J. Wisniewski, D. Ayrault, Commissariat à l'Energie Atomique, GIF SUR YVETTE, France; J. M. Drezet, Ecole Polytechnique Fédérale de Lausanne, LAUSANNE, Switzerland; P. Pilvin, Université de Bretagne Sud, LORIENT, France; A. Durocher, Commissariat à l'Energie Atomique, St PAUL LEZ DURANCE, France; B. Cauwe, Le Bronze Industriel, Suippes, France
The precipitation hardened CuCrZr alloy has been selected as a heat sink material for the first wall components of the International Thermonuclear Experimental Reactor (ITER) due to its good thermophysical and thermomechanical properties. The feedback from its application in Tore Supra (French tokamak) showed that this alloy is very sensitive to hot tearing during electron beam welding. In order to characterize its hot tearing susceptibility, a welding test, based on the investigation of the Joining and Welding Research Institute (JWRI), has been performed. An electron beam weld seam is performed on a thin rectangular plate equipped with thermocouples. As the width of the plate decreases, conditions leading to the formation of hot tears appear. The test is analysed by means of numerical modelling and available hot tearing criteria. To carry out the numerical analysis, the knowledge of the thermophysical properties of the alloy is a prerequisite. Missing physical properties are determined by associating laboratory tests and numerical analysis. Hot tears occur in solidifying parts undergoing tensile stresses that are transmitted to the mushy zone by the coherent solid underneath, as reported in the RDG (Rappaz, Drezet, Gremaud) hot tearing criterion. This criterion is based on the derivation of the ability of the interdendritic flow of liquid to compensate for the thermally-induced deformation at the roots of the dendrites. The results of the welding test presented here are analysed with the help of the RDG criterion and the conditions at which hot tears initiate are discussed.
Summary: The results of a welding test, inspired by the work carried out at the Joining and Welding Research Institute (JWRI), are analysed with the help of the RDG criterion and the conditions at which hot tears initiate are discussed.
