Improvements in Strength and Electrical Conductivity in 7B04 Aluminum Alloy Pre-Stretched Thick Plates Via Low-Temperature Retrogression and Re-Ageing Heat Treatments
The effect of RRA treatment with using low retrogression temperatures between 170°C to 190°C on the strength and electrical conductivity (as an indicator of corrosion resistance) of 7B04 aluminum alloy thick plates was investigated. The research results showed that the low-temperature RRA heat treatment provides a means for improving electrical conductivity of the aluminum alloy 7B04 pre-stretched thick plates without sacrificing the mechanical strength. The RRA temper with retrogression at 180°C for 60 min improved electrical conductivity remarkably (reached 21.0MS/m), with only a 3% reduction in strength below T6 temper. Furthermore, TEM observations showed that the microstructure of RRA treated alloy was a very fine distribution of η′ MgZn2 precipitates in the aluminum matrix, similar to T6 condition and η MgZn2 precipitates on grain boundaries distributed similarly to T73 temper.
Young Won Chang, Nack J. Kim and Chong Soo Lee
Z. H. Li et al., "Improvements in Strength and Electrical Conductivity in 7B04 Aluminum Alloy Pre-Stretched Thick Plates Via Low-Temperature Retrogression and Re-Ageing Heat Treatments", Materials Science Forum, Vols. 561-565, pp. 139-142, 2007