Flow stress, dynamic restoration, strain hardening and ductility in hot working of 316 steel

Ryan, N.D.; McQueen, H.J.

doi:10.1016/0924-0136(90)90005-f

Cited by 161 publications

(92 citation statements)

References 22 publications

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“…These are five types of distinct mechanisms that operate during restoration, after or between deformation passes. Dynamic Recovery (DRV), Dinamic Recrystallization (DRX), Static Recovery (SRV), Static Recrystallization (SRX) and Metadynamic recrystallization (MDRX) 3,[5][6][7][8] . During the plastic deformation, the strength of the material increases due to the hardening phenomenon as a result of the increase in dislocation density.…”

Section: Introductionmentioning

confidence: 99%

Prediction of hot flow plastic curves of ISO 5832-9 steel used as orthopedic implants

et al. 2014

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An austenitic stainless steel ISO 5832-9 used as a biomaterial was torsion-deformed over the temperature range of 1000-1200 °C and strain rates of 0.05, 0.1, 1.0 and 5.0 s -1 . The flow stress curves obtained showed two regions where firstly there is a rising on stress characterized as work hardening mechanism acting and secondly a decreasing in work-softening after a peak stress. The flow curves were modeled by adjusting the experimental data with Zener-Hollomom parameter to construct the constitutive equations that describe the plastic behavior in both regions. The first region was described until the peak stress, taking into consideration the competition between work hardening and recovery while the second one was described applying the softening time of 50% and the Avrami equation. In some hot deformation conditions the simulated curves showed good agreement with the experimental ones while in others conditions the simulated showed differences to experimental curves that was discussed and associated with other mechanisms that acted during hot deformation.

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Section: Introductionmentioning

confidence: 99%

Prediction of hot flow plastic curves of ISO 5832-9 steel used as orthopedic implants

et al. 2014

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“…O aumento na tensão com redução da temperatura e acréscimo na taxa de deformação deve-se ao forte encruamento imediatamente após a deformação de início de escoamento plástico, atribuído ao acréscimo na densidade de discordâncias e pelo tipo de arranjo no qual estes defeitos se apresentam durante a deformação. Este encruamento é tanto maior quanto maior for a dificuldade das discordâncias móveis de caminharem e vencerem os campos de tensão gerados na rede cristalina pelos outros defeitos anteriormente armazenados [10][11][12]. Seguindo com o aumento na deformação, as discordâncias movem-se em seus sistemas de escorregamento.…”

Section: Curvas De Escoamento Plásticounclassified

“…As interações entre estes sistemas e contornos de grão ou qualquer obstáculo substancial, bloqueiam o escorregamento e criam empilhamentos. Este bloqueio e a geração de discordâncias continuam até o estágio onde algumas discordâncias bloqueadas são capazes de evitar os obstáculos através de deslizamento cruzado nos planos de deslizamento com redução na taxa de encruamento e inicia do processo de recuperação dinâmica [5][6][7][8][9][10][11]. Esta região da curva é caracterizada por uma recuperação dinâmica lenta que permite que a densidade de discordâncias aumente até um nível apreciável e, consequentemente, elevando os níveis de tensão de pico.…”

Section: Curvas De Escoamento Plásticounclassified

“…Durante a manufatura dos implantes, os materiais metálicos passam por um processo de forjamento a quente com a evolução da microestrutural da austeníta intimamente relacionado com os fenômenos de amaciamento dinâmico que desempenham um papel importante na determinação da microestrutura final e as propriedades dos aços. Em geral, três fenômenos controlam o comportamento mecânico durante e após a deformação em altas temperaturas: encruamento (WH), recuperação dinâmica (DRV), recristalização dinâmica (DRX) e a recristalização estática (SRX) [8][9][10][11][12]. Cada um destes pode afetar a evolução microestrutural em diferentes condições de processamento.…”

Section: Introductionunclassified

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Evidência Da Precipitação Da Fase Z No Aço Inoxidável Austenítico Alto Nitrogênio Astm F 1586 Por Relaxação De Tensão

Silva¹,

Rocha²,

Boas³

et al. 2018

ABM Proceedings

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ResumoUsando os testes de torção a quente isotérmico contínuo e relaxação de tensão determinou-se as curvas de escoamento plástico e de relaxação de tensão, juntamente com a evolução mecânica e microestrutural do aço inoxidável austenítico ISO 5832-9 segundo as condições de deformação expressa pelo parâmetro de Zener-Hollomon (Z). Equações constitutivas foram usadas para avaliar e prever o amaciamento dinâmico. Verificou-se que os níveis de tensões são elevados com alto valor de energia de ativação aparente e descolamento da deformação crítica e de pico para as condições de alto Z. A tensão crítica encontra-se muito próxima do pico de tensão produzindo um retardo no início da recristalização dinâmica. Além do pico vê-se que o estado estacionário de tensões é alcançado para grandes deformações evidenciando um atraso no amaciamento dinâmico. Este comportamento é consequência da moderada valor de energia de falha de empilhamento (EFE), átomos de soluto em solução sólida (Nb, N, Mo) e presença de partículas de precipitados da fase Z (NbCrN) reduzindo a mobilidade das discordâncias e contornos de grãos retardando a cinética de recristalização. Palavras-chave: Implantes; Amaciamento; Precipitação dinâmica; Fase Z. EVIDENCE OF PRECIPITATION Z-PHASE IN STAINLESS STEEL AUSTENITIC HIGH NITROGEN ASTM F 1586 BY STRESS RELAXATION AbstractUsing the hot torsion testing isothermal and continuous stress relaxation determined whether the plastic flow curves and stress relaxation, together with the mechanical and microstructural evolution of austenitic stainless steel ASTM F 1586 according to strain conditions expressed by the parameter Zener-Hollomon (Z). Constitutive equations were used to evaluate and predict the dynamic softening. It was found that the stress levels are high with high value of the apparent activation energy, critical strain and displacement of the peak for Z high. Conditions of high critical stress are very close to the peak stress producing a delayed start the dynamic recrystallization (DRX). Besides it is seen that peak steady state stress is reached for large strains showing a dynamic delay in softening. This behavior is a consequence of moderate stacking fault energy (SFE) value, solute atoms in the solid solution (Nb, C, Mo) and the presence of precipitated particles of the Z-phase stage (NbCrN) reducing the movement of dislocations and contours grain retarding recrystallization kinetics.

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“…Due to low stacking fault energy of austenite, the major restoration process during hot deformation is dynamic recrystallization (DRX) [10][11][12][13][14]. DRX is an important phenomenon for controlling microstructure and mechanical properties in hot working.…”

Section: Introductionmentioning

confidence: 99%

A simple constitutive model for predicting flow stress of medium carbon microalloyed steel during hot deformation

2015

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 1 A Simple Constitutive Model for Predicting Flow Stress of Medium Carbon Microalloyed Steel during Hot Deformation AbstractThe constitutive behavior of a medium carbon microalloyed steel during hot working over a wide range of temperatures and strain rates was studied using the Johnson-Cook (JC) model, the Hollomon equation, and their modifications. The original JC model was not able to predict the softening part of the flow curves and the subsequent modifications of the JC model to account for the softening stage and the strain dependency of constants were not satisfactory owing to the uncoupled nature of the JC approach regarding strain rate and temperature. The coupled effect of these variables was considered in the form of Zener-Hollomon parameter (Z) and the constants of the Hollomon equation were related to Z. This modification was found to be useful for the hardening stage but the overall consistency between the experimental flow curves and the calculated ones was not good. Therefore, a simple constitutive model was proposed in the current work, in which by utilization of the peak stress and strain into the Hollomon equation, good prediction abilities were attained. Conclusively, the proposed model can be considered as an efficient one for modeling and prediction of hot deformation flow curves.

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Flow stress, dynamic restoration, strain hardening and ductility in hot working of 316 steel

Cited by 161 publications

References 22 publications

Prediction of hot flow plastic curves of ISO 5832-9 steel used as orthopedic implants

Prediction of hot flow plastic curves of ISO 5832-9 steel used as orthopedic implants

Evidência Da Precipitação Da Fase Z No Aço Inoxidável Austenítico Alto Nitrogênio Astm F 1586 Por Relaxação De Tensão

A simple constitutive model for predicting flow stress of medium carbon microalloyed steel during hot deformation

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