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Nucleation Mechanism of Discontinuous Dynamic Recrystallization with Restrained Grain Boundary Sliding
Metals and Materials International ( IF 3.3 ) Pub Date : 2020-08-27 , DOI: 10.1007/s12540-020-00847-x
Bingchao Xie , Baoyun Zhang , Hao Yu , Yongquan Ning

Abstract

The discontinuous dynamic recrystallization (DDRX) nucleation process was investigated during the TMP of a nickel-based superalloy with a coarse columnar-grain structure. Special attention was focused on the formation mechanism of the ‘newborn boundary’ which separates the free-strain volume from deformed grain. The special grain morphology and large grain size restrained the grain boundary sliding of the studied alloy, and hence made it difficult to form a subboundary through strain induction or twining to separate the free-strain volumes from the deformed grains. This is very different with the classical DDRX theory, where the grain boundary sliding has less restraint and hence leads to grain boundary shearing and the following strain induced boundary or twin boundary. However, the experiment results showed that DDRX took place and developed well during the studied deformation process with restrained grain boundary sliding. It was found that the ‘newborn boundary’, which separates the free-strain volume from deformed grain to close this area, was formed through dislocation piling-up and rearrangement instead of strain induction or twinning caused grain boundary shearing. Hence, a potential nucleation theory was then proposed and discussed, which is expected to enrich the discontinuous dynamic recrystallization theory.

Graphic Abstract



中文翻译:

约束晶界滑动不连续动态再结晶的成核机理

摘要

在具有粗柱状晶粒结构的镍基高温合金的TMP过程中研究了不连续动态重结晶(DDRX)成核过程。特别关注的是“新生儿边界”的形成机制,该机制将自由应变量与变形晶粒分开。特殊的晶粒形态和较大的晶粒尺寸限制了所研究合金的晶界滑动,因此使其难以通过应变感应或孪晶形成亚界来将自由应变体积与变形晶粒分开。这与经典的DDRX理论有很大的不同,在传统的DDRX理论中,晶界滑动的约束较少,因此导致晶界剪切和随后的应变诱发边界或孪晶边界。然而,实验结果表明,DDRX在受约束的晶界滑动变形过程中发生并发展良好。人们发现,“新生边界”是通过位错堆积和重排而不是由应变感应或孪晶引起的晶界剪切而形成的,从而将自由应变的体积与变形晶粒分开以封闭该区域。因此,提出并讨论了潜在的成核理论,有望丰富不连续的动态再结晶理论。通过位错堆积和重排而不是由应变感应或孪晶引起的晶界剪切形成位错。因此,随后提出并讨论了一种潜在的成核理论,有望丰富不连续的动态再结晶理论。通过位错堆积和重排而不是由应变感应或孪晶引起的晶界剪切形成位错。因此,随后提出并讨论了一种潜在的成核理论,有望丰富不连续的动态再结晶理论。

图形摘要

更新日期:2020-08-27
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