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Galling resistance and wear mechanisms - cold work tool materials sliding against carbon steel sheets
Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik. (Materials Engineering, Materials Science)ORCID-id: 0000-0002-9441-2502
Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.ORCID-id: 0000-0001-6029-2613
Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
2007 (engelsk)Inngår i: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 26, nr 1, s. 67-72Artikkel i tidsskrift (Fagfellevurdert) Published
sted, utgiver, år, opplag, sider
Berlin: Springer Berlin/Heidelberg, 2007. Vol. 26, nr 1, s. 67-72
HSV kategori
Identifikatorer
URN: urn:nbn:se:kau:diva-2014DOI: 10.1007/s11249-006-9186-5OAI: oai:DiVA.org:kau-2014DiVA, id: diva2:5513
Tilgjengelig fra: 2008-11-19 Laget: 2008-11-19 Sist oppdatert: 2017-12-07bibliografisk kontrollert
Inngår i avhandling
1. Wear mechanisms in sheet metal forming: Effects of tool microstructure, adhesion and temperature
Åpne denne publikasjonen i ny fane eller vindu >>Wear mechanisms in sheet metal forming: Effects of tool microstructure, adhesion and temperature
2008 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The general trend in the car body manufacturing industry is towards low-series production and reduction of press lubricants and car weight. The limited use of lubricants, in combination with the introduction of high and ultrahigh-strength sheet materials, continuously increases the demands on the forming tools. The major cause for tool failure during the forming process is transfer and accumulation of sheet material on the tool surfaces, generally referred to as galling. The adhered material creates unstable frictional conditions and scratching of the tool/sheet interface. To provide the means of forming new generations of sheet materials, development of new tool materialswith improved galling resistance is required, which may include tailored microstructures introducing specific carbides and nitrides, coatings and improved surface finish. In the present work, the galling wear mechanisms in real forming operations have been studied and emulated at a laboratory scale by developing a test equipment. The wear mechanisms, identified in the real forming process, were distinguished into a sequence of events. At the initial stage, local adhesive wear of the sheets led to transfer of sheet material to the tool surfaces. Successive forming operations resulted in growth of the transfer layer with initiation of scratching of the sheets. Finally, scratching changed into severe adhesive wear, associated withgross macroscopic damage. The wear process was successfully repeated in the laboratory test equipment in sliding between several tool materials, ranging from cast iron and conventional ingot cast tool steels, to advanced powder metallurgy tool steel, sliding against medium and high-strength steel sheets. By use of the test equipment, selected tool materials were ranked regarding galling resistance. The controlling mechanism for galling in sheet metal forming is adhesion. The initial sheet material transfer was found to occur, preferably, to the metallic matrix of the tool steels. Hence, the carbides in the particular steels appeared less prone to adhesion as compared to the metallic matrix. Therefore, an improved galling resistance was observed for a tool steel comprising a high amount of small homogeneously distributed carbides offering a low-strength interface to the transferred sheet material.Further, atomic force microscopy showed that nanoscale adhesion was influenced by temperature, with increasing adhesion as temperature increases. A similar dependence was observed at the macroscale where increasing surface temperature led to initiation of severe adhesive wear. The results were in good agreement to the nano scale observations and temperature-induced high adhesion was suggested as a possible mechanism.

sted, utgiver, år, opplag, sider
Karlstad: Karlstad University, 2008. s. 41
Serie
Karlstad University Studies, ISSN 1403-8099 ; 2008:46
Emneord
Galling, sheet metal forming, wear, friction, adhesion, temperature
HSV kategori
Forskningsprogram
Materialteknik
Identifikatorer
urn:nbn:se:kau:diva-2911 (URN)978-91-7063-204-4 (ISBN)
Disputas
2008-12-12, Nyqvistsalen, 9C 203, Karlstads Universitet, Karlstad, 10:15 (svensk)
Opponent
Veileder
Tilgjengelig fra: 2008-11-20 Laget: 2008-10-23 Sist oppdatert: 2011-11-24bibliografisk kontrollert
2. Wear in sheet metal forming
Åpne denne publikasjonen i ny fane eller vindu >>Wear in sheet metal forming
2008 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The general trend in the car body manufacturing industry is towards low-series production and reduction of press lubricants and car weight. The limited use of press lubricants, in combination with the introduction of high and ultra-high strength sheet materials, continuously increases the demands of the forming tools. To provide the means of forming new generations of sheet material, development of new tool materials with improved galling resistance is required, which may include tailored microstructures, introducing of specific(MC, M(C,N))carbides and nitrides, coatings and improved surface finish. In the present work, the wear mechanisms in real forming operations have been studied and emulated on a laboratory scale by developing a test equipment. The wear mechanisms identified in the real forming process, were distinguished into a sequence of events consisting of initial local adhesive wear of the sheets resulting in transfer of sheet material to the tool surfaces. Successive forming operations led to growth of the transfer layer and initiation of scratching of the sheets. Finally, scratching changed into severe adhesive wear, associated with gross macroscopic damage. The wear process was repeated in the laboratory test-equipment in sliding between several tool materials, ranging from cast iron to conventional ingot cast tool steels to advanced powder metallurgy tool steel, against dual-phase carbon steel sheets. By use of the test-equipment, selected tool materials were ranked regarding wear resistance in sliding against ferritic-martensitic steel sheets at different contact pressures.

Wear in sheet metal forming is mainly determined by adhesion; initially between the tool and sheet surface interaction and subsequently, after initiation of material transfer, between a sheet to sheet contact. Atomic force microscopy force curves showed that adhesion is sensitive to both chemical composition and temperature. By alloying of iron with 18wt.% Cr and 8wt.% Ni, alloying in itself, or changes in crystal structure, led to an increase of 3 times in adhesion at room temperature. Hence, alloying may be assumed a promising way for control of adhesive properties. Additionally, frictional heating should be controlled to avoid high adhesion as, generally, adhesion was found to increase with increasing temperature for all investigated materials.

sted, utgiver, år, opplag, sider
Karlstad: Karlstad University, 2008. s. 34
Serie
Karlstad University Studies, ISSN 1403-8099 ; 2008:10
Emneord
Friction, Sheet metal forming, Galling
HSV kategori
Forskningsprogram
Materialteknik
Identifikatorer
urn:nbn:se:kau:diva-1592 (URN)978-91-7063-168-9 (ISBN)
Presentation
2008-04-18, 10:15
Opponent
Veileder
Tilgjengelig fra: 2008-04-17 Laget: 2008-04-17 Sist oppdatert: 2011-11-24

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