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Burman, Christer
Publications (10 of 28) Show all publications
Sadek, M., Bergström, J., Hallbäck, N. & Burman, C. (2018). 20 kHz 3-point bending fatigue of automotive steels. In: MATEC Web of Conferences: . Paper presented at 12th International Fatigue Congress, FATIGUE 2018, 27 May 2018 through 1 June 2018 (pp. 1-7). EDP Sciences, 165, Article ID 22020.
Open this publication in new window or tab >>20 kHz 3-point bending fatigue of automotive steels
2018 (English)In: MATEC Web of Conferences, EDP Sciences, 2018, Vol. 165, p. 1-7, article id 22020Conference paper, Published paper (Refereed)
Abstract [en]

The 20 kHz load frequency enables fatigue tests for very high cycle fatigue life, 109-1013 cycles, within conveniently short time. In automotive applications, many components are subjected to flexural loading and hence bending fatigue is an important test mode. Ultrasound fatigue test instruments have been used successfully in several assessments of fatigue strength and more commonly in uniaxial loading. Here, a 3-point bending fatigue test rig operating in resonance at 20 kHz load frequency has been designed to test plane specimens at R=0.1 loading. The test rig design and stress calculations are presented. Testing for fatigue strength was conducted using the staircase method with 15 specimens of each steel grade, specimens reaching 108 cycles were considered run-outs giving fatigue strength at 108 cycles. Additional 15 specimens of each grade were tested for S-N curves with the upper limit above 109 cycles. Two different common automotive steels, 38MnSiV5, a micro-alloyed ferritic-pearlitic steel, and 16MnCr5, a carburizing martensitic steel, were tested. The fatigue strengths achieved from the staircase testing are 340 and 419 MPa stress amplitudes for the 38MnSiV5 and 16MnCr5 steels, respectively. The S-N curves of the steels appear to be quite flat in the tested life range 107 - 109.

Place, publisher, year, edition, pages
EDP Sciences, 2018
Keywords
Automotive steels, Carburized steel, Ferritic-pearlitic steel, Three-point bending, VHCF, Binary alloys, Chromium alloys, Fatigue of materials, Fatigue testing, Ferrite, Ferritic steel, Pearlite, Silicon alloys, Stairs, Steel metallography, Steel testing, Pearlitic steels, Three point bending, Manganese alloys
National Category
Materials Engineering
Research subject
Materials Science
Identifiers
urn:nbn:se:kau:diva-68076 (URN)10.1051/matecconf/201816522020 (DOI)000478990600218 ()2-s2.0-85048089977 (Scopus ID)
Conference
12th International Fatigue Congress, FATIGUE 2018, 27 May 2018 through 1 June 2018
Available from: 2018-06-26 Created: 2018-06-26 Last updated: 2019-08-29Bibliographically approved
Sadek, M., Bergström, J., Hallbäck, N. & Burman, C. (2016). Computation of and testing crack growth at 20 kHz load frequency. In: F. Iacoviello, L. Susmel, D. Firrao, G. Ferro, (Ed.), 21ST EUROPEAN CONFERENCE ON FRACTURE, (ECF21): . Paper presented at 21st European Conference on Fracture (ECF), JUN 20-24, 2016, Catania, ITALY (pp. 1164-1172). Elsevier
Open this publication in new window or tab >>Computation of and testing crack growth at 20 kHz load frequency
2016 (English)In: 21ST EUROPEAN CONFERENCE ON FRACTURE, (ECF21) / [ed] F. Iacoviello, L. Susmel, D. Firrao, G. Ferro,, Elsevier, 2016, p. 1164-1172Conference paper, Published paper (Refereed)
Abstract [en]

Fatigue properties are evaluated in a large span of fatigue lives ranging from a few load cycles to more than 1013 load cycles. If the interest is focused on fatigue lives above 10(7) load cycles, we speak of the very high cycle fatigue (VHCF) range. For evaluation of properties in the VHCF range one often needs to use higher load frequencies to be able to perform testing within a reasonable time. Therefore, the influence of load frequency on fatigue strength and fatigue crack growth is an important issue, both from testing and design perspectives. Within an EU-RFCS research project on the frequency influence on high strength steel fatigue properties the present study has been conducted on fatigue crack growth testing to determine threshold values and crack growth material parameters. The testing was analyzed by FE-computation to determine geometry factors for AK-determination. The testing was performed in a 20 kHz ultrasound resonance instrument. In such a system the whole load train needs to be designed to run at a resonance frequency of 20 kHz, and it implies that the specimen needs to be designed and computations performed by dynamic computational methods. As the crack grows the dynamic response of the specimen will change, and hence calculation to obtain the geometry factor is made with a progressing crack length. A uniaxial tensile load at 20 kHz frequency is applied to a single edged notched side-grooved flat specimen. The specimen dimensions are calculated in order to have a resonance frequency of 20 kHz, which is the frequency used for the experiments. Dynamic FEM computation, with a 3D-model and a quarter symmetry was used with one of the symmetry planes parallel to and in the crack growth line. To avoid crack surface interpenetration during the simulations a rigid thin sheet was introduced and used as a counter-face to the crack surface. The solution obtained was then combined with the breathing crack model proposed by Chati et. al. (1997) in order to solve for the irregularities observed when crack surface interpenetration occurs. Finally, the whole load train was considered. Thus, also the computed frequencies were very close to frequencies observed in experiments. The computation of stress intensities was made for varying crack lengths in a series of simulations. The geometry factor relation was determined and used in 20 kHz crack growth testing to control the actual stress intensity at the advancing crack tip. Comparison of computations and experimental results were made.

Place, publisher, year, edition, pages
Elsevier, 2016
Series
Procedia Structural Integrity, ISSN 2452-3216 ; 2
Keywords
Crack growth, High frequency, Dynamic analysis, steel, threshold testing
National Category
Materials Engineering
Research subject
Materials Science
Identifiers
urn:nbn:se:kau:diva-62609 (URN)10.1016/j.prostr.2016.06.149 (DOI)000387976801029 ()
Conference
21st European Conference on Fracture (ECF), JUN 20-24, 2016, Catania, ITALY
Available from: 2017-08-10 Created: 2017-08-10 Last updated: 2019-10-21Bibliographically approved
Tofique, M. W., Bergström, J., Burman, C., Hallbäck, N. & Gåård, A. (2016). Fatigue strength, crack initiation, and localized plastic fatigue damage in VHCF of duplex stainless steels. Steel Research International, 87(7), 899-910
Open this publication in new window or tab >>Fatigue strength, crack initiation, and localized plastic fatigue damage in VHCF of duplex stainless steels
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2016 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 87, no 7, p. 899-910Article in journal (Refereed) Published
Abstract [en]

The fatigue strength of two-duplex stainless steel grades, 2304 SRG and LDX 2101, with austenitic–ferritic microstructure is tested using ultrasonic fatigue testing equipment operating at 20 kHz. The testing is conducted in tension-compression mode with the load ratio R=-1. The fatigue strength is evaluated at 107, 108, and 109 load cycles and the estimates of fatigue strength are higher for the LDX 2101 grade. The fatigue crack initiation mechanisms are analyzed using a scanning electron microscope. The fatigue cracks, in all cases, appear to initiate due to accumulation of plastic fatigue damage at the surface. In the 2304 SRG grade, accumulation of fatigue damage occurs at the external surface of fatigued specimens in the form of extrusions at the grain/phase boundaries and in the form of individual slip lines in the austenite phase. Meanwhile, in the LDX 2101 grade accumulation of plastic fatigue damage in the form of extrusions and intrusions occurs mainly within the ferrite grain. When the crack is microstructurally short, the crack growth appears to be crystallographic in nature and the crack appears to change its direction propagating from one grain into another.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2016
Keywords
duplex stainless steel; ultrasonic fatigue testing; plastic fatigue damage; very high cycle fatigue; crystallographic crack growth
National Category
Metallurgy and Metallic Materials
Research subject
Materials Engineering; Mechanical Engineering
Identifiers
urn:nbn:se:kau:diva-38693 (URN)10.1002/srin.201500263 (DOI)000385610500010 ()
Projects
Very High Cycle Fatigue of Stainless Steels - an unknown life
Funder
Knowledge Foundation
Available from: 2015-11-23 Created: 2015-11-23 Last updated: 2017-12-06Bibliographically approved
Tofique, M. W., Bergström, J. & Burman, C. (2016). Very high cycle fatigue crack initiation mechanisms in different engineering alloys. In: F. Iacoviello, L. Susmel, D. Firrao, G. Ferro, (Ed.), 21ST EUROPEAN CONFERENCE ON FRACTURE, (ECF21): . Paper presented at 21st European Conference on Fracture (ECF), JUN 20-24, 2016, Catania, ITALY (pp. 1181-1190). Elsevier
Open this publication in new window or tab >>Very high cycle fatigue crack initiation mechanisms in different engineering alloys
2016 (English)In: 21ST EUROPEAN CONFERENCE ON FRACTURE, (ECF21) / [ed] F. Iacoviello, L. Susmel, D. Firrao, G. Ferro,, Elsevier, 2016, p. 1181-1190Conference paper, Published paper (Refereed)
Abstract [en]

The fatigue crack initiation mechanisms prevalent in high strength martensitic steel grades, hot rolled plate duplex stainless steels, cold rolled strip duplex stainless steel and a super alloy grade were compared. The fatigue testing of all the grades was conducted in the VHCF regime using an ultrasonic fatigue testing equipment operating at 20 kHz. Scanning electron microscope (SEM) observations of the fracture surfaces revealed the presence of a microstructure controlled initial growth of short fatigue cracks in all the tested grades. Fracture surfaces of the failed specimens of a high strength martensitic steel grade revealed the typical fine granular area (FGA) within the fish-eye area around the internal inclusions. Fatigue crack initiation in the cold rolled strip duplex stainless steel grade occurred at surface defects left over by the cold rolling process of this grade. However, the presence of FGA around the surface crack initiating defect was observed similar to the internal crack initiations in the high strength martensitic steels. By mapping the FGA size development during VHCF loading, as obtained from fracture surfaces, FGA growth results were obtained. A similar study on hot rolled plate duplex stainless steel grades, 2304 SRG and LDX 2101, revealed the presence of an initial crystallographic growth region (CGR) in which crack growth direction is changed by microstructural barriers such as phase and grain boundaries. The early plastic fatigue damage accumulation occurred predominantly in one phase or at the austenite-ferrite phase boundaries. On the other hand, an initial transcrystalline fatigue crack growth was observed in the Ni-based super alloy grade Inconel 718.

Place, publisher, year, edition, pages
Elsevier, 2016
Series
Procedia Structural Integrity, ISSN 2452-3216 ; 2
Keywords
Very high cycle fatigue, ultrasonic fatigue testing, fatigue crack initiation, Fine granular area, duplex stainless steel, martensitic steel, super alloy Inconel 718
National Category
Materials Engineering
Research subject
Materials Science
Identifiers
urn:nbn:se:kau:diva-62608 (URN)10.1016/j.prostr.2016.06.151 (DOI)000387976801031 ()
Conference
21st European Conference on Fracture (ECF), JUN 20-24, 2016, Catania, ITALY
Available from: 2017-08-10 Created: 2017-08-10 Last updated: 2019-10-21Bibliographically approved
Bergstrom, J., Burman, C., Svensson, J., Jansson, A., Ivansson, C., Zhou, J. & Valizadeh, S. (2016). Very High Cycle Fatigue of Two Ductile Iron Grades. Steel Research International, 87(5), 614-621
Open this publication in new window or tab >>Very High Cycle Fatigue of Two Ductile Iron Grades
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2016 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 87, no 5, p. 614-621Article in journal (Refereed) Published
Abstract [en]

Two ductile iron grades, EN-GJS-600-3 a ferritic-pearlitic grade, and EN-GJS-600-10 a silicon strengthened ferritic nodular iron grade, are studied in the very high cycle fatigue range using a 20kHz ultrasonic test equipment. Fatigue strengths and SN-curves are achieved, and fracture surfaces and microstructures are investigated. The ferritic grade with higher ductility displays a lower fatigue strength at 10(8) load cycles than the ferritic-pearlitic grade, 142 and 167MPa, respectively. Examination of fracture surfaces shows that fatigue failures are controlled by micropores in both of the ductile iron grades, while the graphite nodule distributions do not seem to influence the difference in fatigue strengths. Prediction of the fatigue strengths, using a model for ductile iron proposed by Endo and Yanase, indicates a large potential for improvement in particular for the ferritic grade.

Keywords
ductile iron, fatigue, very high cycle fatigue, microstructure
National Category
Materials Engineering
Research subject
Materials Science
Identifiers
urn:nbn:se:kau:diva-42622 (URN)10.1002/srin.201500163 (DOI)000375688300009 ()
Available from: 2016-06-03 Created: 2016-06-03 Last updated: 2019-07-10Bibliographically approved
Tofique, M. W., Bergström, J., Hallbäck, N. & Burman, C. (2014). Fatigue initiation and strength of duplex stainless steel strip specimens in the very high cycle fatigue regime. In: Very high cycle fatigue 6 (VHCF6): . Paper presented at 6th International conference on very high cycle fatigue (VHCF6), Chengdu, China.
Open this publication in new window or tab >>Fatigue initiation and strength of duplex stainless steel strip specimens in the very high cycle fatigue regime
2014 (English)In: Very high cycle fatigue 6 (VHCF6), 2014Conference paper, Published paper (Refereed)
Abstract [en]

Fatigue studies of cold-rolled duplex stainless strip steel were performed in the very high cycle fatigue life region. The duplex austenitic-ferritic microstructure gives this grade a combination of high mechanical strength and high corrosion resistance. Fatigue properties of thin steel strips are particular due to cold rolling introducing a very fine microstructure. Crack initiation and fatigue strength are controlled by steel microstructure and alloying. The initiation and growth of the very short initial fatigue crack in very high cycle fatigue are unclear and subject to different descriptions. Fatigue test data of thin strip specimens at very high fatigue lives are scarce due to testing difficulties. For practical reasons testing must be performed at ultrasound test frequencies which involves fixturing problems. A test setup including the load chain ultrasonic horn, fixture and specimen was designed for resonance with a horse-shoe design of a screw fixture. The design of the horse-shoe fixture and the specimens along with FEM calculation of eigenfrequency are presented. Fatigue testing was performed at 20 kHz in R=-1 conditions up to fatigue life of 107 to 5*109 cycles. Fatigue strength was tested and crack initiation was studied on the fracture surface using FEG-SEM at the initiation site.

Keywords
Very high cycle fatigue, initiation, ultrasonic fatigue testing, strip specimen
National Category
Other Materials Engineering
Research subject
Materials Engineering
Identifiers
urn:nbn:se:kau:diva-34633 (URN)
Conference
6th International conference on very high cycle fatigue (VHCF6), Chengdu, China
Projects
Very high cycle fatigue of stainless steels - an unknown life
Funder
Knowledge Foundation
Available from: 2014-11-21 Created: 2014-11-21 Last updated: 2019-11-28Bibliographically approved
Bergström, J., Kazymyrovych, V., Burman, C. & Ekengren, J. (2011). Test specimen geometry, stress calculation and mean stress in 20kHz testing in the very long fatigue life region. In: Christina Berger, Hans-Jurgen Christ (Ed.), VHCF5 5thInternational Conference on Very High Cycle Fatigue: . Paper presented at VHCF5 5thInternational Conference on Very High Cycle Fatigue (pp. 315-320). Berlin: Deutcher Verband fur Materialforschung und prufung
Open this publication in new window or tab >>Test specimen geometry, stress calculation and mean stress in 20kHz testing in the very long fatigue life region
2011 (English)In: VHCF5 5thInternational Conference on Very High Cycle Fatigue / [ed] Christina Berger, Hans-Jurgen Christ, Berlin: Deutcher Verband fur Materialforschung und prufung , 2011, p. 315-320Conference paper, Oral presentation only (Refereed)
Place, publisher, year, edition, pages
Berlin: Deutcher Verband fur Materialforschung und prufung, 2011
Keywords
very high cycle fatigue, steel, ultrasonic testing, notch effect, mean stress, damping
National Category
Materials Engineering
Research subject
Materials Engineering
Identifiers
urn:nbn:se:kau:diva-16131 (URN)978-3-9814516-0-3 (ISBN)
Conference
VHCF5 5thInternational Conference on Very High Cycle Fatigue
Available from: 2012-12-11 Created: 2012-12-11 Last updated: 2019-12-02Bibliographically approved
Kazymyrovych, V., Bergström, J. & Burman, C. (2010). The Significance of Crack Initiation Stage in Very High Cycle Fatigue of Steels. Steel Research International, 81(4), 308-314
Open this publication in new window or tab >>The Significance of Crack Initiation Stage in Very High Cycle Fatigue of Steels
2010 (English)In: Steel Research International, ISSN 1869-344X, Vol. 81, no 4, p. 308-314Article in journal (Refereed) Published
National Category
Materials Engineering
Identifiers
urn:nbn:se:kau:diva-3362 (URN)10.1002/srin.200900139 (DOI)
Note
At the time of the licentiate thesis from Vitaliy Kazymyrovych, this article was unpublished, and had a status as a manuscript.Available from: 2009-01-23 Created: 2009-01-23 Last updated: 2019-07-10Bibliographically approved
Wang, Y., Bergström, J. & Burman, C. (2009). Thermal fatigue behavior of an iron-based laser sintered material. Materials Science & Engineering: A, 513-514(15 july), 64-71
Open this publication in new window or tab >>Thermal fatigue behavior of an iron-based laser sintered material
2009 (English)In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 513-514, no 15 july, p. 64-71Article in journal (Refereed)
National Category
Materials Engineering Mechanical Engineering
Research subject
Materials Engineering; Mechanical Engineering
Identifiers
urn:nbn:se:kau:diva-9824 (URN)
Available from: 2012-02-08 Created: 2012-02-08 Last updated: 2019-07-10Bibliographically approved
Wang, Y., Bergström, J. & Burman, C. (2009). Thermal fatigue behaviour of an iron-based laser sintered material. Materials Science & Engineering: A, 513-514, 67-71
Open this publication in new window or tab >>Thermal fatigue behaviour of an iron-based laser sintered material
2009 (English)In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 513-514, p. 67-71Article in journal (Refereed) Published
Abstract [en]

Direct metal laser sintering is a rapid manufacturing technique to make intricate and near net-shaped parts. An iron-based laser sintered metal was studied to evaluate its thermal fatigue properties. The test was performed using cylindrical specimens in a high power induction heating system equipped with a laser strain gauge for a contactless surface strain measurement. Initiation of thermal fatigue cracks occurred preferentially at pores and layer interfaces, while propagation of cracks followed along phase boundaries and thin inter-dendritic phases and showed an inter-granular fracture. By using the fundamental Fourier equation for heat conduction, the temperature cycle was modeled and calculated. A thermo elastic ideal plastic model was used to deduce the thermal stress based on surface strain experimentally measured. Finally, the temperature distribution, thermal stresses and mechanical strains were discussed with respect to thermal fatigue damage.

Keywords
Laser sintered metal, Thermal fatigue, Thermal crack initiation and propagation, Thermal stress, Strain
National Category
Materials Engineering
Research subject
Materials Engineering
Identifiers
urn:nbn:se:kau:diva-2019 (URN)10.1016/j.msea.2009.01.053 (DOI)
Available from: 2008-04-17 Created: 2008-04-17 Last updated: 2017-12-07Bibliographically approved
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