EFFECT OF CERAMIC COATING THICKNESS ON RESIDUAL STRESS AND FATIGUE CHARACTERISTIC OF 1Cr-1Mo-0.25V STEEL

2002 ◽  
Vol 16 (01n02) ◽  
pp. 181-188 ◽  
Author(s):  
CHANG-MIN SUH ◽  
BYUNG-WON HWANG ◽  
KYUNG-RYUL KIM
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Coating Thickness ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Turbine Rotor ◽  
Fatigue Tests ◽  
Rotor Steel

To evaluate the effect of coatings on the fatigue behaviors of turbine rotor steel, TiN and TiAlN films were deposited on the 1Cr-1Mo-0.25V steels by arc-ion plating (AIP) method with and wihtout screen ion filter. The coating thickness were varied with 2.5 μm, 3.5 μm, and 5.0 μm. A Cu-K α beam source was used as a characteristic X-ray and the crystal plane of (422) was selected to evaluate the residual stresses. In order to clear the relationship between fatigue behavior and residual stress of specimen coated with TiN and TiAlN films, the fatigue tests of specimens with and without coating were carried out at room temperatures respectively. It is shown that the fatigue life of the coated specimen was longer than that of uncoated specimen. The compressive residual stresses on the coatings were higher, and the fatigue crack initiated at an inclusion in the substrate near bond interface. It is known that compressive residual stress caused by hard coating would retard the fatigue crack initiation on the specimen surface, and then led to fatigue strength and fatigue life increasing.

Effect of Processing Layer on Fatigue Strength of Extruded AZ61 Magnesium Alloy

2013 ◽  
Vol 577-578 ◽  
pp. 429-432 ◽  
Author(s):  
Yukio Miyashita ◽  
Kyohei Kushihata ◽  
Toshifumi Kakiuchi ◽  
Mitsuhiro Kiyohara
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Magnesium Alloy ◽  
Crack Initiation ◽  
Crack Growth ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Crack Growth Resistance ◽  
Az61 Magnesium Alloy

Fatigue Property of an Extruded AZ61 Magnesium Alloy with the Processing Layer Introduced by Machining was Investigated. Rotating Bending Fatigue Tests were Carried out with the Specimen with and without the Processing Layer. According to Results of the Fatigue Tests, Fatigue Life Significantly Increased by Introducing the Processing Layer to the Specimen Surface. Fatigue Crack Initiation and Propagation Behaviors were Observed by Replication Technique during the Fatigue Test. Fatigue Crack Initiation Life of the Specimen with the Processing Layer was Slightly Longer than that of the Specimen without the Processing Layer. Higher Fatigue Crack Growth Resistance was also Observed when the Fatigue Crack was Growing in the Processing Layer in the Specimen with the Processing Layer. the Longer Fatigue Life Observed in the Fatigue Test in the Specimen with the Processing Layer could be Mainly due to the Higher Crack Growth Resistance. it is Speculated that the Fatigue Strength can be Controlled by Change in Condition of Machining Process. it could be Effective way in Industry to Improved Fatigue Strength only by the Cutting Process without Additional Surface Treatment Process.

Influence of Residual Stress due to Prior Overloading on the Fatigue Life of a Notched Plate

2016 ◽  
Author(s):  
Kumarswamy Karpanan
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Internal Pressure ◽  
Compressive Residual Stress ◽  
Fatigue Crack Initiation ◽  
Pressure Vessels ◽  
Stress And Strain ◽  
Maximum Shear Strain

During autofrettage, pressure vessels are subjected to high internal pressure, causing the internal wall to yield plastically. When the internal pressure is released, the inner wall of the vessel develops compressive residual stress. Similarly, when a subsea component is hydrotested, some of the highly stressed regions yield during hydrotesting and, when the pressure is released, these regions develop compressive residual stress. Fatigue life is greatly influenced by local stress on the component surface. Fatigue crack initiation primarily depends on the cyclic stress or strain and the residual stress state. Tensile residual stress decreases fatigue life and the compressive residual stress significantly increases fatigue life. This is true for both fatigue crack initiation and propagation. In this paper, effects of residual stress on a notched plate are studied by subjecting it to an initial overload cycle and subsequent low loading cycles. Tensile and compressive overloads on the notched plate induce compressive and tensile residual stresses, respectively. An elastic-plastic finite element analysis (FEA) was performed to simulate the overload and low loading cycles on the notched plate. The stress and strain from the FEA is used to perform strain-based fatigue analysis. ASME VIII-3, Brown-Miller (B-M), Maximum shear strain, Socie-Bannantine, and Fatemi-Socie methods are used for calculating the fatigue life of the notched plate. Fatigue life predicted by both stress and strain methods matches well with the test fatigue data.

Interior-Induced Fracture Mechanism of High Cleanliness Spring Steel (JIS SWOSC-V) in Very High Cycle Regime

2015 ◽  
Vol 664 ◽  
pp. 209-218 ◽  
Author(s):  
Taku Miura ◽  
Takayuki Sakakibara ◽  
Takanori Kuno ◽  
Akira Ueno ◽  
Shoichi Kikuchi ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Fracture ◽  
Fracture Mode ◽  
Fracture Mechanism ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Spring Steel ◽  
Topographic Analysis ◽  
Very High

In order to investigate the interior-induced fatigue crack propagation behavior of high cleanliness valve spring steel (JIS SWOSC-V), rotating bending fatigue tests were performed for various kinds of specimens with different hardness or surface finishings. The harder specimen with higher compressive residual stress showed longer fatigue life. The electrochemical polished specimen pre-treated with shot peening showed almost same fatigue life as the shot-peened specimen in spite of the difference in surface roughness. After fatigue tests, fracture surfaces were observed using a scanning electron microscope (SEM) to evaluate the fatigue fracture mechanism. Most specimens failed in surface-induced fracture mode due to high cleanliness; however, some specimens failed in interior-induced fracture mode in the very high cycle regime. Although non-metallic inclusions were not observed at interior fatigue crack initiation sites, 2 types of significant microstructures (with smooth surface or granular surface) were observed. EBSD analysis, profile analysis and computational simulation using a fracture surface topographic analysis (FRASTA) method were performed to investigate the mechanism of the interior-induced fatigue fracture caused by the microstructure at defect without any inclusion.

scholarly journals Fatigue Life Behavior of Laser Shock Peened Duplex Stainless Steel with Different Samples Geometry

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
César A. Vázquez Jiménez ◽  
Vignaud Granados Alejo ◽  
Carlos Rubio González ◽  
Gilberto Gómez Rosas ◽  
Sergio Llamas Zamorano
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Stress Distribution ◽  
Duplex Stainless Steel ◽  
Fatigue Crack Initiation ◽  
Stress Raiser ◽  
Residual Stress Distribution ◽  
Laser Shock

Two different stress raiser geometries (fillets and notched) were treated by laser shock peening (LSP) in order to analyze the effect of sample geometry on fatigue behavior of 2205 duplex stainless steel (DSS). The LSP treatment was carried through Nd : YAG pulsed laser with 1064 nm wavelength, 10 Hz frequency, and 0.85 J/pulse. Experimental and MEF simulation results of residual stress distribution after LSP were assessed by hole drilling method and ABAQUS/EXPLICIT software, respectively. The fatigue tests (tensile-tensile axial stress) were realized with stress ratio of R = 0.1 and 20 Hz. A good comparison of residual stress simulation and experimental data was observed. The results reveal that the fatigue life is increased by LSP treatment in the notched samples, while it decreases in the fillet samples. This is related to the residual stress distribution after LSP that is generated in each geometry type. In addition, the fatigue crack growth direction is changed according to geometry type. Both the propagation direction of fatigue crack and the anisotropy of this steel results detrimental in fillet samples, decreasing the number of cycles to the fatigue crack initiation. It is demonstrated that the LSP effect on fatigue performance is influenced by the specimen geometry.

Effect of Residual Stress, Temperature and Adhesion on Wheel Surface Fatigue Cracking

2008 ◽  
Author(s):  
Daniel H. Stone ◽  
Scott M. Cummings
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Contact Stress ◽  
Fatigue Cracking ◽  
Fatigue Tests ◽  
Operating Conditions ◽  
Defect Prevention ◽  
Class C ◽  
Research Consortium

The Wheel Defect Prevention Research Consortium (WDPRC) conducted an analysis pertaining to the fatigue cracking of wheel treads by incorporating the effects of residual stresses, temperature, and wheel/rail contact stress. Laboratory fatigue tests were conducted on specimens of wheel tread material under a variety of conditions allowing the analysis to properly account for the residual stresses accumulated in normal operating conditions. Existing literature was used in the analysis in consideration of the effects of contact stress and residual stress relief. This project was performed to define a temperature range in which the life of an AAR Class C wheel is not shortened by premature fatigue and shelling. Wayside wheel thermal detectors are becoming more prevalent on North American railroads as a means of identifying trains, cars, and wheels with braking issues. Yet, from a wheel fatigue perspective, the acceptable maximum operating temperature remains loosely defined for AAR Class C wheels. It was found that residual compressive circumferential stresses play a key role in protecting a wheel tread from fatigue damage. Therefore, temperatures sufficient to relieve residual stresses are a potential problem from a wheel fatigue standpoint. Only the most rigorous braking scenarios can produce expected train average wheel temperatures approaching the level of concern for reduced fatigue life. However, the variation in wheel temperatures within individual cars and between cars can result in temperatures high enough to cause a reduction in wheel fatigue life.

scholarly journals The Effect of Laser Peening without Coating on the Fatigue of a 6082-T6 Aluminum Alloy with a Curved Notch

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 728 ◽  
Author(s):  
Enrico Troiani ◽  
Nicola Zavatta
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Fatigue Behavior ◽  
Surface Hardness ◽  
Element Model ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Laser Peening ◽  
Laser Peening Without Coating

Laser shock peening has established itself as an effective surface treatment to enhance the fatigue properties of metallic materials. Although a number of works have dealt with the formation of residual stresses, and their consequent effects on the fatigue behavior, the influence of material geometry on the peening process has not been widely addressed. In this paper, Laser Peening without Coating (LPwC) is applied at the surface of a notch in specimens made of a 6082-T6 aluminum alloy. The treated specimens are tested by three-point bending fatigue tests, and their fatigue life is compared to that of untreated samples with an identical geometry. The fatigue life of the treated specimens is found to be 1.7 to 3.3 times longer. Brinell hardness measurements evidence an increase in the surface hardness of about 50%, following the treatment. The material response to peening is modelled by a finite element model, and the compressive residual stresses are computed accordingly. Stresses as high as −210 MPa are present at the notch. The ratio between the notch curvature and the laser spot radius is proposed as a parameter to evaluate the influence of the notch.

Effects of Glass-Forming Metallic Film on the Fatigue Behavior of C-2000 Ni-Based Alloy

2005 ◽  
Vol 903 ◽  
Author(s):  
F. X. Liu ◽  
C. L. Chiang ◽  
J. P. Chu ◽  
Y. F. Gao ◽  
P. K. Liaw
Keyword(s):  
Thin Film ◽  
Fatigue Life ◽  
Fatigue Resistance ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Film Coating ◽  
Fatigue Tests ◽  
Glass Forming ◽  
Four Point Bending ◽  
Coated Surface

AbstractGlass-forming Zr47Cu31Al13Ni9 (in atomic percent) films of various thicknesses were deposited on the C-2000 Ni-based alloy substrate by magnetron sputtering. Four-point-bending fatigue tests were conducted on the above system with the coated surface on the tensile side. It has been found that both fatigue life and fatigue-endurance limit can be considerably improved, while the degree of fatigue resistance enhancement depends on the maximum applied stress and the film thickness. Mechanisms of fatigue-resistance enhancements of the coated Ni-based alloy are discussed from the following aspects: reduction of surface roughness by the thin-film coating, good adhesion between thin film and substrate, development of residual compressive stress, and excellent ductility of glass-forming thin film (which would be otherwise brittle in bulk form). Of particular interest, we examine the interaction of substrate slip bands and the thin film ductile property, which would delay fatigue crack initiation process and thus extend the fatigue life.

Welding Residual Stresses in Tubular Joints

2013 ◽  
Vol 768-769 ◽  
pp. 605-612 ◽  
Author(s):  
Majid Farajian ◽  
Thomas Nitschke-Pagel ◽  
Klaus Dilger
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Fatigue Crack Initiation ◽  
Welding Residual Stress ◽  
Structural Safety ◽  
Welding Parameters

In spite of an increased awareness of welding residual stress threat to structural integrity, the extent of its influence on fatigue especially under multiaxial loading is still unclear and is a matter of debate. One important reason for this lack of clarities is that the determination of the initial welding residual stress field in welded structures even at the fatigue crack initiation sites is difficult and requires complementary instruments. Since the fatigue crack initiation in sound welds almost always occurs on the surface, the determination of surface residual stresses could increase the awareness of the extent of their threat to the structural safety. In this paper the development of residual stresses in different TIG-welded tubular specimens out of S355J2H and S690QL steel is studied and compared. The mechanisms of the development of residual stresses based on heat input and cooling rate are discussed. The welding parameters and thus heat inputs are varied and the mechanisms leading to different residual stress states are investigated. X-ray method was used for residual stress state characterization.

The Effect of Proof Loading on the Fatigue Behavior of Open Link Chain

1992 ◽  
Vol 114 (1) ◽  
pp. 27-33 ◽  
Author(s):  
S. M. Tipton ◽  
G. J. Shoup
Keyword(s):  
Fatigue Life ◽  
Residual Stresses ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Strain Gages ◽  
Applied Loading ◽  
Heat Treated ◽  
Strength Tests ◽  
Neuber's Rule ◽  
Failure Site

Open link lifting chain is routinely proof loaded during manufacture. However, the effect of residual stresses imposed by this operation on the fatigue strength of the chain has not been quantitatively investigated. This paper discusses the results of constant amplitude fatigue tests on open link chain segments which have received proof loading at various levels. The chain was initially heat treated to relieve manufacturing residual stresses and then proof loaded at levels ranging from 0 to 82 percent of its break strength. Tests were performed at two different mean loads and four different load amplitudes. Failure site trends are noted as a function of applied loading and are correlated with results of a finite element stress analysis. Residual stresses are estimated using strains measured from strain gages placed at critical locations on individual links during the proof load operation. Residual stress estimates are used with standard fatigue damage parameters to estimate the fatigue life of the chain and predictions are compared to data. Proof loading was shown to substantially increase the fatigue life of the chain. Residual stresses can explain the increase in fatigue life. Neuber’s rule demonstrated the ability to model the data trends.

Fatigue Life Simulation of a High Pressure Breech System

2006 ◽  
Vol 326-328 ◽  
pp. 1027-1030 ◽  
Author(s):  
Seung Kee Koh ◽  
Eui Gyun Na ◽  
Tae Hyun Baek ◽  
K.J. Kang ◽  
S.T. Ahn ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Stress Analysis ◽  
Structural Integrity ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Local Strain ◽  
Fatigue Tests ◽  
Ring Groove

In order to evaluate the structural integrity of the breech system used for a thick-walled cylinder subjected to pulsating high internal pressure, fatigue life simulation of a breech system was performed. A stress analysis of the breech was performed to locate the critical region vulnerable to crack initiation. Low-cycle fatigue behavior of the breech material was investigated to obtain the fatigue crack initiation properties. Elastic-plastic finite element stress analysis resulted in a stress concentration at the breech ring groove root. Strains at the breech ring and block were experimentally measured using strain gages and resulted in similar values compared to the calculated strains. Local strain approach was employed to estimate the fatigue life of the breech system for crack initiation at the groove root of the breech ring. Fatigue tests using simulation specimens were performed and an averaged fatigue life was obtained, showing a very good agreement with the calculated fatigue life within a factor of two.

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