Dynamic recrystallization under warm deformation of a 304 type austenitic stainless steel
Dynamic recrystallization under warm deformation of a 304 type austenitic stainless steel
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DOI：
10.1016/s0921-5093(98)00784-9
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发表时间：
1998-10-31
期刊：
影响因子：
6.4
通讯作者：
Sakai, T
中科院分区：
文献类型：
--
作者：
Belyakov, A;Miura, H;Sakai, T
本文研究了304型奥氏体不锈钢在873-1223 K（0.5- 0.7T·m）温度和10（-4）-10（-1）s（-1）应变速率下的温陆热变形和压缩过程中的组织变化。这两种变形域可以根据其不同的力学和微观组织行为进行分类。在应力低于400 MPa的区域，变形行为为典型的热加工并伴有动态再结晶（DRX）。新晶粒的形成主要通过动态膨胀机制进行，锯齿状晶界和应变诱导位错亚晶界的发展可加速新晶粒的形成。动态晶粒尺寸在2 ~ 7 μ m范围内与峰值流变应力之间的关系可用幂律函数表示，晶粒尺寸指数为-0.72。而在流变应力大于400 MPa的区域，变形行为几乎不依赖于应变速率和温度，因此可以处于非热变形区域。在这种温变形下的应力-应变曲线与仅受动态回复影响的曲线相似。高应变下的显微组织主要表现为在压扁的原始晶粒中形成致密的位错壁，而在这种温变形下也会出现晶界锯齿。结合温变形机制的分析，讨论了这种组织演变的机制。(C)1997年Elsevier Science S.A. All rights reserved.
Warm land hot) deformation of a 304 type austenitic stainless steel was studied in connection with microstructural developments in compression at temperatures of 873-1223 K (0.5-0.7 T-m) under strain rates of 10(-4)-10(-1) s(-1). The two deformation domains can be categorized due to their different mechanical and microstructural behaviors. In the region of how stresses lower than around 400 MPa, the deformation behaviors are typical for hot working accompanied with dynamic recrystallization (DRX). New grains are evolved mainly by dynamic bulging mechanism, which can be accelerated by the development of serrated grain boundaries and strain induced dislocation subboundaries. The relationship between dynamic grain sizes ranged from 2 to 7 mu m and peak flow stress can be expressed by a power law function with a grain size exponent of - 0.72. In contrast, in the region of flow stresses higher than 400 MPa, the deformation behaviors hardly depend on strain rate and temperature and so can be in the region of athermal deformation. The stress-strain curves under such warm deformation are similar to those affected only by dynamic recovery. The microstructures evolved at high strains are mainly characterized by the dense dislocation walls evolved in pancaked original grains, while grain boundary serration also takes place even at such warm deformation. Mechanisms of this microstructural evolution are discussed in combination with analysis of deformation mechanisms operating under warm deformation. (C) 1997 Elsevier Science S.A. All rights reserved.