Abstract
An investigation was conducted into the effect of carbide distribution on fracture toughness in the ductile-brittle transition temperature region of an SA 508 steel used for nuclear reactor pressure vessels. Tensile properties and elastic-plastic cleavage fracture toughness were measured in the transition temperature region, and the fracture toughness data were interpreted by using a simple fracture model containing carbide size distribution. This modeling study indicated that the critical nearest-neighbor distance between coarse carbides was an important microstructural factor affecting elastic-plastic fracture toughness, since it satisfied a linear relationship with the critical distance between a crack tip to a cleavage initiation site. These findings suggested that reducing the total number of carbides, particularly the number of M3C carbides larger than the critical size, and homogeneously distributing fine M2C carbides, were useful ways to improve fracture toughness in the transition temperature region.
| Original language | English |
|---|---|
| Pages (from-to) | 4755-4762 |
| Number of pages | 8 |
| Journal | Acta Materialia |
| Volume | 50 |
| Issue number | 19 |
| DOIs | |
| State | Published - Nov 14 2002 |
| Externally published | Yes |
Funding
This work was supported by the Ministry of Science and Technology of Korea and by the Korea Atomic Energy Research Institute. The authors would like to thank Dr. Byung Ju Lee of Pohang University of Science and Technology and Drs. Yong Jun Oh and Jun Hwa Hong of the Korea Atomic Energy Research Institute for their helpful discussion on mechanisms of the carbide formation.
Keywords
- ASTM E1921 standard test method
- Carbide distribution
- SA508 steel
- Transition region