PA6冷压变形行为研究

Study on Deformation Behavior of PA6 Under Cold Compression

采用镦粗变形对结晶型聚合物尼龙(PA)6进行3种变形速度和4种变形程度的冷压镦粗变形实验,实验结果表明,镦粗变形的几何变形模式及其极限伸长率的几何性质与单向拉伸完全不同,但PA6的屈服应力随变形速度增大而提高的现象与许多材料单向拉伸屈服现象相似。与此同时,冷压镦粗PA6的延性大变形属于"类塑性",其性质和数值与聚合物及其"相-态"结构和变形回弹相关。虽然PA6冷压镦粗后的回弹率很大,但回弹随变形速度提高而减小,因此为了研发聚合物锻造技术,需要提高变形速度或采用加热措施及改用闭式锻造变形模式。

Cold compression experiments for crystalline polyamide （ PA ） 6 were done with upsetting deformation by using three kinds of deformation rates and four kinds of deformation degree. The results showed that geometric deformaton pattern and the geometric characters of limit elongation ratio of upsetting were different from tensile test, but it was similar with yielding behavior of many materials that the yielding stress would become higer with increase of deformation rate. And the large ductile deformation of upsetting PA6 was of ＂plasticity-like behavior ＂ whose characters and value were related to deformation recovery, polymer and its ＂phase structure-condensed state＂. Although the deformation recovery of PA6 was very large after cold upsetting, but it decreased with increase of deformation rate. Therefore in order to develop forging technique for polymer it was necessary to increase deformation rate, or apply hot compression, and change open forging to close forging.