SYMPOSIA PAPER Published: 01 January 1985
STP36249S

A Metallographic Study of Multiaxial Creep-Fatigue Behavior in 316 Stainless Steel

Source

A metallographic examination of elevated temperature multiaxial fatigue specimens of 316 stainless steel was conducted to identify the type of damage and other microstructural changes that occurred during testing. The work hardening which takes place at the beginning of the test is associated with the development of either a cell or a maze dislocation structure. Two main factors contribute to the flow stress, that is, dislocation and carbide precipitation hardening. Dislocation hardening prevails, but precipitation hardening, which increases with testing time, becomes significant for long hold-time and low-strain range tests. Fatigue cracks are predominantly transgranular. However, intergranular cracks have been observed in hold-time specimens and are related to grain-boundary sliding and grain-boundary precipitation. The fatigue fracture is a three stage process, the initial stage (Stage I) is crystallographic, extending for one to three grains. The intermediate stage (Stage II) is dominated by striations, with the exception of some featureless facets in biaxial specimens. The final stage (Stage III) is a dimple type fracture (tension fracture), beginning at shorter crack lengths in the hold-time and high-strain range specimens. Striation spacing calculations give approximate life estimates in low-cycle fatigue.

Author Information

de los Rios, ER
University of Sheffield, Sheffield, U.K.
Kandil, FA
University of Sheffield, Sheffield, U.K.
Miller, KJ
University of Sheffield, Sheffield, U.K.
Brown, MW
University of Sheffield, Sheffield, U.K.
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Details
Developed by Committee: E08
Pages: 669–687
DOI: 10.1520/STP36249S
ISBN-EB: 978-0-8031-4921-2
ISBN-13: 978-0-8031-0444-0