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


Personal Author(s) : Scully, J R ; Gangloff, R P ; Young, L M ; Young, Jr , G A ; Kolman, D G


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a256196.pdf


Report Date : Oct 1992


Pagination or Media Count : 59


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.


Descriptors :   *CRACK PROPAGATION , *HYDROGEN EMBRITTLEMENT , *STRESS CORROSION , *TITANIUM ALLOYS , TEST AND EVALUATION , PROPAGATION , MECHANICAL PROPERTIES , MICROSTRUCTURE , HYDRIDES , AGING(MATERIALS) , DAMAGE , MODELS , CRACKING(FRACTURING) , PRECIPITATES , TRAPS , OCEAN ENVIRONMENTS , BEHAVIOR , TITANIUM , PLATES , HIGH STRENGTH , CRACKS , SITES , FILMS , EMBRITTLEMENT , HYDROGEN , SURFACES , CHEMISTRY


Subject Categories : Metallurgy and Metallography


Distribution Statement : APPROVED FOR PUBLIC RELEASE