Initiation of dynamic recrystallization in constant strain rate hot deformation
Initiation of dynamic recrystallization in constant strain rate hot deformation
复制标题
DOI：
10.2355/isijinternational.43.684
复制
发表时间：
2003-01-01
影响因子：
1.8
通讯作者：
Jonas, JJ
中科院分区：
文献类型：
--
作者：
Poliak, EI;Jonas, JJ
在恒应变速率试验中，动态再结晶（DRX）的发生传统上是根据流变曲线中应力峰的存在来确定的。然而，当在这些条件下测试时，并非所有材料都显示出明确的峰。使用普通的碳，铌轴承和321奥氏体不锈钢，它示出的DRX的发病也可以检测到的应变硬化率0对应力a的曲线图中的拐点，或等效地，从拐点在In θ-In σ和In σ-ε曲线，而不管存在的应力峰值的流动曲线。这些观察结果通过金相学得到了证实。基于通过相应的峰值或稳态值对应力和应变进行归一化，引入了流动曲线的统一描述。这种方法表明，在给定的材料中，DRX临界应力与峰值或稳态应力的比率是恒定的，临界应变与相应的应变值的比率也是恒定的。此外，它表明，本技术可以用来建立DRX的发生时，这不能明确地确定从流量曲线的形状。
In constant strain rate tests, the occurrence of dynamic recrystallization (DRX) is traditionally identified from the presence of stress peaks in flow curves. However, not all materials display well-defined peaks when tested under these conditions. Using plain carbon, Nb-bearing and 321 austenitic stainless steels, it is shown that the onset of DRX can also be detected from inflections in plots of the strain hardening rate 0 against stress a or, equivalently, from inflections in In theta-ln sigma and ln sigma-epsilon plots regardless the presence of stress peaks in the flow curves. These observations are verified by means of metallography. A unified description of the flow curve is introduced based on normalization of the stress and strain by the respective peak or steady state values. This approach reveals that, in a given material, the ratio of DRX critical stress to the peak or steady state stress is constant, as is that of the critical strain to the corresponding strain values. Furthermore, it is shown that the present technique can be used to establish the occurrence of DRX when this cannot be determined unambiguously from the shape of the flow curve.