Influence of crystallographic orientation on the fracture toughness of strongly textured Ti--6Al--4V

Journal Article · Fri Sep 01 04:00:00 EDT 1978 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(78)90157-8· OSTI ID:6556929

Bowen, A W

Fracture toughness values for six test piece orientations in a strongly textured 57-mm thick rolled and annealed Ti--6Al--4V bar have been related to their crystallographic orientations. The K/sub Ic/ values, ranging from 46.3 to 93.3 MPa/m, could be divided into two groups. High values (74.7 to 93.3 MPa/m) were obtained when a crystallographic deformation mode ((1010) <1120> or (1122) <1123> slip) was parallel to the planes of maximum shear stress for plane strain conditions, and the significant fractographic feature for this group was a clearly defined stretch zone. In the second group, where crystallographic deformation modes were not aligned with the planes of maximum shear stress, much lower K/sub Ic/ values were recorded (46.3 to 50.7 MPa/m). In this case there was no stretch zone and, in addition, some test pieces appeared, in effect, to have delaminated in the immediate vicinity of the crack tip. Similar trends were also indicated by the results of Charpy impact tests. The influence of in-plane elastic anisotropy on fracture toughness is discussed, and the importance of test piece geometry highlighted. From the results it could be inferred that high toughness in anisotropic materials is possible only in certain orientations; stretch zone formation and fatigue striation formation are by the same mechanical process; and there will be significantly different critical crack sizes in textured titanium alloy components.

• Research Organization: Royal Aircraft Establishment, Farnborough, Hants, Eng.
• OSTI ID: 6556929
• Journal Information: Acta Metall.; (United States), Journal Name: Acta Metall.; (United States) Vol. 26:9; ISSN AMETA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals &amp; Alloys-- Structure &amp; Phase Studies
360103* -- Metals &amp; Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM ALLOYS
ANISOTROPY
CRACKS
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
ELASTICITY
ELONGATION
FAILURES
FRACTURE PROPERTIES
FRACTURES
MECHANICAL PROPERTIES
ORIENTATION
PHASE TRANSFORMATIONS
TENSILE PROPERTIES
TITANIUM ALLOYS
TITANIUM BASE ALLOYS
VANADIUM ALLOYS