Effect of phase morphology on fatigue crack growth behavior of {alpha}-{beta} titanium alloy -- A crack closure rationale

Journal Article · Thu Jan 01 04:00:00 EST 1998 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-998-0177-z· OSTI ID:605827

Saxena, V K ^[1]; Radhakrishnan, V M ^[2]

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1. Defence Metallurgical Research Lab., Hyderabad (India). Fatigue and Fracture Mechanics Group
2. Indian Inst. of Tech., Madras (India). Dept. of Metallurgical Engineering

Effect of phase morphology on fatigue crack growth (FCG) resistance has been investigated in the case of an {alpha}-{beta} titanium alloy. Fatigue crack growth tests with on-line crack closure measurements are performed in the microstructures varying in primary {alpha} (elongated/equiaxed/Widmanstaetten) and matrix {beta} (transformed/metastable) phase morphologies. The microstructures comprising metastable {beta} matrix are observed to yield higher FCG resistance than those for transformed {beta} matrix, irrespective of primary {alpha} phase morphology (equiaxed or elongated). But, the effect of primary {alpha} phase morphology is dictated by the type of {beta} phase (transformed or metastable) matrix. It is observed that in the microstructures with metastable {beta} matrix, the equiaxed primary {alpha} as second phase possesses higher FCG resistance as compared to that of elongated {alpha} morphology. The trend is reversed if the metastable {beta} matrix is replaced by transformed {beta} phase. The fatigue crack path profiles are observed to be highly faceted. The detailed fractographic investigations revealed that tortuosity is introduced as a result of cleavage in {alpha} or {beta} or in both the phases, depending upon the microstructure. The crack closure concept has been invoked to rationalize the phase morphology effects on fatigue crack growth behavior. The roughness-induced and plasticity-induced crack closure appear to be the main mechanisms governing crack growth behavior in {alpha}-{beta} titanium alloy.

• Sponsoring Organization: USDOE
• OSTI ID: 605827
• 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: 1 Vol. 29; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CRACK PROPAGATION
FATIGUE
MICROSTRUCTURE
MOLYBDENUM ALLOYS
SILICON ADDITIONS
TITANIUM BASE ALLOYS
ZIRCONIUM ALLOYS