Abstract
The small punch (SP) tests were conducted at 77 K and 4 K using austenitic stainless steels JN 1, JJ 1 and JK 2, which have been recently developed for use as a cryogenic structural material. The tests were applied to the steels aged at 923-1 073 K to investigate changes in their toughness at cryogenic temperature due to thermal aging. The area under the load-deflection curve up to the macro-crack initiation was defined as SP energy to evaluate the fracture toughness of the steels. The experimental results showed that the SP energy of JN 1 decreased monotonously with an increase in aging temperature. On the other hand, the SP energy of JK 2 showed no significant change even after the thermal aging at 923 K and 973 K and decreased after the thermal aging at 1 023 K. Metallogra-phic examination revealed that this difference in decrease of SP energy due to thermal aging was caused by the variation in amount and distribution of grain boundary M23C6 carbides. As a consequence, JN 1 was more susceptible to thermal aging embrittlement than the other steels, and high resistance of JK 2 to embrittlement was attributable to the depression of precipitation and coarsening of grain boundary precipitates.
Original language | English |
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Pages (from-to) | 628-635 |
Number of pages | 8 |
Journal | Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A |
Volume | 70 |
Issue number | 692 |
DOIs | |
Publication status | Published - 2004 |
Externally published | Yes |
Keywords
- Austenitic Stain-less Steel
- Brittle Fracture
- Cryogenic Small Punch Test
- Cryogenic Structural Material
- Fracture Toughness
- Grain Boundary Precipitates
- Structural Reliability
- Thermal Aging Embrittlement
ASJC Scopus subject areas
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering