Fatigue crack propagation thresholds for long and short cracks in Rene 95 nickel-base super alloy

Technical Report · Thu Oct 01 00:00:00 EDT 1981

DOI:https://doi.org/10.2172/5893857· OSTI ID:5893857

McCarver, J. F.; Ritchie, R. O.

A study has been made of the near-threshold fatigue crack propagation behavior of a wroght Ni-base superalloy, Rene 95, with reference to the effect of crack size on the threshold stress intensity ..delta..K/sub 0/ for no detectable crack growth. Measured threshold ..delta..K/sub 0/ values at low load ratios (R = 0.1) for physically short cracks (0.01 to 0.20 mm) were found to be 60% smaller than the corresponding ..delta..K/sub 0/ values for long cracks (approx. 25 mm). However, short crack threshold values at R = 0.1 were found to be similar to long crack thresholds at R = 0.8. Such behavior is rationalized in terms of fatigue crack closure, specifically involving the role of fracture surface roughness from crystallographic crack growth in Ni-base alloys. The large difference observed in threshold values for long and physically-short cracks serves to illustrate the potential problems in applying conventional (long crack) fatigue data to defect-tolerant lifetime predictions for structural components containing small flaws.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5893857
• Report Number(s): LBL-13453; ON: DE82005135
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
RENE 95
FATIGUE
STRESS INTENSITY FACTORS
CRACKS
STRESSES
ALLOYS
ALUMINIUM ALLOYS
CARBON ADDITIONS
CHROMIUM ALLOYS
COBALT ALLOYS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
MATERIALS
MECHANICAL PROPERTIES
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIOBIUM ALLOYS
TITANIUM ALLOYS
TUNGSTEN ALLOYS
ZIRCONIUM ADDITIONS
ZIRCONIUM ALLOYS
360103* - Metals & Alloys- Mechanical Properties