Influence of the Casting Process on the Properties of Al Based Automotive Components

This work concerns the study of the fatigue properties of A319, A 356 and A357 Aluminum alloys, produced by means of permament mould casting, sand casting and loast foam. Smooth plane or cylindrical samples were cut out from supension arms, engine blocks and cylinder heads and then they were subjected to axial fatigue testing at room temperature. Some castings were subjected to LHIP (Liquid Hot Isostatic Pressing) and also the effect of this process has been evaluated regarding the improvement of fatigue properties. Optical microscopy and scanning electron microscopy (SEM) were used to document the elimination of porosity after LHIP and to show the different nucleation sites of fatigue cracks on the fracture surfaces in no-LHIP and LHIP conditions.

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Fatigue Properties of a Ck45 Steel Coated with a Post-Heat Treated Ni-Cu-P Electroless Deposit

Materials Science Forum ◽

10.4028/www.scientific.net/msf.514-516.574 ◽

2006 ◽

Vol 514-516 ◽

pp. 574-578

Author(s):

Sasan Yazdani ◽

N. Parvini-Ahmadi ◽

Tohid Saeid

Keyword(s):

Fatigue Life ◽

Fatigue Testing ◽

Crack Nucleation ◽

Fatigue Cracks ◽

Fatigue Tests ◽

Fatigue Properties ◽

Interfacial Cracks ◽

Heat Treated ◽

Base Steel ◽

Surface Notch

The Fatigue tests under rotating bending conditions have been conducted on samples of a quenched and tempered Ck45 steel in two different conditions: (a) uncoated, (b) coated with an electroless Ni-Cu-P deposit, followed by a post-heat treatment (PHT) at 673 K for 1 h. Such a deposit had a thickness of approximately 10µm, with Cu and P contents of 6wt.% and 13.7wt.% respectively. The results indicate that plating the base steel with this kind of deposit leads to a reduction of the fatigue life of the material. The reduction in fatigue life has been quantified in terms of the Basquin parameters of the materials tested under different conditions. The microscopic observation of the fracture surfaces of the samples indicates that the reduction in fatigue life is associated with the nucleation of fatigue cracks on the coating-substrate interface and the deposit remains well adhered to substrate during fatigue testing since interfacial cracks have been very rarely observed. It is therefore concluded that, in the present case, the interface acts as a surface crack source or surface notch, which decreases the fatigue life of the coated material by reducing the crack nucleation stage.

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Improvement in Fatigue Strength of Friction Stir Welded Aluminum Alloy Plates by Laser Peening

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.891-892.969 ◽

2014 ◽

Vol 891-892 ◽

pp. 969-973 ◽

Cited By ~ 1

Author(s):

Yuji Sano ◽

Kiyotaka Masaki ◽

Keiichi Hirota

Keyword(s):

Aluminum Alloy ◽

Fatigue Strength ◽

Fatigue Testing ◽

Large Deviation ◽

Fatigue Cracks ◽

Weld Zone ◽

Base Material ◽

Fatigue Properties ◽

Laser Peening ◽

Friction Stir

Plane bending fatigue testing was performed to study the fatigue properties of friction stir welded (FSW) 3 mm thick AA6061-T6 aluminum alloy plates. Fatigue cracks propagated with bends and curves on the specimens, showing large deviation from a linear line. This might be reflecting the material flow and microstructure in the weld zone. The fatigue strength of the unwelded base material (BM) was 110 MPa at 107 cycles and FSW deteriorated it to 90 MPa. However, laser peening (LP) restored the degraded fatigue strength up to 120 MPa which is higher than that of the BM.

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Fatigue Crack Initiation and Propagation at High Temperature of New-Generation Bearing Steel

Metals ◽

10.3390/met11010025 ◽

2020 ◽

Vol 11 (1) ◽

pp. 25

Author(s):

Zhiwei Wu ◽

Maosheng Yang ◽

Kunyu Zhao

Keyword(s):

Fracture Surface ◽

Failure Mode ◽

Electron Backscatter Diffraction ◽

Fatigue Cracks ◽

Fatigue Crack Initiation ◽

Optical Microscope ◽

Bearing Steel ◽

Fatigue Properties ◽

New Generation ◽

Scanning Electron

The new generation of bearing steel has good comprehensive properties, which can satisfy most of the requirements of bearing steel in a complex environment. In the presented work, fatigue properties of 15Cr14Co12Mo5Ni2 bearing steel have been investigated by means of rotating bending fatigue tests on smooth bar specimens after carburization and heat treatment. Optical microscope, scanning electron microscopy, electron backscatter diffraction, and Image-Pro Plus software were used to analyze the fracture, microstructure, and carbides. The results suggest that the fatigue strength at room temperature and 500 °C is 1027 MPa and 585 MPa, respectively. Scanning electron micrographic observations on the fracture surface of the fatigue specimens at 500 °C show that fatigue cracks usually initiate from voids in the carburized case and oxide layer on the surface of steel. The failure mode in the carburized case is a quasi-cleavage fracture, and with the increase of crack propagation depth, the failure mode gradually changes to fatigue and creep-fatigue interaction. With the increase of the distance from the surface, the size of the martensite block decreases and the fracture surface shows great fluctuation.

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Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel

Metals ◽

10.3390/met9040476 ◽

2019 ◽

Vol 9 (4) ◽

pp. 476 ◽

Cited By ~ 3

Author(s):

Chao Gu ◽

Min Wang ◽

Yanping Bao ◽

Fuming Wang ◽

Junhe Lian

Keyword(s):

Fatigue Life ◽

Quantitative Analysis ◽

Critical Size ◽

Fatigue Behavior ◽

Fatigue Cracks ◽

Fatigue Property ◽

Bearing Steel ◽

Fatigue Properties ◽

Bearing Steels ◽

Inclusion Distribution

The fatigue property is significantly affected by the inner inclusions in steel. Due to the inhomogeneity of inclusion distribution in the micro-scale, it is not straightforward to quantify the effect of inclusions on fatigue behavior. Various investigations have been performed to correlate the inclusion characteristics, such as inclusion fraction, size, and composition, with fatigue life. However, these studies are generally based on vast types of steels and even for a similar steel grade, the alloy concept and microstructure information can still be of non-negligible difference. For a quantitative analysis of the fatigue life improvement with respect to the inclusion engineering, a systematic and carefully designed study is still needed to explore the engineering dimensions of inclusions. Therefore, in this study, three types of bearing steels with inclusions of the same types, but different sizes and amounts, were produced with 50 kg hot state experiments. The following forging and heat treatment procedures were kept consistent to ensure that the only controlled variable is inclusion. The fatigue properties were compared and the inclusions that triggered the fatigue cracks were analyzed to deduce the critical sizes of inclusions in terms of fatigue failure. The results show that the critical sizes of different inclusion types vary in bearing steels. The critical size of the spinel is 8.5 μm and the critical size of the calcium aluminate is 13.5 μm under the fatigue stress of 1200 MPa. In addition, with the increase of the cleanliness of bearing steels, the improvement of fatigue properties will reach saturation. Under this condition, further increasing of the cleanliness of the bearing steel will not contribute to the improvement of fatigue property for the investigated alloy and process design.

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Low Cycle Tension-Tension Fatigue Properties of 316L Stainless Steel Thin Sheets

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.138-139.832 ◽

2011 ◽

Vol 138-139 ◽

pp. 832-835

Author(s):

Yong Jie Liu ◽

Qing Yuan Wang ◽

Ren Hui Tian ◽

Xiao Zhao

Keyword(s):

Stainless Steel ◽

Room Temperature ◽

316L Stainless Steel ◽

Fatigue Testing ◽

Fatigue Properties ◽

Loading Frequency ◽

Thin Sheets ◽

Effect Factor ◽

Mechanical Fatigue ◽

Tensile Fatigue

In this paper, tensile fatigue properties of 316L stainless steel thin sheets with a thickness of 0.1 mm are studied. The tests are implemented by using micro mechanical fatigue testing sysytem (MMT-250N) at room temperature under tension-tension cyclic loading. The S-N curve of the thin sheets descends continuously at low cycle region. Cyclic σ-N curve and ε-N curve are obtained according to the classical macroscopical fatigue theory. The results agree well with the experimental fatigue data, showing that the traditional fatigue research methods are also suitable for description of MEMS fatigue in a certain extent. The effect factor of frequency was considered in this study and the results show that the fatiuge life and the fatigue strength are increased as loading frequency increasing.

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Lifetime Enhancement of Propulsion Shafts Against Corrosion-Fatigue by Laser Peening

10.5957/pss-2018-01 ◽

2018 ◽

Author(s):

Lloyd A. Hackel ◽

Jon E. Rankin

Keyword(s):

Corrosion Fatigue ◽

Fatigue Testing ◽

Salt Water ◽

Fatigue Cracks ◽

Water Immersion ◽

High Energy ◽

General Corrosion ◽

Laser Peening ◽

Corrosion Pits ◽

Deep Pits

This paper reports substantially enhanced fatigue and corrosion-fatigue lifetimes of propulsion shaft materials, 23284A steel and 23284A steel with In625 weld overlay cladding, as a result of shot or laser peening. Glass reinforced plastic (GRP) coatings and Inconel claddings are used to protect shafts against general corrosion and corrosion pitting. However salt water leakage penetrating under a GRP can actually enhance pitting leading to crack initiation and growth. Fatigue coupons, untreated and with shot or laser peening were tested, including with simultaneous salt water immersion. Controlled corrosion of the surfaces was simulated with electric discharge machining (EDM) of deep pits enabling evaluation of fatigue and corrosion-fatigue lifetimes. Results specifically show high energy laser peening (HELP) to be a superior solution, improving corrosion-fatigue resistance of shaft and cladding metal, reducing the potential for corrosion pits to initiate fatigue cracks and dramatically slowing crack growth rates. At a heavy loading of 110% of the 23284A steel yield stress and with 0.020 inch deep pits, laser peening increased fatigue life of the steel by 1370% and by 350% in the corrosion-fatigue testing.

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Fatigue Behavior of Non-Optimized Laser-Cut Medical Grade Ti-6Al-4V-ELI Sheets and the Effects of Mechanical Post-Processing

Metals ◽

10.3390/met9080843 ◽

2019 ◽

Vol 9 (8) ◽

pp. 843 ◽

Cited By ~ 3

Author(s):

André Reck ◽

André Till Zeuner ◽

Martina Zimmermann

Keyword(s):

Surface Roughness ◽

Fatigue Strength ◽

Surface Quality ◽

Laser Cutting ◽

Fatigue Behavior ◽

Fatigue Cracks ◽

Surface Condition ◽

Mechanical Polishing ◽

Fatigue Properties ◽

Post Processing

The study presented investigates the fatigue strength of the (α+β) Ti-6Al-4V-ELI titanium alloy processed by laser cutting with and without mechanical post-processing. The surface quality and possible notch effects as a consequence of non-optimized intermediate cutting parameters are characterized and evaluated. The microstructural changes in the heat-affected zone (HAZ) are documented in detail and compared to samples with a mechanically post-processed (barrel grinding, mechanical polishing) surface condition. The obtained results show a significant increase (≈50%) in fatigue strength due to mechanical post-processing correlating with decreased surface roughness and minimized notch effects when compared to the surface quality of the non-optimized laser cutting. The martensitic α’-phase is detected in the HAZ with the formation of distinctive zones compared to the initial equiaxial α+β microstructure. The HAZ could be removed up to 50% by means of barrel grinding and up to 100% through mechanical polishing. A fracture analysis revealed that the fatigue cracks always initiate on the laser-cut edges in the as-cut surface condition, which could be assigned to an irregular macro and micro-notch relief. However, the typical characteristics of the non-optimized laser cutting process (melting drops and significant higher surface roughness) lead to early fatigue failure. The fatigue cracks solely started from the micro-notches of the surface relief and not from the dross. As a consequence, the fatigue properties are dominated by these notches, which lead to significant scatter, as well as decreased fatigue strength compared to the surface conditions with mechanical finishing and better surface quality. With optimized laser-cutting conditions, HAZ will be minimized, and surface roughness strongly decreased, which will lead to significantly improved fatigue strength.

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THE CHARACTERISTICS OF LAMPUNG LOCAL SAND AS CASTING SAND IN THE METAL CASTING PROCESS

Jurnal Dinamika Penelitian Industri ◽

10.28959/jdpi.v30i1.4626 ◽

2019 ◽

Vol 30 (1) ◽

pp. 10

Author(s):

Yusup Hendronursito ◽

David Candra Birawidha ◽

Kusno Isnugroho ◽

Fathan Bahfie ◽

Wulanda Yurista Persatika ◽

...

Keyword(s):

Casting Process ◽

Metal Casting ◽

Casting Sand

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Fatigue of Metal Free Reed due to Self-Excited Oscillation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.33-37.267 ◽

2008 ◽

Vol 33-37 ◽

pp. 267-272

Author(s):

Yoshinobu Shimamura ◽

Keiichiro Tohgo ◽

Hiroyasu Araki ◽

Yosuke Mizuno ◽

Shoji Kawaguchi ◽

...

Keyword(s):

Fatigue Testing ◽

The Self ◽

Fatigue Properties ◽

Bending Fatigue ◽

Metal Free ◽

Mass Damper ◽

Excited Oscillation ◽

Analytical Research ◽

Fatigue Characteristics ◽

Good Agreement

Metal free reeds are used for musical instruments like harmonica. Free reeds are small, thin cantilevers, and oscillate by blowing air. It is reported that free reeds break due to fatigue during play. In order to elongate the life of free reeds, the fatigue properties should be investigated and a motion analysis method should be developed. The experimental and analytical research on metal free reed, however, has been rarely reported. In this study, two types of fatigue testing machines were developed to obtain basic fatigue characteristics. The fatigue testing machines are designed for bending fatigue of actual free reeds whose thickness is less than 400 μm. An S-N diagram is successfully obtained up to 107 cycles by using the developed fatigue testing machines. The fracture surfaces of fatigued specimens are in good agreement with those of free reeds failed in use. Then, an analytical method for the self-excited oscillation of free reeds was developed based on a mass-damper-spring model. The proposed method can take account for the shape of free reed. The self-excited oscillation of free reeds with different shape are analyzed and in good agreement with experimental results.

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