Performance of strength mis-match welded joints: Comparison of experimental and numerical results

It is known that the fracture behaviour of a welded structure with a weld metal or Heat Affected Zone (HAZ) crack is influenced by the mechanical properties of the neighbouring regions (weld metal, base metal and heat affected zone) the ligament size and the weld dimensions. In order to better understand those phenomena, a research programme using both numerical and experimental approaches has been conducted at EDF and GKSS research centres. Two 70 mm thick 316L austenitic stainless steel plates have been butt-welded using a TIG welding process. The weld metal yield strength is more than twice the base metal yield strength. From this overmatched weld, 25 mm thick Compact Tension, Single Edge Notched Bend and Center Cracked panels in Tension, specimens (a/W=0.5) have been prepared and tested at room temperature. The crack was located in the middle of the weld metal. Those experiments have been modeled by 3D finite element calculations using the Aster code developed at EDF/RSDD. This paper presents the comparison between the experimental and the numerical results in terms of load line displacement, crack mouth opening displacement and crack tip opening displacement measured experimentally using the δ-clip developed at GKSS. Moreover resistance curves determined on those various specimens are also compared, so as to investigate any geometry effect. (authors)