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P.V. Sivaprasad
R&D, Sandvik Materials Technology AB, 81181 Sandviken, Sweden

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Journal article
Published: 17 April 2020 in Metals
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Machining process modeling has been an active endeavor for more than a century and it has been reported to be able to predict industrially relevant process outcomes. Recent advances in the fundamental understanding of material behavior and material modeling aids in improving the sustainability of industrial machining process. In this work, the flow stress behavior of C45E steel is modeled by modifying the well-known Johnson-Cook model that incorporates the dynamic strain aging (DSA) influence. The modification is based on the Voyiadjis-Abed-Rusinek (VAR) material model approach. The modified JC model provides the possibility for the first time to include DSA influence in chip formation simulations. The transition from continuous to segmented chip for varying rake angle and feed at constant cutting velocity is predicted while using the ductile damage modeling approach with two different fracture initiation strain models (Autenrieth fracture initiation strain model and Karp fracture initiation strain model). The result shows that chip segmentation intensity and frequency is sensitive to fracture initiation strain models. The Autenrieth fracture initiation strain model can predict the transition from continuous to segmented chip qualitatively. The study shows the transition from continuous chip to segmented chip for varying feed rates and rake angles for the first time. The study highlights the need for material testing at strain, strain rate, and temperature prevalent in the machining process for the development of flow stress and fracture models.

ACS Style

Ashwin Moris Devotta; P. V. Sivaprasad; Tomas Beno; Mahdi Eynian. Predicting Continuous Chip to Segmented Chip Transition in Orthogonal Cutting of C45E Steel through Damage Modeling. Metals 2020, 10, 519 .

AMA Style

Ashwin Moris Devotta, P. V. Sivaprasad, Tomas Beno, Mahdi Eynian. Predicting Continuous Chip to Segmented Chip Transition in Orthogonal Cutting of C45E Steel through Damage Modeling. Metals. 2020; 10 (4):519.

Chicago/Turabian Style

Ashwin Moris Devotta; P. V. Sivaprasad; Tomas Beno; Mahdi Eynian. 2020. "Predicting Continuous Chip to Segmented Chip Transition in Orthogonal Cutting of C45E Steel through Damage Modeling." Metals 10, no. 4: 519.

Journal article
Published: 26 February 2020 in Materials Science and Engineering: A
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Deformation twinning is known to be one of the reasons that cause texture transition (copper type to brass type) in single phase fcc materials and is studied extensively. The role of deformation twinning in two phase materials is an area yet to be explored. Similarly in two phase materials, the effect of one phase on the texture evolution of the other phase is not well understood. In this work, a combination of experiments and modelling are used to address their effects on texture evolution in duplex stainless steels. The material is cold rolled to 80% thickness reduction and texture evolution is studied at various strain levels. These are compared with a series of crystal plasticity simulations using the Taylor model and grain interaction based LAMEL model which was extended to a two phase material. Deformation twinning in austenite is incorporated by predominant twin reorientation (PTR) scheme. It is observed that only by accounting for the strong local interactions between the phases, the correct textures are predicted. The texture transition from {001}〈110〉 to {112}〈110〉 orientation observed in ferrite at higher strain levels is attributed to deformation twinning in austenite. A number of simulations with ideal orientations observed in fcc and bcc materials are performed to assess the role of one phase on texture evolution of the other. It is concluded that experimental observations are also required to comment on the dominant phase during texture evolution.

ACS Style

Darshan Chalapathi; P.V. Sivaprasad; Anand K. Kanjarla. Role of deformation twinning and second phase on the texture evolution in a duplex stainless steel during cold rolling: Experimental and modelling study. Materials Science and Engineering: A 2020, 780, 139155 .

AMA Style

Darshan Chalapathi, P.V. Sivaprasad, Anand K. Kanjarla. Role of deformation twinning and second phase on the texture evolution in a duplex stainless steel during cold rolling: Experimental and modelling study. Materials Science and Engineering: A. 2020; 780 ():139155.

Chicago/Turabian Style

Darshan Chalapathi; P.V. Sivaprasad; Anand K. Kanjarla. 2020. "Role of deformation twinning and second phase on the texture evolution in a duplex stainless steel during cold rolling: Experimental and modelling study." Materials Science and Engineering: A 780, no. : 139155.

Journal article
Published: 08 May 2019 in Metals
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In this study, the flow stress behavior of ferritic-pearlitic steel (C45E steel) is investigated through isothermal compression testing at different strain rates (1 s−1, 5 s−1, and 60 s−1) and temperatures ranging from 200 to 700 °C. The stress-strain curves obtained from experimental testing were post-processed to obtain true stress-true plastic strain curves. To fit the experimental data to well-known material models, Johnson-Cook (J-C) model was investigated and found to have a poor fit. Analysis of the flow stress as a function of temperature and strain rate showed that among other deformation mechanisms dynamic strain aging mechanism was active between the temperature range 200 and 400 °C for varying strain rates and J-C model is unable to capture this phenomenon. This lead to the need to modify the J-C model for the material under investigation. Therefore, the original J-C model parameters A, B and n are modified using the polynomial equation to capture its dependence on temperature and strain rate. The results show the ability of the modified J-C model to describe the flow behavior satisfactorily while dynamic strain aging was operative.

ACS Style

Ashwin Moris Devotta; P. V. Sivaprasad; Tomas Beno; Mahdi Eynian; Kjell Hjertig; Martin Magnevall; Mikael Lundblad. A Modified Johnson-Cook Model for Ferritic-Pearlitic Steel in Dynamic Strain Aging Regime. Metals 2019, 9, 528 .

AMA Style

Ashwin Moris Devotta, P. V. Sivaprasad, Tomas Beno, Mahdi Eynian, Kjell Hjertig, Martin Magnevall, Mikael Lundblad. A Modified Johnson-Cook Model for Ferritic-Pearlitic Steel in Dynamic Strain Aging Regime. Metals. 2019; 9 (5):528.

Chicago/Turabian Style

Ashwin Moris Devotta; P. V. Sivaprasad; Tomas Beno; Mahdi Eynian; Kjell Hjertig; Martin Magnevall; Mikael Lundblad. 2019. "A Modified Johnson-Cook Model for Ferritic-Pearlitic Steel in Dynamic Strain Aging Regime." Metals 9, no. 5: 528.