Leif Viskari

Forskare at Chalmers, Physics, Materials Microstructure

My research is focused on engineering alloys and the correlation between material structure/chemistry and engineering properties - specifically the degradation of said properties owing to deleterious influence of the operating environment. I conduct my studies mainly using SEM, TEM, and APT with FIB/SEM specimen preparation. I currently investigate the influence of hydrogen (deriving e.g. from corrosion) on the premature failure of bearing steel. This project is performed in my dual role as Researcher at Chalmers and Development Engineer at the bearing company SKF, supported by the SSF Strategic Mobility grant. I have also past experience from likeminded research on Ni-base alloys in aero engines with respect to oxygen and oxidation. Additional experiences include welding of Ni-base alloys and atomic scale microstructure investigations of light alloys (Al, Mg).

Source: chalmers.se

Projects

2015–2016

Influence of hydrogen on premature failure of bearing steel

Leif Viskari Materials Microstructure
Swedish Foundation for Strategic Research (SSF)

2014–2015

Degradation of Bearing Steel Microstructure in Wind Turbines

Mattias Thuvander Materials Microstructure
Leif Viskari Materials Microstructure
Seyed Hosseini Materials Microstructure
ÅForsk (Ångpanneföreningens Foundation for Research and Development)

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Publications

2015

Multi-scale, multi-technique investigation of oxidation assisted cracking

Leif Viskari, Katie L. Moore, Krystyna Marta Stiller et al
Conference contribution
2014

Reduced Dwell-Fatigue Resistance in a Ni-Base Superalloy After Short-Term Thermal Exposure

Leif Viskari, Magnus Hörnqvist Colliander
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science. Vol. 45 (6), p. 2699-2703
Journal article
2014

High-temperature crack growth in a Ni-base superalloy during sustained load

Leif Viskari, Katie L. Moore, Krystyna Marta Stiller et al
Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. Vol. 609, p. 131-140
Journal article
2013

Intergranular crack tip oxidation in a Ni-base superalloy

Magnus Hörnqvist Colliander, Krystyna Marta Stiller, Leif Viskari et al
Acta Materialia. Vol. 61 (10), p. 3630-3639
Journal article
2013

Fracture mechanisms during intergranular hold time fatigue crack growth in Inconel 718 superalloy

Leif Viskari, JJ Moverare, Krystyna Marta Stiller et al
13th International Conference on Fracture 2013, ICF 2013; Beijing; China; 16 June 2013 through 21 June 2013. Vol. 3, p. 1833-1841
Paper in proceedings
2013

Effects of different solution heat treatments on the hot ductility of superalloys Part 3 - Waspaloy

Leif Viskari, Joel Håkan Andersson, Göran Sjöberg et al
Materials Science and Technology. Vol. 29 (1), p. 43-53
Journal article
2013

Atom probe tomography of oxide scales

Hans-Olof Andrén, Gustav Sundell, Krystyna Marta Stiller et al
Oxidation of Metals. Vol. 79 (3-4), p. 227-238
Journal article
2012

Effect of different solution heat treatments on hot ductility of superalloys Part 2-Allvac 718Plus

Joel Håkan Andersson, Göran Sjöberg, Leif Viskari et al
Materials Science and Technology. Vol. 28 (6), p. 733-741
Journal article
2012

Effect of solution heat treatments on superalloys Part 1 - alloy 718

Göran Sjöberg, Joel Håkan Andersson, Leif Viskari et al
Materials Science and Technology. Vol. 28 (5), p. 609-619
Journal article
2011

Atom probe tomography of Ni-base superalloys Allvac 718Plus and Alloy 718

Krystyna Marta Stiller, Leif Viskari
Ultramicroscopy. Vol. 111 (6), p. 652-658
Journal article
2011

Oxygen influenced intergranular crack propagation: analysing microstructure and chemistry in the crack tip region

S. Johansson, Krystyna Marta Stiller, Leif Viskari
Materials at High Temperatures. Vol. 28 (4), p. 336-341
Journal article
2011

Grain boundary microstructure and fatigue crack growth in Allvac 718Plus superalloy

Yu Cao, Mats Norell, Leif Viskari et al
Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. Vol. 528 (6), p. 2570-2580
Journal article
2010

Hold-time fatigue crack growth of Allvac 718Plus

M. Hörnqvist, Leif Viskari, G. Sjob╠łerg et al
7th International Symposium on Superalloy 718 and Derivatives 2010. Pittsburgh, 10-13 October 2010. Vol. 2, p. 705-717
Paper in proceedings
2008

Hot Cracking of Allvac 718Plus, Alloy 718 and Waspaloy at Varestraint testing

Leif Viskari, A. Brederholm, G. Sjöberg et al
Proceedings of the 47th Conference of Metallurgists, August 24-27, Winnipeg, Canada, 2008., p. 401-413
Conference contribution