Quantitative Evaluation of Crystal Rotation Behavior Around the Fatigue Crack in Copper Films

2005 ◽  
Author(s):  
Kenichi Shimizu ◽  
Tasiyuki Torii
Keyword(s):  
Fatigue Crack ◽  
Quantitative Evaluation ◽  
Crystal Orientation ◽  
Rotation Angle ◽  
Fatigue Testing ◽  
Rotation Axis ◽  
Fatigue Cracks ◽  
Pure Copper ◽  
Copper Films ◽  
Crystal Rotation

Using a fatigue testing method by which fatigue cracks can be initiated and propagated in a film adhered to cover a circular through-hole in a base plate subjected to pull-pull cyclic loads, annealed rolled pure copper films of 100μm thickness were fatigued. In order to discuss about the correlation between fatigue crack propagation and the change of crystal orientation, crystal orientation on the surface of the film materials was measured before and after fatigue testing. The crystallo-graphic information of these films was analyzed using the EBSD (Electron Back-scatter Diffraction) system and the quantitative evaluation method for the crystal rotation angle, the rotation axis and the rotation direction with fatigue testing was developed based on the analysis of crystal orientation matrix. As a result, the crystal rotation angle near the fatigue crack is larger than that apart from the crack and the crystal rotation was quantitatively larger around the transgranular crack than the intergranular crack propagated along the annealing twin boundary.

The Rate of Growth of Fatigue Cracks

1936 ◽  
Vol 3 (1) ◽  
pp. A23-A25
Author(s):  
A. V. deForest
Keyword(s):  
Fatigue Crack ◽  
Iron Oxide ◽  
Carbon Steel ◽  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Rate Of Growth ◽  
Steel Bars ◽  
Cold Rolled

Abstract The author discusses the resistance of metal to the propagation of cracks, and points out that in the accepted method of fatigue testing the results are not conclusive because there is no distinction between (1) the load and the number of repeated stresses required to start cracks and (2) the load and the number of reversals needed to propagate the cracks to failure. The investigation reported in the paper was undertaken to determine (a) the stress and number of reversals required to start a fatigue crack, and (b) the resistance of the material to the effect of a fatigue crack once it had been formed. The tests reported were conducted on annealed cold-rolled low-carbon steel bars with various finishes. The author presents data on the rate of progress of the cracks and on the size of the cracks, the latter of which was determined by magnetizing the bars and inspecting them with finely divided iron oxide in a bath of kerosene.

scholarly journals Fatigue crack initiation and propagation of 100Cr6 steel under torsional loading in very high cycle regime

2018 ◽  
Vol 165 ◽  
pp. 20003
Author(s):  
Hongqian Xue ◽  
Tao Gao ◽  
Zhidan Sun ◽  
Xianjie Zhang
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Maximum Shear Stress ◽  
Testing Machine ◽  
Fatigue Crack Initiation ◽  
Longitudinal Direction ◽  
Torsional Fatigue ◽  
Very High

Cyclic torsional fatigue properties of a high strength steel 100Cr6 are investigated using an ultrasonic torsional fatigue testing machine, and the results are compared with those obtained with fatigue tests under axial loading. Fatigue crack initiation and growth under torsion loading are observed in the very high cycle regime. Results show that fatigue cracks initiated from specimen surface as well as subsurface inclusions under torsion loading. However, subsurface MnS inclusions play a dominant role in crack initiation under torsion loading in the very high cycle regime. The initiation and early propagation of fatigue cracks are mostly controlled by the direction of the maximum shear stress. For surface crack initiation, cracks initiated in parallel to the longitudinal direction of the specimens. Once the shear crack propagated to a crack length of about 20-30 μm, crack branched to the angle close to the direction perpendicular to the remote maximum principal stresses. As for the subsurface fatigue crack initiation, the cracks parallel to the longitudinal direction of the specimens could not be observed, and crack propagation followed a spiral shape on a plane with an orientation of 45° with respect to the loading direction, which corresponds to the maximum principal stress plane.

Numerical Simulation of Fatigue Crack Growth of a Welded Structural Component Under Block Program Fatigue Test

2014 ◽  
Author(s):  
Koji Gotoh ◽  
Masao Takuno ◽  
Koichi Okada ◽  
Sadaharu Kusuba
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Numerical Simulations ◽  
Crack Growth ◽  
Structural Component ◽  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Stress Intensity Factor Range ◽  
Stress Criterion ◽  
Growth Profiles

Numerical simulations of fatigue crack growth of welded structural component were performed under fatigue testing conditions with block loading and constant stress range and the fatigue crack growth profiles were measured under the same loading conditions. In the experiments, fatigue cracks developed at the boxing fillet welded toe and grew toward the top flange plates of the specimens. An advanced fracture mechanics approach based on the improved effective stress intensity factor range, which is the RPG (Re-tensile Plastic zone Generating) stress criterion, was applied to perform the numerical simulations of fatigue crack growth in the modeled components. A comparison of estimated fatigue crack growth profiles with measured ones verified that a reasonable estimation of fatigue crack growth can be estimated by applying the proposed numerical method.

Effects of Interlayer Resin Bonding on Fatigue Crack Initiation/Propagation in Laminate Materials With a Surface Layer of Copper Film

2005 ◽  
Author(s):  
Akira Matsuba ◽  
Tashiyuki Torii ◽  
DongHui Ma
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Notch Root ◽  
Surface Film ◽  
Fatigue Cracks ◽  
Pure Copper ◽  
Fatigue Crack Initiation ◽  
Copper Film ◽  
Laminate Materials ◽  
Resin Bonding

As model specimens to examine the effects of interlayer resin bonding on fatigue properties in laminate materials with a surface film, pure copper films with a thickness of 100μm and 50μm were bonded with epoxy resin to steel base plates. The fatigue crack propagation from the notch root of the specimen was slower for the epoxy-bonded film than for the base specimen, because the epoxy bonding interlayer restricted crack propagation from the surface film to the inner base plate. On the epoxy-bonded film, however, many fatigue cracks initiated at multiple sites sufficiently away from the notch root, and propagated only on the surface copper film. In addition, the number of these multiple fatigue cracks, caused mostly at the site of the annealing twin boundaries, was larger on the surface copper film with a thickness of 100μm than 50μm.

scholarly journals Crystal Rotation with Fatigue Crack Propagation in Copper Films

2005 ◽  
Vol 54 (9) ◽  
pp. 903-908 ◽  
Author(s):  
Kenichi SHIMIZU ◽  
Tashiyuki TORII ◽  
Toshiyuki MORI
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Copper Films ◽  
Crystal Rotation

Fatigue Crack Surface Topography after Plasma Nitriding Process

2016 ◽  
Vol 258 ◽  
pp. 298-301
Author(s):  
Zbynek Studeny ◽  
Zdeněk Pokorný ◽  
David Dobrocky
Keyword(s):  
Fatigue Crack ◽  
Surface Topography ◽  
Fatigue Testing ◽  
Plasma Nitriding ◽  
Fatigue Cracks ◽  
Pulse Length ◽  
Nitriding Process ◽  
Mixture Ratio ◽  
Topography Analysis ◽  
Fish Eye

Fatigue characteristics of steel 41CrAlMo7-10 and topography analysis testing methodology of fish eye were studied. Both sets of samples were heat-treated at the same conditions and subsequently were plasma nitrided. The mixture ratio of these main gases, forming the atmosphere during the plasma nitriding was inverted for both sets of samples. Process parameters such as the duration, the applied voltage and the pulse length were identical for all samples. Following test after heat treatment and surface layer formation by plasma nitriding process for both sets of samples was the <em>rotating bending fatigue testing</em> in the machine R.R.Moore L2568 of Instron Co. The fatigue tests were carried out in accordance with the CSN 42 0363 Fatigue Testing of Metals, Methodology of Testing. Then, tests were evaluated numerically and graphically using Wöhler`s (S-N) curve in a semi-logarithmic form. The testing was stopped after reach the fracture of tested sample or after 107 cycles. The surface topography of fatigue cracks were evaluated on Talysurf CCI. The topography analysis was mainly focused on the initial part of fatigue crack called the fish-eye. The topography analysis was performed only on one selected sample of each series.

Investigation for Small Shear-Mode Fatigue Cracks in Bearing Steels

2013 ◽  
Vol 750 ◽  
pp. 236-239
Author(s):  
Saburo Okazaki ◽  
Atsushi Kusaba ◽  
Hisao Matsunaga ◽  
Masahiro Endo
Keyword(s):  
Fatigue Crack ◽  
High Speed ◽  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Testing Machine ◽  
Rolling Contact ◽  
Installation Space ◽  
Shear Mode ◽  
Testing Method ◽  
Small Shear

Flaking and spalling caused by rolling contact fatigue associate with a small crack, and a special testing method and machine are required to study the small fatigue crack behavior under shear mode loading. It was found by authors that the behaviors of small shear-mode fatigue cracks from the inclusions and the artificial defects could be successfully observed by applying the fully-reversed torsion coupled with static axial compressive stress. However, the servo-hydraulic fatigue testing machine is quite expensive for purchase and maintenance, and large installation space is necessary for the hydraulic and cooling systems. Moreover, the presence of axial compression significantly lowers the frequency of torsional loading, which consequently results in low testing speed. In this study, a cost-effective, space-saving and high-speed fatigue testing method was newly proposed, and the shear-mode fatigue crack growth tests were carried out by using the developed machine. Based on the obtained experimental data, the potential of the new testing machine is discussed.

Forecasting and Detection of Fatigue Cracks in Polycrystalline Alloys With Ultrasonic Testing Via Discrete Wavelet Transform

2021 ◽  
Vol 4 (3) ◽  
Author(s):  
Hassan Alqahtani ◽  
Asok Ray
Keyword(s):  
Fatigue Crack ◽  
Wavelet Transform ◽  
Discrete Wavelet Transform ◽  
Ultrasonic Testing ◽  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Ground Truth ◽  
Discrete Wavelet ◽  
Polycrystalline Alloys ◽  
Synergistic Combination

Abstract Forecasting and detection of fatigue cracks play a key role in damage mitigation of mechanical structures (e.g., those made of polycrystalline alloys) to enhance their service life, and ultrasonic testing (UT) has emerged as a powerful tool for detection of fatigue cracks at early stages of damage evolution. Along this line, the work reported in this paper aims to improve the performance of fatigue crack forecasting and detection based on a synergistic combination of discrete wavelet transform (DWT) and Hilbert transform (HT) of UT data, collected from a computer-instrumented and computer-controlled fatigue-testing apparatus. Performance of the proposed method is evaluated by comparison with the images generated from a digital microscope, which are treated as the ground truth in this paper. The results of comparison reveal that forthcoming fatigue cracks can be detected ahead of their appearance on the surface of test specimens. The proposed method apparently outperforms both HT and conventional DWT, when they are applied individually, because the synergistic combination of DWT and HT provides a better characterization of UT signal attenuation for detection of fatigue crack damage.

scholarly journals Intrinsic Fatigue Crack Growth in Al-Cu-Li-Mg-Zr Alloys: The Effect of the Iron Constituent Particles

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 110
Author(s):  
Min Hao ◽  
Liang Wang ◽  
Jun-Zhou Chen ◽  
Ren Wang ◽  
Guo-Ai Li
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Fatigue Crack Initiation ◽  
Metallographic Examination ◽  
Fe Content ◽  
High Level ◽  
Zr Alloys

The influence of iron (Fe)-containing constituent particles on the behavior of fatigue crack initiation and propagation of Al-Cu-Li-Mg-Zr alloys has been studied using fatigue crack growth (FCG) tests and in-situ fatigue testing and detailed metallographic examination based on scanning electron microscopy. Experimental results show that the alloy with a low level of Fe content (2A97-T3 sheet) exhibited a lower density, accompanying equivalent tensile strength and FCG rate compared to the damage-tolerant 2524-T3 sheet. It was found that the fatigue b growth of both alloys is dominated by transgranular mode, accompanied by intergranular expansion, and the high level of Fe content alloy presents more characteristics of intergranular. Coarse constituent particles were detrimental to the resistance against FCG. It is postulated here that the micro-cracks formed around the coarse Fe-containing particles are merged with the primary crack to produce a bridging effect, accelerating the growth of fatigue cracks in the alloy with a high level of Fe content.

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