Corrosion Behavior of 6101 Aluminum Alloy Strands for Automotive Wires

Abstract

Microstructural states produced by each step of the manufacturing process leading to the production of automotive strand arms in 6101 aluminum alloy (AA6101) for wiring harnesses were investigated in relation to their corrosion behavior in NaCl solution. The observed corrosion morphology,i.e., pitting corrosion or intergranular corrosion, was strongly dependent on the precipitation state, i.e., mainly the presence of intergranular Mg2Si precipitates. A ‘grain size – corrosion resistance’ relationship was also evidenced with an ennoblement of the corrosion potential for wires heavily cold drawn, which were characterized by a nanometric grain size. Dislocation density as well as the homogeneity of alloying element distribution were also found to be relevant parameters for explaining the electrochemical behavior of each microstructural state. Plastic deformation and recrystallization phenomena occurring during the manufacturing process were found to be associated with redistribution of alloying elements, which impeded the formation of intergranular Mg2Si precipitates. Therefore, in the present study, the cold drawing process was found to increase the intergranular corrosion resistance of AA6101.