University of Oulu

IMiettunen, I., Ghosh, S., Somani, M. C., Pallaspuro, S., & Kömi, J. (2021). Competitive mechanisms occurring during quenching and partitioning of three silicon variants of 0.4 wt.% carbon steels. Journal of Materials Research and Technology, 11, 1045–1060. 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

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Author: Miettunen, Ilkka1; Ghosh, Sumit1; Somani, Mahesh C.1;
Organizations: 1University of Oulu, Materials and Mechanical Engineering, Centre for Advanced Steels Research, Pentti Kaiteran Katu 1, P.O. Box 4200, 90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 5 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe202102013410
Language: English
Published: Elsevier, 2021
Publish Date: 2021-02-01
Description:

Abstract

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.

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Series: Journal of materials research and technology
ISSN: 2238-7854
ISSN-E: 2214-0697
ISSN-L: 2238-7854
Volume: 11
Pages: 1045 - 1060
DOI: 10.1016/j.jmrt.2021.01.085
OADOI: https://oadoi.org/10.1016/j.jmrt.2021.01.085
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Subjects:
Funding: 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.
Academy of Finland Grant Number: 311934
Detailed Information: 311934 (Academy of Finland Funding decision)
Copyright information: © 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/).
  https://creativecommons.org/licenses/by-nc-nd/4.0/