|About this Abstract
||2010 TMS Annual Meeting & Exhibition
||General Abstracts: Structural Materials Division
||Microstructural and Mechanical Aspects of High Nitrogen Steels at Cryogenic Temperature
||Zurui Zhang, Huabing Li, Zhouhua Jiang, Zhen Li
|On-Site Speaker (Planned)
Charpy V-Notch impact tests of high nitrogen austenitic stainless steels with different nitrogen concentration 0.96, 0.88 and 0.82 (wt. %) from 77K to 293K are processed in this paper. The fracture facets are observed by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to reveal the micro fracture mechanism. With increasing the nitrogen content, the ductile to brittle transition temperature (DBTT) increases. The change of fracture patterns of high nitrogen austenitic stainless steels is dimple→shallow dimple→mixture of quasi-cleavage facets and dimple→cleavage facet. Fracture facets with river patterns or tear ridges, along annealing twin boundary and cross the annealing twin plane are observed in this investigation. Critical dislocation density around crack-tip field <I>ρ</I><SUB>c</SUB>=(6πτ<SUB>p</SUB><SUP>2</SUP>/<I>K</I><SUB>Ic</SUB><SUP>2</SUP>)<SUP>2</SUP> can be used for explaining DBT behavior at cryogenic temperature. Deformation twinning is frequently observed at cryogenic temperature. Crack forms along the coherent twin boundary between twinning and the matrix.
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