Strain-Hardness Correlation in Aluminium Butt Cold Welded Joints

Butt cold welding is a solid phase welding process where welding occurs by plastic deformation of the metals to be welded. It is obtained by cold pressing until the expansion of the contact zone of the two parts creates contaminant-free areas, allowing the contact and creation of a common lattice between the opposing clean surfaces. Consequently, butt cold pressure welding raises interesting theoretical and practical issues related to the material large plastic deformation, and its consequent hardening. The method used to determine the 99.5%Al hardness-strain correlation is based on Vickers micro-hardness HV0.5 test results on upset bars at different values of effective strain. Two approximations of the relationship between hardness and the effective strain were determined, namely as a rational function, and as a power function. These functions were used for validating an original FEM model of 99.5% Al bar butt cold welding