Retrogression and re-aging treatment on short transverse tensile properties of 7010 aluminium alloy extrusions

Effects of pre-treatments on aging precipitates and corrosion resistance of a creep-aged Al–Zn–Mg–Cu alloy

“…Meanwhile, the growth of the new nucleation cores takes in solute atoms from the surroundings, which broadens the PFZ to some extent. This result is consistent with other researchers' report [19]. When the retrogression pre-treatment time is increased to 40 min (case 3), it can be found that the large precipitates appear, as shown in Fig.…”

“…However, the corrosion resistance of the creep-aged alloys after retrogression pre-treatment is significantly improved. This is because that the diffusion of Cu atoms from the aluminum matrix to pre-existing aging precipitates, especially for the grain boundary precipitates, can occur during the retrogression pre-treatment [18,19]. Recently, researches show that the increase of Cu content can result in the weak electrochemical active of MgZn 2 precipitates [24,55].…”

“…Generally, the mechanical properties and corrosion resistance of Al-Zn-Mg-Cu alloys are closely related to microstructures, which are greatly affected by the thermo-mechanical processing [10][11][12]. In the past, some investigations have been carried out to study the relationships between the heat treatments, microstructural evolution and properties of Al-Zn-Mg-Cu alloys [13][14][15][16][17][18][19][20][21][22][23][24]. Liu et al [13] found that the cooling aging treatment can improve the mechanical properties and corrosion resistance of Al-8.35Zn-2.5Mg-2.25Cu alloy.…”

“…Marlaud et al [18] studied the evolution of precipitates during the different steps of RRA heat treatments of Al-10.3Zn-2Mg-1.6Cu alloy, and found that both the final chemistry and size of the precipitate are different in the final RRA temper compared to classical heat treatments. Angappan et al [19] reported that the coarsening of grain boundary precipitate and its copper enrichment during RRA treatment are responsible for the improvement of SCC (stress corrosion cracking) resistance. http Also, Wang et al [20], Dixit et al [21] and Viana et al [22] found that SCC resistance could be improved by the over-aged treatment, but a strength loss of 10-15% is inevitable.…”

Effect of retrogression and re-ageing heat treatment on microstructure and microhardness of aluminium 7010 alloy

“…Apart from coarsening of GBP's the electrochemical potential of the GBP's gets increased by diffusion of more Cu into them, thereby delaying the formation of corrosion pits. This is expected to increase the resistance the alloy towards SCC [15,16]. 1.…”