钛合金高压扭转变形过程数值模拟研究

发布时间：2018-01-13 04:27

本文关键词：钛合金高压扭转变形过程数值模拟研究　出处：《合肥工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：钛合金作为一种轻质材料而被广泛使用。高压扭转(high-pressure torsion,HPT)作为一种大塑性变形(severe plastic deformation,SPD)方法被广泛应用于各种材料的塑性加工过程中。研究钛合金高压扭转变形过程,分析不同变形因素对钛合金高压扭转变形过程的影响规律。对于后续钛合金高压扭转实验的具体实施具有重要的意义。本文利用Deform-3D模拟软件对高压扭转过程进行模拟。首先利用UG造型软件建立三维模型,然后将模型导入Deform-3D软件中,从而就建立了钛合金高压扭转的三维模型。通过改变钛合金高压扭转变形过程中各种参数,利用Deform-3D软件对其进行模拟,分析不同工艺因素对钛合金高压扭转变形过程的影响。本文分析摩擦因子对三种典型钛合金TA11α型钛合金、TB6β型钛合金、TC4α+β型钛合金高压扭转变形过程中等效应变和相对扭转角度的影响,得到不同类型钛合金的高压扭转变形规律。通过分析摩擦因子和变形温度对TC4钛合金高压扭转变形过程的影响规律,得到TC4钛合金在高压扭转过程中破损系数、等效应变、等效应力、表面膨胀比、速度矢量的分布和变化规律。通过置氢与未置氢TC4钛合金高压扭转变形过程的比较,得到置氢对TC4钛合金高压扭转变形过程的影响。数值模拟结果表明:对于TA11α型钛合金,随着摩擦因子的增加,等效应变先降低而后增加,相对扭转角度先升高而后降低;对于TB6β型钛合金,摩擦因子对其高压扭转变形过程中等效应变和相对扭转角度影响规律与TA11α型钛合金一致;而对于TC4α+β型钛合金,随着摩擦因子的增加,等效应变逐渐增加,相对扭转角度先升高后降低最后再次升高。对于TC4钛合金,随着摩擦因子的增加,试样上表面破损系数数值在0.5~0.6左右,高压扭转变形过程中等效应变、表面膨胀比均增加,速度矢量的大小逐渐减小。等效应变在径向和轴向方向分布不均匀,等效应力在径向和轴向方向的分布较为均匀,几乎保持在一条水平线上;随着变形温度的增加,试样上表面的破损系数变化维持在0.6~0.9左右。随着变形温度的增加,高压扭转过程中等效应变和速度矢量的大小逐渐增加,等效应力和表面膨胀比的大小均逐渐减小。等效应变在径向和轴向方向分布不均匀,等效应力在径向和轴向方向分布较为均匀,几乎保持在一条水平线上。置氢能够改善TC4钛合金高压扭转坯料的表面质量,能够使得变形深入到坯料内部,并且使得变形均匀。本文模拟结果表明不同类型钛合金材料高压扭转变形过程不同。摩擦因子越大越有利于高压扭转过程的进行,变形温度越高越有利于塑性变形的进行,实际难以实现高温下钛合金的高压扭转过程。置氢对于钛合金高压扭转过程是有益的。
[Abstract]:Titanium alloy is widely used as a light material. High pressure torsion. HPT) as a kind of large plastic deformation severe plastic deformation. SPD method is widely used in the plastic processing of various materials. The high pressure torsional deformation process of titanium alloy is studied. The influence of different deformation factors on the high-pressure torsional deformation process of titanium alloy is analyzed. It is of great significance to carry out the subsequent high-pressure torsion experiment of titanium alloy. In this paper, Deform-3D software is used to simulate the deformation of titanium alloy. The high-pressure torsion process is simulated. Firstly, the three-dimensional model is built by UG modeling software. Then the model is imported into Deform-3D software, and a three-dimensional model of high pressure torsion of titanium alloy is established. By changing the parameters of the process of high pressure torsion deformation of titanium alloy. The effects of different process factors on the high-pressure torsional deformation of titanium alloy were analyzed by Deform-3D software. The friction factors on three typical titanium alloys TA11 伪 type titanium alloy were analyzed in this paper. The effect of equivalent strain and relative torsion angle on TB6 尾 titanium alloy TC4 伪尾 titanium alloy during high pressure torsional deformation. The effects of friction factor and deformation temperature on the high-pressure torsional deformation of TC4 titanium alloy were analyzed. The damage coefficient, equivalent strain, equivalent stress and surface expansion ratio of TC4 titanium alloy under high pressure torsion were obtained. The distribution and variation of velocity vector. The comparison of the torsional deformation process of TC4 titanium alloy with and without hydrogen insertion was carried out at high pressure. The effect of hydrogen insertion on the high pressure torsional deformation of TC4 titanium alloy is obtained. The numerical simulation results show that for TA11 伪 titanium alloy, the equivalent strain decreases first and then increases with the increase of friction factor. The relative torsion angle increased first and then decreased; For TB6 尾 titanium alloy, the effect of friction factor on equivalent strain and relative torsion angle during high pressure torsion deformation is consistent with that of TA11 伪 titanium alloy. For TC4 伪尾 titanium alloy, the equivalent strain increases gradually with the increase of friction factor, the relative torsion angle increases first, then decreases and then rises again. For TC4 titanium alloy, the equivalent strain increases gradually with the increase of friction factor. With the increase of friction factor, the damage coefficient of the upper surface of the specimen is about 0.5 ~ 0.6, and the equivalent strain and the surface expansion ratio increase in the process of high-pressure torsional deformation. The distribution of equivalent strain is not uniform in radial and axial direction, and the distribution of equivalent stress in radial and axial direction is more uniform, and the equivalent strain is almost kept at a horizontal line. With the increase of deformation temperature, the change of the damage coefficient of the upper surface of the specimen is maintained at 0.6 ~ 0.9. With the increase of deformation temperature, the equivalent strain and velocity vector increase gradually in the process of high-pressure torsion. The magnitude of equivalent stress and surface expansion ratio decrease gradually. The distribution of equivalent strain is not uniform in radial and axial directions, and the distribution of equivalent stress is more uniform in radial and axial directions. It can improve the surface quality of TC4 titanium alloy high pressure torsion blank and make the deformation go deep into the blank. The simulation results show that different types of titanium alloy materials have different high-pressure torsional deformation process. The larger the friction factor is, the more favorable the high-pressure torsion process is. The higher the deformation temperature is, the more favorable the plastic deformation is. It is difficult to realize the high-pressure torsion process of titanium alloy at high temperature, and the hydrogen insertion is beneficial to the high-pressure torsion process of titanium alloy.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.23;TG306

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