ROLE OF ZIRCONIUM TO IMPROVE STRENGTH AND STRESS-CORROSION RESISTANCE OF Al-Zn-Mg AND Al-Zn-Mg-Cu ALLOYS.

Abstract

Addition of approximately 0. 2% zirconium followed by ingot homogenizing at 723 K for 28. 8-57. 6 ks improves strength and stress-corrosion resistance due to the formation of subgrains caused by zirconium-bearing particles. Quench sensitivity since an equilibrium phase (MgZn//2 etc. ) precipitates at the misfit surface around zirconium-bearing particles during slow quenching.