Accession Number : AD0767307

Title :   Sustained-Load Cracking of Titanium: A Survey of 6Al-4V Alloys.

Descriptive Note : Final rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Yoder,G. R. ; Griffis,C. A. ; Crooker,T. W.

Report Date : 24 AUG 1973

Pagination or Media Count : 25

Abstract : This survey reveals that degradation in load-carrying capacity owing to sustained-load cracking (SLC) is widespread and serious in alloys of the Ti-6Al-4V family. Each of eight different one inch (2.5-cm) thick plates tested in air at room temperature exhibited the effect, with degradations ranging up to 35%. The amount of degradation does not seem to correlate with differences in hydrogen content, processing variables, or strength and toughness levels; however, the susceptibility to SLC is orientation dependent. Invalidity of several of the rising-load fracture toughness values, with respect to plane-strain criteria, makes quantitative comparison of degradations uncertain. However, the threshold stress-intensity factor below which SLC failures will not occur, KIt, clearly represents a more conservative fracture-safe design parameter than the plane-strain fracture toughness KIc, which cannot account for insidious time-delayed failures owing to SLC. (Author)

Descriptors :   (*TITANIUM ALLOYS, *FRACTURE(MECHANICS)), CRACK PROPAGATION, LOADS(FORCES), ANISOTROPY, HYDROGEN

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE