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Hot deformation mechanisms in magnesium-aluminum-zinc-manganese alloys.

机译：镁-铝-锌-锰合金的热变形机理。

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摘要

Magnesium sheet for automotive applications is very attractive due to its light weight. The poor formability of magnesium and its alloys at room temperature, however, has limited the applications of these alloys. For this reason, at present, magnesium must be formed at elevated temperatures. This study investigates the hot deformation and fracture characteristics of Mg-1wt% Zn alloys containing a range of Al and Mn levels. Hot-rolled specimens were tensile tested over a range of strain rates and temperatures. Strain rate versus flow stress diagrams plotted on log-log scales revealed a transition in deformation mechanisms as a change in slope (the 'stress exponent'). Specifically, non-uniform deformation (i.e. necking) is observed at high strain rates, while uniform deformation is observed at low rates. This transition is accompanied by a change in fracture mechanism from dimpled rupture at high strain rates to cavitation and cavity interlinkage at low strain rates. Specimens which had a stress exponent of ∼2 and which failed through uniform deformation showing interlinked cavities have been associated with the grain boundary sliding (GBS) deformation mechanism. Specimens which had a stress exponent of ∼5 and which failed through necking showing a dimpled fracture surface have been associated with the dislocation creep deformation mechanism. Increasing aluminum appears to somewhat favour the GBS regime as indicated by a slightly decreasing stress exponent. Manganese also appears to favor the GBS regime, since the onset of cavitation appears at higher strain rates compared to alloys without Mn.
机译：用于汽车应用的镁片由于其重量轻而非常有吸引力。然而，镁及其合金在室温下较差的可成形性限制了这些合金的应用。因此，目前必须在高温下形成镁。本研究研究了含有一定含量的Al和Mn的Mg-1wt％Zn合金的热变形和断裂特性。在一定的应变速率和温度范围内对热轧试样进行拉伸测试。在对数对数刻度上绘制的应变率与流动应力的关系图显示，随着坡度的变化，变形机制发生了转变（“应力指数”）。具体地，在高应变速率下观察到非均匀变形（即颈缩），而在低应变速率下观察到均匀变形。这种转变伴随着断裂机理的变化，从高应变速率下的凹坑破裂到低应变速率下的空化和空洞互连。应力指数为〜2且由于均匀变形而失效并显示出相互连接的空洞的试样与晶界滑动（GBS）变形机制有关。应力指数为〜5且因颈缩而失效，并显示出凹陷的破裂表面的试样与位错蠕变变形机制有关。铝的增加似乎在某种程度上有利于GBS制度，如应力指数略有下降所表明的。锰似乎也支持GBS方案，因为与不含Mn的合金相比，空化的出现以较高的应变速率出现。

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  • 作者

    Seale, Geoff.;

  • 作者单位

    McGill University (Canada).;

  • 授予单位 McGill University (Canada).;
  • 学科 Engineering Metallurgy.
  • 学位 M.Eng.
  • 年度 2007
  • 页码 86 p.
  • 总页数 86
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 冶金工业;
  • 关键词

  • 入库时间 2022-08-17 11:39:05

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