Necking characteristics and dynamic recrystallization during the superplasticity of IN718 superalloy

Huang, Linjie; Hua, Peitao; Sun, Wei; Liu, Fang; Qi, Feng

doi:10.1016/j.msea.2015.09.040

Cited by 21 publications

(6 citation statements)

References 26 publications

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“…The decreasing rate of the flow stress after the peak strain was reduced with decreasing strain rate from 1.0 × 10 −1 to 1.0 × 10 −3 s −1 , and then increased again at the strain rate of 1.0 × 10 −4 s −1 . It is well known that the onset of the necking often occurs around the peak strain in the true stress–true strain curves and the reduction in decreasing rate of the flow stress after the peak strain means a higher necking resistance 31 , 32 . Therefore, necking is considered to be delayed with decreasing strain rate from 1.0 × 10 −1 to 1.0 × 10 −3 s −1 , and then to be accelerated again at the strain rate of 1.0 × 10 −4 s −1 .…”

Section: Resultsmentioning

confidence: 99%

“…According to Huang et al 32 , 33 , necking is closely related to the hardening of the specimen (strain hardening and strain-rate hardening). Although the degree of strain-rate hardening (the m value) was almost constant regardless of strain rate (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…This indicates that the occurrence of necking was influenced primarily by strain hardening during superplastic deformation. The change in decreasing rate of the flow stress after the peak strain with strain rate is considered to be closely related to the degree of softening mainly by dynamic recrystallization 32 .…”

Section: Resultsmentioning

confidence: 99%

“…After tensile failure, the specimens were removed from the furnace and air-cooled to room temperature. The data of true stress and true strain were converted from the measured data of load and displacement by assuming volume constancy and homogeneous deformation 27 , 32 , 33 .…”

Section: Methodsmentioning

confidence: 99%

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Superplasticity in a lean Fe-Mn-Al steel

et al. 2017

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Superplastic alloys exhibit extremely high ductility (>300%) without cracks when tensile-strained at temperatures above half of their melting point. Superplasticity, which resembles the flow behavior of honey, is caused by grain boundary sliding in metals. Although several non-ferrous and ferrous superplastic alloys are reported, their practical applications are limited due to high material cost, low strength after forming, high deformation temperature, and complicated fabrication process. Here we introduce a new compositionally lean (Fe-6.6Mn-2.3Al, wt.%) superplastic medium Mn steel that resolves these limitations. The medium Mn steel is characterized by ultrafine grains, low material costs, simple fabrication, i.e., conventional hot and cold rolling, low deformation temperature (ca. 650 °C) and superior ductility above 1300% at 850 °C. We suggest that this ultrafine-grained medium Mn steel may accelerate the commercialization of superplastic ferrous alloys.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Superplasticity in a lean Fe-Mn-Al steel

et al. 2017

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“…The coefficient of strain rate sensitivity, m , can be expressed as function of logarithmic values of stress σ and strain rate ε˙ shown in Figure 6b as [1,10,29]:m=∂(lnσ)∂(lntrueε˙)|T.…”

Section: Resultsmentioning

confidence: 99%

Superplastic Deformation and Dynamic Recrystallization of a Novel Disc Superalloy GH4151

Jia

et al. 2019

Materials

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The superplastic deformation of a hot-extruded GH4151 billet was investigated by means of tensile tests with the strain rates of 10−4 s−1, 5 × 10−4 s−1 and 10−3 s−1 and at temperatures at 1060 °C, 1080 °C and 1100 °C. The superplastic deformation of the GH4151 alloy was reported here for the first time. The results reveal that the uniform fine-grained GH4151 alloy exhibited an excellent superplasticity and high strain rate sensitivity (exceeded 0.5) under all experimental conditions. It was found that the increase of strain rate resulted in an increased average activation energy for superplastic deformation. A maximum elongation of 760.4% was determined at a temperature of 1080 °C and strain rate of 10−3 s−1. The average activation energy under different conditions suggested that the superplastic deformation with 1 × 10−4 s−1 in this experiment is mainly deemed as the grain boundary sliding controlled by grain boundary diffusion. However, with a higher stain rate of 5 × 10−4 s−1 and 1 × 10−3 s−1, the superplastic deformation is considered to be grain boundary sliding controlled by lattice diffusion. Based on the systematically microstructural examination using optical microscope (OM), SEM, electron backscatter diffraction (EBSD) and TEM techniques, the failure and dynamic recrystallization (DRX) nucleation mechanisms were proposed. The dominant nucleation mechanism of dynamic recrystallization (DRX) is the bulging of original grain boundaries, which is the typical feature of discontinuous dynamic recrystallization (DDRX), and continuous dynamic recrystallization (CDRX) is merely an assistant mechanism of DRX. The main contributions of DRX on superplasticity elongation were derived from its grain refinement process.

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