摩擦对高温合金复杂截面圆环多道次滚压成形不均匀变形作用

The nonuniform defoemation behavior of thin-walled superalloy ring with complex section in multi-pass rolling

摘要:

在高温合金复杂截面薄壁圆环多道次滚压成形过程中,板料要经历多场多因素偶合作用下复杂的不均匀塑性变形和组织演化历程,特别是不均匀塑性变形通常是导致薄壁件成形起皱、椭圆和开裂等缺陷产生的主要因素。摩擦是描述环件与辊轮接触作用的主要参数,很大程度上决定着该环件多道次滚压成形过程中塑性变形的不均匀性,严重的影响着其滚压成形质量。为此,本文以有限元仿真为主并结合实验和理论方法,对高温合金GH4169薄壁w形圆环多道次滚压成形进行了系统的分析；进而提出了不均匀变形度的表征方法,研究获得了摩擦对高温合金复杂截面薄壁圆环多道次滚压成形不均匀变形的影响规律。结果表明：随着滚压成形的进行等效应力极值逐渐增大,且从动辊进给时环件弯曲部分材料变形量较大；随着驱动、从动辊与环件之间摩擦系数的增加,不均匀变形程度先减小,后逐渐增大；导向辊与环件之间的摩擦对不均匀变形度的影响不大。

Abstract:

The material undergoes the complex uneven plastic deformation and microstructure evolution process coupled with multi-fields and multi-factor, during the multi-path roll forming process of the thin-walled super alloy (GH4169) ring with complex section. Especially for the uneven plastic deformation which usually leads to defects of the ring, such as wrinkling, ellipse and crack. Friction is the main parameter to describe the contact between ring and roller, which largely determines the inhomogeneity of plastic deformation during the multi-path rolling process of the thin-walled high temperature alloy (GH4169) ring with w section. And it seriously affects the improvement of roll forming quality. To predict and control the nonuniform plastic deformation, a 3D FE model of the process was built under the ABAQUS/Explicit environment. And the representation method of the nonuniform deformation is proposed.Then the nonuniform deformation behavior in the process was analyzed systematically using FE method combined with experiment and theory. The results show that the maximum value of the equivalent stress increases gradually with the progress of the multi-pass rolling process. And the deformation degree slightly decreases firstly, and then increases gradually with the increase of the friction coefficients between the thin-walled ring and slave roller, drive roller. While the effection of the friction coefficient between guide roller and the ring on the deformation degree can be neglected.