The behaviour of iron and aluminium during the diffusion welding of carbon steel to aluminium

The diffusion welding of carbon steel to aluminium may be achieved when the temperature and compression of the weld metal allows diffusion at the interface between both components; the degree of interdiffusion largely determines the quality of the welded joint. Such diffusion processes can take place under vacuum. However, in this paper, we report that high quality welds can be achieved without the use of vacuum or reducing atmospheres by applying sufficient compression to give very high levels of plastic deformation of an Al layer sandwiched between layers of carbon steel at 550 °C in laboratory air. The resulting structures were characterised using scanning electron microscopy, transmission electron microscopy and microanalysis, which showed that, under these conditions, Fe diffused across the interface into the Al layer.