Work-Hardening Behavior and Evolution of Dislocation-micro-structures in High-nitrogen Bearing Austenitic Steels
Access this Article
Search this Article
Microstructural evolution during deformation at room temperature has been studied by means of transmission electron microscopy to make clear the reason for high work-hardening in high-nitrogen bearing austenitic steels.Tension tests were carried out at room temperature using three SUS316L type steels bearing 0.02 to 0.56 mass% nitrogen and 18Mn–18Cr (retaining ring) type steels bearing 0.51 to 0.84 mass% nitrogen.It is found that both yield strength and work-hardening increase with increasing nitrogen concentration. In high-nitrogen bearing steels, planar dislocation-arrays are formed in the beginning of deformation, frequently showing multi-dipoles. Then, they overlap to make dislocation-walls and at the same time such dislocation-arrays or walls are pinned each other presumably by operation of Lomer–Cottrell reaction at their intersections, The dislocation-wall is expected to play a role similar to grain boundary for further deformation. Microstructure observed in a heavily deformed specimen looks like fine octahedral grid-structure. Thus, dislocation density in a plastically deformed specimen becomes much higher in high-nitrogen bearing steels than in a low-nitrogen bearing steel in which dislocation-cell sttucture is evolved.
- Transactions of the Iron and Steel Institute of Japan
Transactions of the Iron and Steel Institute of Japan 38(5), 474-481, 1998-05-15
The Iron and Steel Institute of Japan