TA1/AZ31B多层复合材料在热模拟过程中的变形行为研究

Study on the Deformation Behaviors of TA1/AZ31B multi-layer Composites during Isothermally Compression Processing

摘要:

本文采用等温压缩试验研究了在变形温度为573K-723K，应变速率范围为0.01s-1-10s-1，压下量30%-50%的条件下TA1/AZ31B多层复合材料的塑性变形行为并利用光学显微镜观察显微组织的变化。研究表明：TA1和AZ31B在压缩复合过程中均发生塑性变形，但是钛镁多层复合材料各层的变形不同时且不均匀，AZ31B层的变形程度大于TA1层，且在变形过程中AZ31B层发生了动态再结晶。当应变速率为10s-1时，中间TA1层出现颈缩和断裂。计算结果证明Arrhenius本构方程可以准确预测TA1/AZ31B多层复合材料的流动应力行为，得到平均绝对相对误差为3.976%，相关系数为0.991。此外，基于动态材料模型(DMM)理论建立了TA1/AZ31B多层复合材料在真应变0.5下的加工图，确定最佳工艺条件在723K温度下，应变速率为0.01s-1，此时最大功率耗散值为28%。同时，TA1/AZ31B多层复合材料的加工图中存在一个不稳定区域，即变形温度范围为573K ~ 692K时应变速率范围为0.6-10s-1。

Abstract:

In the present study, Isothermal compression tests were performed to investigate the hot deformation behavior of TA1/AZ31B multi-layer composites. Flow stress-strain curves were obtained for deformation at temperature from 573K to 723K with the strain rate range from 0.01s-1 to 10s-1, and the height reduction range from 30% to 50%. Effect of the strain on the flow stress, both TA1 and AZ31B had plastic deformation during the compression bonding process. However, all layers deformation of TA1/AZ31B multi-layer composite is not occur at the same time and not uniform. The deformation of AZ31B is larger than that of TA1, and AZ31B occurs dynamic recrystallization during the deformation process. When strain rate is 10s-1, the middle TA1 layer occurs necking and fracture. Based on the flow stress-strain curves, the Arrhenius-type constitutive equation could precisely predict the flow stress behavior of TA1/AZ31B multi-layer composite. Besides, the value of the correlation coefficient was 0.991 when that of average absolute relative error was 3.976%. The processing map at true strain of 0.5 for TA1/AZ31B multi-layer composite was developed using the dynamic materials model (DMM) theory. The processing map of isothermally compressed TA1/AZ31B multi-layer composite exhibited that the optimum parameters were determined at the temperature of 723K and the strain rate of 0.01s-1 with power dissipation’s maximum efficiency of 28%. In the meanwhile, there was one instability domain in the processing map of isothermally compressed TA1/AZ31B multi-layer composite, it is in the deformation temperature range from 573K to 692K and the strain rate range from 0.6s?1 to 10 s?1.