Development of an explosive welding process for producing high-strength welds between niobium and 6061-T651 aluminum

An explosive welding procedure for joining 9.5-mm-thick niobium plate to 203-mm-thick 6061-T651 Al plate has been developed in order to maximize the weld tensile and impact strengths and the amount of welded material across the surface of the plate. This procedure improves upon previous efforts, in which the 9.5-mm-thick niobium plate is welded directly to 6061-T4 Al plate. In this improved procedure, thin Nb and Al interlayers are explosively clad between the thicker niobium and aluminum plates. Welds produced using these optimized parameters display a tensile strength of approximately 255 MPa and an impact strength per unit area of approximately 0.148 J/mm ². Specialized mechanical testing geometries and procedures are required to measure these weld properties because of the unique weld geometry. In order to ensure that differences in the thermal expansion coefficients of aluminum and niobium do not adversely affect the weld strength, the effects of thermal cycling at temperatures between -22° and 45°C on the mechanical properties of these welds have also been investigated by testing samples in both the as-received and thermal cycled conditions. Based on the results obtained from this series of mechanical tests, thermal cycling is shown to have no adverse effect on the resulting tensile and impact strengths of the welds produced using the optimized welding parameters.