A descriptive phenomenological model for white layer formation in hard turning of AISI 52100 bearing steel
Artikel i vetenskaplig tidskrift, 2021

This paper investigates the characteristics and the formation of white layers and dark layers induced by
hard turning of through-hardened AISI 52,100 steel. The investigation showed that different types of
white layers exist e.g., formed predominantly through excessive thermal or mechanical energy loading.
The thermally induced white layer is formed when the cutting temperature is above the critical
austenitisation temperature for the material. The nano-sized microstructure is initiated through dynamic
recovery, which transitions to dynamic recrystallisation when the temperature rises above the onset
temperature for dynamic recrystallisation. The corresponding white layer is characterised by a higher
retained austenite content compared to the unaffected material, and the presence of a dark layer beneath
the white layer. The white layer and the adjacent dark layer are found to be
12% harder and 14% softer,
respectively, compared to the unaffected material. On the other hand, the mechanically induced white
layer is formed through severe plastic deformation, where the formation is controlled by dynamic
recovery and results in an elongated and broken-down substructure. Neither austenite nor an adjacent
dark layer could be found for such white layers. The mechanically induced white layer is
26% harder
than the unaffected material. For both types of white layer, (Fe, Cr)3C carbides are found in the
microstructure. The investigation shows that the heating rate, cooling rate, pressure, and duration of
contact between the cutting tool and workpiece surface should also be considered to understand the
underlying formation mechanisms. The characteristics of the examined white layers and the cutting
conditions are summarised in a descriptive phenomenological model in order to create a systematic
approach for the definition of the different types of white layers.


Dark layer

Phase Transformation

White layer

severe plastic deformation


Seyed Hosseini

Chalmers, Industri- och materialvetenskap, Material och tillverkning

Uta Klement

Chalmers, Industri- och materialvetenskap, Material och tillverkning

CIRP Journal of Manufacturing Science and Technology

1755-5817 (ISSN) 1878-0016 (eISSN)

Vol. 32 299-310


Hållbar utveckling







Chalmers materialanalyslaboratorium



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