Effect of Surface Machining on the Fatigue Life of Low Alloy Steel for Hydrogen Pressure Vessels

2007 ◽  
Author(s):  
Yoru Wada ◽  
Ryoji Ishigaki ◽  
Yasuhiko Tanaka ◽  
Tadao Iwadate ◽  
Keizo Ohnishi
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Pressure Vessels ◽  
Hydrogen Gas ◽  
Annealed Specimen ◽  
Surface Machining ◽  
Hydrogen Fatigue ◽  
Effect Of Surface

The effect of surface machining on fatigue life in high pressure hydrogen gas was investigated. The test was conducted under the elastic range under 45MPa gaseous hydrogen environment by the ground specimen which were machined so that the surface roughness to be Rmax = 19μm(Mark: 19s), 26μm(26s) and 93μm(93s) and by the polished specimen which are prepared so that the surface roughness to be Rmax = 1μm(1s), 3.6μm(3.6s) and 10μm(10s). The hydrogen fatigue life of ground specimens was considerably reduced with increasing surface roughness as compared to the fatigue life in air at the same surface condition. On the other hand, for the annealed conditions of the ground specimen, the reduction by hydrogen effect was fairly small. The residual stress for the ground specimen at the surface rises sharply in tension while the residual stress for the annealed specimen was nearly equal to zero. We have shown that the hydrogen fatigue damage can be evaluated by obtaining the information about residual stress on surface, stress concentration by maximum surface roughness and the threshold stress intensity SH above which hydrogen fatigue damage occurs.

Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Yield Strength ◽  
Residual Stresses ◽  
Solid Mechanics ◽  
Element Model ◽  
Pressure Vessels ◽  
Material Strength ◽  
Element Analysis

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.

scholarly journals PENGARUH PENGHILANGAN KEKASARAN PERMUKAAN TERHADAP KEKUATAN FATIK = EFFECT OF SURFACE ROUGHNESS REMOVAL TO FATIGUE STRENGTH

2015 ◽  
Vol 9 (3) ◽  
pp. 115-130
Author(s):  
H. Agus Suhartono
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Loading ◽  
Bending Fatigue ◽  
Aisi 1045 Steel ◽  
Aisi 1045 ◽  
1045 Steel ◽  
Test Result ◽  
Effect Of Surface

The aim of the study is to investigate and to prove that the fatigue failure of steel is initiated from the surface. Hence the preventif action of smoothening the surface that has been loaded by fatigue loading is very important. The specimen of AISI 1045 Steel is loaded by means of rotary bending fatigue. The fatigue loading will be interupted as the fatigue life reaching 50% of fatigue life and 75% of fatigue life. During the interuption the specimen will be grinded and polished, before tested completely until fatigue fracture occured. The fatigue life of each group of scpecimen based on the art of loading will be compared to the specimen tested by fatigue loading without interuption.The Miner rule is used to evaluated the test result. The influence of interuption and surface treatment is evaluated and analyzed. ABSTRAKTujuan penelitian ini adalah untuk menyelidiki dan membuktikan bahwa kegagalan kelelahan baja dimulai dari permukaan. Oleh karena itu tindakan pencegahan dengan memperhalus permukaan sangat penting untuk mencegah beban kelelahan baja. Spesimen dari AISI 1045 Steel dimuat dengan cara uji kelelahan lentur putar. Kelelahan pemuatan akan disela sebagai umur kelelahan mencapai 50% dari umur kelelahan dan 75% dari umur kelelahan. Selama gangguan lainnya yang spesimen akan digiling dan dipoles, sebelum diuji benar-benar sampai patah akibat kelelahan yang terjadi. Umur kelelahan dari setiap kelompok specimen diuji berdasarkan beban akan dibandingkan dengan spesimen oleh kelelahan bongkar tanpa aturan. The Miner rule digunakan untuk mengevaluasi hasil tes. Pengaruh gangguan lainnya dan perlakuan permukaan dievaluasi dan dianalisis. 

Experimental Study on the Effect of Surface Integrity on Fatigue Performance of Aero-Engine Blades

2021 ◽  
Author(s):  
Yun Huang ◽  
Shaochuan Li ◽  
Guijian Xiao ◽  
Benqiang Chen ◽  
Yi He ◽  
...  
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Test ◽  
Surface Texture ◽  
Surface Characteristics ◽  
Service Performance ◽  
Aero Engine ◽  
Vibration Fatigue

Abstract As the core component of aero-engine, the service performance of aero-engine blade has an important influence on the engine’s reliability and safety performance. Existing studies have shown that machined surface characteristics affect the fatigue strength of components. However, current studies are all based on regular fatigue samples. The structure of blades different from fatigue samples, and the influence mechanism of structural differences on the service performance of blades is still unclear. In addition, the conventional fatigue test conditions are not representative for the blades’ actual service conditions, so it is difficult to realize the processing process for the service performance optimization. In this study, the aero-engine blades processed by abrasive belt grinding and the vibration fatigue test bench were used to explore the influence of surface roughness, surface texture, and surface residual stress on the fatigue performance of aero-engine blades under actual working conditions. The aero-engine blades were ground with different process parameters to obtain different single-factor surface characteristics. By comparing the vibration fatigue life of blades with different surface features, the influence degree of each surface feature on the fatigue life was explored. Results showed that surface roughness has the greatest influence on fatigue strength, followed by residual stress, and surface texture has the least influence on fatigue strength.

A Study on the Fatigue Characteristics of Al6061-T651 by Shot Peening Velocity

2006 ◽  
Vol 326-328 ◽  
pp. 1093-1096 ◽  
Author(s):  
Won Jo Park ◽  
Sun Chul Huh ◽  
Sung Ho Park
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Life ◽  
Shot Peening ◽  
High Speed ◽  
Compressive Residual Stress ◽  
Velocity Increase ◽  
Fatigue Characteristics ◽  
Height Increase ◽  
Small Steel

Small steel ball is utilized in Shot peening process. Called “shot ball” are shot in high speed on the surface of metal. When the shot ball hit the surface, it makes plastic deformation and bounce off, that increase the fatigue life by compressive residual stress on surface. In this study, the results of observation on the tensile strength, hardness, surface roughness, compressive residual stress and fatigue life of a shot peened Al6061-T651 were obtained. Experimental results show that arc height increase tremendously by shot velocity. Also, it shows that surface roughness, hardness, compressive residual stress and fatigue life increase as shot velocity increase.

Effect of Surface Roughness and Residual Stress Induced by High Speed Milling Process on Short Crack Growth

2016 ◽  
Author(s):  
B. Zheng ◽  
H. D. Yu ◽  
X. Wang ◽  
X. M. Lai
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Residual Stresses ◽  
Crack Growth ◽  
Damage Evolution ◽  
High Speed ◽  
Milling Process ◽  
Short Crack ◽  
Machining Process ◽  
Effect Of Surface

Surface scratches and residual stresses inevitably appear on the surface of the component as a result of the machining process. The damage evolution of surface scratch due to the combined effect of cyclic loading and residual stresses will be significantly different from the case where only the cyclic loading is considered. In the damage evolution of surface scratch, the short crack growth is of great importance owing to its apparently anomalous behaviors compared with the long-crack growth. In this paper, the effect of the surface roughness and the residual stress on the short crack growth is studied. Firstly, the surface roughness and the residual stress of 7075-T6 aluminum alloy induced by the high speed milling process with various cutting speeds and feed rates are investigated with the experimental method. The maximum height roughness parameter is measured, which is regarded as the surface defect induced by the milling process. The residual stress on the specimen surface is measured with the X-ray diffraction. Results show that the surface roughness becomes higher with the increase of the feed rate. However, the influence of the cutting speed on the surface roughness is not significant. The residual stresses on the specimen surface are all in the compressive state. The residual stress is more compressive as the feed rate increases. The effects of the process parameters on the surface roughness and the residual stress are described by the fitted formulas. Then a modified model is built to characterize short fatigue crack growth behaviors with the consideration of the residual stress. This model is proved to provide a realistic treatment of the short crack growth, as reflected by comparison with experimental fatigue crack growth data of medium carbon steel and 7075-T6 aluminum alloy published in literature. The effect of surface roughness and residual stress caused by the milling process on the short crack growth is also investigated by using the proposed model. The growth of the scratch is nonlinear when it is subjected to the cyclic load. The compressive residual stress reduces the growth rate of the crack. The crack with larger initial surface roughness grows faster than that with smaller roughness. The correlation of surface roughness, residual stress and crack growth length is obtained by the polynomial fitting. The investigations in this paper can help the damage tolerance design of structures and improve the awareness of the effect of the residual stress and surface roughness induced by the machining process on the short crack growth.

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.

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