University of Oulu

Javaheri, V., Sadeghpour, S., Karjalainen, P., Lindroos, M., Haiko, O., Sarmadi, N., Pallaspuro, S., Valtonen, K., Pahlevani, F., Laukkanen, A., & Kömi, J. (2022). Formation of nanostructured surface layer, the white layer, through solid particles impingement during slurry erosion in a martensitic medium-carbon steel. Wear, 496–497, 204301.

Formation of nanostructured surface layer, the white layer, through solid particles impingement during slurry erosion in a martensitic medium-carbon steel

Saved in:
Author: Javaheri, V.1; Sadeghpour, S.1; Karjalainen, P.1;
Organizations: 1Materials and Mechanical Engineering, Centre for Advanced Steels Research, University of Oulu, Finland
2Integrated Computational Materials Engineering, VTT Technical Research Centre of Finland, Espoo, Finland
3Centre for Sustainable Materials Research and Technology, SMaRT@UNSW, School of Materials Science and Engineering, UNSW, Sydney, Australia
4Tampere Wear Center, Materials Science and Environmental Engineering, Faculty of Engineering and Natural Sciences, Tampere University, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 17.5 MB)
Persistent link:
Language: English
Published: Elsevier, 2022
Publish Date: 2022-05-18


The extremely altered topmost surface layer, known as the white layer, formed in a medium-carbon low-alloy steel as result of impacts by angular 10–12 mm granite particles during the slurry erosion process is comprehensively investigated. For this purpose, the characteristics, morphology, and formation mechanism of this white layer are described based on the microstructural observations using optical, scanning and transmission electron microscopies as well as nanoindentation hardness measurements and modelling of surface deformation. The white layer exhibits a nanocrystalline structure consisting of ultrafine grains with an average size of 200 nm. It has a nanohardness level of around 10.1 GPa, considerably higher than that of untempered martensitic bulk material (5.7 GPa) achieved by an induction hardening treatment. The results showed that during the high-speed slurry erosion process, solid particle impacts brought forth conditions of high strain, high strain rate, and multi-directional strain paths. This promoted formation of a cell-type structure at first and later, after increasing the number of impacts, development of subgrains following by subgrain rotation and eventually formation of a nanocrystalline structure with ultra-high hardness. The model confirmed that high strain conditions — much higher than required for the onset of plastic deformation — can be achieved on the surface resulting in severe microstructural and property changes during the slurry erosion test.

see all

Series: Wear. An international journal on the science and technology of friction, lubrication and wear
ISSN: 0043-1648
ISSN-E: 1873-2577
ISSN-L: 0043-1648
Volume: 496-497
Article number: 204301
DOI: 10.1016/j.wear.2022.204301
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: The authors are grateful for the financial support from the Academy of Finland (#311934 – Genome of Steel Project). The corresponding author would also like to thank Jenny and Antti Wihuri Foundation for the financial support.
Copyright information: © 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (