Steel to titanium solid state joining displaying superior mechanical properties

Joint configuration with Ti inserts, which allows the increase of the bonded area of similar materials at the expense of that of dissimilar ones, is suggested. The force to failure for the specimens with the suggested configuration was about two fold higher than that for the specimens with the planar interface. Microstructural analysis of the joints, fracture characterization, mechanical testing and finite elements simulation were conducted in order to elucidate the mechanical behavior of the suggested joint configuration. Failure of joints with Ti-inserts is governed by the brittle behavior of TiC and α-Ti layers, located at the steel-Ti interface, with cracks initiation within the interfacial layer. The cracks propagate first into the brittle α-Ti phase and then cause the fracture in the Ti/Ti bond. The results of finite elements analysis are in good agreement with the analysis of the fracture surfaces.