In order to study the actions and effects of materials and geometry J matches on the J
integral of welded joint
specimens under mis matched of stress and
geometry match conditions, the critical J integral values of welded joint specimens are investigated by far field uniform tension tests of single edge plates with cracks in this paper. The results show that, under the same load and before the specimen cracks opening, the values of J integral, displacement Δ and crack mouth opening displacement CMOD of welded joints are between those of all base material and all weld material; and that the J integral parameters of under matched welded joints decrease in the order of all base materials and all weld material, while the order of over matched welded joints is on the contrary, via all welded seam materials, welded joints and all base materials. Also, when the geometry width
parameter a/W is low, the tested J integral values of welded joints with different material matches are close to those of all base materials. At the same time, when the geometry width parameter a/W is high, the J integral of welded joints with different material matches are close to those of all welded materials. Thus effects of the seam width parameter a/W must be taken into account in testing J integral values of welded joints.