Frequency Effects on Gigacycle Fatigue Properties of High-Strength Steels

2004 ◽  
Author(s):  
Yoshiyuki Furuya ◽  
Saburo Matsuoka ◽  
Takayuki Abe
Keyword(s):  
Fatigue Test ◽  
Testing Machine ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Test Results ◽  
Frequency Effects ◽  
Fracture Region ◽  
Fish Eye

This report will reveal a series of fatigue test results for high-strength steels at 100 Hz and 20 kHz and discuss frequency effects on gigacycle fatigue properties. The 20 kHz fatigue testing machine is an effective tool to conduct gigacycle fatigue tests in a reasonable term, while frequency effects have to be carefully investigated before applying the machine. The fatigue tests were conducted for two kinds of high-strength steels, that were a low-alloy steel and a spring steel. These fatigue test results showed that the frequency effects were negligible even at 20 kHz in case of fish-eye fracture. The fatigue properties in the fish-eye fracture region showed a good agreement between the 100 Hz and 20 kHz tests. Besides, ODAs (Optically Dark Areas) were also observed on the fracture surface even in 20 kHz tests and no difference was found in the ODA sizes between the 100 Hz and 20 kHz tests. These results meant that the 20 kHz tests could provide us appropriate results at least in the fish-eye fracture region. Therefore, the 20 kHz tests were applicable on the evaluation of gigacycle fatigue properties in high-strength steels.

Three Ways of Sampling and Fatigue Test Results of Steel P92

2014 ◽  
Vol 891-892 ◽  
pp. 273-277
Author(s):  
Josef Volák ◽  
Zbynek Bunda
Keyword(s):  
Mechanical Properties ◽  
Power Plant ◽  
Fatigue Test ◽  
Fatigue Tests ◽  
Energy Industry ◽  
Fatigue Properties ◽  
Test Results ◽  
Steam Turbines ◽  
Standard Samples ◽  
Energy Component

This paper describes the fatigue properties of the steel P92. This material is widely used in the energy industry, especially for pipes and pipe bends of supercritical steam turbines. Steel P92 is alloyed with 2 % of tungsten compared to steel P91. This increases a creep strenght of the material. It is possible to reduce wall thickness of the P92 pipe up to about 20%. Fatigue tests were carried out on standard samples and compared with SFT samples (Small Fatigue Test). Using the device SSam 2 made by company Rolce Royce, it is possible to gently remove a samples from energy component without power plant shutdowns. Consider these correlations, i tis possible to determine mechanical properties of the material from small amount of removed experimental material.

Study on Micro-Mechanism of Crack Initiation and Propagation Induced by Inclusion in Ultra-High Strength Steel

2007 ◽  
Vol 353-358 ◽  
pp. 1185-1190 ◽  
Author(s):  
Yan Ping Zeng ◽  
Hong Mei Fan ◽  
Xi Shu Wang ◽  
Xi Shan Xie
Keyword(s):  
Crack Initiation ◽  
High Strength Steel ◽  
Harmful Effect ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation ◽  
Ultra High Strength Steel

Specially designed SEM in-situ tensile and fatigue tests have been conducted to trace the entire process of crack initiation and propagation till fracture in an ultra-high strength steel MA250. TiN is a typical inclusion and its average size is in the range of 8~10μm in MA250 steel. The micro-mechanism of the effect of TiN inclusion on crack initiation and propagation at tensile and fatigue tests both have been studied in detail. Experimental results show the harmful effect of TiN on tensile and fatigue properties both. This work is helpful to establish the practical life prediction model for the characteristic inclusion parameters in ultra-high strength steel components. It also enlightens us to eliminate TiN in the further development of ultra-high strength steels.

A Study on Fatigue Fracture Mechanism of Cr-Mo Steel SCM435 in Super Long Life Range

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1697-1703 ◽  
Author(s):  
Ri Ichi Murakami ◽  
Daisuke Yonekura ◽  
Taishi Murayama
Keyword(s):  
Fatigue Fracture ◽  
Fatigue Behavior ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Microscopy Observation ◽  
Horizontal Part ◽  
Long Life ◽  
Fatigue Fracture Behavior ◽  
Fish Eye

For high strength steels, a characteristic fatigue behavior, which S-N curve comes down again in the long life region of N > 107 cycles, was reported by many researchers. Specifically, for high strength steel, the fatigue limit is temporal value because of the fish-eye fracture in the long life region over about N = 107 cycles. However, fish eye fracture does not appear for medium strength steel in super long life range. In this paper, cantilever-type rotational bending fatigue tests were carried out for quenched and tempered Cr-Mo steel (JIS: SCM435) up to 109 cycles at room temperature in air. The S-N curve showed a horizontal part in long life region over 107 cycles. In addition, fish- eye fracture was not observed and for all specimens, the crack initiation occurred from the specimen surface. The fatigue fracture behavior of SCM435 in super long life was discussed based on optical microscopy observation and scanning electron microscopy observation.

scholarly journals Fatigue Properties of Polyurethane Foams, with Special Emphasis on Auxetic Foams, Used for Helicopter Pilot Seat Cushion Inserts

2014 ◽  
Vol 2014 (6) ◽  
pp. 72-78 ◽  
Author(s):  
Janusz Lisiecki ◽  
Dominik Nowakowski ◽  
Piotr Reymer
Keyword(s):  
Testing Machine ◽  
Physical Property ◽  
Fatigue Tests ◽  
Polyurethane Foams ◽  
Fatigue Properties ◽  
Test Results ◽  
Maximum Value ◽  
Seat Cushion ◽  
Auxetic Materials ◽  
Number Of Cycles

Abstract Seat cushion inserts in military helicopters crew seats, as suggested by the helicopters manufacturers, are made of traditional polyurethane foams. Elastic polyurethane auxetic foams are materials that exhibit different utility properties compared to traditionally used polyurethane foams, such as polyether or polystyrene foams. All the differences result from the primary physical property of elastic polyurethane auxetic foams which is a negative Poisson’s ratio. Auxetic materials are characterized by better utility properties than conventional foam materials – they can potentially increase safety in the event of a crash and offer higher comfort during regular use. Application of auxetic materials as seat cushion inserts would also decrease harmful health effects of vibrations. This paper presents the results of the fatigue tests carried out on different foam samples by pressing an indenter into the foams' surface that was much larger than the indenter’s surface. A maximum value of the load used during the test was within a defined range in every fatigue cycle. In order to test 150×150×50 mm foam samples a special indenter was designed and manufactured according to the PN-EN ISO 3385 and PN-EN ISO 2439 standards. The indenter’s dimensions were consistent with the standards in relation to the tested foams' size. The fatigue tests of both conventional and auxetic foams were carried out according to the above given standards by applying 80,000 load cycles at 70 cycle/min frequency. Tests of viscoelastic foam and multilayer foam specimens, for which the upper layer was made of viscoelastic foam, were carried out according to the ASTM D 3574 standard applying 12,000 load cycles at 10 cycle/min frequency. All the tests were carried out using the MTS 370.10 strength testing machine. Changes in thickness and density were determined throughout the tests. Moreover, the influence of the volumetric compression ratio on the fatigue properties of auxetic foam samples and the dependence of foam deflection on the number of cycles were examined. Finally, the test results obtained for conventional and auxetic foams were compared and discussed.

Evaluation of Threshold Condition of Interior Annular Crack Growth in Gigacycle Regime

2013 ◽  
Vol 459 ◽  
pp. 65-69 ◽  
Author(s):  
Wei Li ◽  
Ping Wang
Keyword(s):  
Crack Growth ◽  
High Strength Steels ◽  
High Strength ◽  
Theoretical Method ◽  
Fatigue Properties ◽  
Threshold Condition ◽  
Unstable Crack ◽  
Annular Crack ◽  
Small Crack Growth ◽  
Fish Eye

Gigacycle fatigue properties with interior-induced failure of three high strength steels under different loading conditions were investigated, and an experimental-theoretical method is proposed to quantitatively evaluate the threshold condition of interior crack growth. The entire growth process consists of small crack growth within fine granular area (FGA), stable long crack growth outside of FGA within fish-eye and unstable crack growth outside of fish-eye. Based on the comparison between evaluated and experimental results, the validity of method is verified.

Comparison of P92 Steel Fatigue Test Results in Relation to Specimen Size and Manufacturing

2013 ◽  
Author(s):  
Josef Volak ◽  
Zbynek Bunda ◽  
Vaclav Mentl
Keyword(s):  
Fatigue Test ◽  
Positive Influence ◽  
Fatigue Tests ◽  
Energy Industry ◽  
Fatigue Properties ◽  
Strength Increase ◽  
Test Results ◽  
Steam Turbines ◽  
Standard Samples ◽  
P92 Steel

This paper describes fatigue properties of steel P92. This material is used as a standard in the energy industry, especially for production of pipes and flange branches and distance pieces of supercritical steam turbines. This material contains (unlike material P91) up to 2% of tungsten which has positive influence on creep strength increase. Compared to the P91 material, it is possible to reduce wall thickness of the P92 pipe up to 20%. Fatigue tests were carried out on standard samples and compared with SFT samples (Small Fatigue Test). SFT samples can be gently withdrawn from energy component by SSam 2 device made by company Rolls Royce. There is no necessity for shutdown of power plant. Thanks to the existing correlations between SFT and Fatigue tests, it is possible to determine mechanical properties of material from a small amount of withdrawn material. At the same time a comparison between a traditional way of sample production and a sample production by means of waterjet cutting was carried out.

scholarly journals Fretting Fatigue Behaviour of Alloy Steel in the Very High Cycle Region

2019 ◽  
Vol 300 ◽  
pp. 18002
Author(s):  
Yoshinobu Shimamura ◽  
Reo Kasahara ◽  
Hitoshi Ishii ◽  
Keiichiro Tohgo ◽  
Tomoyuki Fujii ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Fatigue Behaviour ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Test Results ◽  
Torsional Fatigue ◽  
Very High

It is well known that fretting fatigue strength is much lower than the fatigue strength of smooth specimens and the fatigue limit disappears. Many studies on fretting fatigue have been reported but most of the studies have not cover fatigue properties in the very high cycle regime more than 107 cycles. In this study, an accelerated fretting fatigue testing method was developed by using an ultrasonic torsional fatigue testing machine with a clamping fretting pad. Fretting fatigue tests of CrMo steel were conducted by using the developed method. Test results showed that fretting fatigue failure occurs in the very high cycle region.

scholarly journals Fatigue Properties of Cruciform and Flange-gusset Joints Using Normal and High Strength Steels

2020 ◽  
Author(s):  
Balázs József Mecséri ◽  
Balázs Kövesdi
Keyword(s):  
Fatigue Behavior ◽  
High Strength Steels ◽  
High Strength ◽  
Steel Grade ◽  
Fatigue Properties ◽  
Test Results ◽  
Stress Range ◽  
Fatigue Lifetime ◽  
Cruciform Joints ◽  
Normal Strength

The objective of this paper is to investigate and compare the fatigue behavior of Normal Strength Steel (NSS) and High Strength Steel (HSS) welded specimens (cruciform and flange gusset joints). Numerous specimens were tested in the framework of the research project. The experimental S-N curves of the test specimens are determined and analyzed by mathematical statistics to consider the uncertainties and scatter of test results. Statistical analysis of the S-N curves showed that the fatigue behavior of as-welded flange gusset joints is identical in the cases of HSS and NSS specimens, which means that there is no difference in the fatigue lifetime depending on the steel grade. However, the as-welded HSS cruciform joints can be more favorable and their fatigue lifetime is longer than the specimens made from NSS, if the stress range is below 100 MPa. The current study shows that the fatigue behavior of as-welded HSS details depends on the geometry of the investigated specimens and its fatigue lifetime can be larger in the small stress range region than for NSS specimens.

Fatigue and Burst Analysis of Hy-140(T) Steel Pressure Vessels

1970 ◽  
Vol 92 (1) ◽  
pp. 11-16 ◽  
Author(s):  
J. M. Barsom ◽  
S. T. Rolfe
Keyword(s):  
Yield Strength ◽  
Pressure Vessel ◽  
Low Cycle Fatigue ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Pressure Vessels ◽  
High Yield ◽  
Corrosion Properties ◽  
Burst Analysis

Increasing use of high-strength steels in pressure-vessel design has resulted from emphasis on decreasing the weight of pressure vessels for certain applications. To demonstrate the suitability of a 140-ksi yield strength steel for use in unwelded pressure vessels, HY-140(T)—a quenched and tempered 5Ni-Cr-Mo-V steel—was fabricated and subjected to various burst and fatigue tests, as well as to various laboratory tests. In general, results of the investigation indicated very good tensile, Charpy, Nil Ductility Transition Temperature (NDT), low-cycle fatigue, and stress-corrosion properties of HY-140(T) steels, as well as very good burst tests results, in comparison with existing high-yield strength pressure-vessel steels. The results also indicate that the HY-140(T) steel should be an excellent material for its originally designed purpose, Naval hull applications.

scholarly journals Analysis of the Correlation between the Static and Fatigue Test Results of the Interlayer Bondings of Asphalt Layers

2016 ◽  
Vol 62 (1) ◽  
pp. 83-98 ◽  
Author(s):  
A. Szydło ◽  
K. Malicki
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Asphalt Mixture ◽  
Fatigue Tests ◽  
Test Results ◽  
Static Tests ◽  
Bonding State ◽  
Road Pavement ◽  
The Future ◽  
Pavement Structure

Abstract The bonding state of the asphalt layers in a road pavement structure significantly affects its fatigue life. These bondings, therefore, require detailed tests and optimization. In this paper, the analyses of the correlation between the results of laboratory static tests and the results of fatigue tests of asphalt mixture interlayer bondings were performed. The existence of the relationships between selected parameters was confirmed. In the future, the results of these analyses may allow for assessment of interlayer bondings’ fatigue life based on the results of quick and relatively easy static tests.

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