Ilkka Miettunen, Sumit Ghosh, Mahesh C. Somani, Sakari Pallaspuro, Jukka Kömi, Competitive mechanisms occurring during quenching and partitioning of three silicon variants of 0.4 wt.% carbon steels, Journal of Materials Research and Technology, 2021, ISSN 2238-7854, https://doi.org/10.1016/j.jmrt.2021.01.085
Competitive mechanisms occurring during quenching and partitioning of three silicon variants of 0.4 wt.% carbon steels
|Author:||Miettunen, Ilkka1; Ghosh, Sumit1; Somani, Mahesh C.1;|
1University of Oulu, Materials and Mechanical Engineering, Centre for Advanced Steels Research, Pentti Kaiteran Katu 1, P.O. Box 4200, 90014 Oulu, Finland
|Online Access:||PDF Full Text (PDF, 2.2 MB)|
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe202102013410
|Publish Date:|| 2021-02-01
Quenching and partitioning (Q&P) treated steels are traditionally alloyed with silicon (Si), but its precise role on microstructural mechanisms occurring during partitioning is not thoroughly understood. In this study, dilatometric analysis has been combined with detailed microstructural characterization to unravel the competing mechanisms occurring during partitioning either in parallel or in succession. Three 0.4 wt.% carbon steels with varying Si contents were quenched to 150 °C for ∼20 % untransformed austenite, and partitioned for 10-1000 s in the temperature range 200-300 °C. The steel with low Si content (0.25 wt.%) exhibited substantial bainitic transformation during partitioning at 300 °C and only 4% retained austenite (RA) at room temperature (RT) even after 1000 s hold. In contrast, a high Si fraction (1.5 wt.%) enabled retention of ∼18 % austenite under similar conditions. While η-carbides precipitated within the martensite laths in the high-Si steel, cementite precipitated in the low-Si variant. Furthermore, carbide precipitation and growth were strongly suppressed by high Si content. Secondary martensite formation occurred from carbon-enriched austenite during final cooling, irrespective of Si-content. Results illustrate that Si retards austenite decomposition at higher partitioning temperatures but does not improve carbon partitioning at lower temperatures.
Journal of materials research and technology
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
216 Materials engineering
The authors convey their sincere thanks to the Academy of Finland for providing resources to conduct this research work under the auspices of the Genome of Steel (Profi3) project #311934.
© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).