Crack initiation at high loading rates applying the four-point bending split Hopkinson pressure bar technique

Henschel, Sebastian; Krüger, Lutz

doi:10.1007/s10704-016-0127-5

Cited by 9 publications

(7 citation statements)

References 35 publications

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“…Investigations of Klepaczko [8,9] showed that there is a minimum plane-strain fracture toughness atK ≈ 10 4 MPa √ m s −1 for a C45 steel. Own studies [10,11] do not show a minimum of the toughness at intermediate loading rates of 10 4 to 10 5 MPa √ m s −1 . Furthermore, pronounced scatter is observed at high loading rates of 2 • 10 6 MPa √ m s −1 .…”

Section: Introductionmentioning

confidence: 83%

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Temperature dependent crack initiation of 42CrMo4 steel at high loading rates

Henschel

Krüger

2018

EPJ Web Conf.

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Dynamic crack initiation with crack tip loading rates K˙ of approximately 2 ‧ 106 MPa√ms− in high-strength 42CrMo4 steel was investigated. To this end, a recently developed split Hopkinson pressure bar with four-point bending was utilized. V-notched and precracked Charpy specimens were tested. The tests were performed at temperatures of –40 °C and 20 °C. The loading of the specimen was determined by analyzing the strain in the incident and transmission bars. Furthermore, strain gauges at the specimen’s surface were applied to measure the crack tip loading. High-speed photography complemented the analysis of the specimens loading and the detection of the crack initiation. Fracture surface analysis by means of scanning electron microscopy enabled the measurement of the fracture surface topography and, consequently, stretch zone height and width. Hence, the macroscopically measured dynamic crack initiation toughness was correlated with the toughness at microscopic scale. It was observed that the resistance against dynamic crack initiation decreased with decreasing temperature. Microscopically, a decrease in toughness was analogously observed. Non-metallic inclusions resulted in crack path deflection with localized shear zones. After a small stable crack extension, cleavage fracture was observed.

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Section: Introductionmentioning

confidence: 83%

“…The drop was caused by the increasing compliance with increasing crack length. A detailed discussion was presented in previous studies [11,18].…”

Section: Fractographymentioning

confidence: 99%

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Temperature dependent crack initiation of 42CrMo4 steel at high loading rates

Henschel

Krüger

2018

EPJ Web Conf.

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“…Among other grades, high‐strength steels are more sensitive to the presence of NMIs in terms of crack initiation . The stress‐raising effect acts under cyclic as well as quasi‐static and dynamic loading conditions …”

Section: Introductionmentioning

confidence: 99%

“…[2] The stress-raising effect acts under cyclic as well as quasi-static and dynamic loading conditions. [3][4][5] According to Kamal and Rahman, at least half of all mechanical failures are caused by fatigue. [6] Most of metallic parts undergo cyclic loading during their utilization.…”

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confidence: 99%

Effect of Filter Functional Coating on Detrimental Nonmetallic Inclusions in 42CrMo4 Steel and Its Resulting Mechanical Properties

et al. 2019

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Carbon‐bonded ceramic foam filters with different functional coatings are immersed in a 42CrMo4 steel melt within a steel casting simulator. The solidified steel is analyzed with respect to the size distribution and the chemical composition of the remaining nonmetallic inclusions (NMI). Cyclic loading and quasi‐static tests are performed to determine the fatigue limit, the strength, deformability, and toughness of the steel after filter immersion. The immersion of filter with calcium hexaluminate (CA6) coating significantly reduces the population of small (4–20 μm) NMIs. This leads to an increased deformability and, thus, ability for energy dissipation during deformation. However, the maximum size of NMIs is increased from 100 to 150 μm, which results in fatigue limit reduction, despite the decrease in NMIs total density. The majority of inclusions are found to be pure alumina. Large (up to 150 μm) plate‐like alumina inclusions introduce most of the detrimental effects on cyclic strength, whereas significant effect on quasi‐static strength is not found.

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Effect of Non-metallic Inclusions on the Temperature and Strain-Rate-Dependent Strength, Deformation and Toughness Behavior of High-Strength Quenched and Tempered Steel

Koch,

Henschel,

Krüger

2024

Springer Series in Materials Science

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This chapter presents results of investigations on the strength, deformation and toughness behavior of quenched and tempered 42CrMo4 steel. Intentional impurification and, afterwards, filtration by functionalized ceramic foam filters were applied in order to process cast steels with different amounts and distributions of non-metallic inclusions. As references, a hot-rolled steel batch and spark-plasma sintered materials were studied. The investigations focused on the loading rate and temperature effects. Both, tensile and fracture mechanics tests, were performed in order to investigate the damaging behavior due to non-metallic inclusions remaining after the melt processing of the steel. A further goal was to predict the fracture toughness of the material based on the combination of microstructural information on the inclusion distribution and the strain rate and temperature-dependent strength and deformation behavior. It was shown that the damaging effect of non-metallic inclusions, in particular agglomerated inclusions properties, is localized which leads to relatively low strain to fracture and fracture toughness, but also to crack path deflection. Furthermore, it could be observed that the small interparticle distances within agglomerated non-metallic inclusions determine the fracture toughness behavior of the materials. By analyzing the acoustic emissions, the onset of crack growth as well as the size of the plastic zone at the crack tip could be estimated.

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Crack initiation at high loading rates applying the four-point bending split Hopkinson pressure bar technique

Cited by 9 publications

References 35 publications

Temperature dependent crack initiation of 42CrMo4 steel at high loading rates

Temperature dependent crack initiation of 42CrMo4 steel at high loading rates

Effect of Filter Functional Coating on Detrimental Nonmetallic Inclusions in 42CrMo4 Steel and Its Resulting Mechanical Properties

Effect of Non-metallic Inclusions on the Temperature and Strain-Rate-Dependent Strength, Deformation and Toughness Behavior of High-Strength Quenched and Tempered Steel

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