Dynamic Strain Aging of Nickel-Base Alloys 800H and 690

Moss, Tyler; Was, Gary S.

doi:10.1007/s11661-012-1335-x

Cited by 16 publications

(9 citation statements)

References 10 publications

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“…Thus, following a procedure suggested elsewhere, [22] the slope of a graph of the natural logarithm of the strain rate vs 1/T separating the two re´gimes of behavior yields the apparent activation energy provided that Eq. [4] correctly represents the deformation process.…”

Section: Determination Of Activation Energymentioning

confidence: 99%

The Portevin-Le Chatelier Effect in the Ni-Based Superalloy IN100

Fernandez-Zelaia

Adair

Barker

et al. 2015

Metall Mater Trans A

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The Portevin-Le Chatelier (PLC) effect has been studied in the Ni-based superalloy IN100 which is currently used as a disk material in jet engines. A series of tensile tests was carried out at 588 K, 755 K, and 922 K (315°C, 482°C, and 649°C) at plastic strain rates ranging from a low of 6.21 9 10 À6 s À1 to a high of 4.92 9 10 À2 s À1 . The activation energy was determined using the slope of a line on a strain rate/temperature graph which divided the area of the graph into two regions: (1) ''PLC behavior observed,'' and (2) ''No PLC behavior observed.'' A new statistical approach was developed to objectively differentiate between a true PLC effect and experimental uncertainty (i.e., ''noise''). The value of the activation energy was found to be 1.14 eV/atom, which strongly suggests that the rate controlling process was bulk diffusion of C in the lattice. A qualitative model, based on the Orowan equation and slip band dislocation mechanics, was proposed, which unifies the seemingly disparate ideas of the process being controlled by a single atom/dislocation interaction while at the same time exhibiting significant strains during PLC load drops.

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Section: Determination Of Activation Energymentioning

confidence: 99%

The Portevin-Le Chatelier Effect in the Ni-Based Superalloy IN100

Fernandez-Zelaia

Adair

Barker

et al. 2015

Metall Mater Trans A

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“…The results showed that the oriented nucleation played a significant role in determining the final annealing texture. The dynamic strain aging (DSA) behavior in Incoloy800H superalloy was characterized under the condition of the strain rate in the range of 10´4 to 10´7 and temperatures between 295 K to 673 K [12]. It showed that, at temperatures above 473 K, the load serrations in Incoloy800H superalloy occurred over a wide range of strain rates.…”

Section: Introductionmentioning

confidence: 99%

Continuous Casting of Incoloy800H Superalloy Billet under an Alternating Electromagnetic Field

Wang

Zhang

Deng

et al. 2015

Metals

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Abstract:We experimentally investigate the influence of an alternating electromagnetic field on the surface and internal qualities of Incoloy800H superalloy billets. The electromagnetic continuous casting experiments for Incoloy800H superalloy were successfully conducted and the billets (0.1 mˆ0.1 mˆ1.2 m) were obtained. We figure out that the high frequency (20.4 kHz) electromagnetic field which is applied in the mould region can improve the surface quality of Incoloy800H superalloy billet remarkably; the depth of oscillation mark decreases from 1.2 mm (without electromagnetic field) to 0.3 mm (with electromagnetic field). The internal quality of the billet was studied using a variety of characterization techniques. The low frequency (5 Hz) electromagnetic field which is applied in the second cooling region can improve the internal quality; the region of the equiaxed grain increases from 2.45% (without electromagnetic field) to 41.45% (with electromagnetic field). Furthermore, macro-and micro-segregation are suppressed and the TiN inclusion number is decreased as well.

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Section: Introductionmentioning

confidence: 99%

“…Much previous work has been done to investigate the influence of different variables on DSA. Related work [3][4][5][6][7][8][9][10][11][12] on different alloys show that increasing strain rate results in decreasing amplitude of the stress drop. The lowest strain rate applied in those works was 10 À7 s À1 .…”

mentioning

confidence: 99%

“…The effect of carbon concentration was also studied by testing samples subjected to different thermal treatments. To date, very limited work has been done to study the DSA of this alloy [9,14,15].The chemical composition of Alloy 690 used in this work is 57.6 wt.% Ni, 32.7% Cr, 8.64% Fe, 0.25% Mn, 0.315% Al, 0.08% Si and 0.02% C. The alloy was received as a forged bar with a diameter of 185 mm. It was solution annealed (SA) at 1100°C for 1 h and then water quenched.…”

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confidence: 99%

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The effects of strain rate and carbon concentration on the dynamic strain aging of cold rolled Ni-based alloy in high temperature water

Kuang

Was

2015

Scripta Materialia

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a b s t r a c tThe effect of strain rate on dynamic strain aging of cold-rolled Ni-based alloy was investigated. With decreasing strain rate, the stress amplitude of serrations first increased and then saturated. Compared with the solution-annealed condition, the thermally-treated condition produced smaller stress amplitudes that saturated at a lower strain rate. Observations are consistent with a mechanism in which the locking strength of solute atmospheres first increases with increasing solute atom arrival at dislocations and gradually saturates as solute reaches a critical level.Serrated plastic flow (dynamic strain aging (DSA) or Portevin-Le Chatelier (PLC)) is observed in many alloys during deformation in specific temperature and strain rate ranges. It is widely believed that it arises from the interactions between diffusing solute atoms and mobile dislocations that are temporarily impeded [1,2]. Much previous work has been done to investigate the influence of different variables on DSA. Related work [3][4][5][6][7][8][9][10][11][12] on different alloys show that increasing strain rate results in decreasing amplitude of the stress drop. The lowest strain rate applied in those works was 10 À7 s À1 . Because many important phenomena, such as stress corrosion cracking, occur at strain rates below this level, it is of interest to understand DSA behavior at lower strain rates. The alloy of interest in this work is Alloy 690 which is widely used in nuclear power plant components exposed to high temperatures and low strains. The typical creep rate of this alloy in simulated pressurized water reactor primary water environment is in the range of 10 À10 -10 À9 s À1 [13]. The effect of carbon concentration was also studied by testing samples subjected to different thermal treatments. To date, very limited work has been done to study the DSA of this alloy [9,14,15].The chemical composition of Alloy 690 used in this work is 57.6 wt.% Ni, 32.7% Cr, 8.64% Fe, 0.25% Mn, 0.315% Al, 0.08% Si and 0.02% C. The alloy was received as a forged bar with a diameter of 185 mm. It was solution annealed (SA) at 1100°C for 1 h and then water quenched. In order to change the carbon concentration in matrix, some solution annealed samples were thermally treated (SA + TT) at 700°C for 17 h and cooled in air. Both SA and SA + TT samples were then cold rolled (CR) to 20% thickness reduction, resulting in a sheet of approximately 8 mm in thickness. The cold rolled sheet was machined into round tensile bars with the sample axis in the rolling direction. The gage section of the tensile bar is 20 mm in length and 2 mm in diameter. Samples were mechanically abraded up to 4000 grit and then electropolished for 30 s at 30 V in a solution of 10% (volume fraction) perchloric acid in methanol. Some coupons were also prepared for carbide analysis using the same procedure. Grain boundary carbides were characterized with scanning electron microscope (SEM) on a FEI Helios Nanolab 650. Tensile bars were strained to failure in 360°C high purity water contai...

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Dynamic Strain Aging of Nickel-Base Alloys 800H and 690

Cited by 16 publications

References 10 publications

The Portevin-Le Chatelier Effect in the Ni-Based Superalloy IN100

The Portevin-Le Chatelier Effect in the Ni-Based Superalloy IN100

Continuous Casting of Incoloy800H Superalloy Billet under an Alternating Electromagnetic Field

The effects of strain rate and carbon concentration on the dynamic strain aging of cold rolled Ni-based alloy in high temperature water

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