Accession Number:

ADA256196

Title:

Environmentally Assisted Cracking of High Strength Beta Titanium Alloys

Descriptive Note:

Annual rept. 15 Sep 1991-15 Sep 1992

Corporate Author:

VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING

Report Date:

1992-10-01

Pagination or Media Count:

59.0

Abstract:

The objective of this research is to define the conditions under which high strength beta-titanium alloys are resistant to environmentally assisted cracking EAC in marine environments. Our goals are to 1 characterize environment enhanced subcritical crack propagation behavior for metallurgical, chemical and mechanical loading conditions that could destabilize crack tip passive films to promote local dissolution and hydrogen uptake, 2 test the hydrogen embrittlement mechanism for EAC, and 3 develop a mechanism- based predictive model of EAC by integrating occluded crack chemistry, surface repassivation, hydrogen uptake and segregation at trap sites, and crack tip process zone micromechanics and damage. The behavior of two peak aged beta alloys, Beta 21S Ti-15Mo-2.7Nb-3AI by wt and sigma sub ys 1380 MPa and Ti- 15-3 Ti-15V-3Cr-3AI-3Sn sigma sub ys 1315 MPa plate, was emphasized during this reporting period. Three papers were published each is summarized as follows. Titanium alloys, Hydrogen embrittlement, Mechanical properties, Intergranular cracking, Transgranular cracking, Microstructure, Alpha precipitates, Beta phase, Hydrides, Passive film, Beta titanium alloys, Fracture threshold.

Subject Categories:

  • Metallurgy and Metallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE