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Life time of cemented carbide inserts with Ni-Fe binder in steel turning
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.ORCID iD: 0000-0002-3955-5746
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Sandvik Coromant R&D, Stockholm, Sweden..
2017 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 376, p. 1822-1829Article in journal (Refereed) Published
Abstract [en]

Health concerns associated with cobalt powder are a strong motivator for conducting research on alternative binders for cemented carbides. It has previously been shown possible to make cemented carbides with alternative binders, which offer good hardness and toughness. However, it is not fully known if these cemented carbides can be successfully used as metal cutting tools. In this study we have tested turning inserts from cemented carbide with a nickel-iron binder and compared these with cobalt based reference inserts in dry face turning of steel in a pairwise comparison. To facilitate relevant comparisons, both the alternative binder and the reference cemented carbide are gradient sintered and coated in the same way as commercial turning grades. It is found that the life time in this dry face turning test is only approximately 15% shorter with the nickel-iron binder than with the cobalt reference, which motivates further studies with this alternative binder. Flaking of the coating and thus less coating adhesion was identified as one reason for the shorter life time.

Place, publisher, year, edition, pages
2017. Vol. 376, p. 1822-1829
Keywords [en]
Cutting tools, Cemented carbide, Alternative binder, Face turning
National Category
Materials Engineering
Identifiers
URN: urn:nbn:se:uu:diva-329133DOI: 10.1016/j.wear.2017.02.018ISI: 000403902000097OAI: oai:DiVA.org:uu-329133DiVA, id: diva2:1148266
Funder
VINNOVAAvailable from: 2017-10-10 Created: 2017-10-10 Last updated: 2019-10-22Bibliographically approved
In thesis
1. Alternative binder hardmetals for steel turning
Open this publication in new window or tab >>Alternative binder hardmetals for steel turning
2017 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The goal of this work is to understand how the wear and deformation mechanisms of hardmetalinserts change when the cobalt binder phase is replaced with a dierent metal or analloy. The focus is on inserts for steel turning. The work presented in this licentiate thesisconsists of the rst steps.Cobalt is the most common binder phase in hardmetal tools based on tungsten carbide asthe hard phase. Metallic cobalt powder, present during the manufacturing, has been associatedwith lung diseases and an increased risk for lung cancer if inhaled. Therefore it is importantto investigate alternative binders as one possible solution.This work studies binder phase alloys from the iron-nickel-cobalt system. These alloyscan be either austenitic, martensitic or a mixture of the two phases. By changing the binderphase composition to change the crystal structure it is possible to tailor the macroscopic mechanicalproperties of the material. It is also possible to tailor the composition in such a waythat the binder is transformation toughening, forming martensite as a response to mechanicaldeformation.The majority of inserts for steel turning are coated, and it is important to investigate if thehardmetals with alternative binder can be coated and if the coating adhesion is sucient forsteel turning.Four dierent alternative binder alloys and one reference with cobalt binder coated bychemical vapour deposition were investigated by scratch testing to determine the adhesion.The scratch test adhesion was sucient on all samples, but signicant variations in coatingadhesion were found.One alternative binder with 86wt%Ni and 14wt%Fe and a reference with cobalt binder manufacturedto mimic state of the art turning inserts were tested in steel turning. The alternativebinder grades had a lower resistance to plastic deformation and this was attributed to earlyaking of the coating due to a lower coating adhesion. Focused ion beam and scanning electronmicroscopy were used to study the deformation of the hard metal in the used cuttinginserts.

Place, publisher, year, edition, pages
Uppsala: Uppsala University, 2017. p. 54
Keywords
hardmetal, cemented carbide, alternative binder, steel turning, scratch testing, plastic deformation, EBSD, transformation toughening
National Category
Materials Engineering
Research subject
Engineering Science with specialization in Tribo Materials
Identifiers
urn:nbn:se:uu:diva-332451 (URN)
Presentation
2017-01-25, Å2001, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2017-10-27 Created: 2017-10-27 Last updated: 2017-10-27Bibliographically approved
2. Insights into wear and deformation of alternative binder hardmetals
Open this publication in new window or tab >>Insights into wear and deformation of alternative binder hardmetals
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This work presents new insights into how hardmetals with alternative binders as well as cobalt based references react to wear and deformation. The main focus has been on hardmetals for steel turning, but also on studying certain fundamental properties of the new binder materials.

Cobalt has traditionally been the most common binder phase for tungsten carbide grains in hardmetals, but recent insights into the carcinogenicity of cobalt powder has led to a need to research alternatives. In this work hardmetals with binder phases consisting of alloys of iron and nickel or iron, nickel and cobalt have been studied.

Coated hardmetal inserts used until end of tool life in steel turning have been evaluated with respect to the plastic deformation and coating adhesion. It was found that grain boundary sliding of tungsten carbide/tungsten carbide grain boundaries is an important deformation mechanism during dry face turning, concluded based on an increased number of binder phase lamellae in tungsten carbide/tungsten carbide grain boundaries in the deformed microstructure.  The lamellae were found to have a preferred orientation, coinciding with the expected flow of material during deformation.

For turning inserts with exposed hardmetal due to flaked coating it was further observed that the microstructure contained cavities caused by the increased temperature of the hardmetal when the protective coating layers are lost. No cavities were found in samples which were still covered by coating at the end of a test. It was therefore concluded that improving the coating adhesion is an important step towards improved performance of alternative binder hardmetals.

Some of the alternative binders in this work were iron rich alloys. Alloys rich in iron can be either austenitic, martensitic or a mixture of the two and this will have a large influence on the final hardmetal properties. It is also possible to make an iron rich alloy which is austenitic at room temperature, but forms deformation induced martensite as a response to stress or strain. This work investigated deformation induced martensite formed during scratching and in abrasive wear of a binder phase alloy of iron, nickel and cobalt. Electron diffraction in both scanning electron microscopes and transmission electron microscopes showed that scratching the surface of this hardmetal resulted in a finely grained surface layer of mixed austenite and martensite. This could prove beneficial in applications.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2019. p. 77
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1873
Keywords
hardmetal, cemented carbide, alternative binders, steel turning, electron microscopy, electron diffraction
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Tribo Materials
Identifiers
urn:nbn:se:uu:diva-395619 (URN)978-91-513-0789-3 (ISBN)
Public defence
2019-12-06, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2019-11-14 Created: 2019-10-22 Last updated: 2019-11-14

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Toller, LisaJacobson, StaffanNorgren, Susanne

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