Fatigue and strain hardening of simulated case microstructure in carburized steels

Conference · Thu Dec 31 23:00:00 EST 1987

OSTI ID:7193017

Zaccone, M A; Krauss, G

Tension, compression, and cyclic stress-strain testing were used to evaluate the effect of retained austenite on high and low cycle fatigue of Cr-Mo-Ni alloy steels containing 0.8 pct C to simulate the high carbon case of carburized steels. In low cycle fatigue, cracks develop at austenite grain boundaries early during tensile and cyclic loading. Propagation of these cracks is stabilized in specimens which contain large amounts of retained austenite which dynamically forms martensite by strain-induced transformation. Without sufficient austenite, incipient cracks are not effectively stabilized, and low cycle fatigue life is reduced. In high cycle fatigue, insufficient strain accumulates for the activation of strain-induced martensite, and large amounts of retained austenite are not as beneficial as in low cycle fatigue. Microstructures with 30--35 volume percent retained austenite and fine mixtures of martensite and austenite which contribute to high elastic limits appear to be the most satisfactory for good high and low cycle fatigue resistance. 18 refs., 6 figs., 4 tabs.

• Research Organization: Rockwell International Corp., Golden, CO (USA). Rocky Flats Plant; Colorado School of Mines, Golden (USA). Dept. of Metallurgial Engineering
• DOE Contract Number: AC04-76DP03533
• OSTI ID: 7193017
• Report Number(s): RFP-4246; CONF-8809113-1; ON: DE88014933
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CARBURIZATION
CHEMICAL COMPOSITION
CHROMIUM ALLOYS
CRYSTAL STRUCTURE
FATIGUE
GRAIN BOUNDARIES
HARDENING
HARDNESS
MECHANICAL PROPERTIES
MICROSTRUCTURE
MOLYBDENUM ADDITIONS
MOLYBDENUM ALLOYS
NICKEL ALLOYS
STRAIN HARDENING
SURFACE HARDENING
SURFACE TREATMENTS