Accession Number:

ADA334640

Title:

Fundamental Studies on Ambient Temperature Creep Deformation Behavior of Alpha and Alpha-Beta Titanium Alloys

Descriptive Note:

Final rept.

Corporate Author:

AIR FORCE RESEARCH LAB BOLLING AFB DC

Personal Author(s):

Report Date:

1994-02-15

Pagination or Media Count:

223.0

Abstract:

Systematic studies were undertaken to determine the ambient temperature tensile and creep deformation behavior, including mechanisms, of alpha Ti-Mn, and alpha-beta and beta Ti-Mn and Ti-V alloys. In regard to the a Ti-Mn alloy, it was found that when creep tested at 95 of the 0.2 Yield Stress YS the creep strain of the coarse grained 500 microns material was significantly higher than the fine grained 45 microns material. This effect was found to be due to the scientifically interesting phenomenon of time dependent twinning in coarse grained alpha phase. Such a phenomenon has never been reported before. Based on optical and scanning electron microscopic observations of displacements of the grid lines obtained by electron lithography and transmission electron microscopic observations, it was found that there are strong sliptwin, twinslip and twintwin interactions during creep deformation. The tensile deformation of beta titanium alloys depended on the alloying elements. In the beta Ti-Mn alloy the tensile deformation mechanisms were found to be coarse and wavy slip whereas in the beta Ti-V alloy the deformation mechanisms were found to be coarse and wavy slip as well as twinning. This difference was attributed to the difference in stability of the beta phase. In contrast to the a Ti-Mn alloy the creep deformation in the beta Ti-Mn alloy was found to be negligibly small at a stress level of 95 YS. With respect to alpha-beta titanium alloys, for similar volume percent and morphology of phases, the tensile and creep deformation mechanisms were also found to depend on the alloying elements. In regard to the alpha-beta Ti-Mn alloy, the deformation mechanisms were found to be predominately fine slip in alpha and beta phases and occasional interface sliding.

Subject Categories:

  • Properties of Metals and Alloys

Distribution Statement:

APPROVED FOR PUBLIC RELEASE