Recent developments in laser joining of dissimilar materials

Abstract

Primary aim of using hybrid structural elements in lightweight design is to reduce weight and maintain or increase mechanical properties and structural performance by joining metals to metals or metals to composites. This is of particular interest for the transportation industries such as car or aircraft production or shipbuilding. In this paper, based on a short analysis of the state-of-the art, the use of laser-based processes for joining of aluminium to steel and aluminium to carbon-fibre reinforced composites (CFRC) is discussed in more detail.In special, it is established that the thickness of the intermetallic phase layer Al5Fe2 (which is crucial for the mechanical properties of aluminium-steel joints) is very sensitive to specific features of the time-temperature cycle in the joining zone. This makes it necessary to precisely adhere to adequate processing conditions within narrow limits. As a potential solution, Laser MIG hybrid welding of aluminium to steel is suggested, which – within a comparably wide parameter envelope - reproducibly produces joints with optimised properties. These properties equal or surpass typical properties obtained by other processes, however at an elevated speed exceeding 6 m/min.Considering the joining of aluminium to CFRP, a novel approach is presented, which is in principle suitable to produce load-bearing integral CFRP-aluminium structures using a laser beam heat conduction welding process.Primary aim of using hybrid structural elements in lightweight design is to reduce weight and maintain or increase mechanical properties and structural performance by joining metals to metals or metals to composites. This is of particular interest for the transportation industries such as car or aircraft production or shipbuilding. In this paper, based on a short analysis of the state-of-the art, the use of laser-based processes for joining of aluminium to steel and aluminium to carbon-fibre reinforced composites (CFRC) is discussed in more detail.In special, it is established that the thickness of the intermetallic phase layer Al5Fe2 (which is crucial for the mechanical properties of aluminium-steel joints) is very sensitive to specific features of the time-temperature cycle in the joining zone. This makes it necessary to precisely adhere to adequate processing conditions within narrow limits. As a potential solution, Laser MIG hybrid welding of aluminium to steel is suggested, which – within a comparabl...