EFFECT OF PRIOR CREEP ON MECHANICAL PROPERTIES OF AIRCRAFT STRUCTURAL METALS (2024-T86 ALUMINUM AND 17-7 PH STAINLESS. Period covered: February 10, 1956 to January 9, 1957

Technical Report · Wed Feb 20 04:00:00 EST 1957

OSTI ID:4135634

Gluck, J V; Voorhees, H R; Freeman, J W

Tests were performed on two typical aircraft structural sheet alloys in an investigation to study changes in mechanical properties brought about by prior exposure to elevatedtemperature creep conditions. Specimens of 2024-T86 aluminum alloy and 17-7PH(TH 1050) precipitation hardening stainless steel were exposed for 10, 50, and 100 hours at stresses giving up to 3% total deformation at 350 to 500 deg F for the 2024-T86, and 600 to 900 deg F for the 17-7PH. Following the exposures, short-time tensile, compression, or tension-impact tests were run at either room temperature, the temperature of exposure, or both. The results indicate that the short-time strength of structural materials may be either raised or lowered. The changes in properties may approach as much as 50% of the original value. The direction of the change depends on the material, test temperature, creep exposure conditions, and property being measured. From the standpoint of the structures designer the most important changes found are a large drop in strength for 2024-T86 after prior creep exposure for times of from 10 to 100 hours, and an apparent decline in the room temperature ductility of 177PH(TH 1050 condition) after prior creep exposure for 100 hours at temperatures near 600 deg F. (auth) Results of extensive testing indicate that the Charpy method is a simple and economical test for notch sensitivity in high-strength sheet materials provided that the sheet can be embrittled by lowering the temperature and the materials are not less than 40 mils thick. (J.R.D.)

• Research Organization: Michigan. Univ., Ann Arbor. Engineering Research Inst.
• NSA Number: NSA-14-017005
• OSTI ID: 4135634
• Report Number(s): WADC-TR-57-150(Pt.I); AD-15095
• Country of Publication: United States
• Language: English

Related Subjects

AIRCRAFT
ALLOYS
ALUMINUM ALLOYS
CREEP
DEFORMATION
DUCTILITY
ELEMENTS
HARDNESS
HIGH TEMPERATURE
IMPACT SHOCK
LATTICES
MEASURED VALUES
MECHANICAL PROPERTIES
METALS, CERAMICS, AND OTHER MATERIALS
PERFORMANCE
PRECIPITATION
SHEETS
STAINLESS STEELS
STRESSES
TEMPERATURE
TENSILE PROPERTIES
TESTING
VARIATIONS