Accession Number : AD0727746

Title :   Develop Metal Alloys of Ultra Fine Grain Size with Improved Mechanical Properties.

Descriptive Note : Final rept.,

Corporate Author : FRANKLIN INST RESEARCH LABS PHILADELPHIA PA

Personal Author(s) : Jones,Robin L.

Report Date : MAR 1971

Pagination or Media Count : 65

Abstract : Unalloyed titanium wire and sheet samples, strengthened by the combined effects of interstitial content, grain refinement to approximately 0.5 microns and cold work have been subjected to a range of evaluation tests, in order to assess the extent to which the two-fold increase in room temperature strength attainable by submicron grain refinement and cold work is accompanied by changes in other mechanical properties. It is shown that the tensile strength is enhanced to roughly the same extent over the temperature range 77 - 550K but that the enhancement is lost at higher testing temperatures. Exposure to a temperatures of 673K also slowly degrades subsequent room temperature properties with about 1/2 the strength enhancement lost after 200 hours exposure. Improvements in fatigue properties (particularly high stress/low cycle fatigue) and increased resistance to stress corrosion cracking in an aggressive methanolic environment are found to accompany the strength enhancement. An increase in notch sensitivity (in comparison to conventional grain size unalloyed titanium) observed for the strengthened materials is not considered important since these materials continue to exhibit notch strength ratios of >1 for stress concentration factors up to 5.4. (Author)

Descriptors :   (*TITANIUM, *GRAIN STRUCTURES(METALLURGY)), HEAT TREATMENT, GRAIN SIZE, TENSILE PROPERTIES, FATIGUE(MECHANICS), STRESS CORROSION, WIRE, SHEETS

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE