Abstract
The quenching and tempering process of SAE 52100 bearing steel was continuously monitored via in-situ dilatometry and high-energy X-ray diffraction, mapping the evolution of the constituent phases and lattice distortions and their direct correlation with observed dimensional changes of the material. During quenching from an austenitisation temperature of 860–50 °C, there was a continuous increase in lattice distortion in the parent austenite. Below the martensite start temperature of MS = 209 ± 15.0 °C, the c - lattice parameter and lattice distortion of the formed martensite initially decreased, then subsequently presented an increasing trend. An increase in sample length was detected only at martensite fractions ≥ 18 vol%, and occurred simultaneously with an increase in the cα’/aα’ tetragonality ratio. An increase in sample length was detected during isothermal holding at 50 °C with a reduction in the martensite cα’ parameter, potentially due to the expulsion of carbon. Tempering promoted the loss of martensite tetragonality at 283 ± 7.80 °C. At a tempering temperature of 340 °C, the austenite retained after quenching transformed completely within 1.5 min. The following reduction in sample length and expulsion of carbon from martensite is correlated to the relaxation of lattice distortion in the martensite-bainitic ferrite matrix.
Original language | English |
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Article number | 102930 |
Number of pages | 11 |
Journal | Materials Today Communications |
Volume | 29 |
Early online date | 27 Oct 2021 |
DOIs | |
Publication status | Published - Dec 2021 |
Bibliographical note
Funding Information:This work was made possible by financial support and samples provided by The Timken Company . The PETRA III synchrotron facility at DESY (Germany) are acknowledged for the time granted on the P07 beam line under the proposal I-20180929 EC. Chris Akey, Matt Hillard, Matt Boyle, Greg Kissiar and Bob Pendergrass of the TIMKEN WHQ are acknowledged for assisting with quench & tempering and microstructure characterization of 52100 steel.
Publisher Copyright:
© 2021 Elsevier Ltd
Keywords
- Dilatometry
- Lattice distortion
- Martensitic transformation
- SAE 52100 steel
- Synchrotron X-ray diffraction
ASJC Scopus subject areas
- General Materials Science
- Mechanics of Materials
- Materials Chemistry