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Moghaddam, P. V., Hardell, J., Vuorinen, E., Caballero, F. G., Sourmail, T. & Prakash, B. (2020). Corrigendum to: The role of retained austenite in dry rolling/sliding wear of nanostructured carbide-free bainitic steels, Wear 428–429 (2019) 193 - 204 [Letter to the editor]. Wear, 446-447, Article ID 203072.
Open this publication in new window or tab >>Corrigendum to: The role of retained austenite in dry rolling/sliding wear of nanostructured carbide-free bainitic steels, Wear 428–429 (2019) 193 - 204
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2020 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 446-447, article id 203072Article in journal, Letter (Other academic) Published
Place, publisher, year, edition, pages
Elsevier, 2020
National Category
Other Materials Engineering Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements; Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-77919 (URN)10.1016/j.wear.2019.203072 (DOI)000513004300001 ()2-s2.0-85075451518 (Scopus ID)
Note

Godkänd;2020;Nivå 0;2020-03-02 (alebob)

Erratum in: Wear, vol. 428-429, p. 193-204, DOI: 10.1016/j.wear.2019.03.012

Available from: 2020-03-02 Created: 2020-03-02 Last updated: 2020-05-30Bibliographically approved
Moghaddam, P. V., Hardell, J., Vuorinen, E. & Prakash, B. (2020). Dry sliding wear of nanostructured carbide-free bainitic steels: Effect of oxidation-dominated wear. Wear
Open this publication in new window or tab >>Dry sliding wear of nanostructured carbide-free bainitic steels: Effect of oxidation-dominated wear
2020 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577Article in journal (Refereed) Epub ahead of print
Abstract [en]

The microstructure has a profound impact on sliding wear behaviour. This paper aims to understand the effect of carbide-free bainitic microstructure on oxidation-dominated wear in a self-mated dry sliding contact and compare the results with quenched and tempered martensitic microstructure. The results show improved wear resistance of the carbide-free bainitic steel austempered at low temperature. Hence, the retained austenite content of the carbide free bainitic microstructure is not the only indicator of excellent wear resistance. Compared to tempered martensitic microstructure, the carbide-free bainite offers a higher resistance against the formation of brittle white etching layer during the sliding wear. In summary, the formation of a thin and mechanically stable compositional mixed layer on top of the surface together with a hard underlying substrate are the main reasons behind the improved wear performance of carbide-free bainitic steel austempered at low temperature.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Wear, White etching layer, carbide-free bainite, Nanostructured, Retained austenite, Oxidation
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Other Materials Engineering
Research subject
Machine Elements; Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-78941 (URN)10.1016/j.wear.2020.203317 (DOI)
Available from: 2020-05-19 Created: 2020-05-19 Last updated: 2020-05-30
Moghaddam, P. V., Hardell, J., Vuorinen, E. & Prakash, B. (2020). Effect of retained austenite on adhesion-dominated wear of nanostructured carbide-free bainitic steel. Tribology International, 150, Article ID 106348.
Open this publication in new window or tab >>Effect of retained austenite on adhesion-dominated wear of nanostructured carbide-free bainitic steel
2020 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 150, article id 106348Article in journal (Refereed) Published
Abstract [en]

Sliding wear performance of carbide-free bainitic steel is significantly affected by microstructure. This investigation is an attempt to find a correlation between microstructure and wear resistance of carbide-free bainitic steel and compare the results with that of a conventional tempered martensitic microstructure. Under predominantly adhesive wear conditions, carbide-free bainitic microstructure with the highest amount of retained austenite offers the best wear resistance. This is mainly attributed to the more pronounced work hardening and TRIP-effect of carbide-free bainitic microstructure austempered at higher temperature. Therefore, higher initial bulk hardness is not the only indicator of wear resistance. Moreover, when both oxidation and adhesion are active, a microstructure with an optimum content of retained austenite and bainitic ferrite shows the highest wear resistance.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
bainite, Carbide-free, Retained austenite, Wear
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Other Materials Engineering
Research subject
Machine Elements; Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-78379 (URN)10.1016/j.triboint.2020.106348 (DOI)2-s2.0-85084407341 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-05-26 (alebob)

Available from: 2020-04-07 Created: 2020-04-07 Last updated: 2020-06-03Bibliographically approved
Gebretsadik, D., Hardell, J. & Prakash, B. (2020). Friction and wear characteristics of PA 66 polymer composite/316L stainless steel tribopair in aqueous solution with different salt levels. Tribology International, 141, Article ID 105917.
Open this publication in new window or tab >>Friction and wear characteristics of PA 66 polymer composite/316L stainless steel tribopair in aqueous solution with different salt levels
2020 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 141, article id 105917Article in journal (Refereed) Published
Abstract [en]

Friction and wear behaviour of a PA 66 composite with 25% glass fibre reinforcement sliding against a 316L stainless steel have been investigated using different aqueous solutions under mixed/boundary lubrication. The aqueous solutions used are deionized water, seawater, seawater without group II metal salts, solution of dissolved Group II metal salts and solution of group II metal salts and NaHCO3. Lower friction and wear was obtained when lubricated with seawater. However, when deionized water or salt solutions without group II metal salts is used, increased wear was observed. The lower friction and wear in seawater solution is due to group II metal ions and bicarbonate ions that facilitate formation of the sparingly soluble carbonates that act as a lubricating tribofilm.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Polyamide, Glass fibre, Seawater, Wear
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-75823 (URN)10.1016/j.triboint.2019.105917 (DOI)000505271400033 ()2-s2.0-85071643762 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-09-10 (johcin)

Available from: 2019-09-03 Created: 2019-09-03 Last updated: 2020-03-04Bibliographically approved
Decrozant-Triquenaux, J. (2020). High Temperature Tribological Behaviour of PVD Coated Tool Steel and Aluminium under Dry and Lubricated Conditions. Friction
Open this publication in new window or tab >>High Temperature Tribological Behaviour of PVD Coated Tool Steel and Aluminium under Dry and Lubricated Conditions
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2020 (English)In: Friction, E-ISSN 2223-7690Article in journal (Refereed) Submitted
Abstract [en]

Aluminium alloys are commonly used as lightweight materials in the automotive industry. This non-ferrous family of metallic alloys offers a high versatility of properties and designs. To reduce weight and improve safety, high strength-to-weight ratio alloys (e.g. 6XXX and 7XXX), are increasingly implemented in vehicles. However, these alloys exhibit low formability and experience considerable springback during cold forming, and are therefore hot formed. During forming, severe adhesion (i.e. galling) of aluminium onto the die surface takes place. This phenomenon has a detrimental effect on the surface properties, geometrical tolerances of the formed parts and maintenance of the dies. The effect of surface engineering as well as lubricant chemistry on galling has not been sufficiently investigated. DLC and CrN PVD coated steel have been studied to reduce aluminium transfer. However, the interaction between lubricants and PVD coatings during hot forming of aluminium alloys is not yet fully understood. The present study thus aims to characterise the high temperature tribological behaviour of selected PVD coatings and lubricants during sliding against aluminium alloy. The objectives are to first select promising lubricant-coating combinations and then to study their tribological response in a high-temperature reciprocating friction and wear tester. Dry and lubricated tests were carried out at 300°C using a commercial polymer lubricant. Tests using DLC, CrN, CrTiN and CrAlN coated tool steel were compared to uncoated tool steel reference tests. The initial and worn test specimen surfaces were analysed with a 3D optical profiler, SEM and EDS as to understand the wear mechanisms. The results showed formation of tribolayers in the contact zone, reducing both friction and wear. The stability of these layers highly depends on both the coatings’ roughness and chemical affinity towards aluminium. The DLC and CrN coatings combined with the polymer lubricant were the most effective in reducing aluminium transfer.

Keywords
high temperature tribology, aluminium, lubrication, PVD coatings, material transfer, adhesion
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-77693 (URN)
Available from: 2020-02-13 Created: 2020-02-13 Last updated: 2020-02-14
Johansson, J. E., Devlin, M. T., Guevremont, J. M. & Prakash, B. (2020). Improving Hypoid Gear Oil Pitting Performance through Friction Reduction. Tribology Transactions, 63(2), 280-295
Open this publication in new window or tab >>Improving Hypoid Gear Oil Pitting Performance through Friction Reduction
2020 (English)In: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 63, no 2, p. 280-295Article in journal (Refereed) Published
Abstract [en]

Earlier studies have shown that the load-dependent friction behavior of various gear oils can affect their pitting performance; that is, low friction resulted in a long pitting life. These studies were limited, however, to test methods and running conditions quite different from those occurring in actual gear transmissions. In the present study, a more gear-like twin-disc machine with test specimens and running conditions relevant for gear contacts was used to investigate whether the same trends could be found. To analyze this possible correlation, the first step was to prepare a set of hypoid gear oils and to test their friction performance to compare various ways of improving friction behavior but also to form an understanding of why their friction performance varied. The second step was to test the pitting performance of the oils. The pitting results could then be compared to the friction properties of the oils to analyze the correlation. Other possible mechanisms behind the formation of pits are also discussed. The results show that for the oils included, the antiwear and extreme-pressure additive package and the base oil type affect friction. The results further show that additive combinations and/or base oils that result in low friction lead to enhanced pitting performance.

Place, publisher, year, edition, pages
Taylor & Francis, 2020
Keywords
Gear lubricants, rolling contact fatigue, EHL friction, antifatigue additives
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-76575 (URN)10.1080/10402004.2019.1686194 (DOI)000497233100001 ()2-s2.0-85075217917 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-04-21 (johcin)

Available from: 2019-10-30 Created: 2019-10-30 Last updated: 2020-04-21Bibliographically approved
Decrozant-Triquenaux, J. (2020). Influence of Lubrication, Tool Steel Composition and Topography on the High Temperature Tribological Behaviour of Aluminium. Friction
Open this publication in new window or tab >>Influence of Lubrication, Tool Steel Composition and Topography on the High Temperature Tribological Behaviour of Aluminium
2020 (English)In: Friction, E-ISSN 2223-7690Article in journal (Refereed) Accepted
Abstract [en]

The use of high strength aluminium alloys, such as 6XXX and 7XXX series, is continuously increasing for automotive applications in view of their good strength-to-weight ratio. Their formability at room temperature is limited and they are thus often formed at high temperatures to enable production of complex geometries. Critical challenges during hot forming of aluminium are the occurrence of severe adhesion and material transfer onto the forming tools. This negatively affects the tool life and the quality of the produced parts. In general, the main mechanisms involved in the occurrence of material transfer of aluminium alloys at high temperature are still not clearly understood. Therefore, this study is focussed on understanding of the friction and wear behaviour during interaction of Al6016 alloy and three different tool steels in as-received and polished state. The tribotests were carried out under dry and lubricated conditions, with two distinct lubricants, using a reciprocating friction and wear tester. The worn surfaces were analysed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results showed a high dependence of friction and wear behaviour on the tool steel roughness as well as on the stability of the lubricant films. Tribolayers were found to develop in the contact zone and their capacity to improve the tribological behaviour is seen to be drastically impacted by the surface roughness of the tool steel. When the tribolayers failed, severe adhesion took place and led to high and unstable friction as well as material transfer to the tool steel.

Keywords
friction, wear, high temperature tribology, aluminium, lubrication, tribolayer
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-77692 (URN)
Available from: 2020-02-13 Created: 2020-02-13 Last updated: 2020-02-17
Torres, H., Caykara, T., Rojacz, H., Prakash, B. & Rodríguez Ripoll, M. (2020). The tribology of Ag/MoS2-based self-lubricating laser claddings for high temperature forming of aluminium alloys. Wear, 442, Article ID 203110.
Open this publication in new window or tab >>The tribology of Ag/MoS2-based self-lubricating laser claddings for high temperature forming of aluminium alloys
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2020 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 442, article id 203110Article in journal (Refereed) Published
Abstract [en]

In recent years, the use of aluminium alloys in the automotive industry has gained significant attention due to their specific strength, corrosion resistance and recyclability. However, their forming at high temperature in processes like hot stamping is challenging due to the poor tribological behaviour of aluminium alloys, which is the source of severe adhesive wear and a poor surface quality of the finished product.

In an effort to overcome these tribological problems, iron- and nickel-based self-lubricating laser claddings with the addition of solid lubricants such as silver and molybdenum disulfide have been evaluated under conditions representative of hot stamping against the aluminium alloy AA6082. It has been found that self-lubricating claddings decrease friction and counter body wear at high temperatures compared to alloys commonly used in forming tools such as grade 1.2367 steel. Furthermore, nickel-based self-lubricating claddings have shown a better tribological behaviour than their iron-based counterparts, due to the formation of a nickel-based sulfide layer on the counter body. It is thus expected that the implementation of self-lubricating claddings can improve the quality of the final product while reducing the need for added lubricant during the hot stamping of aluminium alloys.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
High temperature, Laser cladding, Self-lubrication, Aluminium, Hot stamping
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-76959 (URN)10.1016/j.wear.2019.203110 (DOI)000513000400003 ()2-s2.0-85075403269 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-01-27 (johcin)

Available from: 2019-11-29 Created: 2019-11-29 Last updated: 2020-03-10Bibliographically approved
Hultqvist, T., Vrček, A., Marklund, P., Prakash, B. & Larsson, R. (2020). Transient analysis of surface roughness features in thermal elastohydrodynamic contacts. Tribology International, 141, Article ID 105915.
Open this publication in new window or tab >>Transient analysis of surface roughness features in thermal elastohydrodynamic contacts
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2020 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 141, article id 105915Article in journal (Refereed) Published
Abstract [en]

Understanding the influence of surface roughness in elastohydrodynamically lubricated (EHL) contacts is essential to improve durability and friction performance of machine elements employing non-conformal contacting surfaces. In this work, the transient event of a surface feature passing through a thermal EHL line contact operating under different sliding conditions is investigated with the purpose of providing a deeper understanding of surface roughness influence. This is achieved by solving the EHL problem in space and time. It was seen that sliding influences the temperature rise in the contact significantly, especially in the vicinity of the asperity. However, due to the characteristic behaviour of EHL contacts, the local temperature rise mainly influence the film thickness during exiting of inlet perturbations and the asperity.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Thermal elastohydrodynamic lubrication, Transient conditions, Surface features, Numerical modelling
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-75817 (URN)10.1016/j.triboint.2019.105915 (DOI)000505271400031 ()2-s2.0-85071778495 (Scopus ID)
Funder
Swedish Energy Agency, 41215-1
Note

Validerad;2019;Nivå 2;2019-09-10 (johcin)

Available from: 2019-09-03 Created: 2019-09-03 Last updated: 2020-05-15Bibliographically approved
Gebretsadik, D., Hardell, J. & Prakash, B. (2019). Embeddability behaviour of some Pb-free engine bearing materials in the presence of abrasive particles in engine oil. Tribology - Materials, Surfaces & Interfaces, 13(1), 39-49
Open this publication in new window or tab >>Embeddability behaviour of some Pb-free engine bearing materials in the presence of abrasive particles in engine oil
2019 (English)In: Tribology - Materials, Surfaces & Interfaces, ISSN 1751-5831, E-ISSN 1751-584X, Vol. 13, no 1, p. 39-49Article in journal (Refereed) Published
Abstract [en]

One of the tribological requirements on engine bearing material is its ability to safely embed contaminant particles onto its surface and minimise damage to both the bearing and crankshaft surfaces. In this work, a journal bearing test rig that operates under constant load has been employed to investigate the embeddability behaviour of selected multi-layered Pb-free engine bearing materials at three different rotational speeds using engine oil contaminated with SiC particles. Experimental results have shown that third-body abrasive wear is influenced by the lubricant film thickness. There was also difference in embeddability of the different materials. Bismuth-based overlay and MoS2 containing polyamide-imide-based overlay-coated materials show higher wear compared to tin-based overlay and a polyamide-imide-based composite overlay-coated material. Steel counter surfaces sliding against bismuth-based overlay and MoS2 containing polyamide-imide-based overlay exhibited higher wear than those sliding against tin-based overlay and polyamide-imide-based composite overlay. 

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
Embeddability, third-body abrasive wear, hydrodynamic lubrication, engine bearings, Pb-free
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-72774 (URN)10.1080/17515831.2019.1574452 (DOI)000471166200005 ()
Note

Validerad;2019;Nivå 2;2019-04-12 (oliekm)

Available from: 2019-02-04 Created: 2019-02-04 Last updated: 2019-07-01Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-1454-1118

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