériaux et Procédés

Owing to their low ductility at room temperature, heat resistant cast austenitic stainless steels are very sensitive to weld cracking. Cracks are formed in brittle zones of the heterogeneous microstructure constituted by the carbide rich interdendritic spaces. In order to identify the operating factors affecting the cracking propensity of such steels during welding, a three step method, based on numerical simulation, is presented. First, the macroscopic emperature and stress fields are determined by a finite element calculation, considering a homogeneous material. In a second step, a localisation criterion is defined to identify critical zones, according to the macroscopic fields determined in the first step. Then, the heterogeneous microstructure of the cast steel is modelled in a 'representative cell', and the thermomechanical history of the critical zone previously identified is applied as boundary condition, in order to determine the local stress field. The cracking is then supposed to occur when the maximal principal stress in the interdendritic zone of the representative cell reaches the cleavage stress of the carbides, determined using SEM in situ tensile tests. This method is used to predict cracking during multipass weld repair of bulk samples, under various welding conditions. A comparison is carried out between experiment and simulation to validate the method.

Mots clés: Heat resistant cast steel; Weld cracking; Numerical simulation; Localisation criterion; Cracking criterion

Domaines: Mécanique des matériaux [physics.class-ph]; Mécanique des matériaux [physics.class-ph]

Arnaud Duchosal, Frederic Deschaux-Beaume, Cyril Bordreuil, Gilles Fras, Philippe Lours. Method for predicting risk of cracking during weld repair of heat resistant cast steels. Science and Technology of Welding and Joining, 2008, 13, pp.126-135. ⟨10.1179/174329308X283839⟩. ⟨hal-00562411⟩