Effect of crack path and high angle grain boundaries on fracture toughness and fatigue behaviour of cryorolled AA2219

Abstract

AA2219 aerospace alloys in T87 condition were rolled at room temperature and subzero temperature, followed by analysis on its tensile, fracture toughness and fatigue crack growth characteristics. The cryorolled alloy exhibits lower plane stress fracture toughness (50 kJ m −2) than T87 condition (99 kJ m −2) because of higher high angle grain boundaries (HAGBs) which causes an inability to withstand the cyclic deformation. Nevertheless, the cryorolled alloy has shown higher tensile properties and crack growth resistance due to finer grains and large plastic zone size in the crack tip. The unidirectional rolled samples undergo a distinctive zigzag path than the cross-directional rolled alloy because of deflection from the orderly oriented second phase particles.