Critical assessment of the local cleavage stress [sigma]*[sub f] in notch specimens of C-Mn steel

Journal Article · Tue Jun 01 04:00:00 EDT 1993 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

DOI:https://doi.org/10.1007/BF02668206· OSTI ID:6353951

Yan, C; Chen, J H; Wang, Z ^[1]; Sun, J ^[2]

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1. Gansu Univ. of Technology, Lanzhou (China). Welding Research Institute
2. Xian Jiaotong Univ. (China). Department of Materials Science and Engineering

An elastic-plastic finite element method (FEM) was used to calculate the stress and strain distributions ahead of notches with various root radii in a bending specimen of C-Mn steel with grain sizes of 10 and 30 [mu]m. By accurately measuring the distance of the cleavage initiation site from the root of the notch, the local cleavage stress [sigma]*[sub f] was measured. When the notch radius increased from 0.25 to 1.0 mm, the distribution of high stress had a definite variation but the [sigma]*[sub f] remained relatively constant. In notch specimens with different root radii, the critical fracture event is identical, i.e., propagation of a ferrite grain-sized crack into the neighboring matrix. Therefore, the [sigma]*[sub f] is mainly determined by the length of the critical microcrack, here, the size of ferrite grain instead of the high stress volume for finding an eligible brittle particle. The critical strain for initiating a crack was about 1 pct. The cleavage site ahead of a notch was related to the relative distributions of stress and strain and the random distribution of the weakest grains. The higher fracture load of the fine-grain material can be attributed to its higher value of [sigma]*[sub f]/[sigma][sub 0] as compared with the coarse-grain. The [sigma]*[sub f]/[sigma][sub 0] is a potential engineering parameter for toughness assessment in notch specimens.

• OSTI ID: 6353951
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Journal Name: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States) Vol. 24A:6; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CALCULATION METHODS
CARBON ADDITIONS
CARBON STEELS
CLEAVAGE
CRACK PROPAGATION
ELASTICITY
FERRITE
FINITE ELEMENT METHOD
FRACTURE PROPERTIES
GRAIN SIZE
IRON ALLOYS
IRON BASE ALLOYS
MANGANESE ALLOYS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NOTCHES
NUMERICAL SOLUTION
PLASTICITY
SIZE
STEELS
STRESS ANALYSIS
TENSILE PROPERTIES