Effect of Microstructure on the Cracking Resistance Characteristics of Al-Zn-Mg-Cu-Zr (1933) Wrought High-Strength Alloy

摘要

Effect of the grain structure, primary excessive phases and dispersoids (Zr Al_3) on fracture toughness (K_(1c)) and fatigue crack growth rate (FCGR) have been investigated (with the use of transmissia electron microscopy (TEM), scanning electron microscopy (SEM) and metallographic methods) in alloy 1933T3(T7351) extruded profile manufactured from ingots under different ho-mogenization. The tested samples had the same chemical composition and practically the same level of the tensile properties (UTS=490-510 MPa, YTS=430-450 MPa). However, the tested samples essentially differed in K_(1c) and FCGR values (by 1,3-1,5 times) as well as surface fracture structure. Such combination of properties has been provided by differencies in Zr Al_3 dispersoid particles distribution in the volume of compared spesimens and also by changing of initial ingots homogeni-zation regimes.