ON THE SPOT BRAZING AND SPOT SOLDERING OF TANTALUM

The main goal of this study is to investigate the possibility of joining pure tantalum to itself by resistance classical spot (RS), spot brazing (SB), and spot soldering (SS) welding methods. In order to evaluate the bonding strength and to understand its mechanism for these welding methods, foils of ASTM A63, AWS BCu-1, and AWS BVAg?O were employed as filler?metal alloys. The influence of welding time on the joint strength was studied. Hence, four different welding times (1, 2, 3, and 4 seconds) were chosen to determine the optimum welding time. Reflected optical microscopy tests of welded assemblies were performed to determine the mechanism of joint formation. Moreover, the joint strength was evaluated by a tensile shear strength test (TSST). Then, the total work done (i.e., joint toughness) was determined. Since the welding time is a key factor which controls the microstructure and hence the mechanical properties of the joint strength, it is therefore found that two seconds is the optimum welding time whatever the welding process. Spot brazing via AWS BCu-1 filler metal alloy leads to the best strength.