New Grain Formation in a Coarse-Grained 7475 Al Alloy during Severe Hot Forging
New Grain Formation in a Coarse-Grained 7475 Al Alloy during Severe Hot Forging
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DOI：
10.4028/www.scientific.net/msf.467-470.421
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发表时间：
2004-08
期刊：
影响因子：
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通讯作者：
O. Sitdikov;T. Sakai;A. Goloborodko;H. Miura;R. Kaibyshev
中科院分区：
文献类型：
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作者：
O. Sitdikov;T. Sakai;A. Goloborodko;H. Miura;R. Kaibyshev
通过在 T = 490oC、应变速率 3 x 10-4 s-1 下进行的多向锻造 (MDF)，研究了粗晶 7475Al 合金中应变引起的晶粒细化。积分流动曲线在屈服后表现出显着的功软化，随后在高应变下呈现类似稳态的行为。变形过程中新的细晶粒结构的演化可以通过晶界滑动来协助，从而导致高应变梯度的频繁形成以及随后在晶粒内部的微剪切带。向各个方向发展的微剪切带相互交叉，将原始晶粒细分为定向错误的小区域。变形过程中微剪切带的数量和取向差逐渐增加，最终转变为高角度边界。结论是热MDF条件下晶粒细化是通过一系列变形引起的连续反应发生的；这本质上类似于连续动态重结晶。
Strain-induced grain refinement in a coarse-grained 7475Al alloy was studied by means of multidirectional forging (MDF) carried out at T = 490oC under a strain rate of 3 x 10-4 s-1. Integrated flow curves exhibit significant work softening just after yielding, followed by steady-state-like behavior at high strains. The evolution of new fine grain structure during deformation can be assisted by grain-boundary sliding, resulting in frequent formation of high strain gradients and subsequently microshear bands in grain interiors. Microshear bands developed in various directions are intersected with each other, subdividing original grains into misoriented small domains. The number and the misorientation angle of microshear bands progressively increase during deformation, finally followed by their transformation into high-angle boundaries. It is concluded that grain refinement under hot MDF conditions occurs by a series of deformation-induced continuous reactions; that is essentially similar to continuous dynamic recrystallization.