Fatigue Behavior of A5052 Aluminum Alloy with DLC/Thermally Sprayed WC-12Co Hybrid Coatings

2012 ◽  
Vol 538-541 ◽  
pp. 1693-1696 ◽  
Author(s):  
Y. Uematsu ◽  
T. Kakiuchi ◽  
Y. Kobayashi ◽  
Y. Harada
Keyword(s):  
Fatigue Behavior ◽  
Single Layer ◽  
Fatigue Tests ◽  
Hybrid Coating ◽  
Hybrid Coatings ◽  
Al Alloy ◽  
Dlc Film ◽  
Rotating Bending Fatigue ◽  
Rotating Bending ◽  
Thermally Sprayed

Rotating bending fatigue tests had been performed using A5052 aluminum (Al) alloy with the hybrid coatings which consisted of tungsten carbide including 12% cobalt (WC-12Co) interlayer and diamond-like carbon (DLC) film, in order to investigate the effect of hybrid coating on the fatigue behavior. The WC-12Co layer was thermally sprayed by a high velocity oxygen fuel (HVOF) method on A5052 with the thickness of 70, 120 or 170μm. Subsequently, the DLC film was deposited with the thickness of 15μm. The fatigue strengths of the specimens with WC-12Co single layer were higher than those of the substrate and increased with increasing the thickness of WC-12Co layer. The fatigue strengths of the specimens with the hybrid coating of 70μm WC-12Co interlayer and 15μm DLC film were better than those of the specimen with 70μm WC-12Co single layer. Thus the hybrid coating structure was effective to improve fatigue strengths. However the beneficial effect of hybrid coating was not apparent in the specimens with thicker WC-12Co interlayer of 120 and 170μm.

On the Effect of Electrodischarge Drilling on the Fatigue Life of Inconel 718

2014 ◽  
Vol 891-892 ◽  
pp. 1451-1456
Author(s):  
Elena Bassoli ◽  
Andrea Baldini ◽  
Andrea Gatto ◽  
Antonio Strozzi ◽  
Lucia Denti
Keyword(s):  
Fatigue Life ◽  
Inconel 718 ◽  
Metal Cutting ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Aerospace Applications ◽  
Rotating Bending Fatigue ◽  
Cutting Operation ◽  
Rotating Bending ◽  
Superposition Effect

Difficult-to cut-materials are associated with premature tool failure, most likely in the case of complex geometries and this shapes. However, Nickel-based alloys are commonly used in high-temperature and aerospace applications, where thin deep holes are often required. Then, the only viable manufacturing solution relies on non-contact processes, like electrodischarge (ED) drilling. Morphology of ED machined surfaces is significantly different than obtained by metal-cutting operation and is known to jeopardize fatigue strength, but the extent needs to be gauged and related to the process parameters. Aim of the paper is to study the effect of holes (0.8 mm diameter, aspect ratio 10) produced by ED drilling on the fatigue life of Inconel 718. Rotating bending fatigue tests are carried out on specimens drilled under two ED setups, as well as with a traditional cutting tool. Specimens free from holes are fatigued under the same conditions for comparison. Based on previous studies, extremal ED parameters are selected, giving best surface finish versus highest productivity. S-N curves show that the ED process causes a decrease of the fatigue resistance with respect to traditional drilling, whereas the effect of different ED setups is negligible. Maximum productivity can thus be pursued with no threat to fatigue performance. The fatigue limit variation is quantified by using the superposition effect principle: ED drilling causes an increase of the stress concentration factor around 25% if compared to traditional drilling. The macroscopic fatigue behavior is integrated with a study of the effects of the different drilling processes in the micro-scale, by means of a microstructural and fractographic analysis.

Effect of Shot Peening on Fatigue Behavior of AISI 4340 in Different Loading Conditions

2016 ◽  
Vol 713 ◽  
pp. 30-33 ◽  
Author(s):  
Marcelo A.S. Torres ◽  
D.T. Harada ◽  
Carlos Antonio Reis Pereira Baptista ◽  
Maria P. Cindra Fonseca
Keyword(s):  
Fatigue Life ◽  
Shot Peening ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Residual Stress Field ◽  
Surface Layers ◽  
Tension Tests ◽  
Rotating Bending Fatigue ◽  
Rotating Bending ◽  
Aisi 4340

Shot peening is a method widely used to improve the fatigue strength of materials, through the creation of a compressive residual stress field (CRSF) in their surface layers. In the present research the gain in fatigue life of AISI 4340 steel, obtained by shot peening treatment, is evaluated under the three different hardnesses used in landing gear. Rotating bending fatigue tests and alternating tension tests were conducted and the CRSF was measured by x-ray tensometry prior and after interrupted fatigue tests. The evaluation of fatigue life after shot peening in relation to the relaxation of CRSF, of the crack initiation sites and surface roughness is done.

Effect of Humidity on Fatigue Strength of Age-Hardened Al Alloy

2009 ◽  
Vol 417-418 ◽  
pp. 373-376
Author(s):  
T. Fukudome ◽  
Norio Kawagoishi ◽  
K. Kariya
Keyword(s):  
Fatigue Strength ◽  
Fracture Mechanism ◽  
Fatigue Tests ◽  
Shear Mode ◽  
Al Alloy ◽  
Bending Fatigue ◽  
Rotating Bending Fatigue ◽  
Ultrasonic Fatigue ◽  
Rotating Bending ◽  
The Difference

Ultrasonic and rotating bending fatigue tests were carried out using plain specimens and specimens with a small blind hole for an extruded and age-hardened Al alloy 7075-T6 in different environments in order to investigate the effect of humidity on fatigue strength and fracture mechanism. Fatigue strength was decreased by high humidity under both tests. The effect of humidity on fatigue strength was larger in ultrasonic fatigue. The humidity affected both of crack initiation and propagation processes. Crack propagated in tensile mode then changed to shear mode macroscopically in all environments under ultrasonic fatigue, though it was only in tensile mode under rotating bending fatigue. These differences in fracture mechanism related to the difference in environmental effect on fatigue strength in both tests.

Effect of Humidity on Fatigue Strength of Age-Hardened Al Alloy under Rotating Bending

2010 ◽  
Vol 452-453 ◽  
pp. 745-748 ◽  
Author(s):  
Norio Kawagoishi ◽  
K. Kariya ◽  
Yan Nu ◽  
S. Furumoto ◽  
Eiji Kondo
Keyword(s):  
Fatigue Strength ◽  
Fatigue Tests ◽  
Propagation Mode ◽  
Shear Mode ◽  
Al Alloy ◽  
High Humidity ◽  
Mode Propagation ◽  
Initiation And Propagation ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

In order to investigate the effect of humidity on fatigue strength of an extruded and age-hardened Al alloy 7075-T6, rotating bending fatigue tests were carried out using plain specimens in environments of controlled relative humidity of 25%, 50%, 75% and 85% and distilled water. The cross section of the alloy has a marked texture of (111) plane. Although fatigue strength was decreased by high humidity, the decrease by high humidity was very small when the humidity was lower than about 60% -70% and fatigue strength was largely decreased over the humidity. Both of initiation and propagation of a crack were accelerated by high humidity. In high humidity, a crack propagated in a shear mode macroscopically and it was ductile in company with many glide planes and voids microscopically. That is, the propagation was not a tensile mode with brittle facets even in water. The shear mode propagation inclined about 35° to the extruded direction and fracture surface was (100) plane, meaning that the shear mode propagation of a crack was mainly caused by the marked texture of the alloy. The propagation mode of a crack was affected by not only environment but also stress level.

scholarly journals Fatigue and Vibration Parameters Improvement of Steel DIN 41Cr4 by Ultrasonic Shock Peening Treatment

2019 ◽  
Vol 22 (3) ◽  
pp. 233-239
Author(s):  
Zeina Shaker Mahmood ◽  
Jumaa Salman Chiad
Keyword(s):  
Fatigue Behavior ◽  
Hardness Test ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Fatigue Strength Improvement ◽  
Rotating Bending Fatigue ◽  
Rotating Bending ◽  
Shock Peening ◽  
Number Of Cycles ◽  
Vibration Parameters

The effects of the ultrasonic peening treatment (UPT) on the rotating bending fatigue behavior and the behavior of the vibrations of alloy steel DIN 41Cr4 were studied. Hardness test, Tensile test, Constant amplitude fatigue tests, and the vibrations measurements have been carried out on the specimens. Also, the fracture surface was examined and analyzed by a Scanning Electron Microscope (SEM). The results of the investigations, e.g. stress to number of cycles to failure (S-N) curves, fatigue strength improvement factor was 7%. The decreasing percentage of maximum Fast Fourier Transform (FFT) acceleration of the ultrasonic peened condition compared to the untreated conditions was 45%.

Effect of REM Finishing on Fatigue Behavior of a Shot Peened Low Alloy Steel

2011 ◽  
Vol 488-489 ◽  
pp. 290-293 ◽  
Author(s):  
Sara Bagherifard ◽  
Ramin Ghelichi ◽  
Mario Guagliano ◽  
M. Bandini
Keyword(s):  
Surface Roughness ◽  
Shot Peening ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Polishing Process ◽  
Bending Fatigue ◽  
Finishing Process ◽  
Rotating Bending Fatigue ◽  
Rotating Bending ◽  
Compressive Residual Stresses

The effect of slight surface REM finishing, that is a chemically accelerated polishing process, in order to reduce surface roughness after shot peening has been studied on different series of specimens shot peened by varied peening parameters. Room temperature rotating bending fatigue tests have been performed on the shot peened series and the series subjected to shot peening and successive REM finishing process. The results represent how REM finishing affects the final fatigue behavior of differently treated specimens in two ways: decreasing surface roughness and removing a thin layer of material with compressive residual stresses.

scholarly journals Improvement the Mechanical Characteristics of Alloy Steel DIN 41Cr4 by Shot Peening

2020 ◽  
Vol 26 (7) ◽  
pp. 1-15
Author(s):  
Zeina Shaker Mahmood ◽  
Jumaa Salman Chiad
Keyword(s):  
Alloy Steel ◽  
Shot Peening ◽  
Fatigue Behavior ◽  
Hardness Test ◽  
Fatigue Tests ◽  
Fatigue Strength Improvement ◽  
Rotating Bending Fatigue ◽  
Rotating Bending ◽  
High Roughness ◽  
Number Of Cycles

The effects of shot peening treatment (SPT) were studied at (10,20, and 30) minutes on the rotating bending fatigue behavior and the behavior of the alloy steel DIN 41Cr4 vibrations. The hardness test, tensile test, constant amplitude fatigue tests, and the vibration measurements were performed on samples with and without cracks at room temperature (RT), also, the fracture surface was examined and analyzed by a Scanning Electron Microscope (SEM). The results of the investigations, for example, Stress to Number of cycles to failure (S-N) curves, fatigue strength improvement factor of 5% to 10%, the decreasing percentage of maximum Fast Fourier Transform (FFT) acceleration of the shot-peened condition were compared to untreated conditions ranging between 25% and 40%. All these improvements occurred for up to 20 minutes of shot peening time (20 SPT), exceeding that time the fatigue behavior tended to decrease due to high roughness and the generation of tensile residual stress.

High Cycle Fatigue Behavior of Thermally Oxidized Ti6Al4V Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 2179-2182 ◽  
Author(s):  
Mehmet Cingi ◽  
Onur Meydanoglu ◽  
Hasan Guleryuz ◽  
Murat Baydogan ◽  
Huseyin Cimenoglu ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Yield Strength ◽  
Thermal Oxidation ◽  
Fatigue Behavior ◽  
Surface Hardness ◽  
Ti6al4v Alloy ◽  
Bending Fatigue ◽  
Rotating Bending Fatigue ◽  
Rotating Bending ◽  
Bending Fatigue Strength

In this study, the effect of thermal oxidation on the high cycle rotating bending fatigue behavior of Ti6Al4V alloy was investigated. Oxidation, which was performed at 600°C for 60 h in air, considerably improved the surface hardness and particularly the yield strength of the alloy without scarifying the tensile ductility. Unfortunately, the rotating bending fatigue strength at 5x106 cycles decreased from about 610 MPa to about 400 MPa upon oxidation. Thus, thermal oxidation leaded a reduction in the fatigue strength of around 34%, while improving the surface hardness (HV0.1) and yield strength 85 % and 36 %, respectively.

Improvement of Fatigue Behaviour of High Strength Aluminium Alloys by Fluidized Bed Peening (FBP)

2007 ◽  
Vol 344 ◽  
pp. 87-96 ◽  
Author(s):  
M. Barletta ◽  
F. Lambiase ◽  
Vincenzo Tagliaferri
Keyword(s):  
Fatigue Life ◽  
Fluidized Bed ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Maximum Amplitude ◽  
High Strength ◽  
Operational Parameters ◽  
Bending Fatigue ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

This paper deals with a definition of a relatively novel technique to improve the fatigue behavior of high strength aluminum alloys, namely, Fluidized Bed Peening (FBP). Fatigue samples made from AA 6082 T6 alloy were chosen according to ASTM regulation about rotating bending fatigue test and, subsequently, treated by varying FBP operational parameters and fatigue testing conditions. First, a full factorial experimental plan was performed to assess the trend of number of cycles to rupture of fatigue samples varying among several experimental levels the factors peening time and maximum amplitude of alternating stress applied to fatigue samples during rotating bending fatigue tests. Second, design of experiment (DOE) technique was used to analyze the influence of FBP operational parameters on fatigue life of AA 6082 T6 alloy. Finally, ruptures of FB treated samples and untreated samples were discussed in order to evaluate the influence of operational parameters on the effectiveness of FBP process and to understand the leading process mechanisms. At any rate, the fatigue behavior of processed components was found to be significantly improved, thereby proving the suitability of FBP process as alternative mechanical technique to enhance fatigue life of components made from high strength aluminum alloy.

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