基于薄壁环压缩的铝合金管材应力−应变行为

摘要

采用环压缩实验研究LF2M铝合金薄壁管材在应变速率为0.1~1 s?1,成形温度为350~475℃条件下的应力?应变行为.提出一种薄壁环压缩的方法,得到薄壁管材热压下的变形行为.结果表明:环压缩试样的高度选择需要避免压缩过程中出现起皱缺陷.试样高厚比为1时,随着压缩量增加,切向压应力超过临界值引起起皱失稳;试样高厚比为3时,随着压缩量增加,压应力超过临界值,出现起皱现象;试样的高厚比为2时,压缩后试样无起皱缺陷.因此,壁厚为1 mm时,环压缩试样的最佳高度为2 mm.LF2M铝合金薄壁管材热变形过程中的流变应力可用双曲正弦本构关系来描述,平均激活能为160.67 kJ/mol.%The stress-strain behavior of LF2M aluminum alloy of thin-walled tube during hot compressing deformation was studied, under the conditions of strain rate range of 0.1?1 s?1, and the temperature range of 350?475℃. A method of thin-walled ring compression was proposed to obtain the deformation behavior of the thin-walled tube under hot extrusion. The results show that the height of the ring compression sample is selected to avoid wrinkling defects during the compression process. When the ratio of the height to thickness is 1, with the increase of the amount of compression, the tangent pressure exceeds the critical value caused to the wrinkling destabilization. When the ratio of the height to thickness is 3, the compression stress exceeds the critical value caused to the wrinkling destabilization with the increase of the amount of compression. When the ratio of the height to thickness is 2, the specimen have no wrinkling destabilization. Therefore, when the wall thickness is 1mm, the optimum height of the ring compression specimen is 2 mm. The flow behavior of LF2M aluminum alloy of thin-walled tube is described by the hyperbolic sine constitutive equation, and an activation energy of 160.67 kJ/mol is calculated.