变形速率对搅拌摩擦加工镁合金变形行为的影响

Influence of Deformation Rate on the Deformation Behavior of Magnesium Alloy Modified by Friction Stir Processing

对AZ31镁合金板材进行搅拌摩擦加工（Friction stir processing，FSP）处理，在不同的应变速率下进行室温静态拉伸，研究其应变速率敏感性及加工硬化行为。对搅拌摩擦加工AZ31镁合金的织构进行电子背散射衍射（EBSD）检测，发现其基面法向与加工方向呈60-65°夹角。在不同应变速率下进行的拉伸实验结果表明：试样真应力-真应变曲线均呈S形特征，且随着应变速率的增加，试样的抗拉强度升高、延伸率降低；随着应变的不断增加，试样的应变速率敏感性指数先增后减，在低应变下为负值；加工硬化率随应变的增加呈驼峰状趋势。

The AZ31 magnesium alloys sheet were treated by friction stir processing （FSP）. To study the strain rate sensitivity and work hardening behavior of the FSPed specimen, the room temperature static tensile tests were carried out at different strain rates. The texture of the FSPed AZ31 magnesium alloys shows 60-65°between the normal of basal plane and FSP processing direction using electron backscattered diffraction （EBSD） method. Ten sile tests were conducted at different strain rates. The results showed that the uhimate tensile strength of the FSP specimen increased and elongation decreased with strain increasing. The true stress-strain curves exhibited an S-shaped feature at all strain rates. The strain rate sensitivity index presented a negative value at low strain, and increased to positive value and then decreased with the increase of strain. Work hardening rate exhibited a hump shaped trend.