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.

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.

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.

Effect of Austempering Temperature on High Cycle Fatigue Behavior of an Austempered Ductile Iron (ADI)

2010 ◽  
Vol 457 ◽  
pp. 493-498 ◽  
Author(s):  
Sasan Yazdani ◽  
Amir Sadighzadeh Benam ◽  
Behzad Avishan
Keyword(s):  
Fatigue Life ◽  
Volume Fraction ◽  
Fatigue Behavior ◽  
Salt Bath ◽  
Fatigue Tests ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Test Pieces ◽  
Rotating Bending Fatigue ◽  
Austempering Temperature

Ductile irons with chemical compositions of Fe-3.6%C-2.6%Si-0.50%Cu-0.51%Ni were cast into standard keel blocks. Austenitizing heat treatment was carried out on test pieces at 875°C followed by austempering at 320, 365 and 400°C for times within the austempering processing window in a salt bath furnace. Rotating bending fatigue tests were performed with Roell Amsler UBM 200™ equipment at 3500 rpm at room temperature. Metallography and X-ray diffraction techniques were used to evaluate the fatigue life. Results indicate an increase of 10, 20 and 24% in fatigue life for specimens austempered at temperatures of 320, 365 and 400°C respectively, compared to that of as cast samples. According to the XRD test results; there is an increase in volume fraction of high carbon austenite by increasing the austempering temperature.

Frequency Effect of Torsion on Rotating Bending Fatigue Behavior of Gas Tungsten Arc (GTA) Welded AISI 1018 and AISI 4140 Welded Joints

2018 ◽  
Author(s):  
Saad Aziz ◽  
Ahmet Eren ◽  
Muhammad A. Wahab
Keyword(s):  
Fatigue Life ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Fatigue Behavior ◽  
Frequency Effect ◽  
Gas Tungsten Arc ◽  
Aisi 4140 ◽  
Rotating Bending Fatigue ◽  
Rotating Bending ◽  
Fatigue Life Reduction

Fatigue failures of welded structure are subjected to occur due to multiaxial fatigue load and torsion. In the current research work, the frequency effect of torsion on rotating bending fatigue load is analyzed on AISI 1018 steel and AISI 4140 steel. To perform rotating bending torsional fatigue test of welded and un-welded specimens, a unit was designed and manufactured. Gas Tungsten Arc (GTA) welding was carried out on round bar of AISI 1018 steel and AISI 4140 steel welded using ER70-S2 filler metal for welded specimen. Later, the influence of torsional frequency on rotating bending with torsion is analyzed on both base metal and welded structures. The frequency of torsion was applied on the specimens were - 500 cycle, 1000 cycle, 1500 cycle, 2000 cycle and 2500 cycle. From the analysis, fatigue life of AISI 1018 and AISI 4140 base metal specimens (rotating bending and torsion) were not affected when torsion was applied at different frequencies. However, fatigue behavior of welded AISI 1018 and AISI 4140 specimens were highly affected by the frequency of torsion. For torsion applied at every 500 cycles, 83.8% reduction of fatigue life was observed for AISI 1018 welded specimen with respect to AISI 1018 base metal specimens. In addition, torsion applied for every 1000, 1500, 2000, and 2500 cycles; 81.9%, 80%, 77.1%, and 72.4% reduction on fatigue life were observed for AISI 1018 welded specimen compare to AISI 1018 base metal specimens, respectively. Welded AISI 4140 specimens experienced less change in fatigue life compare to welded AISI 1018 specimens. For torsion applied at every 500 cycles, 73.9% fatigue life reduction was observed for welded AISI 4140 specimens compare to AISI 4140 base metal specimens. For torsion applied at every 1000, 1500, 2000, and 2500 cycles; 65.2%, 60.8%, 50%, and 43.5% fatigue life reduction occurred on welded AISI 1018 specimen. Moreover, hardness measurements for welded specimens of AISI 4140 and AISI 1018 were performed longitudinally. For welded AISI 1018 specimen, 14.8% and 9.7% hardness decrease was observed longitudinally compare to AISI 1018 base metal specimen at heat-affected zone (HAZ) and from heat-affected zone through weld zone, respectively. For welded AISI 4140 specimen, 26.3% reduction of hardness value was observed compare to AISI 4140 base metal through heat-affected zone for longitudinal analysis. Moreover, fracture surface analysis was performed on the welded and non-welded specimens to understand the fracture behavior.

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 tests of pretensioned concrete beams

PCI Journal ◽  
2022 ◽  
Vol 67 (1) ◽  
Author(s):  
Jörn Remitz ◽  
Martin Empelmann
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Concrete Beams ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Design Methods ◽  
Test Results ◽  
Cycle Fatigue ◽  
Pretensioned Concrete ◽  
Current Design

Pretensioned concrete beams are widely used as bridge girders for simply supported bridges. Understanding the fatigue behavior of such beams is very important for design and construction to prevent fatigue failure. The fatigue behavior of pretensioned concrete beams is mainly influenced by the fatigue of the prestressing strands. The evaluation of previous test results from the literature indicated a reduced fatigue life in the long-life region compared with current design methods and specifications. Therefore, nine additional high-cycle fatigue tests were conducted on pretensioned concrete beams with strand stress ranges of about 100 MPa (14.5 ksi). The test results confirmed that current design methods and specifications overestimate the fatigue life of embedded strands in pretensioned concrete beams.

scholarly journals Changing in Fatigue Life of 300 M Bainitic Steel After Laser Carburizing and Plasma Nitriding

2018 ◽  
Vol 165 ◽  
pp. 21002 ◽  
Author(s):  
Antonio J. Abdalla ◽  
Douglas Santos ◽  
Getúlio Vasconcelos ◽  
Vladimir H. Baggio-Scheid ◽  
Deivid F. Silva
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Plasma Nitriding ◽  
Fatigue Behavior ◽  
High Strength ◽  
Tensile Tests ◽  
Steel Sample ◽  
Fatigue Tests ◽  
300M Steel ◽  
Structural Applications

In this work 300M steel samples is used. This high-strength steel is used in aeronautic and aerospace industry and other structural applications. Initially the 300 M steel sample was submitted to a heat treatment to obtain a bainític structure. It was heated at 850 °C for 30 minutes and after that, cooled at 300 °C for 60 minutes. Afterwards two types of surface treatments have been employed: (a) using low-power laser CO2 (125 W) for introducing carbon into the surface and (b) plasma nitriding at a temperature of 500° C for 3 hours. After surface treatment, the metallographic preparation was carried out and the observations with optical and electronic microscopy have been made. The analysis of the coating showed an increase in the hardness of layer formed on the surface, mainly, among the nitriding layers. The mechanical properties were analyzed using tensile and fatigue tests. The results showed that the mechanical properties in tensile tests were strongly affected by the bainitic microstructure. The steel that received the nitriding surface by plasma treatment showed better fatigue behavior. The results are very promising because the layer formed on steel surface, in addition to improving the fatigue life, still improves protection against corrosion and wear.

Sign in / Sign up

Export Citation Format

Share Document