Effect of Cryogenic Processing on Surface Roughness of Age Hardenable AA6061 Alloy

The aging phenomenon in age hardenable aluminum alloys is complex and well under research. The supersaturated solid solution of these alloys, during aging, undergoes complex precipitation causing increase in strength with time. These alloys have wide range of applications in the aviation and automotive industry. The properties such as electrical conductivity and hardness of these alloys are well related to its precipitation behavior. Cryogenic treatment (CT) has been tried on tool and alloy steels where it has been found that this treatment positively affects the wear resistance and also causes uniformity in structure. The CT has become an important step in the manufacturing of tool steels. This work comprises applying CT at -185 degrees C to AA 6061 aluminum alloy for various time periods. The treatment was sequenced in the conventional solutionizing and artificial aging. This sequence of treatment has not been reported in the literature. The characterization was done using scanning electron microscopy. The behavior of this alloy to the treatment was identified by measuring electrical conductivity and hardness. The surface roughness of this alloy was also found to be highly influenced by this treatment.