Accession Number : AD0661463

Title :   EMBRITTLEMENT OF TITANIUM IN SEAWATER,

Corporate Author : NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER ANNAPOLIS MD ANNAPOLIS DIV

Personal Author(s) : Cavallaro,J. L.

Report Date : OCT 1967

Pagination or Media Count : 48

Abstract : Sea-water stress- corrosion tests on notched cantilever-beam specimens of Alloy Ti-7Al-2Cb-1Ta (Ti-721) demonstrated that it has a transition in behavior with increasing notch sharpness. Sea-water tests on Alloy Ti-721 indicate that a threshold stress level exists below which stress corrosion does not occur. Sea-water stress corrosion is dependent on the presence of embrittling constituents in the alloy. Alloy chemistry and heat treatment are the most significant factors which control sensitivity. The results of tests made on a series of Ti-Al binary alloys indicate that aluminum in solid solution does not cause stress corrosion, but that it is caused by a finite amount of a coherent Ti3Al. A decrease in aluminum and oxygen contents and the addition of isomorphous beta stabilizers improve the resistance of Ti-Al alloys to sea-water stress corrosion by suppressing the formation of Ti3Al. A stress-sorption cracking mechanism is suggested as a general model for the embrittlement of titanium and titanium alloys in seawater. (Author)

Descriptors :   (*TITANIUM ALLOYS, EMBRITTLEMENT), (*STRESS CORROSION, TITANIUM ALLOYS), SEA WATER, MICROSTRUCTURE, FRACTURE(MECHANICS), RUPTURE, ALUMINUM ALLOYS, NIOBIUM ALLOYS, TANTALUM ALLOYS

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE