AZ31B镁合金板材纵波与平辊轧制宏观织构演变

Macro-texture Evolution of AZ31B Magnesium Alloy Sheet during Longitudinal Wave and Flat Roll Rolling

摘要:

为探究纵波轧制（LR）对AZ31B镁合金板材基面织构的影响，本文对AZ31B镁合金板材进行400℃/20min和450℃/20min热处理，振幅0.35mm，周期4mm的纵波波纹辊和平辊轧制。采用XRD对热处理及轧制后的板材进行宏观织构表征，运用极图及ODF对织构演变进行了分析，同时对金属在轧制变形区的变形行为进行了仿真分析。结果表明：板材热处理后，400℃下的（0002）极图中极密度最大值由11.21降到8.41，450℃降到7.08，450℃下热处理后的织构强度弱于400℃；LR后板材的基面织构显著弱化，大量晶粒向RD、TD方向发生了偏转，其中向RD方向最多偏转30°，向TD方向最多偏转40°，400℃下的（0002）峰值织构强度降到4.33，450℃下降到5.62，400℃下LR的织构弱化效果比450℃更明显；二道次轧制后的板材，450℃下的基面织构强度要弱于400℃。分析表明：LR使得晶粒的c轴取向由ND向TD、RD方向发生了偏转，这是由于LR过程中存在类似于异步轧制过程中的“搓轧区”，其中产生的剪切力使晶粒沿RD方向发生偏转，弯曲和挤压复合变形下金属流动和剪切促进晶粒TD取向。

Abstract:

To investigate the effect of longitudinal wave rolling (LR) on the texture of AZ31B magnesium alloy sheet, the AZ31B magnesium alloy sheet was heat treated at 400℃/20min and 450℃/20min, with amplitude of 0.35mm and period of 4mm, longitudinal-wave roll and flat-roll rolling. XRD was used to characterize the macro texture of the heat-treated and rolled plates, and the texture evolution was analyzed by polar diagram and ODF. Meanwhile, the deformation behavior of the metal in the rolling deformation zone was simulated. The results show that the peak texture intensity of (0002) at 400℃ decreases from 11.21 to 8.41, and at 450℃ to 7.08. The texture intensity at 450℃ is weaker than that at 400℃. After longitudinal-wave rolling, the substrate texture of the plate is weakened significantly, and a large number of grains are deflected towards RD and TD,with a maximum deflection of 30° towards RD and 40° towards TD. The peak texture intensity of (0002) decreases to 4.33 at 400℃ and 5.62 at 450℃. The texture weakening effect is more obvious at 400℃ than at 450℃. After two passes of rolling, the texture intensity of the base surface at 450℃ is weaker than that at 400℃. The analysis shows that: LR makes the C-axis orientation of grains deflect from ND to TD and RD. The reason is that there is a " cross-shear zone" similar to that in the process of induction rolling in the process of p-wave rolling, in which the shear force prompts grains along the RD direction. While there is also metal flow and shear force similar to the hetero-tooth combined deformation process and the bending and flattening combined deformation technology. This results in a deflection of grain orientation along the direction of TD.