Microstructural mapping in closed die forging process of superalloy Nimonic 80a valve head

Zhu, Yakun; Yin, Zhoulan; Jiangpin, Xu

doi:10.1016/j.jallcom.2011.03.038

Cited by 31 publications

(8 citation statements)

References 9 publications

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“…Once the material reaches a critical density, the normalized dislocation density increases (Figure 14 a) immediately from the original state. The normalized dislocation density for the initial deformed section is highly similar to the effective stress (Figure 14a) because the increment in dislocation density is directly related to plastic strain rates, as described in Equation (1).…”

Section: Predictions Of State Variablesmentioning

confidence: 89%

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Predicting the Microstructure of a Valve Head during the Hot Forging of Steel 21-4N

Huang

et al. 2018

Metals

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Abstract:Valve microstructure is important during hot forging. Austenitic 21-4N steel is often used in exhaust valves. In this study, the microstructure evolution of the forging valve process was predicted using the internal state variables (i.e., average grain size, recrystallized fraction, and dislocation density) modus for 21-4N. First, 21-4N was subjected to hot compression tests on a Gleeble-1500D and static grain growth tests in a heating furnace. A set of uniform viscoplastic constitutive equations was established based on experimental data. Next, the determined unified constitutive equations were conducted in DEFORM-3D, and the microstructure evolution of 21-4N during forging was calculated. Finally, the simulation results of grain size evolution were validated via experiments. Results showed good consistency between the simulations and experiments. Thus, the models adequately predicted the microstructure evolution.

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Section: Predictions Of State Variablesmentioning

confidence: 89%

“…Engine valve failure may cause the entire engine to fail [1][2][3][4][5]. Thus, the quality of the valve head is important.…”

Section: Introductionmentioning

confidence: 99%

Predicting the Microstructure of a Valve Head during the Hot Forging of Steel 21-4N

Huang

et al. 2018

Metals

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“…The amount of water vapor in the exhaust gas reaches 20%, which accelerates the corrosion of the material; in addition, high-frequency cyclic stress results in fatigue damage and eventually material breakage. [7,8] The annual loss due to material failure is %5-10% of the gross national product. If the existing technology is applied appropriately for preventing fracture failure, most of these losses can be avoided.…”

Section: Introductionmentioning

confidence: 99%

“…However, the working conditions of Ni–Cr–Fe superalloys that have a working temperature of 800 °C or higher are extremely demanding. The amount of water vapor in the exhaust gas reaches 20%, which accelerates the corrosion of the material; in addition, high‐frequency cyclic stress results in fatigue damage and eventually material breakage . The annual loss due to material failure is ≈5–10% of the gross national product.…”

Section: Introductionmentioning

confidence: 99%

Effect of Heat Treatment on the Microstructure and Fracture Behaviors of a Ni–Cr–Fe Superalloy

et al. 2020

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The influences of the size and shape of the γ 0 phase and the type and distribution of carbides on the fracture behavior of a new Ni-Cr-Fe superalloy subjected to four different solution aging treatments are examined. The γ 0 phase and γ matrix of the L1 2-ordered structure maintain a coherent orientation relationship on the {100} and {110} atomic planes according to transmission electron microscopy observations. The material becomes stronger because the movement of dislocations is hindered by the γ 0 phase and MC (Nb-rich, Ti-rich) and M 23 C 6 (Cr-rich, Mo-rich) carbides. The two-stage aging system (850 C Â 4 h þ 730 C Â 4 h) substantially increases the size of the γ 0 phase. The solid solution sample shows a microporous-aggregated ductile fracture, and the solution-aged samples show a microporous-aggregated crystalline fracture according to scanning electron microscopy observations. The fracture mechanism is also discussed.

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“…Nimonic 80A, as a nickel-based superalloy, has been widely used in jet engines for aircraft, gas turbines for power plant and marine diesel engines because of its high creep strength, superior oxidation resistance and strong resistance to corrosions at high temperature [1][2][3]. Generally, the Nimonic 80A is used to fabricate exhausting valve.…”

Section: Introductionmentioning

confidence: 99%

Prediction of the Hot Compressive Deformation Behavior for Superalloy Nimonic 80A by BP-ANN Model

2016

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Abstract:In order to predict hot deformation behavior of superalloy nimonic 80A, a back-propagational artificial neural network (BP-ANN) and strain-dependent Arrhenius-type model were established based on the experimental data from isothermal compression tests on a Gleeble-3500 thermo-mechanical simulator at temperatures ranging of 1050-1250˝C, strain rates ranging of 0.01-10.0 s´1. A comparison on a BP-ANN model and modified Arrhenius-type constitutive equation has been implemented in terms of statistical parameters, involving mean value of relative (µ), standard deviation (w), correlation coefficient (R) and average absolute relative error (AARE). The µ-value and w-value of the improved Arrhenius-type model are 3.0012% and 2.0533%, respectively, while their values of the BP-ANN model are 0.0714% and 0.2564%, respectively. Meanwhile, the R-value and ARRE-value for the improved Arrhenius-type model are 0.9899 and 3.06%, while their values for the BP-ANN model are 0.9998 and 1.20%. The results indicate that the BP-ANN model can accurately track the experimental data and show a good generalization capability to predict complex flow behavior. Then, a 3D continuous interaction space for temperature, strain rate, strain and stress was constructed based on the expanded data predicted by a well-trained BP-ANN model. The developed 3D continuous space for hot working parameters articulates the intrinsic relationships of superalloy nimonic 80A.

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Microstructural mapping in closed die forging process of superalloy Nimonic 80a valve head

Cited by 31 publications

References 9 publications

Predicting the Microstructure of a Valve Head during the Hot Forging of Steel 21-4N

Predicting the Microstructure of a Valve Head during the Hot Forging of Steel 21-4N

Effect of Heat Treatment on the Microstructure and Fracture Behaviors of a Ni–Cr–Fe Superalloy

Prediction of the Hot Compressive Deformation Behavior for Superalloy Nimonic 80A by BP-ANN Model

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