uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Galling of high strength steels and stainless steels in sheet metal forming as evaluated using pin-on-disc testing
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The thesis focuses on the problem galling in sheet metal forming operations. Galling occurs when sheet metal transfers from the sheet surface onto the tool surface and causes surface damages to following sheets in the forming operation. When this happens the tool must be replaced causing production stops and additional expenses.

The increasing use of high strength steel grades combined with the desire to use more environmentally friendly or no lubricants exposes the tools used for sheet metal forming for tougher forming conditions with higher contact pressures and thus an increasing risk for material pick-up and galling. To prevent this new tool steels, lubricants and coatings have been developed. In this thesis a number of tool steels, high strength steels, stainless steels, coatings and lubricants have been investigated with the test method pin-on-disc testing in order to explain how different premises, such as chemical composition, mechanical properties and surface topography influence on the galling tendency in sheet metal forming.

The results show that there is a big difference in performance between a conventional cast tool steel and a powder metallurgy tool steel with respect to the galling tendency. The results also show that the surface topography of both the tool steels and the sheet materials influence on the performance of the lubricants and the galling tendency.   

When coating a tool steel, the substrate hardness is of greatest importance for the performance and wear of the coating. For the different coatings investigated, the performance of the coatings depends on whether the sheet material is zinc coated or not. However, the CrC/C coating investigated show a good performance with respect to the galling tendency in contact with all of the investigated high strength steel grades.

Place, publisher, year, edition, pages
Uppsala: Uppsala universitet, 2012. , viii+30 p.
Keyword [en]
Galling, sheet metal forming, high strength steels, stainless steels
National Category
Metallurgy and Metallic Materials Manufacturing, Surface and Joining Technology
Research subject
Engineering Science with specialization in Tribo Materials
Identifiers
URN: urn:nbn:se:uu:diva-164717ISBN: 978-91-506-2266-9 (print)OAI: oai:DiVA.org:uu-164717DiVA: diva2:470063
Supervisors
Available from: 2012-07-18 Created: 2011-12-23 Last updated: 2012-07-18Bibliographically approved
List of papers
1. Ranking the performance of lubricants, tool steels and PVD coatings for the forming of high strength steel using pin-on-disc testing
Open this publication in new window or tab >>Ranking the performance of lubricants, tool steels and PVD coatings for the forming of high strength steel using pin-on-disc testing
2009 (English)In: Tool09: Tool steels, june 2nd-4th 2009 in aachen, germany, 2009Conference paper, Published paper (Other academic)
Abstract [en]

The increasing use of high strength steels in a variety of mechanical engineering applications has illuminated problems associated with galling in sheet metal forming operations. Galling is a tribological phenomenon associated with transfer of material from the steel sheet to the tool surface during forming resulting in seizure of the tool/steel sheet contact and extensive scratching of the steel sheet surface. As a result, a number of concepts have been developed in order to reduce the tendency to galling in sheet metal forming, including the development of new dry lubricants, new forming tool steel grades and improved surface engineering treatments such as the deposition of low friction CVD- and PVD-coatings. In the present study the potential performance of these concepts in the forming of hot and cold rolled high strength steel as well as electro and hot-dip galvanized high strength steel has been evaluated using pin-on disc testing. In the tests, two different lubricants, a dry lubricant and a pre-lube oil, two different cold work tool steels, a conventional steel grade and a nitrogen alloyed PM steel grade, and two different PVD coatings, (Ti,Al)n and CrC/C, were evaluated. Post-test examination of the tribosurfaces using FEG-SEM, EDX and 3D surface profilometry was performed in order to evaluate the mechanisms controlling the material transfer and wear. In summary, the results show that the laboratory testing combined with post-test microscopy and surface analysis give valuable information in order to rank the galling resistance of lubricants, tool steels and PVD-coatings.

Keyword
sheet metal forming, high strength steels, galling, dry lubricant, tool steels, PVD-coatings
National Category
Metallurgy and Metallic Materials
Research subject
Engineering Science with specialization in Tribo Materials
Identifiers
urn:nbn:se:uu:diva-159384 (URN)
Conference
Tool09
Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2012-07-18
2. Evaluation of galling resistance for some selected combinations of tool steels / stainless steel sheet materials/ lubricants using pin-on-disc testing
Open this publication in new window or tab >>Evaluation of galling resistance for some selected combinations of tool steels / stainless steel sheet materials/ lubricants using pin-on-disc testing
2010 (English)In: NordTrib 2010: 14th Nordic Symposium on Tribology, Storforsen, Sweden / [ed] Elisabet Kassfeldt, 2010Conference paper, Published paper (Refereed)
Abstract [en]

Stainless steels are well known to be prone to cold welding and material transfer in sliding contacts and therefore difficult to cold form unless certain precautions as discussed in this paper are taken. In the present study different combinations of tool steels/stainless steels/lubricants has been evaluated with respect to their galling resistance using pin-on-disc testing. The results show that a high galling resistance is favored by a high stainless steel sheet hardness and a blasted stainless steel sheet surface topography. The effect of type of lubricant was found to be more complex. For example, the chlorinated lubricants failed to prevent metal-to-metal contact on a brushed sheet surface but succeeded on a blasted sheet surface of the same stainless steel material. This is believed to be due to a protective tribofilm which is able to form on the blasted surface, but not on the brushed surface.

Keyword
Galling, stainless steels, cold work tool steels, lubricants
National Category
Metallurgy and Metallic Materials
Research subject
Engineering Science with specialization in Tribo Materials
Identifiers
urn:nbn:se:uu:diva-159385 (URN)
Conference
NordTrib 2010
Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2016-04-18
3. Tribological testing of commercial CrN, (Ti,Al)N and CrC/C PVD coatings: Evaluation of galling and wear characteristics against different high strength steels.
Open this publication in new window or tab >>Tribological testing of commercial CrN, (Ti,Al)N and CrC/C PVD coatings: Evaluation of galling and wear characteristics against different high strength steels.
2011 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 205, no 16, 4045-4051 p.Article in journal (Refereed) Published
Abstract [en]

The increasing use of high strength steels in a variety of mechanical engineering applications has illuminatedproblems associated with galling in sheet metal forming operations. Galling is a tribological phenomenonassociated with transfer of material from the steel sheet to the tool surface during forming resulting in seizureof the tool/steel sheet contact and extensive scratching of the steel sheet surface. As a result, a number ofconcepts have been developed in order to reduce the tendency of galling in sheet metal forming, including thedevelopment of new dry lubricants, new forming tool steel grades and improved surface engineeringtreatments such as the deposition of low friction CVD- and PVD-coatings. In the present study the potentialperformance of three commercial PVD coatings, including CrN, (Ti,Al)N and a CrC/C DLC-based coating, in theforming of hot and cold rolled high strength steel as well as electro and hot-dip galvanized high strength steelhas been evaluated using pin-on-disc testing under lubricated contact conditions. Post-test examination ofthe tribosurfaces using FEG-SEM and EDS analyses was performed in order to evaluate the mechanismscontrolling the tendency to material transfer and wear. The results show that in contact with the hot and coldrolled steel the material pick-up tendency of the PVD coatings tend to increase in the order CrC/C–CrN–(Ti,Al)N while in contact with the two galvanized steel sheets, the CrC/C and the (Ti,Al)N coating show a significantlylower material pick-up tendency as compared with the CrN coating. Further, the substrate hardness has astrong influence on the wear of the PVD coatings and consequently on the friction characteristics and gallingtendency of the coating/substrate composite. Low substrate hardness, resulting in a low load bearing capacity,increases the tendency to cracking and subsequently chipping of the brittle coating.

Keyword
PVD coatings, tool steel, high strength steel sheet, galling, friction, wear.
National Category
Metallurgy and Metallic Materials
Research subject
Engineering Science with specialization in Tribo Materials
Identifiers
urn:nbn:se:uu:diva-159386 (URN)10.1016/j.surfcoat.2011.02.053 (DOI)
Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2017-12-08Bibliographically approved

Open Access in DiVA

No full text

Authority records BETA

Eriksson, Jenny

Search in DiVA

By author/editor
Eriksson, Jenny
By organisation
Applied Materials Sciences
Metallurgy and Metallic MaterialsManufacturing, Surface and Joining Technology

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 986 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf