Development of a procedure for estimating the high cycle fatigue strength of some high temperature structural alloys
The generation of strain controlled fatigue data, for the standard strain rate of 4 x 10/sup -3/ sec/sup -1/, presents a problem when the cycles to failure exceed 10/sup 5/ because of the prohibitively long test times involved. In an attempt to circumvent this difficulty an evaluation has been made of a test procedure involving a fast cycling rate (40 Hz) and load controlled conditions. The validity of this procedure for extending current fatigue curves from 10/sup 5/ to 10/sup 8/ cycles and beyond, hinges upon the selection of an appropriate effective strain value, since the strain usually changes rapidly during the early stage of fatigue. Results from annealed 2 1/4 Cr-1 Mo, type 304 stainless steel, Incoloy 800H and Hastelloy X, tested over a wide range of temperatures, show that the strain measured N/sub f/2 is a reasonable estimate since it gives an excellent correlation between the strain and load controlled tests in the 10/sup 5/ cycle range where the data overlap. It seems clear that the differences in cycling rate and early stress-strain history for the two tests do not significantly affect the correlation. It may, therefore, be concluded that such load control test procedures may be used as a valid fast way for extending currently available fatigue curves from 10/sup 5/ to 10/sup 8/ cycles, and beyond.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- DOE Contract Number:
- EY-76-C-02-0016
- OSTI ID:
- 5880590
- Report Number(s):
- BNL-NUREG-26085; CONF-791205-5; TRN: 79-021455
- Resource Relation:
- Conference: ASME winter annual meeting, New York, NY, USA, 2 Dec 1979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHROMIUM-MOLYBDENUM STEELS
FATIGUE
HASTELLOY X
INCOLOY 800
STAINLESS STEEL-304
ANNEALING
CHEMICAL COMPOSITION
FAILURES
HEAT EXCHANGERS
PIPE FITTINGS
STRAIN RATE
STRESSES
TESTING
THERMAL CYCLING
YIELD STRENGTH
ALLOYS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
COBALT ALLOYS
CORROSION RESISTANT ALLOYS
HASTELLOYS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HEAT TREATMENTS
INCOLOY ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MECHANICAL PROPERTIES
MOLYBDENUM ALLOYS
NICKEL ALLOYS
STAINLESS STEELS
STEELS
TUNGSTEN ALLOYS
360103* - Metals & Alloys- Mechanical Properties