Temperature-Dependent Microstructural Evolution of Al-Rich Medium-Mn Steel During Intercritical Annealing

Skowronek, Adam; Grajcar, A.; Kozłowska, Aleksandra; Janik, Aleksandra; Morawiec, Mateusz; Petrov, Roumen

doi:10.1007/s11661-022-06721-2

Cited by 10 publications

(12 citation statements)

References 55 publications

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“…All samples were first heated to the intercritical region at 680 • C for 30 min and then quenched at 60 • C/s to the room temperature. Results of our previous study [7] showed that the applied heat treatment conditions provide full stabilization of austenite to room temperature. After that a short secondary IA step was performed at a higher temperature (850 • C) for 30s followed by cooling to room temperature.…”

Section: Initial Materials and Heat Treatmentmentioning

confidence: 94%

“…However, the significant fraction of this intercritical austenite was insufficiently enriched in C and Mn and consequently unstable at room temperature. In case of steel produced via one-step IA, the fraction of RA is usually from 20% to 40% [4][5][6][7]. However, the aim of the second annealing step is to produce a high fraction of low-C martensite instead of soft ferrite in order to increase strength properties of medium-Mn steels and to reduce the difference in hardness between particular microstructural constituents.…”

Section: Microstructure Characterizationmentioning

confidence: 99%

“…The beneficial mechanical properties exhibited by medium-Mn steels are attributed to the presence of metastable retained austenite (RA), which transforms into martensite upon deformation leading to transformation induced plasticity (TRIP) effect. Typically, these steels are produced via single-step intercritical annealing (IA) process in order to obtain the microstructure composed of fine ferrite (80-60 vol%) and austenite (20-40 vol%) [4][5][6][7]. The proper design of the thermal treatment schedule of IA process is crucial for obtaining an optimal balance between ferrite and austenite volume fractions of desired morphology.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Microstructure Evolution of Medium-Manganese Al-Alloyed Steel Manufactured by Double-Step Intercritical Annealing: Effects of Heating and Cooling Rates

et al. 2022

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Section: Initial Materials and Heat Treatmentmentioning

confidence: 94%

Section: Microstructure Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Microstructure Evolution of Medium-Manganese Al-Alloyed Steel Manufactured by Double-Step Intercritical Annealing: Effects of Heating and Cooling Rates

et al. 2022

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“…[13] In general, an increase of the austenitization temperature increases the austenite fraction and accelerates its formation. [14,15] However, there comes a point when the overall C and Mn concentration in steel and the diffusion rate cannot keep up with the rapid increase in the RA fraction, resulting in a poor stability, and favoring martensitic transformation during cooling, which deteriorates ductility. Therefore, many of the IA optimization attempts have focused on long-time batch annealing at moderate temperatures between 580 °C and 650 °C, depending on the chemical composition.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the use of higher Al content in medium-Mn-containing steels not only widens but also increases the intercritical interval towards higher temperatures, [20] thus promoting an increase of the transformation and diffusion rate. [14] This novel approach, combining the increase of the processing temperature with an appropriate chemical design of the steel, can further shorten the duration of the IA treatment.…”

Section: Introductionmentioning

confidence: 99%

Fracture Toughness Evaluation of Powder Metallurgical ASP2030 High-Speed Steels Using Flexural Specimens and Finite Element Method

Firouzi

Yazdani²,

Tavangar³

et al. 2022

Strength Mater

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The development of superior mechanical properties in medium-Mn requires the optimization of microstructural parameters such as retained austenite (RA) stability, volume fraction, and morphology. The present work explores the possibility of using a continuous annealing approach instead of conventional batch annealing to perform an intercritical annealing (IA) treatment in a hot-rolled strip of an Al-alloyed 5Mn steel. Dilatometric studies were performed at a temperature of 680 ºC with soaking times ranging from 1 to 300 min to follow the microstructural changes as a function of time. The microstructures thus obtained were thoroughly characterized by means of X-ray diffraction, SEM and TEM, TEM-EDS microanalysis and EBSD phase and orientation maps. It was observed that with increasing soaking times, the volume fraction of retained austenite gradually increases, albeit at the cost of its stability. The comparison of martensite start temperatures (M s ) based on the chemical composition of austenite at 680 ºC with that experimentally obtained at higher process temperature revealed the effect of the grain size on the reduction of RA stability for longer process times. Accordingly, mechanical tests results showed that the yield stress, tensile strength and hardness decrease with an increase in the IA soaking time.

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Thermodynamic–kinetic calculations and dilatometric verification of the martensitic and bainitic transformations in 4% medium-Mn steel

Skowronek,

Kozłowska

2024

J Therm Anal Calorim

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The present study investigated the theoretical and experimental phase transitions phenomena during continuous cooling and isothermal holding above and below Ms temperature in 4 mass. % Mn medium-Mn steel. The thermodynamic–kinetic calculations were performed using JMatPro software, and phase transformations were recorded using a BÄHR high-resolution DIL805A/D dilatometer. The research covered continuous cooling rates from 60 to 0.05 °C s–1 and isothermal holding temperatures in a range between 420 °C and 230 °C. The issues related to both modelling and dilatometric methodology were discussed. The CCT and TTT diagrams were prepared on the basis of dilatometry and compared with the results of light microscopy and hardness tests. The alloy containing about 4 mass.% Mn and 0.22% Mo exhibited very high hardenability as only continuous cooling with rates lower than 1 °C s–1 allowed the bainitic transformation to be initiated. The bainitic transformation is accelerated after passing the Ms temperature. Both the incubation time and the time needed to complete the transformation were significantly reduced (the incubation time from 100 s to below 1 s and the completion time from over 4000 s to below 1000 s). The obtained microstructures were homogeneous and refined.

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Temperature-Dependent Microstructural Evolution of Al-Rich Medium-Mn Steel During Intercritical Annealing

Cited by 10 publications

References 55 publications

Microstructure Evolution of Medium-Manganese Al-Alloyed Steel Manufactured by Double-Step Intercritical Annealing: Effects of Heating and Cooling Rates

Microstructure Evolution of Medium-Manganese Al-Alloyed Steel Manufactured by Double-Step Intercritical Annealing: Effects of Heating and Cooling Rates

Fracture Toughness Evaluation of Powder Metallurgical ASP2030 High-Speed Steels Using Flexural Specimens and Finite Element Method

Thermodynamic–kinetic calculations and dilatometric verification of the martensitic and bainitic transformations in 4% medium-Mn steel

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