2219铝合金网格壁板应力松弛时效行为分析

Analysis of stress relaxation behavior of 2219 aluminum alloy mesh panels

整体网格壁板在航天器结构应用中,采用热压罐成形作为2219T87铝合金网格壁板的成形工艺。在壁板与模具贴模之后,通过应力计算和有限元仿真可得到不同厚度层受到的应力大小。在热压罐中时效时,由于拉、压应力的影响,壁板不同位置材料性能有所差异。结果表明:应力的计算值和仿真值吻合,说明模型的有效性;在透射电子显微镜下观察发现,受拉、压应力区的析出相较低应力区的细小、密集,压应力区又比拉应力区的析出相更加细小密集,这是因为受应力区会产生大量的位错,从而为沉淀物的析出提供更多的形核位置,产生更多细小、针状的析出物,在宏观上反映为析出相越细小、密集,抗拉强度及硬度越高。

The autoclave formation method was used as the forming process of 2219T87 aluminum alloy mesh panel applied in spacecraft structure. After the wall panel close to the mould, stress intensity of different thickness layers can be obtained by stress calculation or finite element simulation. In the aging of autoclave, material performance of panel is different at different positions because of the effect of tensile and compressive stress. The results show that the calculated value is consistent with that of simulation, and can illustrate the effectiveness of the model. It can be found from transmission electron microscopy （TEM） that the precipitation of tensile and compressive area is relatively slight and intensive compared with low stress area. The precipitated phase of compressive area is slighter and more intensive than that of tensile area, because the stressed area can produce abundant dislocations, which provide the precipitation of precipitate with more nucleation site and generate more slight and needlelike precipitate. On a macro level, the slighter and more intensive the precipitated phase is, the higher the strength of extension and hardness becomes.