Dynamic strain-aging effect on fracture toughness of vessel steels

Journal Article · Sun Mar 01 00:00:00 EST 1992 · Nuclear Technology; (United States)

OSTI ID:5325512

Kang, S S; Kim, I S ^[1]

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1. Korea Advanced Inst. of Science and Technology, Dept. of Nuclear Engineering, P.O. Box 150, Cheongryang, Seoul 130-650 (KR)

In this paper the effect of dynamic strain aging (DSA) on fracture is investigated on the quenched and tempered specimens of American Society of Mechanical Engineers (ASME) standard SA508 class 3 nuclear pressure vessel steel. Serrated flow by DSA is observed between 180 and 340{degrees}C at a tensile strain rate of 2.08 {times} 10{sup {minus}4}/s and 1.25 {times} 10{sup {minus}3}/s. The DSA causes a sharp rise in the ultimate tensile strength and a marked decrease in ductility. The DSA range shifts to higher temperatures with increased strain rates. The temperature and strain rate dependence of the onset of serrations yields an activation energy of 16.2 kcal/mol, which suggests that the process is controlled by interstitial diffusion of carbon and nitrogen in ferrite. The J{sub i} value obtained from the direct current potential drop (DCPD) method, for true crack initiation, is lowered by DSA. The drop in J{sub i} at elevated temperatures may be because of the interaction of the interstitial impurities with dislocations at the crack front.

• OSTI ID: 5325512
• Journal Information: Nuclear Technology; (United States), Vol. 97:3; ISSN 0029-5450
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
22 GENERAL STUDIES OF NUCLEAR REACTORS
REACTOR VESSELS
STEELS
FRACTURE PROPERTIES
STRAIN AGING
CARBON
CRACK PROPAGATION
DIFFUSION
FERRITE
INTERSTITIALS
MATERIALS TESTING
NITROGEN
QUENCHING
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
AGING
ALLOYS
CARBON ADDITIONS
CONTAINERS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELEMENTS
IRON ALLOYS
IRON BASE ALLOYS
MECHANICAL PROPERTIES
NONMETALS
POINT DEFECTS
TEMPERATURE RANGE
TESTING
360106* - Metals & Alloys- Radiation Effects
220200 - Nuclear Reactor Technology- Components & Accessories