期刊
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
卷 78, 期 -, 页码 146-163出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.ijrmhm.2018.09.010
关键词
Crack tip plasticity; Fracture mechanisms; Metallic material; Polycrystalline material; Electron microscopy
资金
- Deutsche Forschungsgemeinschaft [RE3551/4-1, RE3551/2-1]
The aim of this paper is to elucidate the mechanisms controlling the brittle-to-ductile transition (BDT) in pre deformed, textured, polycrystalline body-centred cubic (bcc) metals by the example of cold rolled tungsten (W). For this purpose, five sheets were rolled out from one and the same sintered ingot, by various levels, representing degrees of deformation of 1.8, 2.5, 3.0, 3.4, and 4.1 (this refers to 83.5%, 91.8%, 95.0%, 96.7%, and 98.3% in the technical notation). Toughness tests show that the BDT temperature decreases with increasing degree of deformation from 115 degrees C +/- 15 degrees C (388 K +/- 15 K) down to -65 degrees C +/- 15 degrees C (208 K +/- 15 K). This is an improvement of > 600 K compared with a sintered ingot. In this paper we perform an in-depth analysis of the microstructure of the five sheets mentioned above. This analysis includes the assessment of (i) crystallographic texture, (ii) grain size and (iii) dislocation density. A comparison between microstructural features and experimental data confirms our working hypothesis which states that the BDT is controlled by the glide of screw dislocations and that the transition temperature decreases with decreasing spacing, lambda, of dislocation sources along the crack front. Sources for dislocations may be the intersection points of grain boundaries with the crack front (BDT-temperature-grain-size-relation) or dislocation multiplication processes such as e.g., the expansion of open and closed loops (impact of dislocation density).
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据