Microstructure Analysis and Mechanical Properties of Low Alloyed Steel with Retained Austenite Obtained by Heat Treatment

Kučerová, Ludmila; Jandová, Andrea; Rubešová, Kateřina

doi:10.21062/ujep/277.2019/a/1213-2489/mt/19/2/243

Cited by 7 publications

(4 citation statements)

References 14 publications

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“…Furthermore, both types of steel were also investigated mainly for applications in the automotive industry. While DP steels aim at a two-phase microstructure consisting of the mixture of ferrite and martensite [2], the TRIP steels possess more complex microstructures of ferrite, bainite and retained austenite [3][4]. DP thus requires quick quenching once the sufficient amount of ferrite is obtained, while TRIP steels need a second isothermal hold at the temperature of intensive bainitic transformation to obtain a special, carbide-free bainite consisting of the bainitic ferrite and retained austenite laths [4].…”

Section: Introductionmentioning

confidence: 99%

“…While DP steels aim at a two-phase microstructure consisting of the mixture of ferrite and martensite [2], the TRIP steels possess more complex microstructures of ferrite, bainite and retained austenite [3][4]. DP thus requires quick quenching once the sufficient amount of ferrite is obtained, while TRIP steels need a second isothermal hold at the temperature of intensive bainitic transformation to obtain a special, carbide-free bainite consisting of the bainitic ferrite and retained austenite laths [4]. Nevertheless, the TRIP steel requires alloying with manganese and silicon to retain a sufficient amount of retained austenite at room temperature.…”

Section: Introductionmentioning

confidence: 99%

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Effect of various heat and thermo-mechanical treatments on low alloyed CMnAlNb high strength steel

Kučerová¹,

Tichá²,

Stehlík³

2022

Manufacturing Technology

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Low carbon low alloyed high strength steel with the chemical composition suitably designed to support the stabilization of retained austenite was used in this work. The steel was processed by conventional annealing for a reference and several different heat and thermomechanical treatments were further proposed to test typical TRIP (transformation induced plasticity), DP (dual phase) steel and QP (quenching and partitioning) processing routes. All the processing methods used the same soaking temperature of 1050 °C. Processed samples were subjected to metallographic analysis, hardness measurement and tensile test to characterise resulting microstructures. While simple annealing reached tensile strength of 861 MPa with 25% of total elongation, the best combination of the highest tensile strength of 903 MPa and a total elongation of 32% was obtained after processing typical for TRIP steel. QP treatment resulted in the highest tensile strength of 1289 MPa with a total elongation of 19%.TRIP steel DP steel QP treatment high strength steel

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of various heat and thermo-mechanical treatments on low alloyed CMnAlNb high strength steel

Kučerová¹,

Tichá²,

Stehlík³

2022

Manufacturing Technology

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“…In magnetization measurements, the saturation magnetization can be obtained from the magnetization curve of a reference fully ferric or martensitic material. In this method, the amount of paramagnetic retained austenite can be measured due to a decrease of saturation magnetization compared to the fully ferromagnetic reference material [ 31 , 32 ].…”

Section: Methodsmentioning

confidence: 99%

Austenite Decomposition of a Lean Medium Mn Steel Suitable for Quenching and Partitioning Process: Comparison of CCT and DCCT Diagram and Their Microstructural Changes

et al. 2022

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The present work deals with the dilatometric study of a hot-rolled 0.2C3Mn1.5Si lean medium Mn steel, mainly suitable for the quenching and partitioning (Q&P) heat treatment in both hot-rolled or cold-rolled condition, subjected to a variation of austenitization temperature. These investigations were performed in a temperature range of 800–1200 °C. In this context, the martensite transformation start temperature (Ms) was determined as a function of austenitization temperature and in turn obtained prior austenite grain size (PAGS). The results show rise in prior austenite grain size due to increasing austenitization temperature, resulting in elevated Ms temperatures. Measured dilatation curves were confronted with the metallographic analysis by means of scanning electron microscopy (SEM). The present paper also focuses on the construction of a continuous cooling transformation (CCT) and deformation continuous cooling transformation (DCCT) diagram of the investigated lean medium Mn steel in a range of cooling rates from 100 to 0.01 °C/s and their subsequent comparison. By comparing these two diagrams, we observed an overall shift of the DCCT diagram to shorter times compared to the CCT diagram, which represents an earlier formation of phase transformations with respect to the individual cooling rates. Moreover, the determination of individual phase fractions in the CCT and DCCT mode revealed that the growth stage of ferrite and bainite is decelerated by deformation, especially for intermediate cooling rates. Microstructural changes corresponding to cooling were also observed using SEM to provide more detailed investigation of the structure and present phases identification as a function of cooling rate. Moreover, the volume fractions obtained from the saturation magnetization method (SMM) are compared with data from X-ray diffraction (XRD) measurements. The discussion of the data suggests that magnetization measurements lead to more reliable results and a more sensitive detection of the retained austenite than XRD measurements. In that regard, the volume fraction of retained austenite increased with a decrease of cooling rate as a result of larger volume fraction of ferrite and bainite. The hardness of the samples subjected to the deformation was slightly higher compared to non-deformed samples. The reason for this was an evident grain refinement after deformation.

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“…High-strength stainless steels with the necessary set of properties have found the widest application [16]. These are transitional stainless steels, in the structure of which, after a cycle of deformation-thermal action (rolling + aging), there is a certain amount of retained austenite [17], which can undergo a γ → α transformation during operation [18]. The stability of retained austenite to martensitic transformation will determine the resistance of martensite to the centers of initiation and propagation of cracks [19], that is, to the intensity of destruction of the material under the action of operating factors [20,21].…”

Section: Introductionmentioning

confidence: 99%

Increasing the Structural Strength of Corrosion-resistant Steel for Elastic Components of Diaphragm Compressor

Krmela¹,

Говорун²,

Berladir³

et al. 2021

Manufacturing Technology

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The design features of diaphragm compressors are discussed in this article. For preventing the formation of local stresses in certain areas of the diaphragm, it is recommended to use thin sheet stainless steel of the transition class. A comparative analysis is made of two batches of steel tape, differing in the value of the saturation magnetic induction, which is identical to the content of the martensite phase in the structure of the material before the final cycle of cold plastic deformation. The results of the study of the influence of the deformation temperature (20-300 ºС) on the change in mechanical properties (σb, σ0.2, δ) revealed a different tendency to embrittlement of the material of the tapes for these batches. For increasing the operational reliability of the compressor's diaphragm elements, it is recommended to use a material, the structure of which contains a certain amount of workhardened retained austenite. This makes it possible to undergo additional martensitic transformation under the action of peak loads in local areas and increases the structural strength of corrosion-resistant steel for the manufacture of a compressor diaphragm.

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Microstructure Analysis and Mechanical Properties of Low Alloyed Steel with Retained Austenite Obtained by Heat Treatment

Cited by 7 publications

References 14 publications

Effect of various heat and thermo-mechanical treatments on low alloyed CMnAlNb high strength steel

Effect of various heat and thermo-mechanical treatments on low alloyed CMnAlNb high strength steel

Austenite Decomposition of a Lean Medium Mn Steel Suitable for Quenching and Partitioning Process: Comparison of CCT and DCCT Diagram and Their Microstructural Changes

Increasing the Structural Strength of Corrosion-resistant Steel for Elastic Components of Diaphragm Compressor

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