Physical-Based Constitutive Modeling of Hot Deformation in a Hot-Extruded Powder Metallurgy Nickel-Based Superalloy

Tan, Gang; Li, Huizhong; Wang, Yan; Yang, Lei; Huang, Zhengqin; Qiao, Shi-chang; Liu, Min-xue

doi:10.1007/s11665-020-05291-x

Cited by 13 publications

(5 citation statements)

References 40 publications

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“…The flow curves were not corrected by friction. Contrary to the tendency obtained in the work of G. Tan et al [32] and in many other publications, the largest barrelling observed in our work occurred at the smallest strain rate. This must be related to a different mechanism of barrelling, such as wedge cracking promoted by diffusion, already observed by S.C. Medeiros et al [33].…”

Section: Compression Testscontrasting

confidence: 99%

Hot Deformation Behavior of a Ni-Based Superalloy with Suppressed Precipitation

Lizzi

Pradeep

Stanojević

et al. 2021

Metals

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Inconel®718 is a well-known nickel-based super-alloy used for high-temperature applications after thermomechanical processes followed by heat treatments. This work describes the evolution of the microstructure and the stresses during hot deformation of a prototype alloy named IN718WP produced by powder metallurgy with similar chemical composition to the matrix of Inconel®718. Compression tests were performed by the thermomechanical simulator Gleeble®3800 in a temperature range from 900 to 1025 °C, and strain rates scaled from 0.001 to 10 s−1. Flow curves of IN718WP showed similar features to those of Inconel®718. The relative stress softening of the IN718WP was comparable to standard alloy Inconel®718 for the highest strain rates. Large stress softening at low strain rates may be related to two phenomena: the fast recrystallization rate, and the coarsening of micropores driven by diffusion. Dynamic recrystallization grade and grain size were quantified using metallography. The recrystallization grade increased as the strain rate decreased, although showed less dependency on the temperature. Dynamic recrystallization occurred after the formation of deformation bands at strain rates above 0.1 s−1 and after the formation of subgrains when deforming at low strain rates. Recrystallized grains had a large number of sigma 3 boundaries, and their percentage increased with strain rate and temperature. The calculated apparent activation energy and strain rate exponent value were similar to those found for Inconel®718 when deforming above the solvus temperature.

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Section: Compression Testscontrasting

confidence: 99%

Hot Deformation Behavior of a Ni-Based Superalloy with Suppressed Precipitation

Lizzi

Pradeep

Stanojević

et al. 2021

Metals

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“…For the as-cast 40Mn steel, as shown in Eqs. (11) and (15), eight parameters (r 0 , r s , k 2 , r ss , e c , e p , k d , and n d ) need to be determined. Parameter Z, as defined by Eq.…”

Section: Physically Based Modelmentioning

confidence: 99%

Comparison Between Four Flow Stress Models Characterizing the Constitutive Behavior of Hot Deformation of 40Mn Steel

Huang

Lei

Fang

2021

J. of Materi Eng and Perform

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Isothermal compression tests of as-cast 40Mn steel specimens were carried out at temperatures of 900-1100 °C and strain rates of 0.01-10 s -1 . Based on the obtained flow stress curves, four flow stress models, namely, strain-compensated, physically based, back propagation artificial neural network (BP-ANN), and modified BP-ANN based on a genetic algorithm (GA-BP-ANN), were established to predict the flow stress. The prediction performance of each model was assessed using the correlation coefficient (R) and average absolute relative error (AARE). The values of R from the strain-compensated, physically based, BP-ANN, and GA-BP-ANN models were 96.85, 98.53, 99.10, and 99.73%, respectively, while the values of AARE were 6.14, 5.95, 4.89, and 2.62%, respectively. The genetic algorithm provides the optimal initial weights and thresholds of the BP-ANN model. Thus, the GA-BP-ANN model has the highest accuracy and stability for predicting the flow stress. Integrated with finite element simulation, the four flow stress models were applied to predict the hot compression stroke responses of the 40Mn steel specimens. The results indicate that the GA-BP-ANN model has the best predictive ability and great potential for practical applications.

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“…Therefore, it can be seen that the correction applied is predominantly to address the strain outside the 2 mm gauge length in the centre of the sample. Constitutive models have been used to predict the flow stress at elevated temperatures [27][28][29][30][31] ; however, it is well known that a constitutive model is heavily dependent on the material characteristics (i.e., microstructure), the strain rate and the temperature at which the tests were carried out. Therefore, it is assumed that further work would need to be carried out to determine the robustness of Equation ( 3), to see if it is representative of all precipitation hardened materials, and for what temperature and strain rate regimes.…”

Section: Aarementioning

confidence: 99%

Optimisation of sample geometry for thermo‐mechanical testing of precipitation hardenable nickel‐based superalloys with an ETMT machine

King

Rahimi

2023

Strain

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Accurate determination of thermo‐mechanical properties in precipitation hardenable materials using an electro‐thermal mechanical testing (ETMT) system is a well‐established challenge. The non‐uniform distribution of temperature resulting from heating based on the joule effect (i.e., resistivity heating) leads to heterogeneous deformation along the gauge length, owing to the temperature dependency of mechanical properties, which makes their direct measurements complicated. This study presents an evaluation of four different miniaturised sample geometries that were tested to achieve an optimised sample with acceptable uniform strain and temperature distributions in the gauge volume. In‐situ displacement mapping, using digital image correlation (DIC), was utilised to calibrate the optimised sample dimensions with the aim of forcing the deformation to the hottest region of the gauge lengths during the tests. Tests were carried out on Inconel 718 (IN718) at 720°C, an optimal temperature for the precipitation of γ″, the primary strengthening particle in this alloy. The results showed that only in the case of the geometry proposed in this study (i.e., a sample with a short gauge length [~2 mm]) did the deformation acceptably localise at the centre, compared to other geometries. A correction methodology is developed that equates the strain measured using DIC over the 2 mm gauge length of the modified sample geometry with the strain measured using the linear variable differential transformer (LVDT) integrated to the ETMT, making future tests on IN718, and other precipitation hardenable materials, possible without the need for the use of a DIC system.

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Physical-Based Constitutive Modeling of Hot Deformation in a Hot-Extruded Powder Metallurgy Nickel-Based Superalloy

Cited by 13 publications

References 40 publications

Hot Deformation Behavior of a Ni-Based Superalloy with Suppressed Precipitation

Hot Deformation Behavior of a Ni-Based Superalloy with Suppressed Precipitation

Comparison Between Four Flow Stress Models Characterizing the Constitutive Behavior of Hot Deformation of 40Mn Steel

Optimisation of sample geometry for thermo‐mechanical testing of precipitation hardenable nickel‐based superalloys with an ETMT machine

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