Influence of retrogression and reaging on microstructure, mechanical properties and susceptibility to stress corrosion cracking of an Al‐Zn‐Mg alloy

Abstract

The aim of the present work was to determine the influence of the retrogression and reaging (RRA) heat treatment on the correlation between microstructure, mechanical properties and susceptibility to stress corrosion cracking (SCC) of the AlZn5Mg1 alloy in dry air and sea water. The alloy received in the T6 temper was subjected to 9 different heat treatments, including retrogression at temperature 453 -513 K for 600 -3600 s, and reaging at temperature 363 K or 403 K for 16 h, 24 h or 48 h. The susceptibility to SCC was investigated by slow strain rate tensile tests at 10 À6 s À1 strain rate; change in time to failure, fracture energy and reduction in area were taken into account. Generally, the heat treatment improving mechanical properties increased susceptibility to SCC. The observed effects were discussed in terms of change in microstructure, especially size and distribution of phase precipitates. The role of change in dislocation network was the most likely of no importance.

Effect of retrogression and re‐aging (RRA) heat treatment on the corrosion behavior of B206 aluminum–copper casting alloy

“…Therefore, the RRA heat treatment provides for large grain boundary precipitates and coherent matrix precipitates which are responsible for enhanced SCC resistance and high strength, respectively, in 7075 aluminum alloy . It has also been indicated that RRA treatment in 7xxx series wrought alloys reduces the dislocation density, and therefore, reduces the susceptibility to SCC …”

“…[29] It has also been indicated that RRA treatment in 7xxx series wrought alloys reduces the dislocation density, and therefore, reduces the susceptibility to SCC. [24,30] To date, only a few reports, such as Refs. [8,31] , have investigated the effects of RRA heat treatment, which have been successful in 7xxx series aluminum alloys, on the corrosion behavior of B206.…”

Evaluation of Mechanical Properties of Retrogression and Reaged Al 7075 Alloy Reinforced With Sicp Composite Material

“…Retrogression and reaging treatment can improve the stress corrosion behavior of the alloy while maintaining the mechanical resistance of the T6 temper [4][5][6][7][8][9][10][11][12]. The following are the steps involved in retrogression and reaging:  Specimens are placed in the muffle furnace for preaging.…”

“…The increase in the strength of the specimens are due to the formation of the more stable interphases like MgZn 2 [12][13][14] and also refinement of the grains at the said elevated temperature of retrogression for short interval of time.…”

“…Signal-to-noise: Larger is better The increase in the strength of the specimens are due to the formation of more stable interphases like MgZn 2 [12][13][14] and also refinement of the grains at the said elevated _______________________________________________________________________________________ Volume: 03 Issue: 11 | Nov-2014, Available @ http://www.ijret.org 120 temperature of retrogression for short interval of time.…”