Effect of high-temperature pre-precipitation on stress corrosion cracking of Al-Zn-Mg aluminum alloy plate

The effect of high-temperature pre-precipitation on the microstructure, age hardening and stress corrosion cracking of 7A52 alloy has been investigated. The optical and transmission electron microscopy and energy spectrum analysises show that the high-temperature pre7precipitation could enhance the discontinuity of grain boundary precipitates and make Cu content of grain boundary precipitates increasing. The stress corrosion cracking resistance could be improved with non-deteriorated strength and plasticity via the high-temperature pre-precipitation. After pre-precipitating stress intensity factor K-ISCC of 7A52 alloys solution treated at 480 degrees C raised from 7.6 MPa.m(1/2) to 9.1 MPa.m(1/2). And after pre-precipitating stress intensity factor K-ISCC of 7A52 alloys solution treated at 475 degrees C raised from 8.9 MPa.m(1/2) to 11.1 MPa.m(1/2).