Effects of Pre-Crack Depth and Hydrogen Absorption on the Failure Strain of Zircaloy-4 Cladding Tubes Under Biaxial Strain Conditions

2020 ◽  
Author(s):  
Feng Li ◽  
Takeshi Mihara ◽  
Yutaka Udagawa ◽  
Masaki Amaya
Keyword(s):  
Heat Treatment ◽  
Crack Depth ◽  
Strain Ratio ◽  
Final Heat Treatment ◽  
Fuel Cladding ◽  
Hoop Strain ◽  
Final Heat ◽  
Treatment Status ◽  
Biaxial Tensile Stress ◽  
Cold Worked

Abstract Fuel cladding may be subjected to biaxial tensile stress in axial and hoop directions during pellet-cladding mechanical interaction (PCMI) of a reactivity-initiated accident (RIA). Incipient crack in the hydride rim assisted by the scattered hydrides in the metal phase may lead to failure of the cladding at small hoop strain level during PCMI. To get insight of such phenomenon, biaxial-EDC tests under axial to hoop strain ratios ranging from 0 to 1 were performed with pre-cracked (outer surface) and uniformly hydrided Zircaloy-4 cladding tube samples with final heat-treatment status of cold worked (CW), stress relieved (SR) and Recrystallized (RX). Results showed dependencies of failure hoop strain on pre-crack depth, strain ratio, hydrogen content and final heat-treatment status on fabrication, but no apparent dependencies were observed on the distribution pattern of hydrides (with similar hydrogen contents and hydrides predominantly precipitated in hoop direction) and the heat-treatment process for hydrogen charging. J integral at failure seems to be available to unify the effect of pre-crack depth.

Biaxial-EDC Test Attempts With Pre-Cracked Zircaloy-4 Cladding Tubes

2017 ◽  
Author(s):  
Feng Li ◽  
Takeshi Mihara ◽  
Yutaka Udagawa ◽  
Masaki Amaya
Keyword(s):  
Crack Depth ◽  
Strain Ratio ◽  
Propagation Mode ◽  
Failure Behavior ◽  
Test Apparatus ◽  
Fuel Cladding ◽  
Energy Agency ◽  
High Burnup ◽  
Cold Worked ◽  
Hoop Direction

When the pellet-cladding mechanical interaction (PCMI) occurs in a reactivity-initiated accident (RIA), the states of stress and strain in the fuel cladding varies in a range depending on the friction and degree of bonding between cladding and pellet. Japan Atomic Energy Agency has developed the improved Expansion-due-to-compression (EDC) test apparatus to investigate the PCMI failure criterion of high-burnup fuel under such conditions. In this study, the failure behavior of cladding tube was investigated by using the improved EDC test apparatus. Cold-worked, stress-relieved and recrystallized Zircaloy-4 tubes with a pre-crack were used as test specimens: this pre-crack simulated the crack which is considered to form in the hydride rim of high-burnup fuel cladding at the beginning of PCMI failure. In the EDC test, a tensile stress in axial direction was applied and displacement-controlled loading was performed to keep the strain ratio of axial/hoop as a constant. The data of cladding deformation had been achieved in the range of strain ratio of 0, 0.25, 0.5 and 0.75 and pre-crack depth of 41–87 micrometers. Failures in hoop direction were observed in all the tested samples, and a general trend that higher strain ratio and deeper crack depth lead to lower failure limit in hoop direction could be seen. Different crack propagation mode was observed between recrystallized and stress relieved and cold worked samples, which might be due to the difference in microstructure caused by the final heat treatment at the fabrication of cladding.

Dense and smooth epitaxial BaTiO3 thin films by the dipping-pyrolysis process

1999 ◽  
Vol 14 (2) ◽  
pp. 592-596 ◽  
Author(s):  
S. Kim ◽  
T. Fujimoto ◽  
T. Manabe ◽  
I. Yamaguchi ◽  
T. Kumagai ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Heat Treatment ◽  
Oxygen Partial Pressure ◽  
Smooth Surface ◽  
Precursor Solution ◽  
Final Heat Treatment ◽  
Pyrolysis Process ◽  
Low Oxygen ◽  
Final Heat

Dense and smooth BaTiO3 thin films were prepared on SrTiO3 (100) substrates by the dipping-pyrolysis process using a mixed precursor solution of barium and titanium naphthenates. Combination effects of prefiring [at 150–450 °C in air or low oxygen partial pressure, p(O2)[ and final heat treatment [at 850 °C in air or low p(O2)[ on preparation of BaTiO3 thin films were examined. An epitaxial BaTiO3 thin film with a dense and smooth surface consisting of nanosized grains about 70 nm was prepared by prefiring under low p(O2) at 250 °C and final heat treatment under low p (O2) at 850 °C.

Microstructure and Mechanism of Three Spheroidizing Treatment for the Carbide of GCr15 Steel

2012 ◽  
Vol 476-478 ◽  
pp. 351-356 ◽  
Author(s):  
Chong Cai Zhang ◽  
Xiao Lan Yi ◽  
Qun Qun Yuan ◽  
Long Wang
Keyword(s):  
Heat Treatment ◽  
Final Heat Treatment ◽  
Tempered Martensite ◽  
Final Heat ◽  
Gcr15 Steel ◽  
Heat Treated ◽  
Spheroidizing Annealing

Three groups of GCr15 steel were heat-treated respectively by conventional spheroidizing annealing, circulation spheroidizing annealing, 1050°C for 30min oil cooling quenching + 700°C tempering. The final heat treatment of these GCr15 steel was 840°C oil cooling quenching + 150°C tempering. The microstructure of the heat-treated GCr15 were observed and the mechanism of three spheroidizing treatment were discussed in this paper. The results showed that: There is obvious difference among the three groups carbide of GCr15 for the mechanism of three spheroidizing treatments is different. The GCr15 has 1050°C for 30min oil cooling quenching + 700°C tempering showed the best result of carbide spheroidizing. The microstructure of GCr15 after 840°C oil cooling quenching + 150 °C tempering was tempered martensite and carbide which is fine, round and widely distributed.

FABRICATION AND CHARACTERIZATION OF Ni-SHEATHED MgB2 SUPERCONDUCTING TAPES

2003 ◽  
Vol 17 (04n06) ◽  
pp. 461-467 ◽  
Author(s):  
A. MALAGOLI ◽  
G. GRASSO ◽  
A. TUMINO ◽  
M. MODICA ◽  
V. BRACCINI ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Final Heat Treatment ◽  
Superconducting Tapes ◽  
Final Heat ◽  
Nickel Tube ◽  
Preparation Route ◽  
Working Procedure ◽  
The Magnetic Field ◽  
Powder In Tube

The preparation route for Nickel-sheathed MgB2 tapes has been studied in order to achieve improved transport properties at temperatures above that of liquid helium. Superconducting tapes have been manufactured by the Powder-In-Tube method, that consists in the cold working of a Nickel tube filled by reacted MgB2 powders, and in a final heat treatment carried out in Argon atmosphere. The could working procedure has been tuned in order to achieve the highest degree of MgB2 density, while limiting the formation of sausaging of the superconducting core cross section. The effect of the final heat treatment has been studied both on the superconducting and microstructural properties of the MgB2 tapes. The critical current of the reacted MgB2 tapes has been measured as a function of the magnetic field and of the temperature on short samples as well as on a small pancake coil. Finally, the microstructural and XRD analyses have revealed the clear presence of a MgB2Ni2.5 reaction layer between the Nickel sheath and the Nickel sheath and the MgB2 superconducting core in the reacted samples.

STEM BSE imaging and Monte Carlo simulation of α-β microstructures in NbTi superconductors

1992 ◽  
Vol 50 (1) ◽  
pp. 86-87
Author(s):  
T. J. Headley ◽  
J. R. Michael ◽  
F. A. Greulich ◽  
M. J. Carr ◽  
J. M. Seuntjens
Keyword(s):  
Heat Treatment ◽  
Current Density ◽  
Volume Fraction ◽  
High Current Density ◽  
Cold Drawing ◽  
Final Heat Treatment ◽  
Two Phase ◽  
Final Heat ◽  
Pinning Properties ◽  
Image Analysis Techniques

High current density NbTi multifilamentary superconductors have α-β microstructures tailored by thermo-mechanical processing involving interspersed cold drawing and heat treatment. A final heat treatment in the two-phase α-β field controls the volume fraction of α-Ti precipitates and subsequent cold drawing refines the scale of the microstructure to a level that optimizes flux pinning properties which affect critical current density (Jc). The volume fraction, particle size, shape and spacing of α-Ti precipitates present after the final heat treatment are important parameters of interest, and should be measurable by image analysis techniques if suitable images were available.

Studies Concerning the Hardening Capacity of Aluminium Alloys through Heat Treatment in Electromagnetic Field

2007 ◽  
Vol 23 ◽  
pp. 201-204
Author(s):  
Maria Stoicănescu ◽  
I. Giacomelli ◽  
Maria Simona Pantelimon
Keyword(s):  
Heat Treatment ◽  
Electromagnetic Field ◽  
Aluminum Alloys ◽  
Electromagnetic Fields ◽  
Aluminium Alloys ◽  
Final Heat Treatment ◽  
Final Heat ◽  
Long Period ◽  
Hardening Process ◽  
Treatment Conditions

It is well known that the aluminum alloys containing Cu and/or Mg lead to soluble compounds which themselves allow the hardening during the process of strengthening and ageing. At the same time, the hardening process during ageing takes a relatively long period of time, and the registered rises are generally not too high. There are presented studies regarding to alloy AlCu4Mg1,5Mn which was tested in several heat treatment conditions. These alloy, after final heat treatment of hardness by and ageing, suffers a sensitive hardening – the ageing is recommended for pieces used under medium and intense mechanical stresses Using the alternative electromagnetic fields is more efficient by 10 to 12% than stationary one, not only regarding to the period of ageing, but also regarding to the highest values of hardness; Also other specific results are given in the paper.

EFFECT OF INTERMEDIATE DEFORMATION ON THE TEXTURING OF Bi-2223/Ag TAPES

2005 ◽  
Vol 19 (01n03) ◽  
pp. 295-297
Author(s):  
H. P. YI ◽  
D. LIN ◽  
X. H. SONG ◽  
W. LIU ◽  
Q. LIU ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Final Heat Treatment ◽  
Rocking Curve ◽  
Final Heat ◽  
Peak Value ◽  
Intermediate Deformation

The effect of intermediate deformation (ID) on texturing of Bi -2223 phase was studied by SEM and rocking curve. There exists a peak value for the degree of texturing as a function of ID reduction. The optimum reduction for intermediate rolling and intermediate pressing is 14.3% and 10.7%, respectively. The texturing of the Bi -2223 phase was further improved by the final heat treatment after ID. Moreover, the critical current density ( Jc ) of the tapes was directly proportional to the texturing of Bi -2223 phase.

Improving the Toughness of 3-1/2NiCrMoV Steam Turbine Disk Forgings

1989 ◽  
Vol 111 (1) ◽  
pp. 61-70 ◽  
Author(s):  
R. L. Bodnar ◽  
K. A. Taylor ◽  
K. S. Albano ◽  
S. A. Heim
Keyword(s):  
Heat Treatment ◽  
Stress Corrosion ◽  
Steam Turbine ◽  
Stress Corrosion Cracking ◽  
Turbine Disk ◽  
Notch Toughness ◽  
Preliminary Heat Treatment ◽  
Final Heat Treatment ◽  
Final Heat ◽  
Turbine Disks

Due to the in-service stress corrosion cracking of some 3-1/2NiCrMoV steam turbine disks, the Charpy V-notch toughness requirements for replacement forgings have dramatically increased in recent years. In response to the new requirements, several avenues for improving the toughness of 3-1/2NiCrMoV steel have been explored and are discussed in this paper. Improvements in forging practice, preliminary heat treatment, final heat treatment and composition are recommended which allow the new requirements to be met.

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