Structure of the aluminum alloy Al-Cu-Mg cryorolled to different strains

Abstract

Methods of optical metallography, X ray diffraction, and transmission and scanning electron microscopy were used to study changes in the structure of the aluminum alloy D16 (2024) caused by isother mal rolling at a temperature of liquid nitrogen. It has been established that the basic structural changes that take place in the material upon deformations to e ~ 2.0 are due to the formation and evolution of the dislo cation structure, which contains cells of nanometer size. With further straining to e~3.5, the processes of recovery and recrystallization become activated, which lead to the formation of a mixed grain-subgrain nanosized structure.

Development of High Performance of Al Alloys via Cryo‐Forming: A Review

“…For AA2XXX, the total rolling reduction ratio was >85%. [ 57 ] Furthermore, Deng et al [ 58 ] reported that the total rolling reduction of Al–Li alloy was over 83% at cryogenic temperature. AA5XXX, as a strain‐strengthening alloy, exhibited excellent deformability in CR and the total strain accumulation was more than 90%.…”

“…For Al alloys, multipass deformation is usually required to achieve large plastic strain, [ 54,56 ] and the process of cryogenic cooling and forming is also repeated for multiple times according to previous reports. [ 16,25,54,57,64,72–75 ] After cooling and forming repeatedly, materials with specific microstructure and excellent mechanical properties will be obtained.…”

“…Sekhar and Narayanasamy [ 64 ] suggested that a total CR reduction of 50% would result in better formability compared with 75%, though the latter exhibited higher strength. Krymskiy et al [ 57 ] found that the dislocation density in AA2024 was increased from 0.8 × 10 14 m −2 to 7.2 × 10 14 m −2 when CR reduction increased from 60% to 87%, while recovery and recrystallization of AA2024 were activated when the CR reduction ratio was more than 87%. For AA5052, Shi et al [ 77 ] stated that the improvement of the strengthening effects required 70% or larger CR reductions.…”

“…In addition, cryo‐forming has the potential to change the thermophysical parameters of Al alloys, [ 57,74,77 ] which causes the variation of heat treatment parameters. Shahsavari et al [ 74 ] found that CR can reduce the aging temperature of Al–Cu–Mg–Mn alloy from 463 to 433 K. Krishna et al [ 68 ] investigated the behavior of precipitation processes through differential scanning calorimetry (DSC) curves (as shown in Figure ) and the results indicated that CR increased the precipitation kinetics of Al–4Zn–2Mg alloy, resulting in fine and closely spaced strengthening precipitates.…”

“…The EBSD analysis showed an enhanced fraction of ultrafine grains with sizes of 113 nm in cryorolled samples, whereas RTRed samples exhibited submicron grains with sizes of 300 nm. In the study of cryorolled AA2024 alloy, [ 57 ] a mixed grain–subgrain structure was observed with sizes of 141–150 nm and 50–60 nm. Panigrahi et al [ 70 ] prepared the UFG AA6063 with CR and the grains lie in the range of 113–300 nm.…”