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Deng, L., Pelcastre, L., Hardell, J., Prakash, B. & Oldenburg, M. (2018). Experimental Evaluation of Galling Under Press Hardening Conditions. Tribology letters, 66(3), Article ID 93.
Open this publication in new window or tab >>Experimental Evaluation of Galling Under Press Hardening Conditions
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2018 (English)In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 66, no 3, article id 93Article in journal (Refereed) Published
Abstract [en]

Severe adhesion, also referred to as galling, is a critical problem in press hardening, especially in stamping tools used for hot forming of Al–Si-coated ultra-high strength steel. Galling is known to develop rapidly on the tool surface and it negatively affects the quality of the formed products. Earlier research on this topic has focused on the galling initiation. However, studies on the galling development during extended sliding and the corresponding quantitative measurement still lack depth. In the present study, a tribological test is established to study the galling development under press hardening conditions. The tribological test set-up aims to simulate extended sliding between the Al–Si-coated boron steels and the tool die material. The contact conditions in the interface are studied by a numerical model of the tribological test. The friction coefficients and material transfer are discussed taking into account the variation of the different test conditions. Using the results from the tribological tests, the galling simulation is performed in the numerical model. A geometry-updated sample based on the galling (transferred material build-up) height is simulated and the consequent pressure fluctuation is obtained in the numerical model. This contributes to the explanation of the severe transferred material accumulation during the test.

Place, publisher, year, edition, pages
Springer, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Applied Mechanics
Research subject
Machine Elements; Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-69943 (URN)10.1007/s11249-018-1023-0 (DOI)
Note

Validerad;2018;Nivå 2;2018-06-27 (andbra)

Available from: 2018-06-27 Created: 2018-06-27 Last updated: 2018-06-27Bibliographically approved
Burkhart, C., Johansson, J., Uukonsari, J. & Prakash, B. (2018). Performance of lubricating oils for wind turbine gear boxes and bearings. Paper presented at 17th Nordic Symposium on Tribology - NORDTRIB 2016, Hämeenlinna, Finland, 14th - 17th June 2016. Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, 232(1), 62-72
Open this publication in new window or tab >>Performance of lubricating oils for wind turbine gear boxes and bearings
2018 (English)In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 232, no 1, p. 62-72Article in journal (Refereed) Published
Abstract [en]

In this study, the friction and wear properties of six different new and used wind turbine gear oils (ISO VG 320), with different base oil formulations and additives packages, were investigated. For that purpose, a four-ball tribometer and an Optimol SRV were used. Moreover, the lubricants extreme pressure properties were also evaluated, using the same four-ball tribometer. The study also includes a characterization of the lubricants. The main objective was to compare the new and used gear oils in order to identify performance differences and predict oil change intervals. The results indicate that a use of 3 to 4 years is within the lifetime of the lubricant.

Place, publisher, year, edition, pages
Sage Publications, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-66356 (URN)10.1177/1350650117739764 (DOI)000419852700007 ()2-s2.0-85040449368 (Scopus ID)
Conference
17th Nordic Symposium on Tribology - NORDTRIB 2016, Hämeenlinna, Finland, 14th - 17th June 2016
Note

Konferensartikel i tidskrift

Available from: 2017-11-02 Created: 2017-11-02 Last updated: 2018-01-25Bibliographically approved
Gebretsadik, D., Hardell, J. & Prakash, B. (2018). Seizure behaviour of Pb-free engine bearing materials under dry condition. Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, 232(2), 106-116
Open this publication in new window or tab >>Seizure behaviour of Pb-free engine bearing materials under dry condition
2018 (English)In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 232, no 2, p. 106-116Article in journal (Refereed) Published
Abstract [en]

Due to new environmental regulations, Pb-free engine bearing materials are becoming more common and there is a need for studying their tribological performance. Under severe operating conditions, failure due to seizure can occur in engine bearings. In this work, seizure behaviour of different multi-layered engine bearing materials has been studied by using a block-on-ring test setup under dry condition. These materials included Al–Sn-based lining with no overlay, bronze lining with polyamide-imide-based overlay containing MoS2 and graphite, bronze lining with two overlays of Al–Sn-based and polyamide-imide-based material, bronze-based lining with Sn-based overlay and bismuth (Bi)-containing bronze with Sn-based overlay. The tests were performed by gradually increasing the load at a specific time interval and in a stepwise manner and at a constant speed under unidirectional dry sliding conditions. The test materials, counter surfaces and the wear debris were analysed using SEM with a view to understand the seizure mechanisms. Bronze-based lining with a polyamide-imide-based overlay containing MoS2 and graphite does not exhibit seizure up to a load of 475 N. For Al–Sn-based lining without overlay, seizure occurs at a relatively lower load of 125 N. The Al–Sn-based lining with no overlay shows higher friction and the polyamide-imide-based overlay containing MoS2 and graphite shows lower friction during the seizure test. In most cases, there is material transfer onto the test ring counter surface. Material transfer onto the counter surface either due to severe adhesion or wear debris adhered and smeared on it. Al–Sn-based lining and an exposed Al–Sn-based overlay show severe adhesion that causes seizure. On the other hand, exposed Pb containing lining and Bi containing lining seize due to mechanical interlocking caused by the adhered wear debris on both surfaces.

Place, publisher, year, edition, pages
Sage Publications, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-63437 (URN)10.1177/1350650117706641 (DOI)000424781600002 ()2-s2.0-85042873912 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-02-12 (svasva)

Available from: 2017-05-18 Created: 2017-05-18 Last updated: 2018-03-16Bibliographically approved
Mozgovoy, S., Hardell, J., Deng, L., Oldenburg, M. & Prakash, B. (2018). Tribological Behavior of Tool Steel under Press Hardening Conditions Using Simulative Tests. Journal of tribology, 140(1), Article ID 011606.
Open this publication in new window or tab >>Tribological Behavior of Tool Steel under Press Hardening Conditions Using Simulative Tests
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2018 (English)In: Journal of tribology, ISSN 0742-4787, E-ISSN 1528-8897, Vol. 140, no 1, article id 011606Article in journal (Refereed) Published
Abstract [en]

Press hardening is employed in the automotive industry to produce advanced high-strength steel components for safety and structural applications. This hot forming process depends on friction as it controls the deformation of the sheet. However, friction is also associated with wear of the forming tools. Tool wear is a critical issue when it comes to the dimensional accuracy of the produced components and it reduces the service life of the tool. It is therefore desirable to enhance the durability of the tools by studying the influence of high contact pressures, cyclic thermal loading, and repetitive mechanical loading on tool wear. This is difficult to achieve in conventional tribological testing devices. Therefore, the tribological behavior of tool-workpiece material pairs at elevated temperatures was studied in a newly developed experimental setup simulating the conditions prevalent during interaction of the hot sheet with the tool surface. Uncoated 22MnB5 steel and aluminum-silicon (Al-Si)-coated 22MnB5 steel were tested at 750 °C and 920 °C, respectively. It was found that higher loads led to lower and more stable friction coefficients independent of sliding velocity or surface material. The influence of sliding velocity on the coefficient of friction was only marginal. In the case of Al-Si-coated 22MnB5, the friction coefficient was generally higher and unstable due to transfer of Al-Si coating material to the tool. Adhesion was the main wear mechanism in the case of uncoated 22MnB5

Place, publisher, year, edition, pages
ASME Press, 2018
National Category
Applied Mechanics Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Solid Mechanics; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-65268 (URN)10.1115/1.4036924 (DOI)000415376300018 ()2-s2.0-85027285991 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-08-28 (andbra)

Available from: 2017-08-23 Created: 2017-08-23 Last updated: 2018-01-13Bibliographically approved
Torres, H., Vuchkov, T., Rodríguez Ripoll, M. & Prakash, B. (2018). Tribological behaviour of MoS2-based self-lubricating laser cladding for use in high temperature applications. Tribology International, 126, 153-165
Open this publication in new window or tab >>Tribological behaviour of MoS2-based self-lubricating laser cladding for use in high temperature applications
2018 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 126, p. 153-165Article in journal (Refereed) Published
Abstract [en]

Many high temperature (HT) forming processes require the use of solid lubricants in order to control friction and reduce wear. In an attempt to eliminate the need for solid lubrication in high temperature sliding applications, nickel-based self-lubricating coatings with the addition of Ag and MoS2 were prepared by means of laser cladding on stainless steel substrates.

The behaviour of the resulting laser claddings was thoroughly evaluated up to 600 °C, including the oxidation behaviour and reciprocating tribotesting using different counter body geometries (ball and flat pin). The self-lubricating coatings showed lower friction than the unmodified reference alloy at all tested temperatures, in addition to a significant microstructural stability after prolonged exposure at high temperatures. The addition of solid lubricants to the claddings was also found to be beneficial in terms of the counter body wear at HT, as no material loss could be measured for the bearing balls after testing at 600 °C against the self-lubricating claddings, despite the significant softening experienced by AISI 52100 bearing steel at HT.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-68937 (URN)10.1016/j.triboint.2018.05.015 (DOI)2-s2.0-85047212660 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-05-28 (andbra)

Available from: 2018-05-28 Created: 2018-05-28 Last updated: 2018-05-31Bibliographically approved
Torres, H., Rodríguez Ripolla, M. & Prakash, B. (2018). Tribological behaviour of self-lubricating materials at high temperatures. International Materials Reviews, 63(5), 309-340
Open this publication in new window or tab >>Tribological behaviour of self-lubricating materials at high temperatures
2018 (English)In: International Materials Reviews, ISSN 0950-6608, E-ISSN 1743-2804, Vol. 63, no 5, p. 309-340Article in journal (Refereed) Published
Abstract [en]

Self-lubricating materials are becoming more widespread in fields like metal forming or power generation due to the inability to use conventional lubricants in high-temperature (HT) applications. In an effort to summarise the progress done in this field, a detailed literature review has been carried out, ranging from micron-thickness thin films to hardfacings and bulk materials, and classified by the reported solid lubricants. Moreover, the most-cited deposition techniques have been reviewed for each lubricant class in addition to their advantages and limitations. HT friction and wear data for self-lubricating materials have also been examined in order to identify effective lubrication ranges and general trends in their tribological behaviour, which is expected to be useful for researchers interested in this field. Finally, several apparent research gaps have been described, with suggestions for new experimental work that could lead to the development of new high-temperature self-lubricating materials.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-67041 (URN)10.1080/09506608.2017.1410944 (DOI)000427943900002 ()
Note

Validerad;2018;Nivå 2;2018-03-22 (rokbeg)

Available from: 2017-12-18 Created: 2017-12-18 Last updated: 2018-06-11Bibliographically approved
Deng, L., Pelcastre, L., Hardell, J., Prakash, B. & Oldenburg, M. (2017). A Tribological Test under Press Hardening Conditions for Galling Research. In: Mats Oldenburg, Braham Prakash, Kurt Steinhoff (Ed.), 6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2: June 4-7 2017, Atlanta, Georgia, USA : proceedings. Paper presented at 6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2, Atlanta, Georgia, 4-7 June 2017 (pp. 453-460). Warrendale, PA: Association for Iron & Steel Technology, AIST
Open this publication in new window or tab >>A Tribological Test under Press Hardening Conditions for Galling Research
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2017 (English)In: 6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2: June 4-7 2017, Atlanta, Georgia, USA : proceedings / [ed] Mats Oldenburg, Braham Prakash, Kurt Steinhoff, Warrendale, PA: Association for Iron & Steel Technology, AIST , 2017, p. 453-460Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Warrendale, PA: Association for Iron & Steel Technology, AIST, 2017
Series
CHS2-series ; 6
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Applied Mechanics
Research subject
Machine Elements; Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-64313 (URN)978-1-935117-66-7 (ISBN)
Conference
6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2, Atlanta, Georgia, 4-7 June 2017
Available from: 2017-06-21 Created: 2017-06-21 Last updated: 2018-01-13Bibliographically approved
Deng, L., Mozgovoy, S., Hardell, J., Prakash, B. & Oldenburg, M. (2017). Development of a Tribological Test Programme Based on Press Hardening Simulations. Tribology letters, 65(2), Article ID 43.
Open this publication in new window or tab >>Development of a Tribological Test Programme Based on Press Hardening Simulations
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2017 (English)In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 65, no 2, article id 43Article in journal (Refereed) Published
Abstract [en]

Press hardening is widely utilized to form ultra-high-strength steels characterized by a high strength-to-weight ratio for automotive components. Press hardening processes include heating boron–manganese steels to austenite phase, forming the steels at a high temperature, and cooling the formed blanks until the martensite phase is reached . However, press hardening processes lead to severe contact conditions between the blank and the tools including contact pressure, relative sliding, and high temperatures, which result in tool wear and increased maintenance cost. The contact conditions that occur in the stamping tool are difficult to study on site. Additionally, simplified tests, such as pin on disc and ball on disc, are insufficient to reproduce press hardening conditions in laboratory environments . The aim of this study includes developing a tribological test with press hardening conditions in which tool steel pins continuously slide on fresh and hot boron–manganese steel strips. The test programme mimics press hardening conditions with respect to sliding distance, sliding velocity, contact pressure, and surface temperature that were studied based on finite element (FE) simulations of a press hardening experiment. Furthermore, a FE simulation of the tribological test is established and it provides contact temperature in the pin tip with a high accuracy. A tribological test is used to study friction and mass loss with variational pressures and velocities that represented typically variational contact conditions in the press hardening. The tribological test is also used to obtain correlations between the tribological behaviours and process parameters in press hardening including pressure and sliding velocity.

Keywords
FE-simulation
National Category
Applied Mechanics Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Solid Mechanics; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-62220 (URN)10.1007/s11249-017-0826-8 (DOI)000401437000013 ()2-s2.0-85013392461 (Scopus ID)
Projects
FFI
Funder
VINNOVA, 196219
Note

Validerad; 2017; Nivå 2; 2017-03-02 (andbra)

Available from: 2017-02-28 Created: 2017-02-28 Last updated: 2018-07-10Bibliographically approved
Pelcastre, L., Heikkilä, I., Hardell, J. & Prakash, B. (2017). High Temperature Tribological Behaviour of Thermal-Spray Coated Toll Steels Sliding Against Al-Si Coated Ultra-High Strength Steel. In: Mats Oldenburg, Braham Prakash, Kurt Steinhoff (Ed.), 6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2: June 4-7 2017, Atlanta, Georgia, USA : proceedings. Paper presented at 6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2, Atlanta, Georgia, 4-7 June 2017 (pp. 223-232). Warrendale, PA: Association for Iron & Steel Technology, AIST
Open this publication in new window or tab >>High Temperature Tribological Behaviour of Thermal-Spray Coated Toll Steels Sliding Against Al-Si Coated Ultra-High Strength Steel
2017 (English)In: 6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2: June 4-7 2017, Atlanta, Georgia, USA : proceedings / [ed] Mats Oldenburg, Braham Prakash, Kurt Steinhoff, Warrendale, PA: Association for Iron & Steel Technology, AIST , 2017, p. 223-232Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Warrendale, PA: Association for Iron & Steel Technology, AIST, 2017
Series
CHS2-series ; 6
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-64311 (URN)978-1-935117-66-7 (ISBN)
Conference
6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2, Atlanta, Georgia, 4-7 June 2017
Available from: 2017-06-21 Created: 2017-06-21 Last updated: 2018-01-13Bibliographically approved
Hernandez, S., Hardell, J. & Prakash, B. (2017). High-Temperature Friction and Wear of Boron Steel and Tool Steel in Open and Closed Tribosystems. Tribology Transactions
Open this publication in new window or tab >>High-Temperature Friction and Wear of Boron Steel and Tool Steel in Open and Closed Tribosystems
2017 (English)In: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397XArticle in journal (Refereed) Epub ahead of print
Abstract [en]

More and more components in automotive, material processing and mining industries are operating under harsh conditions involving high temperatures and high contact pressures. Tribotesting for such applications is done using both open (one surface meeting a fresh counter-surface) and closed (one surface follows the same track on the counter-surface) test configurations. In order to enable development of new materials and processes intended for such conditions, there is a need for better understanding pertaining to tribological phenomena occurring under these different test configurations.

In this work, friction and wear characteristics of quenched and tempered tool steel sliding against boron steel (22MnB5) have been studied. The experiments were conducted using a specially designed hot strip tribometer (HST) under dry conditions at R.T. and 400°C in open as well as closed configurations. Scanning electron microscopy/energy dispersive spectroscopy and X-ray techniques were carried out to analyse the worn surfaces. Additionally, the results from the closed test configuration were compared to previous tests carried out with the same materials and parameters using a pin-on-disk (POD) test rig. The results have shown that wear was reduced at higher temperatures as well as with repeated sliding on the same contacting surfaces (i.e. closed configuration) compared to those with open configuration. A good correlation of wear mechanisms and coefficient of friction between closed configuration tests and those carried out with the POD test rig was observed especially at 400°C.

Place, publisher, year, edition, pages
Taylor & Francis, 2017
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-65170 (URN)10.1080/10402004.2017.1350310 (DOI)
Available from: 2017-08-17 Created: 2017-08-17 Last updated: 2018-02-22
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1454-1118

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