Prediction of Structure Change of Austenite of Low Carbon Steels

Wakita, Jun–ichi; Takahashi, Manabu; Haji, Junji; Kawano, Osamu; Esaka, Kazuyoshi

doi:10.2355/tetsutohagane1955.82.7_617

Cited by 2 publications

(1 citation statement)

References 2 publications

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“…The past numerous studies of dynamic restoration process of metals and alloys were conducted mostly using their wrought materials, [18][19][20][21][22][23] and very few dynamic recrystallization study has been performed for as cast austenite of steels. Currently the present authors reported hot deformation behavior and g grain refinement due to dynamic recrystallization, including necessity of g grain refinement in as cast austenite of HSLA steels.…”

Section: Hot Deformation Behavior and Dynamically Recrystallized G G mentioning

confidence: 99%

Effects of Dynamic Recrystallization on .GAMMA. Grain Refinement and Improvement of Micro Segregation of As Cast Austenite in 9% Ni Steel

et al. 2005

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Effects of dynamic recrystallization on g grain refinement and improvement in micro segregation of elements such as Ni and Mn of as cast austenite in 9 % Ni steel were investigated by two kinds of experimental methods. The first one was a hot compression test using the specimens prepared from the strand cast slab and the hot rolled plate of 9 % Ni steel, and the other was a hot tensile straining test in the austenitic region after levitation melting and solidification. In the hot compression test, variations in onset strain and flow stress of steady state flow of dynamic recrystallization with hot deformation conditions were investigated. The onset strain was found to decrease below 0.25 at the temperatures above 1 523 K and the strain rate below 1ϫ10 Ϫ2 s Ϫ1. The activation energy value obtained from steady state flow stress was 421 kJ/mol. Dynamically recrystallized g grain size in as cast austenite of this steel was controlled simply by Z value with no dependence on the initial g grain size. This beneficial feature of dynamic recrystallization was confirmed by the experiment of tensile straining in austenite formed after levitation melting and solidification, where extremely coarse initial g grain size of around 1.9 mm was markedly refined down to 140 mm by straining such a small strain as 0.40. Micro segregation ratio of Ni and Mn in the strand cast 9 % Ni steel examined by EPMA analysis was 1.20 and 1.36, respectively. These values were found to decrease continuously with reduction in strain rate in hot deformation of austenite. That is, dynamic recrystallization in austenite taken place at lower strain rate deformation is much more effective for homogenization of segregated elements compared with high strain rate deformation.

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Section: Hot Deformation Behavior and Dynamically Recrystallized G G mentioning

confidence: 99%

Effects of Dynamic Recrystallization on .GAMMA. Grain Refinement and Improvement of Micro Segregation of As Cast Austenite in 9% Ni Steel

et al. 2005

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Critical Strain for Dynamic Recrystallisation. The Particular Case of Steels

Varela-Castro

Cabrera

Prado

2020

Metals

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The knowledge of the flow behavior of metallic alloys subjected to hot forming operations has particular interest for metallurgists in the practice of industrial forming processes involving high temperatures (e.g., rolling, forging, and/or extrusion operations). Dynamic recrystallisation (DRX) occurs during high temperature forming over a wide range of metals and alloys, and it is known to be a powerful tool that can be used to control the microstructure and mechanical properties. Therefore, it is important to know, particularly in low stacking fault energy materials, the precise time at which DRX is available to act. Under a constant strain rate condition, and for a given temperature, such a time is defined as a critical strain (εc). Unfortunately, this critical value is not always directly measurable on the flow curve; as a result, different methods have been developed to derive it. Focused on carbon and microalloyed steels subjected to laboratory-scale testing, in the present work, the state of art on the critical strain for the initiation of DRX is reviewed and summarized. A review of the different methods and expressions for assessing the critical strain is also included. The collected data are well suited to feeding constitutive models and computational codes.

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Prediction of Structure Change of Austenite of Low Carbon Steels

Cited by 2 publications

References 2 publications

Effects of Dynamic Recrystallization on .GAMMA. Grain Refinement and Improvement of Micro Segregation of As Cast Austenite in 9% Ni Steel

Effects of Dynamic Recrystallization on .GAMMA. Grain Refinement and Improvement of Micro Segregation of As Cast Austenite in 9% Ni Steel

Critical Strain for Dynamic Recrystallisation. The Particular Case of Steels

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