Kinetic model for ductile-brittle fracture mode transition behavior

Journal Article · Mon Dec 01 00:00:00 EST 1986 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(86)90142-2· OSTI ID:7009924

Kameda, J

A kinetic model for ductile-brittle fracture mode transition has been developed. In the ductile-brittle transition temperature range, brittle and ductile fracture are characterized in terms of thermally activated growth processes of tensile model I and shear model II cracks, respectively. The thermally activated bond breaking in tension and shear are assumed to proceed under the conditions of local stress relaxation due to dislocation nucleation at the crack tip. The dislocation nucleation rate is considered to be proportional to the strain rate. The tensile and shear fracture probabilities are defined by the product of the jump probability from the stretching to the breaking state of bonds at the crack tip, the active volume, and the density of microcracks or microvoids. The ductile-brittle transition temperature can be determined provided both the tensile and shear fracture probabilities are the same. The ductile-brittle transition temperature is given as a function of the activation energies for bond breaking in tension and shear and dislocation nucleation as well as the microstructural and mechanical parameters. This kinetic model provides a rationale for an experimentally determined linear relationship of the ductile-brittle transition temperature measured by small punch test to that by Charpy V notch tests on temper embrittled steels.

• Research Organization: Ames Lab., Iowa State Univ., Ames, IA (US)
• OSTI ID: 7009924
• Journal Information: Acta Metall.; (United States), Vol. 34:12
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
STEELS
CHEMICAL REACTION KINETICS
DUCTILE-BRITTLE TRANSITIONS
FRACTURE MECHANICS
MATHEMATICAL MODELS
CHARPY TEST
CRACK PROPAGATION
DISLOCATIONS
EMBRITTLEMENT
NUCLEATION
SHEAR
STRESS RELAXATION
STRUCTURAL CHEMICAL ANALYSIS
TEMPERING
TRANSITION TEMPERATURE
ALLOYS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DESTRUCTIVE TESTING
HEAT TREATMENTS
IMPACT TESTS
IRON ALLOYS
IRON BASE ALLOYS
KINETICS
LINE DEFECTS
MATERIALS TESTING
MECHANICAL TESTS
MECHANICS
PHYSICAL PROPERTIES
REACTION KINETICS
RELAXATION
TESTING
THERMODYNAMIC PROPERTIES
360103* - Metals & Alloys- Mechanical Properties
360102 - Metals & Alloys- Structure & Phase Studies