Study on the Effect of Ultra-low Temperature Compression on the Microstructure of 6061 Aluminum Alloy and Its Deformation Mechanism

doi:10.3901/JME.2025.14.056

Abstract

Abstract: The challenges of microstructural coarsening and inhomogeneity during high-temperature and room-temperature deformation of aluminum alloys are addressed through compression tests of 6061 aluminum alloy at different temperatures. The influence of deformation temperature on microstructure and mechanical properties is elucidated, with a focus on grain refinement mechanisms under cryogenic conditions (-196 ℃) using electron backscatter diffraction. Experimental results show that dynamic recrystallization occurs at 500 ℃, producing an average grain size of approximately 30 μm. At 20 ℃ (room temperature), deformation is dominated by dislocation slip, preferentially in grains with high Schmid factors, resulting in inhomogeneous microstructures and an average grain size of 8.57 μm. Under cryogenic deformation (-196 ℃), recovery processes are significantly suppressed, and dislocation motion is hindered by the pinning effect of point defects. The increased density of subgrain boundaries raises the critical resolved shear stress for slip system activation. Weakened thermal activation and enhanced Peierls forces under cryogenic conditions jointly increase deformation resistance. This resistance promotes uniform dislocation distribution and generates straight, elongated slip bands with higher average misorientation angles (≥15°), ultimately yielding an ultrafine-grained structure with an average grain size of 1.13 μm. The findings provide new theoretical insights into grain refinement mechanisms during plastic deformation of aluminum alloys.

Key words: 6061 aluminum alloy, ultra-low temperature compression deformation, misorientation, dislocation slip

CLC Number:

TG146

FU Yunfan, YI Youping, HUANG Shiquan, HE Hailin, DONG Fei. Study on the Effect of Ultra-low Temperature Compression on the Microstructure of 6061 Aluminum Alloy and Its Deformation Mechanism[J]. Journal of Mechanical Engineering, 2025, 61(14): 56-62.

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