Further study on the mechanism of cleavage fracture at low temperatures

Journal Article · Sat Jan 01 04:00:00 EST 1994 · Acta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-7151(94)90067-1· OSTI ID:143910

Chen, J H; Yan, C ^[1]; Sun, J ^[2]

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1. Univ. of Technology, Lanzhou (China). Welding Research Inst.
2. Jiaotong Univ., Xian (China). Inst. for Strength of Metal

On the basis of finite element analyses of stress and strain ahead of a precrack tip and metallographic observation, the RKR model for cleavage fracture was reviewed, and the following conclusions were made: the critical event for cleavage fracture of a precracked specimen of C-Mn steel, tested around -- 100 C, is the propagation of a second phase particle-sized crack into the neighboring ferrite grain; there is a minimum distance X{sub min} from the precrack tip to the initiation position of cleavage fracture. This X{sub min} is not determined by the criterion of the principal stress {sigma}{sub yy} exceeding the cleavage stress {sigma}{sub f}, or the probability assuring the presence of an eligible cracked particle for which the criterion is satisfied. The X{sub min} has a definite physical meaning at which triaxiality {sigma}{sub m}/{bar {sigma}} reaches the critical value {Tc}, to prevent a produced crack nucleus from blunting. From the X{sub min} and the measured cleavage stress {sigma}{sub f}, the lower boundary value of K{sub 1C} in the lower shelf of the transition curve could be calculated. A physical model for the statistical description of the scattering of the measured value of K{sub 1C} from its lower boundary value is suggested.

• OSTI ID: 143910
• Journal Information: Acta Metallurgica et Materialia, Journal Name: Acta Metallurgica et Materialia Journal Issue: 1 Vol. 42; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRACK PROPAGATION
DEFECTS
FRACTURE PROPERTIES
MANGANESE STEELS
MICROSTRUCTURE