Accession Number:

ADA076948

Title:

Some Aspects of Fatigue Crack Closure in Titanium Alloys.

Descriptive Note:

Final scientific rept. 1 Jan-30 Jun 79,

Corporate Author:

BIRMINGHAM UNIV (ENGLAND) DEPT OF PHYSICAL METALLURGY AND SCIENCE OF MATERIALS

Personal Author(s):

• Beevers,C. J.

Report Date:

1979-08-31

Pagination or Media Count:

43.0

Abstract:

Fatigue crack growth at intermediate rates and R 0.1 has been measured in compact tension specimens of the alloys Ti-6Al-4V and Ti-6Al-5Zr-0.5Mo-0.25Si. Crack length was determined from the output of a crack mouth displacement gauge and by using a d.c. potential drop technique. The incidence of crack closure was examined during fatigue by using both of the above methods COD was found to be more reliable for closure measurement than potential drop. In contrast to the fine microstructured Ti-6Al-4V, the coarse Ti-6Al-5Zr-0.5Mo-0.25Si showed substantial load transfer across the crack faces during fatigue and this was attributed to a non-closure mechanism. Low crack growth rates in the latter alloy were rationalized in terms of an effective delta K. Marked reductions in growth rate produced by variable amplitude loading ot Ti-6Al-4V could not be explained by crack closure. Author

Descriptors:

• *GROWTH(GENERAL)
• *CRACKS
• *CRACK PROPAGATION
• *FATIGUE(MECHANICS)
• *TITANIUM ALLOYS
• MEASUREMENT
• MICROSTRUCTURE
• LOADS(FORCES)
• RATES
• REDUCTION
• LENGTH
• TRANSFER
• AMPLITUDE
• GAGES
• FACINGS

Subject Categories:

• Properties of Metals and Alloys
• Test Facilities, Equipment and Methods
• Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE