Effects of morphology and volume fraction of {alpha}{sub 2} phase on the fatigue crack propagation of a Ti-24Al-11Nb alloy

Journal Article · Mon Dec 01 04:00:00 EST 1997 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-997-0010-0· OSTI ID:590058

Chung, H H ^[1]; Lee, C S; Kim, N J ^[2]

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1. Korea Gas Corp. R and D Center, Kyunggi (Korea, Republic of). LNG Facilities Technology Research Center
2. Pohang Univ. of Science and Technology (Korea, Republic of). Center for Advanced Aerospace Materials

The main objective of the present investigation is to study the individual effect of {alpha}{sub 2} morphology and volume fraction on the fatigue crack propagation behavior of a two-phase ({alpha}{sub 2} + {beta}) Ti-24Al-11Nb alloy. With systematic heat treatments, three distinct morphologies have been obtained: fine colony, fine equiaxed, and fine basket-weave structures. Volume fraction of {alpha}{sub 2} has been varied from 40 to 68 pct by changing the two-phase annealing temperature. It has been shown that the volume fraction and morphology of {alpha}{sub 2} phase have a large influence on the fatigue crack propagation behavior. Fine colony structure shows no variation in the fatigue crack propagation rate with the {alpha}{sub 2} volume fraction. On the other hand, equiaxed and basket-weave structures show the increased resistance to fatigue crack propagation as {alpha}{sub 2} volume fraction decreases. Such increased resistance to crack growth is attributed primarily to tortuous crack paths, which result in a reduction in the crack driving force from crack deflection and roughness-induced crack closure mechanism. Quantitative metallography and experimental crack closure measurements are presented to substantiate such interpretations.

• Sponsoring Organization: USDOE
• OSTI ID: 590058
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 12 Vol. 28; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CRACK PROPAGATION
FATIGUE
HEAT RESISTING ALLOYS
METALLURGICAL EFFECTS
MICROSTRUCTURE
NIOBIUM ALLOYS
TITANIUM BASE ALLOYS