Shear band structure in ballistically tested bainitic steels

Fielding, L. C. D.; Bhadeshia, H. K. D. H.

doi:10.1179/1743284713y.0000000403

Cited by 4 publications

(5 citation statements)

References 21 publications

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“…Analysis of mechanisms of interaction of armour plate with the core of a different type of projectiles indicate that shear strength, energy of shearing and plastic deformation capacity in shear test are crucial parameters responsible for resistance to perforation [13][14][15][16]. Moreover, during deformation with high strain rate and additionally on impact, adiabatic shear bands (ASBs) can form in the vicinity of the hit points [17][18][19][20]. One problem that has delayed understanding of the shear banding phenomenon is the difficulty of comparing results obtained from the different types of laboratory tests that have been developed, because shear bands will usually nucleate from geometrical defects in preference to microstructural defects [19].…”

Section: Introductionmentioning

confidence: 99%

“…The final fracture path coincides with adiabatic shear bands. The structure of the bands generated by ballistic testing were examined in order to reveal the governing mechanisms [25]. The authors attempt to distinguish in particular whether local reaustenitisation occurs, or if the microstructural change are a reflection simply of intense deformation.…”

Section: Introductionmentioning

confidence: 99%

“…The bands consist of deformed layers in which the original structure becomes mechanically mixed, and resembles a warm-worked microstructure that is still in an unrecrystallised state. Adiabatic shear bands are unlikely to represent phase transformation from retained austenite that forms during adiabatic heating and transforms subsequently into martensite [25].…”

Section: Introductionmentioning

confidence: 99%

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Archives of Metallurgy and Materials

Marcisz¹,

Janiszewski²

2019

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MECHANICAL BEHAVIOUR OF NANOSTRUCTURED BAINITIC STEEL UNDER HIGH STRAIN RATE SHEAR AND COMPRESSION LOADINGThe article presents the results of investigation of ultra-strength nanostructured bainitic steel Fe-0.6%C-1.9%Mn-1.8%Si-1.3%Cr-0.7%Mo (in wt. %) subjected to shear and uniaxial compression under high strain rate loading. Steel of microstructure consisted of carbide-free bainite and carbon enriched retained austenite presents a perfect balance of mechanical properties especially strength to toughness ratio. Two retained austenite morphologies exist which controlled ductility of the steel: film between bainite laths and separated blocks. It is well established that the strain induced transformation of carbon enriched retained austenite to martensite takes place during deformation. Shear localisation has been found to be an important and often dominant deformation and fracture mode in high-strength steels at high strain rate. Deformation tests were carried out using Gleeble simulator and Split Hopkinson Pressure Bar. Shear and compression strength were determined and toughness and crack resistance were assessed. Susceptibility of nanostructured bainitic steel to the formation of adiabatic shear bands (ASBs) and conditions of the bands formation were analysed. The results suggest that the main mechanism of hardening and failure at the dynamic shearing is local retained austenite transformation to high-carbon martensite which preceded ASBs formation. In the area of strain localization retained austenite transformed to fresh martensite and then steel capability to deformation and strengthening decreases.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Archives of Metallurgy and Materials

Marcisz¹,

Janiszewski²

2019

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“…The authors suggested that the bands consist of deformed layers in which the original structure becomes mechanically mixed, and resembles a warm-worked microstructure that is still in an unrecrystallised state. Moreover their observations show that the bands are unlikely to represent phase transformation from austenite that forms during adiabatic heating and transforms subsequently into martensite [12]. Meyers et al analysed the microstructural processes occurring in the different classes of materials deformed at high strain rates.…”

Section: Introductionmentioning

confidence: 99%

“…Fielding and Bhadeshia examined shear bands generated in the carbide-free bainitic steel by ballistic testing [12]. The authors suggested that the bands consist of deformed layers in which the original structure becomes mechanically mixed, and resembles a warm-worked microstructure that is still in an unrecrystallised state.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Changes of the Nanostructured Bainitic Steel Induced by Quasi-Static and Dynamic Deformation

Marcisz

Burian

Rozmus

et al. 2017

Archives of Metallurgy and Materials

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Changes in the microstructure of nanostructured bainitic steel induced by quasi-static and dynamic deformation have been shown in the article. The method of deformation and strain rate have important impact on the microstructure changes especially due to strain localization. Microstructure of nanostructured steel Fe-0.6%C-1.9Mn-1.8Si-1.3Cr-0.7Mo consists of nanometer size carbide-free bainite laths and 20-30% volume fraction of retained austenite. Quasi-static and dynamic (strain rate up to 2×10 2 s -1 ) compression tests were realized using Gleeble simulator. Dynamic deformation at the strain rate up to 9×10 3 s -1 was realized by the Split Hopkinson Pressure Bar method (SHPB). Moreover high energy firing tests of plates made of the nanostructured bainitic steel were carried out to produce dynamically deformed material for investigation. Adiabatic shear bands were found as a result of localization of deformation in dynamic compression tests and in firing tests. Microstructure of the bands was examined and hardness changes in the vicinity of the bands were determined. The TEM examination of the ASBs showed the change from the internal shear band structure to the matrix structure to be gradual. This study clearly resolved that the interior (core) of the band has an extremely fine grained structure with grain diameter ranging from 100 nm to 200 nm. Martensitic twins were found within the grains. No austenite and carbide reflections were detected in the diffraction patterns taken from the core of the band. Hardness of the core of the ASBs for examined variants of isothermal heat treatment was higher about 300 HV referring to steel matrix hardness.

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