Assessment of hot cracking during tig welding of B206 aluminum alloy

In this study, the hot cracking susceptibility of B206 aluminum (Al) alloy during TIG welding was investigated using the moving torch Varestraint test method. B206 Al alloy billets were cast with and without the addition of titanium-based grain refiner. The billets were then machined to 3mm thick plates and tested. In all, two levels of titanium (i.e. 0.02 and 0.05 wt%) were used. The results suggest that addition of titanium significantly reduced the hot cracking susceptibility in B206. This was attributed to a finer and more equiaxed grain structure throughout the welding regions. In addition, residual stress measurements (carried out using neutron diffraction) showed that the cracked sample contained a lower magnitude of stress as a result of relief from cracking, while a crack-free sample was found to have relatively higher magnitude of residual stress, since the stress remained 'locked-in' to resist the formation of hot cracks. Copyright © 2014 by The Minerals, Metals & Materials Society.