Prediction of Stress-Strain Curves of Hot Deformed IF Austenite.

Vilela, Jefferson José; Barbosa, Ronaldo

doi:10.2355/isijinternational.42.319

Cited by 12 publications

(8 citation statements)

References 16 publications

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“…3 (a). To quantify these phenomena, an evaluation is done considering the inflections of the work hardening parameter (θ=dσ/dε) as a function of either true stress or strain [9,27,28], see Fig. 3 (b) and (c).…”

Section: Flow Curve Analysismentioning

confidence: 99%

“…(3), denoted as C, is equal to , and therefore it is different at each temperature. Parameter α is usually reported as a set value for austenitic steels, ranging between 0.012 and 0.019 MPa -1 [3,9,11,33]. In this work α is not determined but imposed as 0.012 MPa -1 for calculating the apparent stress exponent, n. Once all the values of n were determined, the apparent activation energy was calculated, considering families of strain rates, by rewriting Eq.…”

Section: Determination Of N and Q Hw Valuesmentioning

confidence: 99%

“…Many works reported in the literature have been conducted to determine the role of chemical constituents such as C, Mn and Si and precipitation forming elements, such as Nb, V and Ti on the high temperature behavior of carbon and stainless steels. Viella et al [9] and Jorge et al [10] modeled the stress-strain curves of a Ti added interstitial free (IF) and of an ultra-low carbon steel obtained by torsion, reporting apparent activation energy for hot deformation of 342 and 280 kJ/mol, respectively. Medina et al [11] studied the influence of alloying elements on Z and hence on the Q HW of carbon steels, having as a result that the Si contribution was 30 times larger than the one of Mn and opposite to the role played by C. These authors determined an α value of 0.012 MPa -1 which led to a stress exponent of 4.458.…”

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confidence: 99%

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Effect of Silicon on the Hot Flow Behavior of Ultra-Low Carbon Austenite

Calvillo

Schneider

Houbaert

et al. 2019

Materials Performance and Characterization

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The influence of Si on the high temperature deformation behavior of ultra low carbon austenite was studied in the range of temperature and strain rate from 1000 to 1100ºC and 0.001 and 0.1 s-1, respectively. The flow curves of the steels exhibit the classic softening due to dynamic recrystallization. The characteristic pairs of stress/strain values (zero, critical, peak, saturation and steady state) were determined by the analysis of the work hardening curves. These values were analyzed by applying first the classical Garofalo approach. Once the apparent stress exponents and activation energies were determined, being in the vicinity of 5 and above 270 kJ/mol, respectively, a modified hyperbolic-sine equation was used. The flow curves were characterized by work hardening, dynamic recovery and recrystallization terms at any processing conditions, showing a direct relationship with the Si content of the steels. Finally all the flow curves of studied steels were discussed and modeled as a function of the processing parameters and Si content.

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Section: Flow Curve Analysismentioning

confidence: 99%

Section: Determination Of N and Q Hw Valuesmentioning

confidence: 99%

mentioning

confidence: 99%

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Effect of Silicon on the Hot Flow Behavior of Ultra-Low Carbon Austenite

Calvillo

Schneider

Houbaert

et al. 2019

Materials Performance and Characterization

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“…Também é importante mencionar os trabalhos de Andrade et al [6] e Gomes et al [7] que investigaram, respectivamente, os efeitos da concentração de S e de Nb na trabalhabilidade a quente de um aço inoxidável duplex tipo UNS S32304. Uma técnica adequada para se estudar a laminação a quente é através da simulação de laminação por ensaios de torção a quente, permitindo a reprodução dos processos termomecânicos envolvidos na conformação industrial [8][9][10][11]. Este trabalho teve como objetivo avaliar a fragilidade durante a conformação a quente de dois aços inoxidáveis duplex e estabelecer "janelas" de temperaturas mais favoráveis para evitar fraturas durante o processo de laminação a quente.…”

Section: Introductionunclassified

Estudo Da Ductilidade De Aços Inoxidáveis Duplex Durante a Conformação a Quente

Silva¹,

Reis²,

Oliveira³

et al. 2017

Anais Do Seminário De Laminação E Conformação

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ResumoO objetivo deste trabalho foi estudar a fragilidade a quente de dois aços inoxidáveis duplex utilizando-se ensaios de torção. Ensaios de torção isotérmicos e em resfriamento contínuo, ambos com múltiplas deformações, foram realizados em corpos de prova de aços UNS S32304 e S31803. A caracterização microestrutural foi realizada por microscopia óptica e estudos sobre o equilíbrio de fases em temperaturas elevadas foram conduzidos utilizando simulação computacional. Nos ensaios em resfriamento contínuo, foi observada maior ductilidade no aço UNS 31803. Nos ensaios isotérmicos, foi constatada diminuição da ductilidade para os dois aços com a diminuição da temperatura do ensaio nos casos em que a fração volumétrica de austenita permaneceu constante. Palavras-chave: Aço inoxidável duplex; Conformação a quente; Simulação computacional; Fração volumétrica de fases. STUDY OF DUPLEX STAINLESS STEEL DUCTILITY DURING HOT DEFORMATION AbstractThe hot brittleness of a duplex stainless steel was analyzed by hot torsion tests. Continuous cooling and isothermal torsion tests, both with multiples strains, were performed on UNS S32304 and S31803 steels. The microstructural characterization was performed by optical microscopy and phases equilibrium studies, in high temperature, were carried out by computational simulation. Continuous cooling results show a higher ductility for the UNS 31803. Isothermal results show a decrease in ductility for both steels with the decreasing of temperature when volumetric fraction of austenite is constant.

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“…Several researchers [4][5][6][7] have attempted to investigate the effects of P and B on recrystallization, phase transformation, and the ductile-brittle transition. Hayakawa and Szpunar [6] and Vilela and Barbosa [7] presented the recrystallization kinetics as functions of strain, strain rate, and temperature for mild IF steel with lower tensile strength. However, they did not consider the influence of alloying elements on the recrystallization kinetics.…”

Section: Introductionmentioning

confidence: 99%

Study on roll force and dynamic recrystallization of high-strength interstitial-free steels in hot rolling

Byon

Kim

Lee

2006

Proceedings of the Institution of Mechanical Engineers, Part B:

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This paper presents a constitutive model for two interstitial-free (IF) steels that can be used for calculating the roll force during hot rolling. The constitutive models assume that the deformation behaviour of material can be described with reference to strain, strain rate, and temperature together with the volume fraction of dynamically recrystallized grains. The two IF steels are Nb-Ti-added IF steel containing 0.001 wt% B and 0.1 wt% P, and IF steel with no B and P. To verify the proposed constitutive model, a laboratory-scale hot-plate rolling experiment, together with three-dimensional finite element analysis coupled with the proposed model, has been performed. The capability of the proposed model was demonstrated through comparing predicted roll forces with measured values. A series of finite element simulations has then been carried out to study the variation in the distribution of the dynamically recrystallized volume fraction in the deformed workpiece by changing the rolling temperature and reduction ratio. Good agreement was obtained between the predicted roll forces and experimental measurements for two IF steels. The roll force of IF steel with P and B components was 11.6 per cent larger than that of IF steel without them since dynamic recrystallization was delayed owing to the alloying elements. It has been found that, as the reduction ratio increases, the effect of those alloys on the volume fraction of dynamic recrystallization becomes more dominant and leads to considerable differences between the roll force of the steels.

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Prediction of Stress-Strain Curves of Hot Deformed IF Austenite.

Cited by 12 publications

References 16 publications

Effect of Silicon on the Hot Flow Behavior of Ultra-Low Carbon Austenite

Effect of Silicon on the Hot Flow Behavior of Ultra-Low Carbon Austenite

Estudo Da Ductilidade De Aços Inoxidáveis Duplex Durante a Conformação a Quente

Study on roll force and dynamic recrystallization of high-strength interstitial-free steels in hot rolling

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