Precipitation Hardening of the Electrical Conductor Aluminum Alloy 6201

Abstract

Aluminum alloy 6201 is a wrought, heat-treatable alloy, which is used in electricity transmission and distribution lines. The alloy is processed in a commercial continuous casting and rolling system, which includes a series of in-line thermomechanical processes involving hot working, quenching, cold working and artificial aging. In this study and following cold working, the alloy is subjected to a solution heat treatment at 510 °C for an hour, quenched in ice water, and artificially aged at various temperatures for various times (150–200 °C for 2–30 h) (T6-temper) in order to investigate the effect of precipitation on mechanical properties and electrical conductivity. The results show that optimum mechanical properties and electrical conductivity were obtained after artificial aging at 155 °C for 30 h (155-30). The tensile strength was almost equal to that of the as received cold drawn wire of 326 MPa, but interestingly, electrical conductivity significantly increased to 58.6% IACS from a value of 52.7% IACS of the as received cold drawn wire. Intermetallic particles α-AlFeSi (Al8Fe2Si) and β-AlFeSi (Al5FeSi and Al9Fe2Si2) were observed in all samples, which were nucleated during solidification and homogenization; they were not affected by the aging process. β″/β′/β -precipitates formed during artificial aging, which affected the final mechanical properties and the final electrical conductivity.