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.

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.

Effects of Shot-Peening on Fretting-Fatigue Behavior of Ti-6Al-4V

2002 ◽  
Vol 124 (2) ◽  
pp. 222-228 ◽  
Author(s):  
S. A. Namjoshi ◽  
V. K. Jain ◽  
S. Mall
Keyword(s):  
Fatigue Life ◽  
Shot Peening ◽  
Fatigue Behavior ◽  
Contact Region ◽  
Fretting Fatigue ◽  
Initiation Site ◽  
Fatigue Tests ◽  
Residual Tensile Stress ◽  
X Ray Diffraction ◽  
Element Analysis

The effects of shot-peening on the fretting fatigue behavior of titanium alloy, Ti-6Al-4V were investigated. Specimens were shot-peened as per AMS 2432 standard. X-ray diffraction analysis measured a maximum compressive stress of 800 MPa at the specimen surface, which reduced to zero at a depth of 188 μm. The compensatory residual tensile stress in the specimen was estimated using a curve fitting technique, the maximum value of which was found to be 260 MPa at a depth of 255 μm. Fretting fatigue tests were conducted at room temperature at a cyclic frequency of 200 Hz. Scanning electron microscopy of the shot-peened fretting fatigue specimens showed that the crack initiated at a point below the contact surface, the depth of which was in the range of 200–300 μm. Finite element analysis of the fretting fatigue specimens was also conducted. Fatigue life diagrams were established for the fretting fatigue specimens with and without shot-peening, and were compared to those under the plain fatigue condition, i.e. without fretting. Shot-peening improved the fretting fatigue life of Ti-6Al-4V; furthermore, it moved the crack initiation site from the fretting contact region to a region inside the specimen. Moreover, stress analysis showed that the fatigue failure of shot-peened specimens was caused by the compensatory 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.

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.

High Cycle Fatigue Behavior of Recycled Additive Manufactured Electron Beam Melted Titanium Ti6Al4V

2020 ◽  
Author(s):  
Melody Mojib ◽  
Rishi Pahuja ◽  
M. Ramulu ◽  
Dwayne Arola
Keyword(s):  
Electron Beam ◽  
Fatigue Life ◽  
Rough Surface ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
High Strength ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Initiation And Propagation ◽  
Powder Recycling

Abstract Metal Additive Manufacturing (AM) has become a popular method for producing complex and unique geometries, especially gaining traction in the aerospace and medical industries. With the increase in adoption of AM and the high cost of powder, it is critical to understand the effects of powder recycling on part performance to move towards material qualification and certification of affordable printed components. Due to the limitations of the Electron Beam Melting (EBM) process, current as-printed components are susceptible to failure at limits far below wrought metals and further understanding of the material properties and fatigue life is required. In this study, a high strength Titanium alloy, Ti-6Al-4V, is recycled over time and used to print fatigue specimens using the EBM process. Uniaxial High Cycle Fatigue tests have been performed on as-printed and polished cylindrical specimens and the locations of crack initiation and propagation have been determined through the use of a scanning electron microscope. This investigation has shown that the rough surface exterior is far more detrimental to performance life than the powder degradation occurring due to powder reuse. In addition, the effects of the rough surface exterior as a stress concentration is evaluated using the Arola-Ramulu. The following is a preliminary study of the effects powder recycling and surface treatments on EBM Ti-6Al4V fatigue life.

The Effects of Mechanical Properties on Fatigue Behavior of ECAPed AA7075

2016 ◽  
Vol 35 (3) ◽  
pp. 225-234 ◽  
Author(s):  
Hasan Kaya ◽  
Mehmet Uçar
Keyword(s):  
Electron Microscope ◽  
Fatigue Life ◽  
Fatigue Behavior ◽  
Optical Microscope ◽  
Fatigue Tests ◽  
Angular Pressing ◽  
Four Point Bending ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Hardness Values

AbstractIn this study, the effects of equal channel angular pressing (ECAP) on high-cycle fatigue and fatigue surface morphology of AA7075 have been investigated at a constant temperature (483 K) and the “C” route for four passes at ECAP process. ECAPed and as-received specimens were tested by four-point bending fatigue device. Fatigue tests were carried out by using 100, 120 and 140 MPa strength values. ECAPed specimens were characterized for each pass with optical microscope (OM), scanning electron microscope (SEM), energy-dispersive spectroscope (EDS), transmission electron microscope (TEM), selected area electron diffraction (SAED) and hardness measurements. Fracture surfaces of the specimens were also characterized with SEM. The results show that the highest hardness values (137 HV) and the best fatigue life (5.4 × 107for 100 MPa) were measured in ECAPed four-pass sample. For this reason hardness values and fatigue life were increased with increasing number of severe plastic deformation (SPD) process.

scholarly journals Multiaxial fatigue behavior of 2618 aluminum alloy

2019 ◽  
Vol 300 ◽  
pp. 09003
Author(s):  
Benaïssa Malek ◽  
Catherine Mabru ◽  
Michel Chaussumier
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Internal Pressure ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Mean Stress ◽  
Research Project ◽  
Pressure Tests

The purpose of the present research project is to study multiaxial fatigue behavior of 2618 alloy. The influence of mean stress on the fatigue behavior under tension and torsion is particularly investigated. Fatigue tests under combined tensile-torsion, in or out of phase, as well as combined tensile-torsion-internal pressure tests have also been conducted. Multiaxial fatigue results are analyzed according to Fatemi-Socie criterion to predict the fatigue life.

scholarly journals Effect of UV Ageing on the fatigue life of bulk polyethylene

2018 ◽  
Vol 165 ◽  
pp. 08002 ◽  
Author(s):  
Hamza Lamnii ◽  
Moussa Nait-Abdelaziz ◽  
Georges Ayoub ◽  
Jean-Michel Gloaguen ◽  
Ulrich Maschke ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Uv Irradiation ◽  
Chemical Structure ◽  
Fatigue Behavior ◽  
Crystalline Polymer ◽  
Fatigue Loading ◽  
Chain Scission ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Irradiation Effect

Polymers operating in various weathering conditions must be assessed for lifetime performance. Particularly, ultraviolet (UV) radiations alters the chemical structure and therefore affect the mechanical and fatigue properties. The UV irradiation alters the polymer chemical structure, which results into a degradation of the mechanical and fatigue behavior of the polymer. The polymer properties degradation due to UV irradiation is the result of a competitive process of chain scission versus post-crosslinking. Although few studied investigated the effect of UV irradiation on the mechanical behaviour of thermoplastics, fewer examined the UV irradiation effect on the fatigue life of polymers. This study focuses on investigating the effect of UV irradiation on the fatigue properties of bulk semi-crystalline polymer; the low density Polyethylene (LDPE). Tensile specimens were exposed to different dose values of UV irradiation then subjected to fatigue loading. The fatigue tests were achieved under constant stress amplitude at a frequency of 1Hz. The results show an important decrease of the fatigue limit with increasing absorbed UV irradiation dose.

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