Kinetics of the partitioning of carbon and substitutional alloying elements during quenching and partitioning (Q&amp;P) processing of medium Mn steel

Seo, Eun Jung; Cho, Lawrence; Cooman, Bruno C. De

doi:10.1016/j.actamat.2016.01.059

Cited by 124 publications

(50 citation statements)

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“…As the diffusion distance from martensite to austenite is decreased by the refinement of the grain size, the kinetics of the C partitioning is accelerated. Recent report has shown the partitioning of substitutional alloying elements near the phase boundaries [20]. Therefore, the austenite stabilizing effect by partitioning of C and substitutional alloying elements is expected to be amplified in a microstructure consisting of small martensite packet and UFG austenite.…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 98%

Near-Ac3 austenitized ultra-fine-grained quenching and partitioning (Q&P) steel

2016

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Section: Contents Lists Available At Sciencedirectmentioning

confidence: 98%

Near-Ac3 austenitized ultra-fine-grained quenching and partitioning (Q&P) steel

2016

Self Cite

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“…The reason is the carbon in martensite diffuses to the retained austenite and make it rich in carbon, the increase of retained austenite from table 2 can reflect this phenomenon. When the partition time is extended to 1200s, the strength is increased instead, which is due to the transformation of reduction leaded by decomposition of martensite [16][17]. Figure(a),the main alloying elements of the carbides are C and Cr, the mass fraction were 29% and 18% respectively, and it was determined that the carbides were rich in Cr.…”

Section: B Effect Of Carbide Size Distribution On Mechanical Propertmentioning

confidence: 99%

Study of The Precipitation Behavior and Strengthening of Carbides during the Partition Process

Jiang¹,

Zhao²

2018

Proceedings of the 4th Annual International Conference on Material Engineering and Application (ICMEA 2017)

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Abstract-In this paper, the size distribution and quantity of carbides precipitated during the partition process of 60Si 2 CrVA spring steel treated by Q&P with different partition time were statistically analyzed by SEM. Carbide particles were obtained by electrolytic extraction of 60Si 2 CrVA treated by Q&P with partition time of 1200s, and the contribution of different kinds of carbides to the yield strength was calculated. The results show: during the partition process of 60Si2CrVA spring steel, the size and volume fraction of carbides increase continuously with the extension of partition time, while the contribution of carbides to yield strength decreases gradually. Carbides rich in V(≤80nm)and carbides rich in Cr(>80nm)are mainly precipitated in the partition process, and carbides rich in V play the key role in precipitation strengthening.Keywords-60Si2CrVA spring steel; Q&P process; Partition time; Carbides; Precipitation strengthening I INTRODUCTIONSpring steel is widely used in aircraft, railway vehicles, such as automobiles and tractors transport and other industrial products. It mainly work in bending periodic, alternating torsion stress conditions, subjected to pull, pressure, shock, torsional fatigue, corrosion and other effects, sometimes bear high short-term sudden load. So the comprehensive mechanical properties of spring steel high requirements.The microstructure of martensite and retained austenite can be obtained by heat treatment of spring steel by Q&P process, and it has the advantages of both high strength and high plasticity in performance [1][2][3][4].Although the Si and Al elements in the spring steel can inhibit the precipitation of cementite in the Q&P process,E.P.Da Siva, D.De knijf, D.V.Edmods and Moor [5][6] all indicate that carbides precipitation in the partition period cannot be completely suppressed even in low carbon steels with relatively high Si and Al content, especially transition carbides [7][8].While precipitation of carbides and the diffusion of carbon in martensite into austenite are a competition mechanism.Carbides precipitation not only lead to the less content of retained austenite at room temperature, but also contribute to poor carbon in martensite,which can reduce comprehensive mechanical properties.As the second phase particle precipitation, the size of carbides will affect the mechanical properties of steel [9][10].The large size carbide particles formed in partition time are easy to cause stress concentration, reduce the plasticity and toughness,and it will result in serious brittle fracture.So,in addition to martensite,precipitation of carbides is also an important factor determining the mechanical properties of spring steel treated by Q&P process [11][12].There were no systemic study of precipitation of spring steel in the partition of carbides and its effects on the mechanical properties in the domestic and foreign literatures.The purpose of the present work was to explore the influence ofcarbides on mechanical properties by the statistics of carbides precip...

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“…are incorporated in the model to account for the di usion constant in austenite (D γ (c)) and martensite (D α ), respectively [49,50,51]. In Eqn.…”

Section: Carbon DI Usivitymentioning

confidence: 99%

Phase-field analysis of quenching and partitioning in a polycrystalline Fe-C system under constrained-carbon equilibrium condition

Amos

Schoof

Streichan

et al. 2019

Computational Materials Science

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Mechanical properties of steels are signi cantly enhanced by retained austenite. Particularly, it has been shown that a recently developed heat-treatment technique called enching and Partitioning (Q&P) stabilises austenite e ectively. In the present work, the phase-eld approach is adopted to simulate the phase transformation and carbon di usion, which respectively accompanies the quenching and partitioning process of the polycrystalline Fe-C system. By incorporating the chemical driving-force from the CALPHAD database, the elastic phase-eld model, which recovers the sharp-interface solutions, simulates the martensite (α ) transformation at three di erent quenching temperatures. e resulting martensite volume-fractions are in complete agreement with the analytical predictions. For the rst time, in this study, the constrained carbon equilibrium (CCE) condition is introduced in the polycrystalline set-up to yield the predicted partitioning endpoints. Under the CCE condition, the carbon partitioning in two alloys of varying composition is analysed through the phase-eld model which employs chemical potential as the dynamic variable. e volume fraction and distribution of retained austenite is determined from the carbon distribution and its temporal evolution during the partitioning is investigated. It is identi ed that in the initial stages of partitioning carbon gets accumulated in the austenite (γ) along the γα -interface, owing to the substantial di erence in the di usivities and CCE endpoints. is accumulation stabilises the austenite adjacent to the interface. However, depending on the martensite volume-fraction and the alloy composition, the evolution of the arXiv:1812.04306v1 [cond-mat.mtrl-sci] 11 Dec 2018 stabilised austenite varies. Furthermore, the in uence of the phase distribution on the kinetics of the temporal evolution of retained austenite is elucidated.

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Kinetics of the partitioning of carbon and substitutional alloying elements during quenching and partitioning (Q&P) processing of medium Mn steel

Cited by 124 publications

References 35 publications

Near-Ac3 austenitized ultra-fine-grained quenching and partitioning (Q&P) steel

Near-Ac3 austenitized ultra-fine-grained quenching and partitioning (Q&P) steel

Study of The Precipitation Behavior and Strengthening of Carbides during the Partition Process

Phase-field analysis of quenching and partitioning in a polycrystalline Fe-C system under constrained-carbon equilibrium condition

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