Product Code: ICA13_1801

Welding of Dissimilar Metallic Materials Using a Scanned Laser Beam
Authors:
Paola De Bono, Twi Ltd; Cambridge Great Britain
Paul Hilton, Twi Ltd; Cambridge Great Britain
Jonathan Blackburn, TWI Ltd; Cambridge Great Britain
Michael Gittos, TWI Ltd; Cambridge Great Britain
Sullivan Smith, Twi Ltd; Cambridge Great Britain
Presented at ICALEO 2013

For most dissimilar metal combinations, a key challenge which must be addressed for fusion joining processes is the chemical incompatibility of the metals, which typically leads to the formation of brittle intermetallic phases and, consequently, inadequate weld properties. To counteract this issue, a technique which uses a scanned laser beam has been investigated for overlap joints of 1.0 mm CW004 to 1.0mm Al6061 and 0.6mm Ti-6Al-4V to 1.0mm Al6061. Through optimisation of the scanning profile, scan speed and laser power, tailored heat inputs were developed to control the depth of melting in the lower sheet and limit the formation of brittle intermetallic phases. In addition, it was found that the agitation of the weld zone by the scanned laser beam ensured any intermetallic phases formed were small and dispersed, and were partially dissolved back into the aluminium weld matrix. For both dissimilar material combinations, the resulting welds contained very little cracking and were an order of magnitude stronger than conventional continuous-wave keyhole welds. The joint strengths achieved in the CW004 to Al6061 and Ti-6Al-4V to Al6061 overlap joints were, respectively, >90% and >80% of the joint strength achieved in homogeneous aluminium welds.