Effect of environment on fatigue crack propagation behavior of alloy 718 at elevated temperatures

Conference · · TMS (The Metallurgical Society) Paper Selection; (USA)

OSTI ID:5367214

Smith, H H; Michel, D J ^[1]

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1. Naval Research Laboratory, Washington, DC (USA)

The influence of test environment on the fatigue crack propagation rates in alloy 718 was studied at 593 and 649 C in air and in vacuum for wrought material given a conventional duplex age heat treatment. The results show that the fatigue crack propagation rate was lower in vacuum that in air at both temperatures. However, the slope of the experimental relationship between da/dN and {Delta}K was determined to be approximately 2 in air and from 4 to 6 in vacuum at either temperature. Fractographic examination of the test specimens revealed that, in vacuum, the mode of crack propagation was transgranular at both test temperatures for tests conducted with continuous cycling and with a one minute hold time at the maximum cyclic load. For tests conducted in air, the mode of crack propagation was transgranular for the continuous cycling tests and became intergranular with the inclusion of the one minute hold time in the loading cycle. The results are discussed from the viewpoint of the environmental influence on the mechanism of crack propagation in the alloy.

• OSTI ID: 5367214
• Report Number(s): CONF-840909-; CODEN: TMPSA
• Journal Information: TMS (The Metallurgical Society) Paper Selection; (USA), Vol. 56; Conference: TMS-AIME fall meeting, Detroit, MI (USA), 16-20 Sep 1984; ISSN 0197-1689
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
INCONEL 718
CRACK PROPAGATION
AIR
FATIGUE
FRACTURE MECHANICS
HEAT TREATMENTS
LOW PRESSURE
TEMPERATURE DEPENDENCE
ALLOY-NI53CR19FE19NB5MO3
ALLOYS
ALUMINIUM ADDITIONS
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
CORROSION RESISTANT ALLOYS
FLUIDS
GASES
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
INCONEL ALLOYS
IRON ALLOYS
MATERIALS
MECHANICAL PROPERTIES
MECHANICS
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIOBIUM A
360103* - Metals & Alloys- Mechanical Properties