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利用室温单向拉伸实验、EBSD和TEM等手段,研究了柱状晶组织HAl77-2铝黄铜的力学性能与加工硬化行为,探讨了晶粒尺寸对拉伸变形加工硬化速率和塑性变形能力的影响及其机制.结果表明,柱状晶组织HAl77-2铝黄铜加工硬化速率-真应变关系曲线第2阶段具有显著上升趋势,晶内形成平行分布的小角度亚晶界使位错滑移长度减小并阻碍位错运动是加工硬化速率上升的主要原因,不同于文献报道的等轴晶组织黄铜加工硬化第2阶段形成形变孪晶使滑移长度减小的机制.随着晶粒尺寸的增大,柱状晶组织HAl77-2铝黄铜的屈服强度和抗拉强度降低,而断后伸长率显著增大,由晶粒尺寸为2.0 mm的70.4%增大到晶粒尺寸为6.0 mm的84.4%.较高的抗塑性失稳能力和较好的晶内变形均匀性是大晶粒柱状晶试样具有更优塑性变形能力的主要原因.
The mechanical properties and work hardening behavior of HAl77-2 aluminum brass with columnar crystal structure were studied by uniaxial tensile test at room temperature, EBSD and TEM. The effects of grain size on the work hardening rate and plastic deformation capacity The results show that the second stage of the strain hardening-rate-strain curve of HAl77-2 aluminum brass with columnar crystal structure shows a significant upward trend, and the small-angle subgrain boundaries formed in parallel in the grain make the dislocation slip length Reducing and hindering the dislocation movement is the main reason for the increase of the work hardening rate, which is different from the mechanism that the deformation twinning decreases the slippage length in the second stage of the work-harden of brass with equiaxed grain structure reported in the literature.With the grain size , The yield strength and tensile strength of HAl77-2 aluminum brass with columnar crystal structure decrease while the elongation at break increases remarkably from 70.4% of 2.0 mm of grain size to 6.0 mm of grain size Of 84.4% .The higher resistance to plastic instability and better in-plane deformation uniformity are the main reasons for the greater plastic deformation capacity of large-grain columnar grains.