Effect of Ageing on the Hardness and Tensile Properties of Aluminum Alloy 7001 with Special Reference to the Influence of Delay Time between the Quenching and Ageing Treatments.

摘要

The change in hardness of aluminum alloy 7001 with time at temperatures 22 C, 50 C and 121 C following quenching from solution heat treatment at 460 C has been determined. At 22 C, natural ageing caused a hardness increase from 104 HV to 191 HV in 6 1/2 years and the hardness was still rising. Ageing at 50 C caused an increase in hardness from 104 HV to 179 HV in 96 h and the hardness was still rising. After approximately 72 h at 121 C a peak hardness of 216 HV was reached. Subsequent heating at 121 C after various periods of time up to 4 years at 22 C and 96 h at 50 C caused an initial reversion in hardness. Delay times varying from zero to 217 days at 22 C between quenching and ageing at 121 C for 24 h did not appear to have any significant effect on the hardness and tensile properties. (Author)