Effect of recrystallization on plasticity, fracture toughness and stress corrosion cracking of a high-alloying Al-Zn-Mg-Cu alloy

摘要

The plasticity, fracture toughness and stress corrosion cracking resistance of a high-alloying Al-Zn-Mg-Cu alloy with various recrystallization degrees introduced by solution treatment were investigated. The results exhibited that the elongation increased from 14.73% to 16.38% with the deepening of recrystallization degree from 8.80% to 20.20%, as well as the enhancement of fracture toughness (K-IC) from 25.7 MPa.m(1/2) to 28.9 MPa.m(1/2). On the contrast, the critical stress intensity factor for stress corrosion cracking (K-ISCC) declined from 29.9 MPa.m(1/2) to 25.0 MPa.m(1/2). The recrystallization benefited plasticity and fracture toughness by not only breaking the tight connection between two deformed grains and eliminating the dislocations density but also increasing the "lubricating" thin grain boundary phases. Meanwhile, it degraded stress corrosion cracking resistance due to the increase of coarsening precipitated particles distributed on recrystallized grain boundaries. This work revealed the opposition trend among properties by modifying recrystallization in the high-alloying Al-Zn-Mg-Cu alloy. (C) 2020 Elsevier B.V. All rights reserved.