Fracture Energy Characteristics of High-Strength Steels Hardox 450 and Armox 500T Under Impact Bending

The processes of impact loading have been studied for a long time, but there are still many questions, the solution of which is vital for various industries, especially for the military. This paper presents the results of comprehensive experimental studies to determine the energy characteristics of...

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Bibliographic Details
Published in:Strength of materials 2022-11, Vol.54 (6), p.1009-1018
Main Authors: Kravchuk, A. V., Kondryakov, E. O., Kharchenko, V. V.
Format: Article
Language:English
Subjects:
Abrasion resistant steels
Characterization and Evaluation of Materials
Chemistry and Materials Science
Classical Mechanics
Crack initiation
Crack propagation
Data recording
Deformation
Ductile fracture
Ductile-brittle transition
Energy
Energy value
Fracture surfaces
High speed
High strength steels
Impact loads
Impact strength
Materials Science
Nucleation
Propagation
Propagation velocity
Solid Mechanics
Steel, High strength
Velocity
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Summary:The processes of impact loading have been studied for a long time, but there are still many questions, the solution of which is vital for various industries, especially for the military. This paper presents the results of comprehensive experimental studies to determine the energy characteristics of fracture during crack initiation and propagation in Charpy specimens of high-strength steel Hardox 450 and armored steel Armox 500T, cut from sheets in two different directions, during impact bending tests. The tests were carried out on an instrumented vertical tester equipped with a high-speed data recording system in the temperature range from –196 to 300 °C. According to the test results, the load diagrams in the force-time coordinates were obtained. The total deformation and fracture energy and its components, nucleation energy, ductile growth, brittle crack slip, and ductile fracture energy of the specimen were calculated. Using quantitative fractography methods, the specimens’ fracture surfaces were studied, and the specific deformation and fracture energies and their components were determined. It is shown that the direction of cutting of specimens significantly affects the energy characteristics of fracture. On the upper shelf in the specimens cut in the longitudinal direction, the energy value is higher than for the transverse direction for both steels. This difference is approximately 38% for Hardox 450 and almost 118% for Armox 500T. Using a high-speed recording system allows us to determine the average crack propagation velocity and crack velocities in separate areas by comparing the corresponding zones on the load diagram and on the fracture surface of the specimens. The results showed that the average crack propagation velocity for specimens cut in the transverse direction was 10–15% higher than for specimens cut in the longitudinal direction for both steels.
ISSN:0039-2316
1573-9325
DOI:10.1007/s11223-023-00476-w