Microstructure Evolution of a Precipitation Hardened Cu-Ni-Si Alloy during Low Cycle Fatigue

2016 ◽  
Vol 258 ◽  
pp. 546-549 ◽  
Author(s):  
Maxime Delbove ◽  
Jean Bernard Vogt ◽  
Jeremie Bouquerel ◽  
Thierry Soreau ◽  
Nicolas François ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Copper Matrix ◽  
Cycle Fatigue ◽  
Strain Variation ◽  
Deformation Bands ◽  
Strain Localisation ◽  
Transmission Electron ◽  
Mechanisms Of Plasticity

The low cycle fatigue (LCF) resistance of a precipitation hardened Cu-Ni-Si alloy has been investigated. Fully reversed strain controlled LCF tests were performed in air at room temperature at a total strain variation Δεt included between 0.6 and 1.5% and at a strain rate equal to 4.10-3 s-1. The cyclic accommodation of the alloy is composed of a hardening step (for Δεt > 0.8 %) followed by a continuous softening until the specimen fracture, except at Δεt = 0.6 % where only a slight softening is observed. For all tested strain variations, the microstructure study of the fatigued alloy by transmission electron microscope (TEM) revealed some grains with a high density of isolated short dislocations pinned between two nanoprecipitates. For Δεt ≥ 0.8 %, some grains present also deformation bands observed by TEM. The strain localisation into these bands implies an important shearing of the precipitates. It leads to their dissolution into the copper matrix and forms precipitate-free bands. The resulting macroscale cyclic accommodation depends on the ratio between the two mechanisms of plasticity accommodation at the microscale.

Strain Hardening by High Density SISFs During Low Cycle Fatigue in Ni3(Al,Zr) Single Crystal

1994 ◽  
Vol 364 ◽  
Author(s):  
Yuefeng Gu ◽  
Yi Liu ◽  
Jianting Guo ◽  
Dongliang Lin
Keyword(s):  
Electron Microscope ◽  
Single Crystal ◽  
Strain Hardening ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Stacking Faults ◽  
Cyclic Strain ◽  
Cycle Fatigue ◽  
Transmission Electron ◽  
Stress Asymmetry

AbstractStress response and its correlation with dislocation substructures in Ni3(Al,Zr) single crystal fatigued at room temperature have been studied. Cyclic strain hardening was found to be asymmetric and increased with increasing applied cyclic strain. Transmission Electron Microscope (TEM) observation showed that there are a profusion superlattic intrinsic stacking faults (SISFs) in fatigued Ni3(Al,Zr) single crystal samples. The cyclic strain hardening and stress asymmetry are explained by the movement of the SISF.

Observations of thick and thin sections in a field-emission SEM

1994 ◽  
Vol 52 ◽  
pp. 1018-1019
Author(s):  
W. P. Wergin ◽  
S. Roy ◽  
E. F. Erbe ◽  
C. A. Murphy ◽  
C. D. Pooley
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Uranyl Acetate ◽  
Chemical Fixation ◽  
Thin Sections ◽  
Transmission Electron ◽  
Conventional Transmission Electron Microscope ◽  
Scanning Electron

Larvae of the nematode, Steinernema carpocapsae Weiser strain All, were cryofixed and freezesubstituted for 3 days in acetone containing 2% osmium tetroxide according to established procedures. Following chemical fixation, the nematodes were brought to room temperature, embedded in Spurr's medium and sectioned for observation with a Hitachi S-4100 field emission scanning electron microscope that was equipped with an Oxford CT 1500 Cryotrans System. Thin sections, about 80 nm thick, similar to those generally used in conventional transmission electron microscope (TEM) studies were mounted on copper grids and stained with uranyl acetate for 30 min and lead citrate for 5 min. Sections about 2 μm thick were also mounted and stained in a similar fashion. The grids were mounted on an Oxford grid holder, inserted into the microscope and onto a cryostage that was operated at ambient temperature. Thick and thin sections of the larvae were evaluated and photographed in the SEM at different accelerating voltages. Figs. 4 and 5 have undergone contrast conversion so that the images would resemble transmitted electron micrographs obtained with a TEM.

scholarly journals Impact of Temperature on Low-Cycle Fatigue Characteristics of the HR6W Alloy

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6741
Author(s):  
Grzegorz Junak ◽  
Anżelina Marek ◽  
Michał Paduchowicz
Keyword(s):  
Fatigue Life ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Total Strain ◽  
Cycle Fatigue ◽  
Fatigue Characteristics

This paper presents the results of tests conducted on the HR6W (23Cr-45Ni-6W-Nb-Ti-B) alloy under low-cycle fatigue at room temperature and at 650 °C. Fatigue tests were carried out at constant values of the total strain ranges. The alloy under low-cycle fatigue showed cyclic strengthening both at room temperature and at 650 °C. The degree of HR6W strengthening described by coefficient n’ was higher at higher temperatures. At the same time, its fatigue life Nf at room temperature was, depending on the range of total strain adopted in the tests, several times higher than observed at 650 °C.

Short Crack Initiation during Low-Cycle Fatigue in SAF 2507 Duplex Stainless Steel

2007 ◽  
Vol 345-346 ◽  
pp. 343-346 ◽  
Author(s):  
M.C. Marinelli ◽  
Suzanne Degallaix ◽  
I. Alvarez-Armas
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
Surface Strain ◽  
The Other ◽  
Cycle Fatigue ◽  
Cyclic Tests ◽  
Characteristic Microstructure

In this work, the formation of fatigue cracks is considered as a nucleation process due to the development of a characteristic microstructure formed just beneath the specimen surface. Strain controlled cyclic tests were carried out at room temperature at total strain ranges εt = 0.8 and 1.2% in flat specimens of SAF 2507 Duplex Stainless Steel (DSS). The results show that for this DSS, at εt = 0.8%, the correlation between phases (Kurdjumov-Sacks crystallographic relation) plays an important role in the formation of microcracks. On the other hand, at εt = 1.2%, microcracks initiate in the ferritic phase and the K-S relation does not seem to affect the formation of the cracks.

In situ transmission electron microscope measurements of solid Al-solid Pb and solid Al-liquid Pb surface-energy anisotropy in rapidly solidified Al-5% Pb (by mass)

1987 ◽  
Vol 414 (1847) ◽  
pp. 499-507 ◽  
Keyword(s):  
Electron Microscope ◽  
Melting Point ◽  
Surface Energy ◽  
Transmission Electron Microscope ◽  
Room Temperature ◽  
Transmission Electron ◽  
Increasing Temperature ◽  
Rapidly Solidified ◽  
Al Matrix

Alloys of Al-5% Pb and Al-5% Pb-0.5% Si (by mass) have been manufactured by rapid solidification and then examined by transmission electron microscopy. The rapidly solidified alloy microstructures consist of 5-60 nm Pb particles embedded in an Al matrix. The Pb particles have a cube-cube orientation relation with the Al matrix, and are cub-octahedral in shape, bounded by {100} Al, Pb and {111} Al, Pb facets. The equilibrium Pb particle shape and therefore the anisotropy of solid Al-solid Pb and solid Al-liquid Pb surface energies have been monitored by in situ heating in the transmission electron microscope over the temperature range between room temperature and 550°C. The ani­sotropy of solid Al-solid Pb surface energy is constant between room temperature and the Pb melting point, with a {100} Al, Pb surface energy about 14% greater than the {111} Al, Pb surface energy, in good agreement with geometric near-neighbour bond energy calculations. The {100} AI, Pb facet disappears when the Pb particles melt, and the anisotropy of solid Al-liquid Pb surface energy decreases gradually with increasing temperature above the Pb melting point, until the Pb particles become spherical at about 550°C.

PREPARATION, CHARACTERIZATION AND LUMINESCENCE PROPERTIES OF Eu DOPED CaAl2O4 NANOCONES

2013 ◽  
Vol 27 (19) ◽  
pp. 1341018 ◽  
Author(s):  
J. M. LIANG ◽  
L. L. HE ◽  
Z. Q. SHEN ◽  
D. L. ZHANG
Keyword(s):  
Electron Microscope ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
The Body ◽  
Monoclinic Structure ◽  
Thermal Evaporation Method ◽  
Room Temperature Photoluminescence ◽  
Spectrum Measurement ◽  
Transmission Electron ◽  
First Time

Europium doped CaAl 2 O 4 nanocones have been grown first time by thermal evaporation method. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to analyze the morphology, size and crystal structure of the nanocones. The body of the nanocones are about 2–20 μm in length and their diameters are 200 nm to 1 μm at one end and tapers off to a ~ 40–200 nm at the tip end. The as-synthesized nanocones are single crystalline in monoclinic structure and grow along the [010] direction and the normal direction of (100) and (001). The room temperature photoluminescence (PL) and cathodoluminescence (CL) spectrum measurement reveals that CaAl 2 O 4: Eu 2+ nanocones emit light at about 440 nm.

Coalescence between Au nanoparticles as induced by nanocurvature effect and electron beam athermal activation effect

Nanoscale ◽  
2018 ◽  
Vol 10 (17) ◽  
pp. 7978-7983 ◽  
Author(s):  
Liang Cheng ◽  
Xianfang Zhu ◽  
Jiangbin Su
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Room Temperature ◽  
Electron Beam Irradiation ◽  
Au Nanoparticles ◽  
Beam Irradiation ◽  
Activation Effect ◽  
Transmission Electron

The coalescence of two single-crystalline Au nanoparticles on surface of amorphous SiOxnanowire, as induced by electron beam irradiation, wasin situstudied at room temperature in a transmission electron microscope.

Low Cycle Fatigue of Nuclear Pipe Components

1974 ◽  
Vol 96 (3) ◽  
pp. 171-176 ◽  
Author(s):  
J. D. Heald ◽  
E. Kiss
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Room Temperature ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
304 Stainless Steel ◽  
Code Design ◽  
Hydraulic Pressure ◽  
Cycle Fatigue ◽  
Cyclic Bending

This paper presents the results of low-cycle fatigue testing and analysis of 26 piping components and butt-welded sections. The test specimens were fabricated from Type-304 stainless steel and carbon steel, materials which are typically used in the primary piping of light water nuclear reactors. Components included 6-in. elbows, tees, and girth butt-welded straight sections. Fatigue testing consisted of subjecting the specimens to deflection-controlled cyclic bending with the objective of simulating system thermal expansion type loading. Tests were conducted at room temperature and 550 deg F, with specimens at room temperature subjected to 1050 psi constant internal hydraulic pressure in addition to cyclic bending. In two tests at room temperature, however, stainless steel elbows were subjected to combined simultaneous cyclic internal pressure and cyclic bending. Predictions of the fatigue life of each of the specimens tested have been made according to the procedures specified in NB-3650 of Section III[1] in order to assess the code design margin. For the purpose of the assessment, predicted fatigue life is compared to actual fatigue life which is defined as the number of fatigue cycles producing complete through-wall crack growth (leakage). Results of this assessment show that the present code fatigue rules are adequately conservative.

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