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.

The Evaluation of Fretting Fatigue Life for Inconel 600 and 690 Alloy

2006 ◽  
Vol 321-323 ◽  
pp. 703-706 ◽  
Author(s):  
Dae Kyu Park ◽  
Yong Tak Bae ◽  
Sung Jong Choi ◽  
Young Suck Chai ◽  
Jae Do Kwon
Keyword(s):  
Fatigue Strength ◽  
Structural Integrity ◽  
Fatigue Behavior ◽  
Aqueous Media ◽  
Type Specimen ◽  
Fretting Fatigue ◽  
Mechanical Tests ◽  
Fatigue Tests ◽  
Alloy 600 ◽  
Inconel Alloy

The initial crack under fretting condition occurs at lower stress amplitude and at lower cycles of cyclic loading than that under plain fatigue condition. INCONEL alloy 600 and 690 are high–chromium nickel alloy having excellent resistance to many corrosive aqueous media and high-temperature atmospheres. In this paper, the effect of fretting damage on fatigue behavior for INCONEL alloy 600 and 690 were studied. Also, various kinds of mechanical tests such as hardness, tension and plain fatigue tests are performed. Fretting fatigue tests were carried out with 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 decreased about 40~70% compared to the plain fatigue strength in two materials. In fretting fatigue, the wear debris is observed on the contact surface, and the oblique micro-cracks at an earlier stage are initiated. These results can be used as basic data in a structural integrity evaluation of heat and corrosion resisting alloy considering fretting damages.

The Evaluation of Fretting Fatigue Behavior in Room Temperature for INCOLOY Alloy 800

2007 ◽  
Vol 353-358 ◽  
pp. 89-93 ◽  
Author(s):  
Dae Kyu Park ◽  
Seung Wan Woo ◽  
Yong Tak Bae ◽  
Il Sup Chung ◽  
Young Suck Chai ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Fatigue Behavior ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Chromium Alloy ◽  
Alloy 800 ◽  
Incoloy Alloy

Mechanical breakdown often comes from the fatigue in many structural parts and nuclear power plants. Among the fatigue phenomenon, especially fretting fatigue occurs in mechanical joints showing small relative movements between contact surfaces. Although the research was developed for one hundred years, occurrence mechanism is not clearly identified yet. INCOLOY alloy 800 is a iron-nickel-chromium alloy having excellent resistance to many corrosive aqueous media and high-temperature atmospheres. This alloy is used extensively in the nuclear power plants industry, the chemical industry, the heat-treating industry and the electronic industry. In this paper, the effect of fretting damage on fatigue behavior for INCOLOY alloy 800 was studied. Also, various kinds of mechanical tests such as tension and plain fatigue tests are performed. Fretting fatigue tests were carried out with 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 decreased about 50% compared to the plain fatigue strength. In fretting fatigue, the oblique micro-cracks at an earlier stage are initiated. These results can be used as basic data in a structural integrity evaluation of heat and corrosion resisting alloy considering fretting damages.

A STUDY ON FRETTING BEHAVIOR IN ROOM TEMPERATURE FOR INCONEL ALLOY 690

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4303-4308 ◽  
Author(s):  
JAE DO KWON ◽  
YOUNG SUCK CHAI ◽  
YONG TAK BAE ◽  
SUNG JONG CHOI
Keyword(s):  
Fatigue Strength ◽  
Nuclear Power ◽  
Structural Integrity ◽  
Fatigue Behavior ◽  
Aqueous Media ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Inconel Alloy ◽  
Alloy 690 ◽  
Fretting Damage

The initial crack under fretting condition occurs at lower stress amplitude and lower cycles of cyclic loading than that under plain fatigue condition. The fretting damage, for example, can be observed in fossil and nuclear power plant, aircraft, automobile and petroleum chemical plants etc. INCONEL alloy 690 is a high-chromium nickel alloy having excellent resistance to many corrosive aqueous media and high-temperature atmospheres. This alloy is used extensively in the industries of nuclear power, chemicals, heat-treatment and electronics. In this paper, the effect of fretting damage on fatigue behavior for INCONEL alloy 690 was studied. Also, various kinds of tests on mechanical properties such as hardness, tension and plain fatigue tests are performed. Fretting fatigue tests were carried out with 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 decreased about 43% compared to the plain fatigue strength. In fretting fatigue, the wear debris is observed on the contact surface, and the oblique micro-cracks are initiated at an earlier stage. These results can be used as the basic data in a structural integrity evaluation of heat and corrosion resistant alloy considering fretting damages.

Evaluation of Fretting Fatigue Life for Steam Generator Tubes in Nuclear Power Plants

2007 ◽  
Vol 345-346 ◽  
pp. 243-246 ◽  
Author(s):  
Dae Kyu Park ◽  
Seung Wan Woo ◽  
Il Sup Chung ◽  
Young Suck Chai ◽  
Jae Do Kwon
Keyword(s):  
Fatigue Life ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Fretting Fatigue ◽  
Alloy 600 ◽  
Inconel Alloy ◽  
Alloy 800 ◽  
Incoloy Alloy ◽  
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. INCONEL alloy 600, 690 and INCOLOY alloy 800 are iron-nickel-chromium alloy having excellent resistance to many corrosive aqueous media and high-temperature atmospheres. These alloy are used extensively in the nuclear power plants industry, the chemical industry, the heat-treating industry and the electronic industry. In this paper, the effect of fretting damage on fatigue behavior for INCONEL alloy 600, 690 and INCOLOY alloy 800 were studied. Also, various kinds of mechanical tests such as tension and plain fatigue tests are performed. The objective of this study is to guarantee reliability of the facility applied in a power plant by comparing three materials in respect to fretting fatigue.

Evaluation of Low-Cycle Fatigue in Simulated PWR Environment

2006 ◽  
Vol 326-328 ◽  
pp. 1011-1014 ◽  
Author(s):  
Ill Seok Jeong ◽  
Sang Jai Kim ◽  
Taek Ho Song ◽  
Sung Yull Hong
Keyword(s):  
Fatigue Life ◽  
Nuclear Power ◽  
Power Plants ◽  
Low Cycle Fatigue ◽  
Water Environment ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Fatigue Design ◽  
Number Of Cycles ◽  
Measured Length

For developing fatigue design curve of cast stainless steel that is used in piping material of nuclear power plants, a low-cycle fatigue test rig was built. It is capable of performing tests in pressurized high temperature water environment of PWR. Cylindrical solid fatigue specimens of CF8M were used for the strain-controlled environmental fatigue tests. Fatigue life was measured in terms of the number of cycles with the variation of strain amplitude at 0.04%/s strain rates. The disparity between target length and measured length of specimens was corrected by using finite element method. The corrected test results showed similar fatigue life trend with other previous results.

Investigation of Effect of Pre-Strain on Very High-Cycle Fatigue Strength of Austenitic Stainless Steels

2008 ◽  
Author(s):  
Takeshi Ogawa ◽  
Motoki Nakane ◽  
Kiyotaka Masaki ◽  
Shota Hashimoto ◽  
Yasuo Ochi ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Nuclear Power ◽  
Power Plants ◽  
Austenitic Stainless Steels ◽  
Fatigue Tests ◽  
Structural Components ◽  
Very High Cycle Fatigue ◽  
Tension And Compression ◽  
Strained Materials ◽  
Very High

The austenitic stainless steels have excellent mechanical and chemical characteristics and these materials are widely used for the main structural components in the nuclear power plants. A part of structural components using these materials is considered to have strain-history by machining, welding and etc in the process of manufacturing and these parts would be hardened because these materials have a remarkable work-hardening property. On the other hand, conventional studies for the fatigue strength used to be investigated by the results of fatigue tests applying normal specimens without the effect of hardening by pre-strain. This paper describes the effect of large pre-strain on very high cycle fatigue strength of the materials in consideration for the evaluation of strength of actual structures in the nuclear power plants. In order to achieve this purpose, the fatigue tests were carried out with strain hardened specimens. The material served in this study was type SUS316NG. Up to ±20% pre-strain was introduced to the round bar shaped materials by tension and compression load test, and the materials were mechanically machined to the hourglass shaped smooth specimens. On the other hand, the pre-strain of some specimens were introduced after machining so as to study the influence of roughness of the surface of the specimens for the fatigue property. Fatigue tests were conducted by ultrasonic and rotating-bending fatigue test machines and conditions were decided by preliminary examinations to control temperature elevation of the specimen during the fatigue test. The S-N curves obtained from fatigue tests show that increase in magnitude of the pre-strain cause increase in the fatigue strength of the material and this relationship is independent of type of the pre-strains of tension and compression. Though all specimens were fractured by the surface initiated fatigue crack, only one specimen was fractured by the internal crack and so-called “fish-eye” was observed on the fracture surface. However, the internal fracture of the SUS316NG does not cause sudden drop of the fatigue strength. Also, the Vickers hardness tests were carried out to discuss the relationship between fatigue strength and hardness of the pre-strained materials. It is found that the increase in fatigue limit of the pre-strained materials strongly depend on the hardness derived from the indentation size equals to the scale of stage I fatigue crack.

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.

Analysis of Fatigue Life for Main Steam Isolation Valve in Nuclear Power Plants

2013 ◽  
Author(s):  
Xian Zeng ◽  
Hong Xia ◽  
YeMin Dong ◽  
Zhen Liu
Keyword(s):  
Fatigue Life ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Fatigue Cracks ◽  
Surface Damage ◽  
Fretting Fatigue ◽  
Critical Plane Approach ◽  
Contact Surfaces ◽  
Main Steam

This paper focuses on the analysis of fatigue life for main steam isolation valve (MSIV) in nuclear power plants (NPPs). The contraction of throat is also in the form of sonic resonance cavity, which causes big vibration and noise. The vibration result in the fretting fatigue, which is the reason of the contact surface damage of the disc and the disc guide. By using FEM, the distribution of the stress on the contact surfaces of the disc and the disc guide was calculated. The influences of vibration on the distribution of the stress on the contact surfaces, together with the effect of the contact stress on the initiation of fretting fatigue cracks and fretting fatigue life have been studied. A critical plane approach the Smith–Watson–Topper fatigue parameter has also been adopted here, to predict crack initiation position and orientation, fatigue life. The results show that the predicted cracks location and fatigue life are well accordance with the practical situation.

An Experimental Study on the Corrosion and Fatigue of Structural Steels

2006 ◽  
Vol 326-328 ◽  
pp. 1059-1062
Author(s):  
Byeong Choon Goo
Keyword(s):  
Fatigue Strength ◽  
Atmospheric Corrosion ◽  
Structural Integrity ◽  
Fatigue Behavior ◽  
Electrochemical Corrosion ◽  
Fatigue Tests ◽  
Rolling Stock ◽  
Electrochemical Characteristics ◽  
Test Bed ◽  
Corrosion Tests

In general, structural integrity of rolling stock structures should last more than 25 years. During the lifetime corrosive degradation occurs. For structural design and diagnosis, quantitative relationship between corrosive degradation and variation of mechanical properties such as tensile strength and fatigue strength is needed. In this study, electrochemical corrosion tests, atmospheric corrosion tests and fatigue tests of corroded specimens were carried out. The electrochemical characteristics of SS400, SM490A, SUS205L and SUS304 were examined. At regular intervals tensile and fatigue tests were carried out by using specimens of SM490A and SS400 on the atmospheric corrosion test bed. The fatigue strength decreases as the atmospheric corrosion period increases. In addition, the effect of heat treatment on the tensile and fatigue behavior was studied.

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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