Tempering Behavior of a Si-Rich Low-Alloy Medium-Carbon Steel

Owing to the addition of Si, 0.33C-1.8Si-1.44Mn-0.58Cr steel exhibits a unique tempering behavior. The tempering takes place in two distinct sequential stages that are significantly different from those in steels containing 0.2–0.5 wt.% of Si. Stage I is associated with the precipitation of transiti...

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Main Authors: Sergey Borisov, Yuliya Borisova, Evgeniy Tkachev, Tatiana Kniaziuk, Rustam Kaibyshev
Format: Article
Language:English
Published: MDPI AG 2023-08-01
Series:Metals
Subjects:
Online Access:https://www.mdpi.com/2075-4701/13/8/1403
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author Sergey Borisov
Yuliya Borisova
Evgeniy Tkachev
Tatiana Kniaziuk
Rustam Kaibyshev
author_facet Sergey Borisov
Yuliya Borisova
Evgeniy Tkachev
Tatiana Kniaziuk
Rustam Kaibyshev
author_sort Sergey Borisov
collection DOAJ
description Owing to the addition of Si, 0.33C-1.8Si-1.44Mn-0.58Cr steel exhibits a unique tempering behavior. The tempering takes place in two distinct sequential stages that are significantly different from those in steels containing 0.2–0.5 wt.% of Si. Stage I is associated with the precipitation of transition carbides in a paraequilibrium manner, can take place in temperatures ranging from ~200 to ~474 °C, and concurrently increases strength, ductility, and toughness. Stage II is associated with the decomposition of retained austenite to bainitic ferrite and transition carbides. As a result, no significant effect of overlapping of Stage I with Stage II takes place. Stage III does not occur at temperatures below ~474 °C, since the precipitation of cementite in a orthoequilibrium manner is suppressed by the addition of 1.8 wt.% of Si. It was shown that a major portion of carbon atoms redistributes to Cottrell atmospheres under quenching. During low-temperature tempering at 200–400 °C, the precipitation of transition carbides consumes a large portion of carbon atoms, thereby increasing the number of ductile fractures and improving the impact toughness without strength degradation. The formation of chains of cementite particles on boundaries takes place in Stage IV at a tempering temperature of 500 °C. This process results in the full depletion of excess carbon from a ferritic matrix that provides increased ductility and toughness but decreased strength.
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spelling doaj.art-a54c3bce8571422997152bb77cecdb8c2023-11-19T02:10:41ZengMDPI AGMetals2075-47012023-08-01138140310.3390/met13081403Tempering Behavior of a Si-Rich Low-Alloy Medium-Carbon SteelSergey Borisov0Yuliya Borisova1Evgeniy Tkachev2Tatiana Kniaziuk3Rustam Kaibyshev4Laboratory of Advanced Steels for Agricultural Machinery, Russian State Agrarian University—Moscow Timiryazev Agricultural Academy, 127550 Moscow, RussiaLaboratory of Advanced Steels for Agricultural Machinery, Russian State Agrarian University—Moscow Timiryazev Agricultural Academy, 127550 Moscow, RussiaLaboratory of Advanced Steels for Agricultural Machinery, Russian State Agrarian University—Moscow Timiryazev Agricultural Academy, 127550 Moscow, RussiaLaboratory of Advanced Steels for Agricultural Machinery, Russian State Agrarian University—Moscow Timiryazev Agricultural Academy, 127550 Moscow, RussiaLaboratory of Advanced Steels for Agricultural Machinery, Russian State Agrarian University—Moscow Timiryazev Agricultural Academy, 127550 Moscow, RussiaOwing to the addition of Si, 0.33C-1.8Si-1.44Mn-0.58Cr steel exhibits a unique tempering behavior. The tempering takes place in two distinct sequential stages that are significantly different from those in steels containing 0.2–0.5 wt.% of Si. Stage I is associated with the precipitation of transition carbides in a paraequilibrium manner, can take place in temperatures ranging from ~200 to ~474 °C, and concurrently increases strength, ductility, and toughness. Stage II is associated with the decomposition of retained austenite to bainitic ferrite and transition carbides. As a result, no significant effect of overlapping of Stage I with Stage II takes place. Stage III does not occur at temperatures below ~474 °C, since the precipitation of cementite in a orthoequilibrium manner is suppressed by the addition of 1.8 wt.% of Si. It was shown that a major portion of carbon atoms redistributes to Cottrell atmospheres under quenching. During low-temperature tempering at 200–400 °C, the precipitation of transition carbides consumes a large portion of carbon atoms, thereby increasing the number of ductile fractures and improving the impact toughness without strength degradation. The formation of chains of cementite particles on boundaries takes place in Stage IV at a tempering temperature of 500 °C. This process results in the full depletion of excess carbon from a ferritic matrix that provides increased ductility and toughness but decreased strength.https://www.mdpi.com/2075-4701/13/8/1403quenching and temperingmartensitelow-alloy steelmechanical propertiesmicrostructurephase transformation
spellingShingle Sergey Borisov
Yuliya Borisova
Evgeniy Tkachev
Tatiana Kniaziuk
Rustam Kaibyshev
Tempering Behavior of a Si-Rich Low-Alloy Medium-Carbon Steel
Metals
quenching and tempering
martensite
low-alloy steel
mechanical properties
microstructure
phase transformation
title Tempering Behavior of a Si-Rich Low-Alloy Medium-Carbon Steel
title_full Tempering Behavior of a Si-Rich Low-Alloy Medium-Carbon Steel
title_fullStr Tempering Behavior of a Si-Rich Low-Alloy Medium-Carbon Steel
title_full_unstemmed Tempering Behavior of a Si-Rich Low-Alloy Medium-Carbon Steel
title_short Tempering Behavior of a Si-Rich Low-Alloy Medium-Carbon Steel
title_sort tempering behavior of a si rich low alloy medium carbon steel
topic quenching and tempering
martensite
low-alloy steel
mechanical properties
microstructure
phase transformation
url https://www.mdpi.com/2075-4701/13/8/1403
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