Evaluation of interfacial crack growth in bimaterial metallic joints loaded by symmetric three-point bending

摘要

Bimetallic three-point bend specimens (TPB) were produced from explosive clad alloy aluminium LY12/pure aluminium Al by electron beam welding of homogeneous Al and homogeneous LY12 to the respective surfaces. Cracks were introduced at the interface in the specimens by milling and spark-erosion. Similar bimetallic specimens of explosive clad LY12/steel were also prepared. Finite element analyses were undertaken to evaluate the J-integral and the deformation ahead of the bimetallic interfacial crack tip field of the TPB specimens loaded normally. The calculations showed that, even for symmetric TPB loading of the specimens, a sharpening-blunting deformation existed on the profile of the interfacial crack tip for bimetals with a mismatch in mechanical properties. J-resistance curves for two kinds of bimetal interface were obtained from symmetric TPB tests. The results demonstrated that the resistance to crack propagation along the bimetallic interfaces was always lower than those of the respective counterpart metals.