Atomic Force And Scanning Electron Microscopy Of Corrosion And Fatigue Of An Aluminum-Copper Alloy

1995 ◽  
Vol 409 ◽  
Author(s):  
K. Kowal ◽  
J. DeLuccia ◽  
J.Y. Josefowicz ◽  
C. Laird ◽  
G.C. Farrington
Keyword(s):  
Fatigue Life ◽  
Crack Nucleation ◽  
Mechanical Deformation ◽  
Simultaneous Action ◽  
Second Phase ◽  
Corrosive Environment ◽  
Intergranular Cracking ◽  
Early Stages ◽  
Atomic Force ◽  
Persistent Slip Bands

AbstractThe morphological features of 2024-T3 aluminum alloy were delineated using atomic force microscopy (AFM) during separate and combined actions of corrosion and fatigue.In-situ AFM corrosion studies in hydrochloric acid environments without mechanical deformation showed accelerated dissolution in the vicinity of second phase precipitates leading to intergranular corrosion. During fatigue in air, AFM images revealed steps along grain boundaries, as well as parallel extrusions and intrusions during the early stages of fatigue life. At later stages of mechanical deformation persistent slip bands (PSBs) were observed on the sample's surface. Cracks were observed to nucleate and propagate along PSBs. For experiments where samples were subjected to the simultaneous action of a corrosive environment and mechanical deformation, intergranular cracking was observed during the early stages of fatigue life. The corrosive environment was observed to accelerate the crack nucleation process.

Aluminum Drill Pipe Fatigue Analysis

2004 ◽  
Author(s):  
Guilherme Farias Miscow ◽  
Joa˜o Carlos Ribeiro Pla´cido ◽  
Paulo Emi´lio Valada˜o de Miranda ◽  
Theodoro Antoun Netto
Keyword(s):  
Fatigue Life ◽  
Structural Integrity ◽  
Crack Nucleation ◽  
Drill Pipe ◽  
Drill String ◽  
Small Scale ◽  
Second Phase ◽  
Horizontal Section ◽  
Steel Drill ◽  
Drill Pipes

While drilling extended reach wells, the weight per foot of the drill string is a critical design parameter that can limit the depth to be reached. One practical solution is the use of drill pipes made of alternative materials to the conventional steel drill pipes. The most direct options are titanium and aluminum. Titanium is in general impaired due to its high cost, although the titanium alloy Ti-6Al4V has already been used in the airplane industry. More recently, Russia has been manufacturing drill pipes using aluminum alloys of the system Al-Cu-Mg, similar to alloys 2024, also used in airplanes. These pipes present a reasonable commercial cost. Drill pipe fatigue damage occurs under cyclic loading conditions due to, for instance, rotation in curved sections of the well. Failures caused by crack nucleation and propagation are one of the highest risks to the structural integrity of these pipes. Usually, failure mechanisms develop in the transition region of the tool joint. Several mechanical and metallurgical factors affect the fatigue life of drill pipes. The former are mainly geometric discontinuities such as transition zones, pits and slip marks. The latter are related to the size and distribution of crystalline grains, phases and second phase particles (inclusions). In this study, the roles played by both factors in the fatigue life of drill pipes are studied through an experimental test program. The fundamental fatigue mechanisms are investigated via laboratory tests in small-scale coupons performed in an opto-mechanical fatigue apparatus. Additionally, full-scale fatigue testes on three aluminum drill pipes were performed. The pipes tested are being used in the horizontal section of some extended reach wells in the Northeast of Brazil.

Drill Pipe Fatigue Analysis: Full Size Apparatus and Coupon Tests

2002 ◽  
Author(s):  
Joa˜o Carlos Ribeiro Pla´cido ◽  
Guilherme F. Miscow ◽  
Paulo E. V. de Miranda ◽  
Theodoro A. Netto
Keyword(s):  
Fatigue Life ◽  
Structural Integrity ◽  
Crack Nucleation ◽  
Drill Pipe ◽  
Small Scale ◽  
Second Phase ◽  
Transition Zones ◽  
Second Phase Particles ◽  
Geometric Discontinuities ◽  
Drill Pipes

Drill pipe fatigue damage occurs under cyclic loading conditions due to, for instance, rotation in curved sections of the well. Failures caused by crack nucleation and propagation are one of the highest risks to the structural integrity of these pipes. Usually, failure mechanisms develop in the transition region of the tool joint. Several mechanical and metallurgical factors affect the fatigue life of drill pipes. The former are mainly geometric discontinuities such as transition zones, pits and slip marks. The latter are related to the size and distribution of crystalline grains, phases and second phase particles (inclusions). In this study, the roles played by both factors in the fatigue life of drill pipes are studied through an extensive experimental test program. To this end, a fatigue simulator was designed and built to test full-scale drill pipes under rotating cyclic bending and constant tension loading. Additionally, the fundamental fatigue mechanisms are investigated via laboratory tests in small-scale coupons. These tests were performed in an opto-mechanical fatigue apparatus that was specially designed to perform in-situ real time monitoring surface analysis during the experiments.

Fatigue life prediction of structural steel using acoustic birefringence and characteristics of persistent slip bands

2021 ◽  
Author(s):  
Alexander Victorovich Gonchar ◽  
Konstantin Vladimirovich Kurashkin ◽  
Olga Vyacheslavovna Andreeva ◽  
Maxim Sergeevich Anosov ◽  
Vyacheslav Alexandrovich Klyushnikov
Keyword(s):  
Fatigue Life ◽  
Structural Steel ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Slip Bands ◽  
Persistent Slip Bands ◽  
Acoustic Birefringence

scholarly journals Effects of Pre-Tensile Deformation on the Fatigue Fracture Behavior of Annealed 7005 Aluminum Alloy Plate

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 623
Author(s):  
Ni Tian ◽  
Zhen Feng ◽  
Xu Shi ◽  
Wenze Wang ◽  
Kun Liu ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Fatigue Fracture ◽  
Tensile Deformation ◽  
Thin Strip ◽  
Second Phase ◽  
Alloy Matrix ◽  
Alloy Plate ◽  
Dislocation Distribution ◽  
Aluminum Alloy Plate

In the present study, the fatigue life and fatigue fracture characteristics of annealed 7005 aluminum alloy plates subjected to different pre-tensile deformations were investigated. The results obtained upon increasing the pre-tensile deformation of the alloy plate to 20% revealed that the second-phase particles did not show any obvious changes, and that the thickness of the thin strip grain slightly decreased. The dislocation distribution in the alloy matrix varied significantly among the grains or within each grain as the dislocation density gradually increased with increasing pre-tensile deformation. Moreover, the fatigue performance of the annealed 7005 aluminum alloy plate was significantly improved by the pre-tensile deformation, and the alloy plate subjected to 20% pre-tensile deformation exhibited an optimal fatigue life of ~1.06 × 106 cycles, which was 5.7 times and 5.3 times that of the undeformed and 3% pre-stretched alloy plates, respectively. Two fatigue life plateaus were observed in the pre-tensile deformation ranges of 3–5% and 8–12%, which corresponded to heterogeneous dislocation distribution among various grains and within each grain, respectively. Moreover, two large leaps in the plot of the fatigue-life–pre-tensile-deformation curve were observed, corresponding to the pre-tensile deformation ranges of 5–8% and 16–20%, respectively.

Chronological Framework for the Early Talayotic Period in Menorca: The Settlement of Cornia Nou

Radiocarbon ◽  
2014 ◽  
Vol 56 (02) ◽  
pp. 411-424 ◽  
Author(s):  
Montserrat Anglada ◽  
Antoni Ferrer ◽  
Lluís Plantalamor ◽  
Damià Ramis ◽  
Mark van Strydonck ◽  
...  
Keyword(s):  
Second Phase ◽  
Archaeological Excavation ◽  
The South ◽  
The West ◽  
South Side ◽  
Early Stages ◽  
Architectural Structures

The prehistoric site of Cornia Nou (Menorca) features a number of well-preserved architectural structures belonging to the Talayotic culture. Over the last 6 yr, a team linked to the Museum of Menorca has conducted an archaeological excavation project of a large rectangular building attached to the south side of a substantial and massivetalayot, which is considered the westerntalayot.The main objective of this paper is to present the chronological framework of this building, specifying the period of use and the time of abandonment of the building, as well as the dating of the different phases of its construction. A total of 2714C analyses were obtained from samples of the stratigraphic layers and architectonic structures inside the South Building (SB). This research has provided new insights concerning the early stages of the Talayotic culture. The14C dates allow us to place the first recorded occupation phase of the SB in an interval dated within 1100–900 BC (phase 4). A second phase in the occupation of the SB dates to ∼900–800 BC (phase 5). A final occupation phase could be situated between 800–600 BC (phase 6). However, this record provides evidence to suggest that the construction of the westtalayotmay pertain to a time before the beginning of the 1st millennium cal BC.

Hydrides Effect on the SCC Initiation on Zircaloy-4 Claddings

2007 ◽  
Vol 23 ◽  
pp. 249-252
Author(s):  
Alice Dinu ◽  
M. Radulescu ◽  
D. Ionescu ◽  
Silviu Florea
Keyword(s):  
Radial Direction ◽  
Zirconium Hydride ◽  
Simultaneous Action ◽  
Thermal Treatments ◽  
Corrosive Environment ◽  
Metallographic Method ◽  
Before And After ◽  
Cause Of Failure ◽  
Different Content ◽  
Type Fuel

The main cause of failure of CANDU-type fuel bundles during their operation is the Stress Corrosion Cracking (SCC). This mechanism appears in presence of the simultaneous action of a corrosive agent and of mechanical stress. The presence of precipitated zirconium hydride platelets can affect the propagation of the SCC cracks. For this reason, we studied the influence of content of hydrogen on the initiation and the propagation of SCC crack. To do this study, some Crings samples with different content of hydrogen (100-500ppm) were exposed in a corrosive environment containing iodine (10-4g/cm2) at 320°C. The stress state, the concentration of the corrosive environment and the temperature were maintained constant. For comparison, in the same conditions some as-received samples were exposed. To relieve the morphology of the precipitates of the zirconium hydride the samples were been investigated using metallographic method, before and after thermal treatments. While before the experiment a circumferential orientation of the hydrides precipitates was observed, after the thermal treatments a reorientation of hydrides in a radial direction was been remarked. Investigation by SEM method revealed the propagation modes of cracks in the case of the as-received samples and it was put in evidence the existence of the microcracks on the inner surface of tested samples.

Cavitation Damage Studies With Rotating Disk in Water

1967 ◽  
Vol 89 (1) ◽  
pp. 98-109 ◽  
Author(s):  
G. M. Wood ◽  
L. K. Knudsen ◽  
F. G. Hammitt
Keyword(s):  
Rotating Disk ◽  
Grain Structure ◽  
Second Phase ◽  
Intergranular Cracking ◽  
Damage Resistance ◽  
Cavitation Damage ◽  
Design Changes ◽  
Heat Treated ◽  
Vortex Patterns ◽  
High Suction

The cavitation damage resistance of alloys of aluminum, columbium (niobium), tantalum, molybdenum, and stainless steel was evaluated in water using a rotating disk apparatus that simulated the cavitation vortex patterns encountered in pumps operating at high suction specific speed. The alloys in decreasing order of cavitation resistance were Ta-8W-2Hf, Cb-18W-8Hf, Ta-10W, 316SS, Mo-.5Ti, Cb-1Zr, Al-4Cu-.7Mn-.5Mg, and Al-2.5Mg-.25Cr. The damage resistance order does not follow the variation of any single property such as strain energy to failure, yield strength, or hardness, but appears to be a combination of mechanical properties and phase structure. Photomicrographs show predominant intergranular cracking for the molybdenum alloy and transgranular erosion and cracking for the remaining alloys tested. The second phase precipitate in the aluminum alloy appears to hinder the erosion of material. Investigation of small variations in the grain size of the heat-treated Cb-1Zr alloys resulted in some variation in damage resistance, with the largest grain structure exhibiting the highest resistance. Correlation curves of volume loss as a function of the peripheral velocity are presented for all materials tested. In addition, the operation of the rotating disk apparatus itself was examined in considerable detail and the effects of various design changes were evaluated.

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