Q235覆管对AA5052铝合金基管颗粒介质胀形行为的影响

采用AA5052铝合金挤压管作内层基管、Q235碳素结构钢卷焊管作外层覆管的钢铝复合管对复合管颗粒介质胀形行为进行研究。通过塑性理论分析胀形过程中管间切向摩擦力及法向压力对基管应力大小的影响；利用数值模拟分析管间摩擦因数和覆管各向异性对基管的应变成形极限的综合影响，并给出单管、复合管胀形时的壁厚减薄情况和基管的应力、应变分布；通过管材颗粒介质内高压胀形试验，对比单管和复合管胀形条件下铝合金管的极限胀形比，分析复合管的变形协调性。结果表明：通过施加Q235碳素结构钢覆管，减小了AA5052基管胀形区中间截面处的双向拉应力，基管胀形区壁厚减薄变小，胀形比提高了22%，复合管下基管最大减薄率为17.5 %，成形性能显著提高。

Effects of Q235 Coated Tubes on Bulging Behavior of AA5052 Aluminum Alloy Base Tube with Granular Medium

The AA5052 aluminum alloy extruded tube was used as inner base tube, the Q235 carbon structure steel coil welded tube was used as outer cladding steel/aluminum composite tube, and the particle media bulging behavior of the composite tubes was studied. The influences of tangential friction forces between tubes and the normal pressures on the stress of the base tubes during the bulging processes were analyzed through plastic theory. Numerical simulation was used to analyze the comprehensive influences of the friction coefficients between tubes and the anisotropy of the coated tubes on the strain forming limit of the base tubes. In addition, the wall thickness reduction of the single tubes and composite tubes and the stress and strain distribution of the base tubes during the bulging were given. Through the high-pressure bulging tests in the tube granular medium, limit bulging ratios of aluminum alloy tubes were compared under single tube and composite tube bulging conditions. The deformation compatibility of the composite tubes was analyzed. Results show that by applying Q235 carbon structural steel clad tubes, the bidirectional tensile stresses are reduced at the middle section of the bulging zones of the AA5052 base tubed, the wall thickness reduction of the base tube bulging zones is decreased, and the bulging ratio is increased by 22%. The maximum thinning rate of the base tubes under the composite tube is as 17.5%. The forming performance is significantly improved.