Hot deformation constitutive modeling of 6111 aluminum alloy linking Z-parameter to the associated microstructural evolution and precipitation strengthening
Minglong Kang, Yunlai Deng, Du Fei, Shuhui Liu, Binhu Wang, Ming‐Chun Zhao
Abstract
This work investigates the hot deformation behavior and microstructure evolution of 6111 aluminum alloy (core layer in 4343/3003/6111/3003 brazed sheets) via thermal compression (300–500 °C, 0.01–10 s -1 ). A strain-compensated Arrhenius constitutive model was developed, accurately predicting flow stress (Mean Absolute Relative Error (AARE)=4.31%, Correlation Coefficient (R)=0.996). The Z-parameter governs dynamic recovery/recrystallization (DRV/DRX): high Z (lnZ=42.2) suppresses softening, retaining high dislocation density (0.699×10 14 m -2 ) and fine subgrains (5.1 μm); low-Z (lnZ=24.9) promotes DRV/DRX, reducing dislocations (0.207×10 14 m -2 ) and coarsening subgrains (13.7 μm). Crucially, high-Z deformation preserves substructures (dislocation walls, subgrain boundaries), which act as nucleation sites for Q′-phase precipitates during aging. This yields finer precipitates (8.5 nm vs. 9.5 nm), enhancing precipitation strengthening (Δτ p =62.1 MPa vs. 47.8 MPa) and hardness (145 HV vs. 126 HV), compared to low-Z conditions (lnZ=42.2 vs 24.9). Optimizing Z during hot rolling controls substructure retention, maximizing post-aging strength in brazed sheets. The findings establish a theoretical basis for optimizing process parameters and controlling microstructure in composite-brazed sheet production.