Brushing for High Performance Cold Pressure Welded Bonds

Abstract

Joining of steel and aluminum is a commonly applied manufacturing process to obtain lightweight components. Cold pressure welding by means of direct extrusion allows gaining high bond strengths between these two materials. The contacting surfaces are usually prepared by using scratch brushing to enhance the bond strength. Most studies have shown the benefit of the brushing whereas the resulting bond strength scatters. Variations in the parameters of the brush treatment are presumed to be a major cause for the variations in strength. Within the presented work, scratch brushing parameters are adjusted to further improve the resulting bond strength. Cracking of the surfaces at low strains is a beneficial effect to enhance the bond strength. Therefore, the crack formation of the surfaces brushed under different conditions is analyzed in tensile tests. Roughness, residual stresses and microstructural changes of the aluminum surfaces resulting from brushing processes are evaluated to enhance the understanding of the cracking mechanism. Concluding, the brushing parameters are adjusted to improve bond strengths up to the material strength of the used aluminum.