Cavitation and failure during hot forging of Ti-6Al-4V

Journal Article · Sat May 01 00:00:00 EDT 1999 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-999-0289-0· OSTI ID:363997

Semiatin, S L ^[1]; Goetz, R L; Seetharaman, V ^[2]; Shell, E B ^[3]; Ghosh, A K ^[4]

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1. Air Force Research Lab., Wright-Patterson AFB, OH (United States). Materials and Mfg. Directorate
2. UES, Inc., Dayton, OH (United States). Materials and Processes Div.
3. Univ. of Dayton, OH (United States). Dept. of Chemical Engineering
4. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering

The occurrence of cavity initiation and gross, free-surface fracture during subtransus hot pancake forging of Ti-6Al-4V with a transformed beta (colony) microstructure was established. Cavity initiation mechanisms were one of two distinct types. At temperatures approximately 75 C or more below the beta transus temperature (T{sub {beta}}), cavity initiation occurred at relatively low strains in the beta phase lying between the grain-boundary alpha phase and the lamellar colonies. By contrast, at temperatures near the transus (i.e., T {approx} T{sub {beta}} {minus} 25 C), cavity initiation occurred at much larger strains as a result of microfracture of partially-to-fully globularized alpha phase. Finite element method (FEM) modeling of the pancake forging process revealed that secondary tensile stresses were used to correlate both the cavity initiation and the gross free-surface fracture results to previous observations from uniaxial hot tension tests in which identical damage mechanisms had been observed. The tensile work criterion of Cockcroft and Latham (C + L) gave moderately good (quantitative) correlation between the forging and uniaxial tension behaviors. An alternate comparison based on the Rice and Tracey cavity growth model gave reasonable predictions of free-surface fracture but tended to overestimate the incidence of subsurface cavity initiation.

• Sponsoring Organization: USDOE
• OSTI ID: 363997
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 30, Issue 5; Other Information: PBD: May 1999
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
MICROSTRUCTURE
FORGING
TITANIUM BASE ALLOYS
ALUMINIUM ALLOYS
VANADIUM ALLOYS
CAVITIES
FRACTURES
TEMPERATURE DEPENDENCE
MATHEMATICAL MODELS
FINITE ELEMENT METHOD