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.

Analyses of Contact Pressure and Stress Amplitude Effects on Fretting Fatigue Life

2000 ◽  
Vol 123 (1) ◽  
pp. 85-93 ◽  
Author(s):  
K. Iyer ◽  
S. Mall
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Contact Pressure ◽  
Stress Amplitude ◽  
Normal Load ◽  
Contact Region ◽  
Local Stress ◽  
Fretting Fatigue ◽  
Element Analysis ◽  
Stress Ratios

Elastic-plastic finite element analyses of a cylinder-on-plate configuration, studied experimentally, were performed to provide an explanation for the decrease in fretting fatigue life with increasing contact pressure. Three values of normal load, namely 1338 N, 2230 N, and 3567 N, and three stress ratios (0.1, 0.5, and 0.7) were considered. Based on a previously determined dependency between contact pressure and friction coefficient, the effect of coefficient of friction was also evaluated. The deformation remained elastic under all conditions examined. Cyclic, interfacial stresses, and slips were analyzed in detail. The amplification of remotely applied cyclic stress in the contact region is shown to provide a rationale for the effect of contact pressure and stress amplitude on life. Comparisons with previous experiments indicate that the local stress range computed from finite element analysis may be sufficient for predicting fretting fatigue life. Further, the results suggest that the slip amplitude and shear traction may be neglected for this purpose.

scholarly journals Influence of Ultrasonic Surface Rolling Process and Shot Peening on Fretting Fatigue Performance of Ti-6Al-4V

2021 ◽  
Author(s):  
Ning Wang ◽  
Jin long Zhu ◽  
Bai Liu ◽  
Xiancheng Zhang ◽  
Jiamin Zhang ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Shot Peening ◽  
Surface Hardness ◽  
Rolling Process ◽  
Fretting Fatigue ◽  
Fatigue Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Strengthening ◽  
Stress Layer

Abstract The shot-peening (SP) and ultrasonic surface rolling process (USRP) were performed on Ti–6Al-4V plate specimens. The surface hardness and residual stresses of the material were tested by vickers indenter and X-ray diffraction residual stress analyzer. The effects of different surface strengthening on its fretting fatigue properties were verified by fretting fatigue experiments. It is shown (i) that the fretting fatigue life of Ti–6Al-4V effectively improved after USRP and SP and（ii）that the surface integrity of specimens after USRP is the best, which has deeper residual compressive stress layer and more refined grain. The fretting fatigue fracture surface and wear morphology of the samples were studied and analyzed by means of microscopic observation, and the mechanism of improving fretting fatigue life by surface strengthening process was further explained

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.

scholarly journals Fretting-Fatigue Analysis of Shot-Peened Al 7075-T651 Test Specimens

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 586 ◽  
Author(s):  
Vicente Martín ◽  
Jesús Vázquez ◽  
Carlos Navarro ◽  
Jaime Domínguez
Keyword(s):  
Fatigue Life ◽  
Residual Stresses ◽  
Shot Peening ◽  
Normal Load ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Material Surface ◽  
Tangential Load ◽  
Bulk Stress ◽  
Al 7075

Shot peening is a mechanical treatment that induces several changes in the material: surface roughness, increased hardness close to the surface, and, the most important, compressive residual stresses. This paper analyzes the effect of this treatment on alloy Al 7075-T651 in the case of fretting fatigue with cylindrical contact through the results of 114 fretting fatigue tests. There are three independent loads applied in this type of test: a constant normal load N, pressing the contact pad against the specimen; a cyclic bulk stress σ in the specimen; and a cyclic tangential load Q through the contact. Four specimens at each of 23 different combinations of these three parameters were tested—two specimens without any treatment and two treated with shot peening. The fatigue lives, contact surface, fracture surface, and residual stresses and hardness were studied. Improvement in fatigue life ranged from 3 to 22, depending on fatigue life. The relaxation of residual-stress distribution related to the number of applied cycles was also measured. Finally, another group of specimens treated with shot peening was polished and tested, obtaining similar lives as in the tests with specimens that were shot-peened but not polished.

A STUDY ON THE FRETTING FATIGUE LIFE OF ZIRCALOY ALLOYS

2008 ◽  
Vol 22 (11) ◽  
pp. 851-856
Author(s):  
JAE-DO KWON ◽  
DAE-KYU PARK ◽  
SEUNG-WAN WOO ◽  
YOUNG-SUCK CHAI
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
Fatigue Behavior ◽  
Fretting Fatigue ◽  
Mechanical Tests ◽  
Fatigue Tests ◽  
Cyclic Damage

Studies on the strength and fatigue life of machines and structures have been conducted in accordance with the development of modern industries. In particular, fine and repetitive cyclic damage occurring in contact regions has been known to have an impact on fretting fatigue fractures. The main component of zircaloy alloy is Zr , and it possesses good mechanical characteristics at high temperatures. This alloy is used in the fuel rod material of nuclear power plants because of its excellent resistance. In this paper, the effect of the fretting damage on the fatigue behavior of the zircaloy alloy is studied. Further, various types of mechanical tests such as tension and plain fatigue tests are performed. Fretting fatigue tests are performed with a flat-flat contact configuration using a bridge-type contact pad and plate-type specimen. Through these experiments, it is found that the fretting fatigue strength decreases by about 80% as compared to the plain fatigue strength. Oblique cracks are observed in the initial stage of the fretting fatigue, in which damaged areas are found. These results can be used as the basic data for the structural integrity evaluation of corrosion-resisting alloys considering the fretting damages.

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.

scholarly journals Experimental and numerical investigation into effect of elevated temperature on fretting fatigue behavior

2011 ◽  
Vol 2 (1) ◽  
pp. 2-11
Author(s):  
R. Hojjati Talemi ◽  
M. Soori ◽  
M. Abdel Wahab ◽  
Patrick De Baets
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Elevated Temperature ◽  
Gas Turbines ◽  
Fatigue Behavior ◽  
Surface Oxidation ◽  
Fretting Fatigue ◽  
Growth Increment ◽  
Fatigue Tests ◽  
New Device

t Fretting fatigue damage occurs in contacting parts when they are subjected to fluctuating loadingsand sliding movements at the same time. This phenomenon may occur in many applications such asbearings/ shafts, bolted and riveted connections, steel cables, and steam and gas turbines. In this paper,the effect of elevated temperature on fretting fatigue life of Al7075-T6 is investigated using a new device forfretting fatigue tests with variable crank shaft mechanism. Also a finite element modeling method was usedto estimate crack propagation lifetime in aluminum alloy, Al7075-T6 specimens at elevated temperatureunder fretting condition. In this method, shear and normal stresses that are caused by contact load areupdated at each crack growth increment. Finally, a comparison between the experimental and numericalresults is done in order to evaluate the FE simulation.Department of mechanical engineering, Islamic Azad University, Takestan Branch, Takestan, IranThe experimental results show that: (i) fretting fatigue life of the material increases with temperature up to350°C by 180% for low stresses and decreases by 40% for high stresses, (ii) this fashion of variation offretting fatigue life versus temperature is believed to be due to degradation of material properties whichoccurs by overaging and wear resistance increase due to oxidation of aluminum alloy. While overaginggives rise to degradation of mechanical strength of material and hence the reduction of its fretting fatiguelife, surface oxidation of the specimens brings some improvement of fatigue behavior of the material.Metallurgical examination of the specimens reveals that temperature results in precipitation of impurities ofal-7075-T6. The size of precipitated impurities and their distances gets bigger as temperature increases.This could be a reason for material degradation of specimens which are exposed to heating for longer timeduration.

Fatigue Evaluation of 8630 Cast Steel Subjected to Post-Weld Heat Treatment and Stress Relieving

2014 ◽  
Author(s):  
Alireza Shirazi ◽  
Ihab Ragai
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Behavior ◽  
Cast Steel ◽  
Fatigue Tests ◽  
Filler Materials ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Stress Relieving ◽  
Weld Heat

The effect of post weld heat treating and stress relieving on the fatigue strength of AISI 8630 cast steel, weld repaired with different filler materials, is the primary objective of the study. To determine the material properties, experiments included monotonic tensile tests, load-controlled fatigue tests as well as hardness tests. Moreover, specimens were micro-etched to examine the morphology of the fracture surface. The results of the fatigue tests are presented in the form of S-N charts. The test findings are then employed in a generalized numerical solution to predict the fatigue behavior of similar components. Finite element models are used to calculate stresses in tested samples, stress concentrations, and in fatigue life comparisons. Stress-life predictions were performed using the modified Goodman criterion to account for the mean stress effects caused by the stress ratio R = 0.1 loading. Predictions based off of finite element analysis and analytical solution for fatigue life provided reasonable estimates which are confirmed by the experimental results.

Effects of Stress-Relieving Slots on Fretting Fatigue Behavior of Ti-6Al-4V

2005 ◽  
Author(s):  
R. H. Wang ◽  
V. K. Jain ◽  
S. Mall
Keyword(s):  
Fatigue Resistance ◽  
Fatigue Behavior ◽  
Contact Region ◽  
Maximum Shear Stress ◽  
Fretting Fatigue ◽  
Maximum Tensile Stress ◽  
Element Analysis ◽  
Fatigue Specimen ◽  
Stress Relieving ◽  
The Finite Element Analysis

Fretting is a complex phenomenon, it alters the stress and strain fields in the contact region between two bodies, due to micro-slip, which decreases the fatigue resistance of materials. This study investigates the effect of stress-relieving slots, machined in flat pads, on the fretting fatigue behavior of Ti-6Al-4V alloy. Three types of slots including U-notch, V-notch, and a simple hole were used. Conventional fretting fatigue model, involving a contact between a flat pad with rounded edges and a fatigue specimen loaded by a cyclic axial load, was used. Several fretting fatigue parameters such as the maximum tensile stress, Smith Watson Topper, Maximum Shear Stress Range, and MSSR parameters were considered for this study. The stress, strain, and displacement distribution in the contact region of fatigue specimen were computed using the finite element analysis code ABAQUS. The data were used to calculate the fretting fatigue parameters and evaluate the effectiveness of the slots in improving the fretting fatigue resistance. The analytical results were verified by the experimental data.

The Analysis on the Low Cycle Fatigue Behavior of a Directionally Solidified Superalloy with Recrystallized Surface Layers

2008 ◽  
Vol 44-46 ◽  
pp. 43-50 ◽  
Author(s):  
Hui Ji Shi ◽  
Xian Feng Ma ◽  
Da Wei Jia ◽  
Hai Feng Zhang ◽  
Li Sha Niu
Keyword(s):  
Fatigue Life ◽  
Shot Peening ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Directionally Solidified ◽  
Surface Layers ◽  
Time Observation

Specimens of a directionally solidified superalloy with different shot peening pressure were annealed at 1220oC in vacuum condition to get recrystallized surface layers with different micro-structures. Low cycle fatigue tests of these specimens were performed at room temperature and 400oC by using an electrohydraulic load frame in the SEM system for real-time observation. The initiation and propagation of cracks were inspected and the influence of the micro-structure of the recrystallized layer on the material fatigue behavior was analyzed. The low cycle fatigue life of the specimens depends mainly on the characteristics of the recrystallized layer. When the shot peening pressure is lower, the recrystallized layer is thin and not integrated, and the fatigue life decreases obviously in comparison with that of the specimen without recrystallized surface layer. When the shot peening pressure increases, the recrystal grains are more integrated, and the fatigue life rises. A comparison of the recrystallized layers between the blade surface and the specimen surface has been done and it points that the incompact surface recrystal layer is very dangerous to gas turbine blades.

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