Thermo-mechanical Processing of TRIP-Aided Steels

Ranjan, Ravi; Beladi, Hossein; Singh, Shiv Brat; Hodgson, Peter

doi:10.1007/s11661-015-2885-5

Cited by 36 publications

(31 citation statements)

References 39 publications

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“…As can be seen in Fig. 18(c), the carbon content rapidly increased across the interface between bainitic ferrite lath and cementite while the silicon content obviously decreased due to its rejection from cementite [13,18]. A slight enrichment of Mn in cementite is also present.…”

Section: Ebsd and Apt Analysis Of The T 400 Samplementioning

confidence: 84%

“…12(c)). Such observations in the phase variation could be explained by an increase in the driving force for bainite transformation with a decrease in IBT temperature [7,13,50], leading to a larger fraction of remaining austenite transforming to bainitic ferrite and granular bainite (Fig. 11).…”

Section: Mechanical Propertiesmentioning

confidence: 99%

“…The X-ray diffraction (XRD) scans were conducted over range of 2θ = 38 -150° at a step size of 0.01° and a step time of 750 s on the surface of electropolished samples. The RA fraction was calculated using the integrated intensities of four austenite peaks {(111), (200), (220) and (113)} and four ferrite peaks {(110), (200), (211) and (310)} [13]. The carbon content in RA was determined using the following empirical equation [30]:…”

Section: X-ray Diffraction Techniquementioning

confidence: 99%

“…When the IBT temperature increased to 450 °C, the amount of RA decreased to 0.025±0.002. This could be explained by the increase in IBT temperature reducing the driving force for bainite formation, leading to a lower bainite fraction [13,17,50]. Therefore, the remaining austenite was insufficiently stabilised and transformed to martensite during quenching to room temperature.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

“…The microstructure of TRIP steel consists of polygonal ferrite, bainite, retained austenite (RA) and martensite [3][4][5][6][7][8][9][10][11]. RA is a key phase which ensures a good combination of high strength and high ductility through the transformation of RA to martensite during deformation [12][13][14][15][16]. The production of TRIP steel includes a two-stage heat treatment following hot rolling or cold rolling [15,17].…”

Section: Introductionmentioning

confidence: 99%

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Microstructures and mechanical properties of TRIP steel produced by strip casting simulated in the laboratory

Xiong

Kostryzhev

Saleh

et al. 2016

Materials Science and Engineering: A

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Conventional transformation induced plasticity (TRIP) steel (0.17C-1.52Si-1.61Mn-0.03Al, wt%) was produced via strip casting technology simulated in the laboratory. Effects of holding temperature, holding time and cooling rate on ferrite formation were studied via analysis of the continuous cooling transformation diagram obtained here. A typical microstructure for conventional TRIP steels consisting of ~ 0.55 fraction of polygonal ferrite with bainite, retained austenite and martensite was obtained. However, coarse prior austenite grain size of ~80 μm led to large polygonal ferrite grain size of ~17 μm, coarse second phase regions of ~21 μm size, small amount of retained austenite (0.02-0.045) and the presence of Widmanstätten ferrite. Optimisation of the microstructure-property relationship was reached via a variation in the isothermal bainite transformation temperature. The highest retained austenite fraction of 0.045±0.003 with medium carbon content of 1.23±0.01 wt% was obtained after holding at 400 °C, resulting in the highest ultimate tensile strength of 590±35 MPa and largest total elongation of 0.27±0.05. The presence of TRIP effect in the studied steel was revealed through the analysis of strain hardening exponent and modified Crussard-Jaoul model. Effect of processing parameters on retained austenite retention and stress-strain behaviour was discussed. Conventional transformation induced plasticity (TRIP) steel (0.17C-1.52Si-1.61Mn-0.03Al, wt. %) was produced via strip casting technology simulated in the laboratory. Effects of holding temperature, holding time and cooling rate on ferrite formation were studied via analysis of the continuous cooling transformation diagram obtained here. A typical microstructure for conventional TRIP steels consisting of ~ 0.55 fraction of polygonal ferrite with bainite, retained austenite and martensite was obtained. However, coarse prior austenite grain size of ~ 80 μm led to large polygonal ferrite grain size of ~ 17 μm, coarse second phase regions of ~ 21 μm size, small amount of retained austenite (0.02 -0.045) and the presence of Widmanstätten ferrite. Optimisation of the microstructure-property relationship was reached via a variation in the isothermal bainite transformation temperature. The highest retained austenite fraction of 0.045±0.003 with medium carbon content of 1.23±0.01 wt. % was obtained after holding at 400 °C, resulting in the highest ultimate tensile strength of 590±35 MPa and largest total elongation of 0.27±0.05. The presence of TRIP effect in the studied steel was revealed through the analysis of strain hardening exponent and modified Crussard -Jaoul model. Effect of processing parameters on retained austenite retention and stress-strain behaviour was discussed.

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Section: Ebsd and Apt Analysis Of The T 400 Samplementioning

confidence: 84%

Section: Mechanical Propertiesmentioning

confidence: 99%

Section: X-ray Diffraction Techniquementioning

confidence: 99%

Section: Mechanical Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Microstructures and mechanical properties of TRIP steel produced by strip casting simulated in the laboratory

Xiong

Kostryzhev

Saleh

et al. 2016

Materials Science and Engineering: A

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The Characteristic and Thermodynamics/Kinetics of Martensitic Transformation in Fe₅₀Mn₃₀Co₁₀Cr₁₀ High‐Entropy Alloy during Deformation/Heat Treatment

Yang

Wang

2019

Adv Eng Mater

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The characteristic of martensitic transformation in the Fe50Mn30Co10Cr10 high‐entropy alloy during deformation/heat treatment is analyzed with optical microscopy (OM) and X‐ray diffraction (XRD). The mechanism of martensitic transformation is first quantitatively analyzed based on Olson–Cohen thermodynamics calculation and kinetics calculation of critical stresses required for martensitic transformation, twinning, and dislocation slip. The content of martensite in the HR (the as‐cast sample hot rolled at 1173 K and air quenched) sample is decreased, whereas in the HRQ (the HR sample annealed at 1273 K for 2 h and water quenched) sample is increased. The content of martensite in the CR (the HRQ sample cold rolled with 40% deformation) sample is significantly increased, whereas in the CRQ (the CR sample annealed at 1173 K for 5 min and water quenched) sample is decreased. Thermodynamics and kinetics calculations show that the martensitic transformation is inhibited at high temperature due to its positive martensitic transformation free energy difference (ΔGγ→ε), high stacking fault energy, and the highest critical stress required for martensitic transformation compared with twinning and dislocation slip. Martensitic transformation is promoted by deformation at low temperature due to its negative ΔGγ→ε, low stacking fault energy, and the lowest critical stress.

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Thermomechanical Treatment of Steels - A Real Disruptive Technology Since Decades

Buchmayr

2017

steel research int.

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The basic concept of thermomechanical treatment (TMT) or thermomechanical controlled processing (TMCP) is responsible for the development of many advanced steel grades with improved mechanical properties during the last 50 years. A retroperspective view, an explanation of the most important influencing factors and a presentation of the enormous benefits for the costumer are given in this review. A sound knowledge on the synergism of recrystallization, precipitation, and transformation phenomena forms the basis to produce fine, homogeneous microstructures with improved properties. Starting from structural steels, improvements can be achieved with respect to higher strength and toughness values combined with better weldability and formability, mainly based on reduction of carbon content and finer grain sizes. The benefits in the application areas are described in detail. TMCP is not only used for flat products, but also for long products and forgings of different steel grades. Physical simulation and modeling contribute significantly to these developments, which also form the basis for computer-aided control or real-time online-models. In the next years, a complete shift to cyber physical systems (CPS) is predicted, which needs an aligned education effort. REVIEW A Brief Historical ReviewSince the mid-sixties, steel mills began to produce fine grained structural steels by lowering the final rolling temperature. Based on fundamental research in Germany, USA, UK, Germany, and Japan, the fundamental understanding was further developed in metallurgical laboratories. Pioneers at that time were Haneke, [10] Schmidtmann, [11,12] Meyer, [13,14] Kaspar, [15][16][17][18][19][20][21][22][23][24] Streißelberger, [9,15,[25][26][27] DeArdo, [28,29] Jonas, [30][31][32][33] Sellars, [34][35][36][37] Hodgson, [38][39][40][41][42] Tamura und Tanaka, [43] Saito, [44] Ouchi, [45] Militzer, [46,47] and many others. The basic idea was to improve the strength and toughness behavior of structural steels by grain refining. Compared to conventional hot rolling at high rolling temperatures, the new steels were rolled at lower final rolling temperature. It was found that repeated recrystallization of the austenite structures leads to a decrease of grain size, but there is a limit, which is difficult to overcome. Deformation at temperatures, where no recrystallization takes place was successful in the conditioning of austenite having a dense population of glide planes, high dislocation density, and a high intrinsic energy, which provided a high density of nucleation sites for the transformation products of austenite.At the beginning, mainly ferrite plus pearlite microstructures were considered and later the role of rapid cooling became an additional opportunity to increase the strength level.Higher cooling rates or higher undercooling increase the driving force and with a lower diffusivity a finer microstructure like bainite and martensite can be reached.A comparison of the contributions of the strengthening mechanism in a commercial hot rolle...

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Thermo-mechanical Processing of TRIP-Aided Steels

Cited by 36 publications

References 39 publications

Microstructures and mechanical properties of TRIP steel produced by strip casting simulated in the laboratory

Microstructures and mechanical properties of TRIP steel produced by strip casting simulated in the laboratory

The Characteristic and Thermodynamics/Kinetics of Martensitic Transformation in Fe₅₀Mn₃₀Co₁₀Cr₁₀ High‐Entropy Alloy during Deformation/Heat Treatment

Thermomechanical Treatment of Steels - A Real Disruptive Technology Since Decades

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Thermo-mechanical Processing of TRIP-Aided Steels

Cited by 36 publications

References 39 publications

Microstructures and mechanical properties of TRIP steel produced by strip casting simulated in the laboratory

Microstructures and mechanical properties of TRIP steel produced by strip casting simulated in the laboratory

The Characteristic and Thermodynamics/Kinetics of Martensitic Transformation in Fe50Mn30Co10Cr10 High‐Entropy Alloy during Deformation/Heat Treatment

Thermomechanical Treatment of Steels - A Real Disruptive Technology Since Decades

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The Characteristic and Thermodynamics/Kinetics of Martensitic Transformation in Fe₅₀Mn₃₀Co₁₀Cr₁₀ High‐Entropy Alloy during Deformation/Heat Treatment