Effect of strain rate on the cyclic hardening of Zircaloy-4 in the dynamic strain aging temperature range

Moscato, M.G.; Ávalos, Martina; Alvarez‐Armas, I.; Petersen, C.; Armas, A.F.

doi:10.1016/s0921-5093(97)00405-x

Cited by 16 publications

(7 citation statements)

References 6 publications

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“…1. Consequently, the range of temperature where the maximum effects of DSA take place is shifted towards higher temperatures at the fastest strain rate [7]. This fact would explain why the dislocation structure observed in Fig.…”

Section: Influence Of the Strain Rate On The Evolution Of The Dislocamentioning

confidence: 83%

“…In a previous paper [7], the effect of strain rate on the cyclic behaviour of Zircaloy-4 in the DSA region was studied but not its influence on the dislocation evolution. Therefore, the aim of this work is to evaluate the influence of the temperature and strain rate on the dislocation structure evolution of an hcp material which presents anomalous cyclic behaviour as well as to establish whether there is a drastic change in the dislocation structure during DSA.…”

Section: Introductionmentioning

confidence: 99%

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Influence of dynamic strain aging on the dislocation structure developed in Zircaloy-4 during low-cycle fatigue

Alvarez‐Armas

Hereñú

2004

Journal of Nuclear Materials

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Section: Influence Of the Strain Rate On The Evolution Of The Dislocamentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Influence of dynamic strain aging on the dislocation structure developed in Zircaloy-4 during low-cycle fatigue

Alvarez‐Armas

Hereñú

2004

Journal of Nuclear Materials

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“…It depends on deformation rate and temperature, which govern the velocities of mobile dislocations and diffusing solute atoms, respectively. The DSA regime for Zircaloys has been reported to be 300-500°C for both monotonic and cyclic loading [Derep et al 1980, Ahn and Nam 1990, Moscato et al 1997, Alvarez-Armas and Herenu 2004. The DSA regime for Zr-2.5Nb under monotonic tensile loading was found to be in the temperature range of 250-350°C [Singh et al 2005].…”

Section: Cyclic Stress Response and Cyclic Stress-strain Behaviormentioning

confidence: 94%

“…An interesting feature was observed in the cyclic stress response at relatively low strain amplitudes and long fatigue lives that progressive cyclic hardening occurred after cyclic saturation. Secondary cyclic hardening has been observed in several Zr-based alloys including Zr-Sn-Nb alloy [Tan et al 2006] and Zircaloys [Armas et al 1992, Moscato et al 1997, Armas et al 1996. The occurrence of secondary cyclic hardening in zirconium alloys was suggested to be associated with the development of secondary dislocations due to the activation of the dynamic strain aging [Alvarez- Armas and Herenu 2004].…”

Section: Cyclic Stress Response and Cyclic Stress-strain Behaviormentioning

confidence: 99%

Fatigue Behavior of Pressure Tube Material Zr-2.5Nb in Air and in Simulated CANDU-Reactor Water Environments

Li¹,

Soppet²,

Natesan³

2014

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An experimental program was initiated to develop fatigue data in strain-controlled conditions for an assessment of the fatigue behavior of Zr-2.5Nb pressure tube material in support of CANDU reactors for Atomic Energy of Canada Limited (AECL)/Chalk River Laboratories (CRL). Fatigue tests were conducted on specimens fabricated from a Zr-2.5Nb pressure tube to determine the fatigue performance in air and in simulated CANDUreactor water environments. This report summarizes the fatigue data of Zr-2.5Nb material obtained in both environments. Fatigue tests in air were performed under constant total strain amplitudes in the fully reversed (R=-1) strain control. Fatigue behavior of Zr-2.5Nb pressure tube material was examined over a range of total strain amplitudes from 0.4 to 0.75% at 300°C with a balanced triangular wave form (equal strain rates in tension and in compression) at a strain rate of 0.4%/s. The temperature dependence of the fatigue response was examined at 20 and 100°C at total strain amplitude of 0.6%. The strain rate dependence of the fatigue performance was investigated by applying an unbalanced triangular waveform with a slower strain rate of 0.004%/s in tension and a faster strain rate of 0.4%/s in compression. Fatigue tests in water environments were performed under the stroke control mode. The axial stroke response was correlated with the axial strain control from the air tests, and was used to provide control for the fatigue tests in the autoclave system. Fatigue behavior of Zr-2.5Nb pressure tube material was examined over a range of total strain amplitudes from 0.45 to 0.75% at 300°C with an unbalanced triangular waveform with a slower strain rate of 0.004%/s in tension and a faster strain rate of 0.4%/s in compression in lowdissolved oxygen (DO) LiOH-containing water. Fatigue data were analyzed to obtain the strain-life relation, the cyclic stress response during fatigue cycling, half-life hysteresis loops, and half-life cyclic stress-strain curves. The cross-sectional fracture surfaces and longitudinal surfaces of the gage section of tested specimens were examined by scanning electron microscopy (SEM) to understand the fatigue crack initiation and propagation behavior in this material. The fatigue life of Zr-2.5Nb was significantly reduced in simulated CANDU-reactor water environments at 300°C, compared to the fatigue data obtained in air. The synergistic effect of the aqueous environment and the strain rate is most detrimental to the fatigue resistance of Zr-2.5Nb. The fatigue life of Zr-2.5Nb in water under the slow-fast cyclic loading was reduced in both high-strain and low-strain amplitudes when compared with the fatigue data in air under the fast-fast cycling. The influence of the aqueous environment on the fatigue resistance is more pronounced in the high strain amplitudes than in the low strain amplitudes when compared with the fatigue data in air under slow-fast cyclic loading. Significant reduction in fatigue life was observed at 300°C in air when a lower strain rate (0.004%/s) was ap...

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“…It was found in recent years that the influence of DSA phenomenon on the mechanical behavior of materials should not be ignored [5][6][7]. Most of the literature shows that the tensile strength [8,9] and fatigue strength [10,11] of the material are increased by DSA and ductility and rupture toughness [12] are also influenced. Typical macroscopic features of DSA include serrated flow behavior, sharp yield points, maxima in the work hardening temperature plot, negative strain-rate sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Formability of Austenitic Stainless Steel 316 Sheet in Dynamic Strain Aging Regime

Hussaini¹,

Singh²,

Gupta³

2014

Acta Metall Slovaca

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Dynamic strain aging region for austenitic stainless steel 316 was investigated from room temperature to 650°C at constant strain rates of 1x10 -2 , 1x10 -3 and 1x10 -4 sec -1 . Characteristics indicators of serrated plastic flow were observed in the temperature range of 400°C to 600°C at these strain rates. Strain rate sensitivity of the material is found to be negative in this region. Study of fracture surface of tensile test specimen by scanning electron microscope revealed that ductility in this region decreased. The limiting drawing ratio of sheet metal is the indicator of formability in deep drawing. LDR of the sheet metal was estimated by performing the deep drawing of different diameter blanks in finite element simulation software LS-DYNA in DSA temperature region. It was observed that in DSA region, formability of sheet metal decreased. These simulations are validated and compared with experimental results.

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Effect of strain rate on the cyclic hardening of Zircaloy-4 in the dynamic strain aging temperature range

Cited by 16 publications

References 6 publications

Influence of dynamic strain aging on the dislocation structure developed in Zircaloy-4 during low-cycle fatigue

Influence of dynamic strain aging on the dislocation structure developed in Zircaloy-4 during low-cycle fatigue

Fatigue Behavior of Pressure Tube Material Zr-2.5Nb in Air and in Simulated CANDU-Reactor Water Environments

Formability of Austenitic Stainless Steel 316 Sheet in Dynamic Strain Aging Regime

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