Warm Precision Forging on Extruded AZ61 Magnesium Alloy

温式精密锻造作为塑性成形中直接获得成品形状和高尺寸精度的一体化生产工艺，正受到人们的关注。本文研究了具有高塑性加工性和高强度的AZ61镁合金挤压坯料的温式精密锻造工艺。本研究旨在寻找t形精密锻件的最佳工艺条件，并对其力学性能和织构进行分析。此外，还对AZ61挤压坯料的热轴向镦粗性能进行了评价。这对于实际应用广泛的t形锻件尤其有用，如汽车零部件、管接头、阀体等。对t形锻件的润滑条件、温度和背压条件进行了研究。还研究了AZ61挤压坯料的热轴镦粗作为锻造工艺的基准。分析了AZ61挤压坯料在热轴压缩过程中的变形行为和不稳定变形。结果表明：(1)对于t形锻件，在成形温度为463 K、成形速度为14 mm/min时，获得了背压为250kN的无断口锻件。(2)镦粗能力方面，在温轴镦粗过程中出现了垂直方向的不对称变形，且与首选取向有关。这种现象发生在由坯料上部加载区域的晶体旋转引起的变形之前。(3)采用铸造镁合金，在483K下，以3倍于挤压坯料的速度获得t形锻件。由于镁合金锻造后的硬度和抗压强度都很好，铸造镁合金的锻造技术备受期待。

Warm precision forging is receiving attention as integrated producing process to directly obtain finished product form and high dimensional accuracy in the plastic forming In this research warm precision forging of an AZ61 Magnesium alloy extruded billet with an expected high plastic workability and high strength was investigated. This research aims to find the best condition for producing T-shaped precision forging, and to analyze the resultant mechanical properties and texture. In addition, warm axial upset ability of AZ61 extruded billet is also evaluated. This is particularly useful for T-shaped forging, which have broad practical application, such as automobile parts, pipe joints, valve bodies, etc. For T-shaped forging, the lubricant, temperature and backpressure condition were investigated. Warm axial upsetting of an AZ61 extruded billets is also investigated as the base date of a forging process. Deformation behavior and unstable deformation of AZ61 extruded billets during warm axial compression are also analyzed. Obtained results are as follows:(1)For T-shaped forging, at forming temperature of 463 K, and velocity of 14 mm/min, fracture-free forging with an applied backpressure of 250kN were obtained(2)For upset ability, asymmetrical deformation in the vertical direction was appeared in warm axial upsetting, and is related to the prefer orientation. This phenomenon occurs prior to deformation caused by crystal rotation in the upper loaded region of the billet.(3)By using cast magnesium alloy, T-shaped forging were obtained at the speed three times or more the extruded billets, at 483K. As the both of hardness and compression strength after forged is excellent, forged technology that used the casting magnesium alloy is expected.