Effect of critical temperatures on microstructures and mechanical properties of Nb–Ti stabilized IF steel processed by multiaxial forging

Ghosh, Sumit; Singh, Ajay; Mula, Suhrit

doi:10.1016/j.matdes.2016.03.107

Cited by 34 publications

(10 citation statements)

References 36 publications

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“…The microstructures of the as-received CP Ti were polygonal grains with clear grain boundaries (GBs) and some deformation twins, with the mean grain size about 35 µm, as shown in Figure 1. Severe plastic deformation led to more dislocation accumulations and the production of finer subgrain structures [16,17]. After the first cycle of MDF, polygonal grains were disappeared for refinement, and GBs were ambiguous.…”

Section: Opticalmentioning

confidence: 99%

Changes of Microstructures and Mechanical Properties in Commercially Pure Titanium after Different Cycles of Proposed Multi-Directional Forging

Zheng

Zhang

Xie

et al. 2019

Metals

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A newly proposed multi-directional forging (MDF) was successfully applied to a commercially pure titanium (CP Ti). Severe plastic deformation would result in significant and complex changes of microstructure and mechanical properties, so microstructure characterization and a mechanical test of CP Ti were conducted after different cycles of MDF. The results demonstrated that dynamic recrystallization was the dominant grain refinement mechanism of MDF CP Ti. With increasing the cycles of MDF, grain size, fraction of low angle grain boundaries and dislocations density decreased due to grain refined. After three cycles of MDF, the mean grain size was about 200 nm. The values of tensile strength and hardness increased significantly from zero cycles to one cycle of MDF, but increased slowly after one MDF cycle. Numerous dimples and tear ridges were present, but the dimples were smaller and shallower with increasing cycles of MDF.

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Section: Opticalmentioning

confidence: 99%

Changes of Microstructures and Mechanical Properties in Commercially Pure Titanium after Different Cycles of Proposed Multi-Directional Forging

Zheng

Zhang

Xie

et al. 2019

Metals

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“…Crystal slips are the primary mode of deformation, and the mechanism of ferrite refinement is comprised grain segmentation and recovery. Sumit et al [15] found that when the steel was forged in pure ferrite regions, the mechanical properties of steel had the best combination of yield…”

Section: Introductionmentioning

confidence: 99%

Microstructure Evolution and Mechanical Properties of 0.4C-Si-Mn-Cr Steel during High Temperature Deformation

et al. 2020

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Herein, the effects of height-diameter ratios (H/D) on the microstructure evolution and mechanical properties of 0.4C-Si-Mn-Cr steel during high temperature deformation are reported. The compression experiments were performed on steel samples using Gleeble to obtain a reasonable deformation temperature, and the degree of deformation was assessed in the range of 1.5 to 2.0 H/D via forging. The forged specimens were quenched using the same heat treatment process. The hardness and impact toughness of the steel samples were tested before and after heat treatment. Grain sizes gradually increased with an increase in the compression temperature from 950 °C to 1150 °C, and the grain sizes decreased with an increase in H/D. The microstructure of the steel samples contained pearlite, bainite, martensite, and retained austenite phase. The microstructure after forging was more uniform and finer as compared to that of as-cast steel samples. The hardness and impact toughness of the steel samples were evaluated after forging; hardness first increased and then decreased with an increase in H/D, while the impact toughness continuously increased with an increase in H/D. Hence, the microstructure and properties of steel could be improved via high temperature deformation, and this was primarily related to grain refinement.

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“…During the steel cooling, ferrite grains preferentially nucleate in the austenite grains boundaries at temperatures around Ar 3 and then grow continuously, consuming all austenite. It is observed that increasing the cooling rate, the transformations will begin and finish in lower temperatures, result of a higher austenite undercooling 24 .…”

Section: Methodsmentioning

confidence: 99%

“…Aiming to improve the steel manufacturing processes, as well as the post-welding microstructures, the understanding of the kinetics of the primary phase transformations (austenite → ferrite) is relevant. As the IF steels may be manufactured and applied with different chemical compositions and their final ferrite morphologies depend on the steel cooling condition, to characterize and to predict the austenite→ferrite transformation is a great contribution to the material processing planning 1,[22][23][24] .…”

Section: ( )mentioning

confidence: 99%

Proposition of an Empirical Functional Equation to Predict the Kinetics of Austenite to Ferrite Transformation in a Continuous Cooled IF-Ti-Stabilized Steel

Cezário

Faria

2021

Mat. Res.

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The kinetics of phase transformations in isothermal processes is well described by the classic JMAK model. However, it is known that most industrial facilities employ continuous cooling processes and, for this condition, the JMAK model is adapted but, sometimes, without success. Considering the importance to predict critical temperatures, the present work proposes an alternative empirical functional equation to describe the kinetics of steel phase transformation under continuous cooling, being useful when the JMAK use is not successful. In this study, the continuous cooling austenite to ferrite transformation was experimentally characterized by dilatometry for an IF-Ti-stabilized steel. The proposed equation was compared with the classic adapted JMAK model regarding to evaluate its efficacy to fit the dilatometric experimental data. Using the constants obtained by the both model fittings as input parameters, a computational simulation was performed to determine the CCT diagram of the IF-Ti steel. The proposed functional equation was efficient to predict the critical temperatures, the kinetics of austenite decomposition and the CCT diagram of the studied steel. The results predicted by the proposed model greatly met the experimental data measured by dilatometry.

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Effect of critical temperatures on microstructures and mechanical properties of Nb–Ti stabilized IF steel processed by multiaxial forging

Cited by 34 publications

References 36 publications

Changes of Microstructures and Mechanical Properties in Commercially Pure Titanium after Different Cycles of Proposed Multi-Directional Forging

Changes of Microstructures and Mechanical Properties in Commercially Pure Titanium after Different Cycles of Proposed Multi-Directional Forging

Microstructure Evolution and Mechanical Properties of 0.4C-Si-Mn-Cr Steel during High Temperature Deformation

Proposition of an Empirical Functional Equation to Predict the Kinetics of Austenite to Ferrite Transformation in a Continuous Cooled IF-Ti-Stabilized Steel

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