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U.S. Department of Energy
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EFFECT OF STATIC PRESTRAIN ON THE PROT-FATIGUE PROPERTIES OF UNNOTCHED AND NOTCHED MATERIALS AT ROOM AND ELEVATED TEMPERATURE. Period covered: January 1956 to December 1957

Technical Report ·
OSTI ID:4293541

A study was conducted on the effect of short time and creep prestrain on the fatigue properties of unnotched and notched specimens of the alloys 7075-T6 extruded, 2024-T4 extruded, 16-25-6 hot-cold-worked, and S-816 solution treated and aged. Fatigue properties were determined using a Prot-type test with a single loading rate of 0.01 psi per cycle. The unnotched and notched specimens were prestrained at test temperature and then immediately subjected to a Prot- type fatigue test at the same temperature and in the same testing machine. The test temperature for the short time prestrain and creep prestrain, respectively, were 75 and 300 deg F for 7075-T6, 300 and 5OO deg F for 2024-T4, 1200 deg F for 16-25-6, and 1500 deg F for 8-816. Short-time prestrains up to 10% were applied. Stresses used for the creep prestrains corresponded to those which produced rupture in 100 to 200 hours at test temperature. The main factors influencing the Prot-failure stress were residual stresses, metallurgical reactions, and cracks produced by prestraining. Strain hardening and relaxation of residual stress appeared to be of secondary importance for the materials and range of testing variables investigated. (auth)

Research Organization:
Minnesota. Univ., Minneapolis
NSA Number:
NSA-13-008997
OSTI ID:
4293541
Report Number(s):
WADC-TR-58-214; AD-155738; PB-
Country of Publication:
United States
Language:
English