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Influence of tool steel hard phase orientation and shape on galling
Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
2014 (English)In: Advanced Materials Research, ISSN 1022-6680, E-ISSN 1662-8985, Vol. 966-96, 249-258 p.Article in journal (Refereed) Published
Abstract [en]

Conventionally manufactured cold work tool steel is often used in sheet metal forming as die material. Due to the forging process, the as-cast network structure of carbides is broken into elongated particles. Depending on the tool cross-section, the orientation and shape of carbides in the active tool surface is different. In the present research, the influence of tool steel hard phase orientation and shape on galling was investigated. D2 type tool steel was cut in three different orientations and tested in lubricated sliding conditions against AISI 304 austenitic stainless steel. Tests were performed using a Slider-On-Flat-Surface and galling was detected by changes in friction and post-test microscopy. The lubricant was Castrol FST8 using 5 g/m2 sheet material. Results showed a strong correlation between sliding distance to galling and tool steel hard phase orientation and shape at low loads, whereas high load contact resulted in early galling in all cases. Material transfer was observed mainly to the tool steel matrix. The worst performance was observed for specimens cut so that the tool steel hard phase, M7C3 carbides in the D2 steel, were oriented along the sliding direction, which resulted in longer open tool matrix areas contacting the sheet material.

Place, publisher, year, edition, pages
Trans Tech Publications, 2014. Vol. 966-96, 249-258 p.
Keyword [en]
Austenitic stainless steel; Carbides; Industrial engineering; Joining; Lubricants; Plastic deformation; Production engineering; Sheet metal; Tribology; Wear of materials, Cold work tool steels; Elongated particles; Galling; Material transfers; Metal transfers; Network structures; Sliding conditions; Strong correlation, Tool steel
National Category
Tribology
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kau:diva-32112DOI: 10.4028/www.scientific.net/AMR.966-967.249ScopusID: 2-s2.0-84904014001OAI: oai:DiVA.org:kau-32112DiVA: diva2:717963
Conference
6th International Conference on Tribology in Manufacturing Processes and Joining by Plastic Deformation, ICTMP 2014 ; Conference Date: 22 June 2014 Through 24 June 2014
Available from: 2014-05-19 Created: 2014-05-19 Last updated: 2016-06-15Bibliographically approved
In thesis
1. The influence of tool steel microstructure on galling
Open this publication in new window or tab >>The influence of tool steel microstructure on galling
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In sheet metal forming (SMF) of materials such as stainless steels there is a major problem with transfer and accumulation of sheet material to the metal forming tool surface. The problem is known as galling; a sort of severe adhesive wear, which results in severe scratching of produced parts. In this thesis, the overall aim was to gain knowledge of the influence of tool steel microstructure on galling initiation under sliding conditions. It was discovered that material transfer and tool steel damage caused by sheet material flow creating wear-induced galling initiation sites occurred in the early stage of galling. The galling resistance was higher for tool steels with higher matrix hardness due to better resistance to tool steel damage. Initial friction and critical contact pressure to galling was influenced by the strength of the sheet material. Material transfer happened at low pressures and the friction value was high in a case of sheet materials with lower proof strength, possibly due to the sheet contact against the tool steel matrix resulting in high adhesion and quicker tool damage. It was demonstrated that, in addition to hardness of the tool steel matrix and sheet material proof strength, tool steel microstructural features like size, shape, distribution and height of hard phases are important parameters influencing galling. Tool steels comprising homogeneously distributed, small and high hard phases better prevented the contact between sheet material and the tool steel matrix. Thus, a metal to metal contact with high friction was more efficiently avoided, which resulted in better tool performance.

 

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2014. 42 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2014:35
Keyword
Galling, Microstructure, Material transfer, Tool steel, Stainless steel, Metall transfer
National Category
Tribology
Research subject
Materials Engineering
Identifiers
urn:nbn:se:kau:diva-32113 (URN)978-91-7063-568-7 (ISBN)
Public defence
2014-08-29, Ljungbergsalen, 21A 244, Universitetsgatan 2, Karlstad, 10:15 (English)
Opponent
Supervisors
Available from: 2014-06-17 Created: 2014-05-19 Last updated: 2014-06-17Bibliographically approved

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Karlsson, PatrikGåård, AndersKrakhmalev, Pavel
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