The stabilitity of strain-stress relation of aluminum alloy in high strain rate
Date Issued
2004
Date
2004
Author(s)
Chen, Hsin-Yi
DOI
zh-TW
Abstract
Two common aluminum alloys, namely , Al2024-T351 and Al7075-T6 are adopted as the specimen materials. We operated an uniaxial-stress compression test on the Material Testing System, at temperatures ranging from 20℃ to 350℃ and at average true-strain rates greater than 100.
The experiment results show that the trend of the flow stresses of materials depends on the effects of work-hardening and work-softening. Dynamic recovery and dynamic recrystallization were the chief mechanisms of work-softening. At temperatures near the recrystallization temperatures of the alloys, the effect of temperature was equivalent to that of strain-rate. On the trend of flow stress, the variation of yield stress is obvious. When the test temperature was lower than recrystallization temperature, work-hardening and dynamic recovery are the main mechanisms that affect the trend of flow stresses. At higher temperature, dynamic recrystallization dominates over dynamic recovery . At temperatures that was much higher than the recrystalliization temperature, the alloys have undergone recrystallization and grain growth. The yield stress increased with strain-rate increasing, but the phenomenon of strain-hardening became undefined.
When Al2024-T351 was subjected to high-strain-rate deformation, the principle slip system formed a cone–like shear band. Macroscopic fracture occurs at the edges of shear bands at low temperature.
Key words：high-strain-rate、dynamic recovery、dynamic
recrystallization、
Subjects
加工硬化
動態回復
high-strain-rate
work-hardening
dynamic recrystallization
dynamic recovery
Type
thesis