Accession Number : ADA189555

Title :   Thermal-Mechanical Fatigue Testing of a Titanium-Aluminide Alloy.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s) : Pernote, John J

PDF Url : ADA189555

Report Date : Dec 1987

Pagination or Media Count : 134

Abstract : There is a continuing need to study the affect of combined thermal and mechanical cycling of materials. This combined cycling is referred to as thermal-mechanical fatigue (TMF) cycling. This study emphasizes the development of a computer-controlled testing system that can mechanically fatigue a specimen under a variety of thermal conditions. These conditions include isothermal temperatures, as well as cyclic temperatures in phase (IP) or out of phase (OP) with the load. To demonstrate the capability of this system, both a 1200 F isothermal load fatigue test and a 600 F to 1200 F IP TMF test were carried out on a titanium-aluminide alloy, Ti3AL. Crack growth relations were established for both cases by plotting the da/dN versus Delta K data on log-log axis and fitting the power law relations, da/dN = C (Delta K) superscript n to the data. The results show the crack growth rate for the isothermal test is slightly high than the growth rate for the IP TMF test at a given value of stress intensity range, Delta K. The crack surfaces were very rough and crack growth was not along the mid-plane of the specimen.

Descriptors :   *FATIGUE TESTS(MECHANICS), *THERMAL FATIGUE, *TITANIUM ALUMINIDE, COMPUTER APPLICATIONS, CRACK PROPAGATION, HEATING, ISOTHERMS, MECHANICAL PROPERTIES, STRESS CONCENTRATION, TEMPERATURE, TEST AND EVALUATION, THERMAL PROPERTIES, THESES, TITANIUM ALLOYS, GRAIN GROWTH, SURFACE ROUGHNESS, THERMAL STRESSES, CYCLIC TESTS

Subject Categories : Properties of Metals and Alloys
      Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE