2D70铝合金热变形行为及加工图

Hot deformation behavior and processing map of aluminum alloy 2D70

采用THERMECMASTOR-Z热模拟实验机对2D70铝合金进行等温恒应变速率压缩实验，基于加工图技术研究该合金在320-530℃和0.001-70.0 s-1范围内的变形特性，并优化出适宜的变形热力学参数范围。结果表明：在热变形过程中，随着真应变的增加，合金的变形失稳区域增大。当应变速率较大（≥1.0 s-1）时，变形多处于失稳区域；当变形温度低于350℃、应变速率大于1.0 s-1时，微观组织中出现了裂纹；当变形温度高于500℃、应变速率大于1.0 s-1时，易出现机械失稳；而在变形温度低于350℃、应变速率低于0.1 s-1时，微观组织中出现楔形裂纹。综合加工图以及微观组织观察结果，获得了试验参数范围内热变形的最佳工艺参数，变形温度为370-460℃、应变速率为0.004-0.1 s-1。

The isothermal compression tests with constant strain rate for aluminum alloy 2D70 were conducted by THERMECMASTOR-Z hot simulator. The hot deformation behaviors in the temperature range of 320-530℃and the strain rate range of 0.001-70.0 s-1 were investigated. Then, the processing maps under these deformation conditions were constructed and the deformation thermomechanical parameters were then optimized based on the generated processing maps. The results show that the flow instability zone increases with true strain increasing during the hot deformation process. Otherwise, when the strain rate is higher than 1.0 s-1, most of the deformation behavior is located at the flow instable zone. Under this condition, the domain of flow localization appears at the temperature lower than 350℃ and mechanical instability exhibits at the temperature higher than 500℃. While, when the strain rate is lower than 0.1 s-1 and the temperature is lower than 350℃, the wedge cracking can be found. On the base of the experimental results including processing map and microstructure, the optimum deformation thermomechanical parameter ranges of aluminum alloy 2D70 can be confirmed to the temperature range of 370-460℃and the strain rate range of 0.004-0.1 s-1.