In Situ Characterization of Inconel 718 Post-Dynamic Recrystallization within a Scanning Electron Microscope

Zouari, Meriem; Logé, Roland E.; Bozzolo, Nathalie

doi:10.3390/met7110476

Cited by 34 publications

(35 citation statements)

References 39 publications

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“…After compression, the specimen was held for more than 5 s to leave time for post‐dynamic evolutions to occur, and then water quenched. The PDRX kinetics are indeed known to be very fast, and 5 s holding time after deformation should be enough to get a significant evolution (Na et al ., ; Zouari et al ., ). Following this procedure, the final microstructure should thus encompass both DRX and PDRX grains.…”

Section: Materials and Proceduresmentioning

confidence: 99%

Discrimination of dynamically and post‐dynamically recrystallized grains based on EBSD data: application to Inconel 718

Nicolaÿ

Franchet

Cormier

et al. 2018

Journal of Microscopy

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Summary The importance of angular resolution in EBSD analyses is discussed based on an Inconel 718 sample containing several populations of recrystallized grains, with subtle differences in dislocation contents. Classical EBSD analyses (with angular resolution in the range of 0.5–1°) do not allow for distinguishing recrystallized grains grown dynamically or post‐dynamically. The angular resolution of EBSD orientation and misorientation data can be significantly improved (down to about 0.1–0.2°) either using more sophisticated Kikuchi pattern indexing methods and/or using the recently proposed LLASS denoising filter (Local Linear Automatic Smoothing Splines). Then the coexistence of both dynamically and post‐dynamically recrystallized grains in the sample can be confirmed and quantified. ECCI images unambiguously confirm the conclusions drawn from the analysis of improved angular resolution EBSD data, and furthermore reveal the presence of thermal stress induced dislocations with typical patterns in water quenched Inconel 718 recrystallized grains. Lay Description EBSD is widely used to study recrystallization phenomena. Conventional EBSD is nevertheless not able to distinguish dynamic recrystallized grains from post‐dynamic recrystallized grains which differ by subtitle differences in dislocation contents. In this paper, we show that improving the orientation precision of EBSD data by means of different methods allows distinguishing these two recrystallized grains populations. Analyses and discussion are based on an Inconel 718, a famous Nickel‐based superalloy in aeronautic.

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Section: Materials and Proceduresmentioning

confidence: 99%

Discrimination of dynamically and post‐dynamically recrystallized grains based on EBSD data: application to Inconel 718

Nicolaÿ

Franchet

Cormier

et al. 2018

Journal of Microscopy

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“…The variations of average GND density, SSD density, and average hardness in the mixed microstructure can qualitatively represent changes in the dislocation and hardness of the prior austenite grains [31,32]. [15], a sole SRX process occurred in sample A when the interruption strain was lower than the critical strain [11]; however, only MDRX was observed in sample B because the rapid MDRX quickly consumed all available stored dislocations before SRX could occur [16]. With the aid of the SPM, the indentation arrays were found to be located in the center of the deformed grains and recrystallized grains (including dynamically recrystallized grains, SRX grains, and MDRX grains), as shown in Figure 2a.…”

Section: Hardness Testsmentioning

confidence: 99%

“…Studies have shown that the softening phenomena during post-deformation annealing can be attributed to the MDRX and SRX process [12][13][14][15][16][17]. Djaic and Jonas [12] first proposed the concepts of SRX and MDRX and designed several double-pass compression experiments to distinguish the softening effects caused by these two varieties of recrystallization regimes.…”

Section: Introductionmentioning

confidence: 99%

“…Zeng et al [15] conducted an in situ laser confocal observation of heating experiments on 300M samples with different initial DRX volume fractions and analyzed the effects of strain-induced grain boundary migration on the softening effects which resulted from SRX and MDRX. Using the same characterization method as employed by Huang [14], the twin boundary fractions and grain growth of Inconel 718 were observed by Zouari et al [16] to be strongly dependent on the progress of MDRX and SRX. Huang et al [17] examined the softening mechanism of 5753 aluminum alloy during post-deformation annealing and developed a kinetic model to describe the softening fractions of MDRX.…”

Section: Introductionmentioning

confidence: 99%

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Softening Characterization of 300M High-Strength Steel during Post-Dynamic Recrystallization

Zeng

Huang

et al. 2018

Metals

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This paper investigates softening phenomena within the post-dynamic recrystallization (PDRX) process in 300M high-strength steel specimens with different initial dynamically recrystallized volume fractions. Isothermal, interrupted compression experiments were performed on a Gleeble-3500 at a temperature of 1273 K and strain rate of 0.01 s −1. To acquire different initial volume fractions of dynamically recrystallized (DRX) grains, deformation was interrupted at two strain levels and immediately followed by isothermal annealing treatments. The softening behaviors respectively caused by the static recrystallization (SRX) and metadynamic recrystallization (MDRX) were qualitatively characterized by variations in the mechanical properties of the deformed and recrystallized grains. On the basis of the Taylor dislocation model, the evolution of geometric necessary dislocations (GNDs) and statistically stored dislocations (SSDs) densities were also discussed to qualitatively clarify the nature of different softening behaviors. Results indicate that the SRX occurred alone in samples without initial DRX grains, after an incubation time of approximately 50 s, while MDRX initially appeared within 1 s and completed at about 8 s in samples with a high initial volume fraction of DRX grains. The microhardness, indentation hardness, and Young's modulus in the deformed and recrystallized grains decreased gradually with an increase of MDRX and SRX volume fractions. The sink-in and pileup phenomena were enhanced by the SRX and MDRX softening processes, respectively. The SSDs density decreased more noticeably during the MDRX process than that during the SRX, which indicates that the MDRX process contributed to a more significant softening effect within the microstructural evolution regimes.

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“…Guo [5] investigated the high-temperature softening characteristics of dynamic recrystallization and dynamic recovery during high-temperature deformation and proposed optimal hot forging conditions. In addition, Lee [6] and Zouari [7] proposed a process method for lowering the strain resistance of SPF8090 Al-Li and for the grain refinement of Inconel 718. Bang [8] and Cho [9] offered a method to predict the forming load and microstructure during the high-temperature deformation of carbon steel.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on the Deformation Behavior of Inconel 625 Superalloy at High Temperatures

Jeong

Jin

Seo

et al. 2019

Metals

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Inconel 625 alloys are widely applied for high-corrosion resistance and as high-efficiency materials in aeronautical, aerospace, chemical, nuclear, petrochemical, and marine industries. Although Inconel 625 alloys are excellent materials, they cannot be formed at room temperature owing to difficulties in processing. To improve the formability of Inconel 625, it is necessary to investigate its formability at a high-temperature range and its strain rate variation. In this study, high-temperature deformation behavior after forming was investigated. A high-temperature compression test was performed with a Gleeble 3500 testing machine at various temperatures (approximately 900–1200 °C) and strain rates (10 and 30 s−1) to obtain the high-temperature deformation characteristics of Inconel 625. Furthermore, high-temperature tensile tests were performed to measure elongations and reductions in the area of the Inconel 625 alloy. The tests focused on obtaining the flow stress data and optimal hot forging conditions under various strain rates and temperatures. The results of this research are expected to contribute to hot forming processes and to formability in hot extrusion and pilger processes.

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In Situ Characterization of Inconel 718 Post-Dynamic Recrystallization within a Scanning Electron Microscope

Cited by 34 publications

References 39 publications

Discrimination of dynamically and post‐dynamically recrystallized grains based on EBSD data: application to Inconel 718

Discrimination of dynamically and post‐dynamically recrystallized grains based on EBSD data: application to Inconel 718

Softening Characterization of 300M High-Strength Steel during Post-Dynamic Recrystallization

Experimental Investigation on the Deformation Behavior of Inconel 625 Superalloy at High Temperatures

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