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Influence of Nitrogen Alloying on Galling Properties of PM tool steels
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. (Trigomaterial)
2002 (English)In: -, 216-226 p.Article in journal (Refereed) Published
Abstract [en]

The objective of this study is to investigate the effect of nitrogen alloying of tool steels on their galling properties. Nitrogen is introduced to the steel composition by solid state nitriding  with ammonia gas at 550-600 oC. The base material composition is in powder form during nitriding. Different nitrogen contents are experimented. The hard phases present in steel composition are of type M(C,N) and M6C. The materials are consolidated by HIP process. Galling behaviour of the produced alloys is evaluated with slider-on-sheet tribological test method. As a reference for nitrogen alloyed compositions various PM tool steel grades and CVD coated tool steels are chosen. The ability of the test materials to avoid formation of galling adherants is tested against AISI 304 stainless steel with a low viscose lubricant. The test results show that nitrogen alloying increases manifold resistance against galling reaching equal behaviour as for CVD coated tool steels.


Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2002. 216-226 p.
Keyword [en]
carbonitride, PM tool steel, nitriding, galling, stainless steel
National Category
Materials Engineering
Research subject
Engineering Science with specialization in Tribo Materials
URN: urn:nbn:se:uu:diva-198744OAI: oai:DiVA.org:uu-198744DiVA: diva2:617640
6th International Tooling ConferenceKarlstad 10-13 September 2002
Available from: 2013-04-24 Created: 2013-04-24 Last updated: 2013-05-13
In thesis
1. The Positive Effect of Nitrogen Alloying of Tool Steels Used in Sheet Metal Forming
Open this publication in new window or tab >>The Positive Effect of Nitrogen Alloying of Tool Steels Used in Sheet Metal Forming
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Sheet metal forming processes are mechanical processes, designed to make products from metal sheet without material removal. These processes are applied extensively by the manufacturing industry to produce commodities such as heat exchangers or panels for automotive applications. They are suitable for production in large volumes.

A typical problem in forming operations is accumulation of local sheet material adherents onto the tool surface, which may deteriorate the subsequent products. This tool failure mechanism is named galling. The aim of this work is to explain the mechanisms behind galling and establish factors how it can be reduced.

The focus of this work is on the influence of tool material for minimum risk of galling. Experimental tool steels alloyed with nitrogen were designed and manufactured for systematic tribological evaluation. Reference tool materials were conventional cold forming tool steels and coated tool steels. The sheet material was austenitic stainless steel AISI 304, which is sensitive for galling. A variety of lubricants ranging from low to high viscous lubricants were used in the evaluation.

The properties of the tool materials were characterized analytically and their tribological evaluation included industrial field tests and several laboratory-scale tests. The testing verified that nitrogen alloying has a very positive effect for improving galling resistance of tool steels. Tool lives comparable to the coated tool steels were achieved even with low viscous lubricants without poisonous additives.

The hypothesis used for the explanation of the positive effect of nitrogen alloying is based on the critical local contact temperature at which the lubrication deteriorates. Therefore, the contact mechanism at the tool-sheet interface and the local energy formation were studied systematically. Theoretical considerations complemented with FEA analysis showed that a small size of hard particles with a high volume fraction gives low local contact loads, which leads to low frictional heating. Also, an even spacing between the hard particles and their frictional properties are of importance. Nitrogen alloyed tool steels have these properties in the form of small carbonitrides.

The finding of this work can be applied to a wide range of applications that involve sliding metal contacts under severe tribological loading.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 56 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1045
galling, nitrogen, tool steel, sliding contact, metal forming
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Tribo Materials
urn:nbn:se:uu:diva-198747 (URN)978-91-554-8673-0 (ISBN)
Public defence
2013-06-12, Sal 2001 Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
Available from: 2013-05-21 Created: 2013-04-24 Last updated: 2013-08-30Bibliographically approved

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