Material flow and hardening at butt cold welding of aluminium

The paper investigates the material flow and the hardening during butt cold welding process of 99.5% Al bars. The material flow inside and outside the bars is described both experimentally and theoretically, with important conclusions on the relation between the material deformation and hardening. The Mechanically Affected Zone (MAZ) is identified, defined and described for the first time through the FEM based analysis of the strain–stress field, and validated through the hardness field. The analytical description of the strain state, the hardness tests, and the experimental relation between the material hardness and the strain state are used to validate the FEA results. Tensile tests, microscopic and macroscopic analysis results are discussed to underscore the material flow and hardening features. Various parametric graphs are presented accompanied by discussion about their relevance on the process and equipment design.