Recrystallization Behavior in the Notch Region of AA8014 Aluminum Alloy Burst Vents and Its Effect on Burst Pressure

In this study, isothermal annealing of AA8014 aluminum alloy burst vents was performed at 250-500 °C for 10 s to 2 h, and Johnson-Mehl-Avrami-Kolmogorov (JMAK) kinetic analysis was employed to determine the recrystallization parameters at 300 °C. An Avrami exponent of n = 1.87 and an apparent activation energy of Q = 156 kJ/mol were obtained, revealing a recrystallization mechanism driven by high stored energy and synergistically regulated by particle-stimulated nucleation at coarse second-phase particles and Zener pinning by fine Al(Fe,Mn)Si dispersoids. The burst pressure evolution was highly temperature-dependent: annealing at or below 300 °C led to sluggish recrystallization and a gradual pressure decline, whereas annealing at 350 °C and above resulted in recrystallization completion within 10 s and a sharp pressure drop to a stable plateau of approximately 0.92 MPa. The Al(Fe,Mn)Si dispersoids showed no significant differences in size distribution or grain-boundary pinning after 1 h at both 300 °C and 500 °C. This invariance across the tested range rendered the microstructure and burst performance insensitive to process variations. A quantitative predictive model correlating the recrystallized fraction with the burst pressure was established, with prediction errors less than 4.1%. The 300-350 °C interval is identified as the critical temperature window for regulating recrystallization kinetics and burst pressure, providing a rational basis for the heat-treatment design of burst vents.