Abstract
The formation mechanisms and properties of white layers produced in machining of hardened steels are not clearly understood to date. In particular, detailed analysis of their structure and mechanical properties is lacking. This paper investigates the differences in structure and properties of white layers formed during machining of hardened AISI 52100 steel (62 HRC) at different cutting speeds. A combination of experimental techniques including transmission electron microscopy (TEM), X-ray diffraction (XRD), and nano-indentation are used to analyze the white layers formed. TEM results suggest that white layers produced at low-to-moderate cutting speeds are in large part due to grain refinement induced by severe plastic deformation, whereas white layer formation at high cutting speeds is mainly due to thermally-driven phase transformation. The white layers at all speeds are found to be comprised of very fine (nano-scale) grains compared to the bulk material. XRD-based residual stress and retained austenite measurements, and hardness data support these findings.
Original language | English |
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Pages (from-to) | 88-97 |
Number of pages | 10 |
Journal | Materials Science and Engineering: A |
Volume | 390 |
Issue number | 1-2 |
DOIs | |
State | Published - Jan 15 2005 |
Funding
The first two authors would like to acknowledge the support of the National Science Foundation (Grant No. DMI-0100176) and the NIST ATP Award No. 70NANBOH3045. The authors are also grateful to the HTML Users Program in the Oak Ridge National Lab for access to XRD, TEM and nanoindentation equipment for the experiments.
Keywords
- Hard turning
- Phase transformation
- Plastic deformation
- White layers