On the controlling parameters for fatigue-crack threshold at low homologous temperatures

Journal Article · Sat Jan 01 04:00:00 EST 1983 · Scr. Metall.; (United States)

DOI:https://doi.org/10.1016/0036-9748(83)90080-7· OSTI ID:5581604

Yu, W; Gerberich, W W

Fatigue crack propagation phenomena near the threshold stress intensity level ..delta..K /SUB TH/ , has been a vigorously studied topic in recent years. Near threshold the crack propagates rather slowly, thus giving enough time for various physical and chemical reactions to take place. Room air, which is the most commonly encountered environment, can still supply various ingredients such as oxygen, water vapor (and thus hydrogen) to support these reactions. Much effort had been directed toward the environmental aspects of near threshold fatigue crack growth. By conducting tests under vacuum, Suresh and coworkers found that the crack propagation rate in a 2-1/4 Cr-1Mo steel was higher in vacuum than in air. An oxide induced closure, which served to reduce the effective stress intensity at the crack tip, seems to furnish a good explanation. Neumann and coworkers proposed that during the fatigue process, extrusion-intrusion pairs can develop as a consequence of reversed slip around the crack tip when the crack was propagated near threshold stress intensity. Beevers demonstrated that fatigue fracture surfaces contact each other during unloading even under tension-tension cycling. Kanninen and Atkinson also reached the conclusion that the compressive stress acting at the crack tip due to residual plasticity can induce closure. Microstructural effects have also been cited as important factors in near threshold crack growth. It is generally accepted that coarser grains have a beneficial effect on the resistance to the near threshold crack propagation.

• Research Organization: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455
• DOE Contract Number: AC02-79ER10433
• OSTI ID: 5581604
• Journal Information: Scr. Metall.; (United States), Journal Name: Scr. Metall.; (United States) Vol. 17:1; ISSN SCRMB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-MOLYBDENUM STEELS
CORROSION
CRACK PROPAGATION
CRYSTAL STRUCTURE
DEFORMATION
ELEMENTS
FATIGUE
FLUIDS
FRACTURE MECHANICS
GASES
GRAIN GROWTH
INTERGRANULAR CORROSION
IRON ALLOYS
IRON BASE ALLOYS
MECHANICAL PROPERTIES
MECHANICS
MICROSTRUCTURE
NONMETALS
OXYGEN
PARAMETRIC ANALYSIS
PHASE TRANSFORMATIONS
PLASTICITY
RESOLUTION
STEELS
STRAIN RATE
STRESS ANALYSIS
TEMPERATURE DEPENDENCE
TEMPERATURE EFFECTS
TIME RESOLUTION
TIMING PROPERTIES
VAPORS
WATER VAPOR