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wall thinning Characteristics of Ti-3Al-2.5V Tube in Numerical Control Bending Process

Journal of Shanghai Jiaotong university(Science) 2019年第5期24卷 647-653页

作者： HUANG Tao WANG Kun ZHAN Mei GUO Junqing CHEN Xuewen CHEN Fuxiao SONG Kexing School of Materials Science and Engineering Henan University of Science and TechnologyLuoyang471023HenanChina Collaborative Innovation Center of Nonferrous Metals of Henan Province Luoyang471023HenanChina State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwesternPolytechnical UniversityXi'an710072China

A finite element(FE) model for the numerical control(NC) bending of Ti-3 Al-2.5 V titanium alloy seamless tube is established, considering the variation in the contractile strain ratio(CSR) and elastic modulus(E). The wall thinning characteristics of Ti-3 Al-2.5 V tube under different geometric and process conditions were investigated. The results showed that the CSR-E variation can change the wall thickness, but has no remarkable effect on the change characteristics. The reasonable parameter ranges are as follows: a bending-radius range not less than 1.5 times the outer diameter, a bend angle up to 180?, and a mandrel extension of 0-3 mm. The friction coefficient between the pressure die and the tube should be in the range of 0.20-0.35, and between the bending die and the tube should be in the range of 0.05-0.15. As long as the performance meets the requirements, the relative push-assistant speed should be as small as possible.

关键词： titanium alloy tube numerical control bending wall thinning contractile strain ratio elastic modulus

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Cause Analysis for wall thinning of Small-Bore Piping in Nuclear Power Plant by ToSPACE, FLUENT and Theoretical Evaluation

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World Journal of Nuclear Science and Technology 2022年第3期12卷 101-112页

作者： Kyeongmo Hwang Ilsu So Hyukki Seo KEPCO E&C Gimcheon-si Korea

It has been known that FAC, LDIE, cavitation and flashing are the damage mechanisms that can cause the pipe thickness of the secondary system of nuclear power plants thinner. Severe wall thinning was found in the MSR drain pipes at a Korean nuclear power plant a decade ago, and all the affected pipes were replaced with low alloy steel with higher chromium contents. Therefore, this study was conducted to reduce the possibility of similar thinning cases that may occur in the future by identifying the exact cause of thinning. ToSPACE and FLUENT codes and theoretical evaluation method were applied to analyze the causes of thinning. ToSPACE and FLUENT analyses and theoretical evaluation including all the operating conditions show a relatively large pressure drop and a pressure lower than the saturated vapor pressure in common at the end of the pipe entering the condenser. This means that flashing occurs at the end of the pipe under all operating conditions, and the effect can be greater than that of other parts. As a result, since severe wall thinning occurred at the end of the pipeline entering the condenser, it was evaluated that flashing by the high-velocity two-phase fluid was the direct cause of the wall thinning in the MSR drain pipes. The results of this study will contribute to establishing appropriate countermeasures in the event of pipe wall thinning in the future.

关键词： wall thinning ToSPACE FLUENT Flashing Cavitation

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Measurement of wall thinning through insulation with ferromagnetic cladding using pulsed eddy current testing

Measurement of wall thinning through insulation with ferroma...

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2011 2nd International Conference on Advanced Measurement and Test (AMT 2011)

作者： Zhiyuan Xu Xinjun Wu Chen Huang Yihua Kang State Engineering Research Center of Manufacturing Equipment Digitization Huazhong University of Science and Technology

Pulsed eddy current（PEC） technique has been successfully used for measuring wall thinning of carbon steel equipments without removal of the insulation. In field applications, the probe performance decreases in presence of ferromagnetic claddings. This paper presents a method based on saturation magnetization to solve this problem. The main principle of this method is to weaken the magnetic shielding effect of the cladding by magnetizing it to saturation. A U-shaped magnetizer is designed to realize this method. Contrast experiments are performed on a Q235 steel plate covered by a galvanized steel cladding. The experiment results show that the thickness measurement range and lift-off range are increased by applying this method to the common PEC probe.

关键词： Pulsed eddy current wall thinning Ferromagnetic cladding Thickness measurement Magnetic saturation

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‘Size effect’ related bending formability of thin-walled aluminum alloy tube

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Chinese Journal of Aeronautics 2013年第1期26卷 230-241页

作者： Li Heng Yang He Zhang Zhiyong Wang Zekang State Key Laboratory of Solidification Processing School of Materials Science and Engineering Northwestern Polytechnical University

Aluminum alloy （Al-alloy） thin-walled （D/t ＆gt; 20, diameter D, wall thickness t） bent tubes have attracted increasing applications in many industries with mass quantities and diverse specifications due to satisfying high strength to weigh ratio requirements of product manufacturing. However, due to nonlinear nature of bending with coupling effects of multiple factors, the similarity theory seems not applicable and there occurs a challenge for efficient and reliable evaluation of the bending formability of thin-walled tube with various bending specifications. Considering the unequal deformation and three major instabilities, the bending formability of thin-walled Al-alloy tube in changing tube sizes such as D and t are clarified via both the analytical and FE modeling/ simulations. The experiments of rotary draw bending are conducted to validate the theoretical models and further confirm ＇size effect＇ related bending formability. The major results show that （1） The anti-wrinkling capability of tube decreases with the larger D and smaller t, and the effect significance of t is larger than that of D even under rigid supports; （2） The wall thinning increases with the larger D and smaller t, and this tendency becomes much more obvious under rigid supports; （3） The cross-section deformation increases with the larger D and smaller t according to the analytical model obtained intrinsic relationship, while this tendency becomes opposite due to the nonlinear role of mandrel die; （4） The size factor D/t can be used as a nondimensional index to evaluate both the bending formability regarding the wall thinning and cross-section deformation.

关键词： Al-alloy Bending formability Flattening Size effect Tube bending wall thinning Wrinkling

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Overview and Lessons from More Than a Decade of Feeder Life Management

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Journal of Energy and Power Engineering 2013年第11期7卷 2164-2173页

作者： Aman Usmani Zane Walker Manager and Principal Consultant Engineering Services AMEC NSS Power and Process Americas M5G 1E6 Ontario Canada Chemistry and Material Section Candu Energy Inc. Mississauga L5K 1BI Ontario Canada

This paper provides an overview of the degradation in CANDU^a （Canadian Deuterium Uranium） feeders in operating plants observed from the mid 1990s onward. The degradation has been dominated by feeder wall thinning, caused by FAC （flow accelerated corrosion） and feeder cracking. This paper summarizes the industry＇s response to the discovery of these two degradation mechanisms and the methodologies, tools and technologies developed to monitor the degradation and assess the continued fitness for service to manage the plant life. This paper identifies some of the lessons gained from more than a decade of industry effort, and discusses how these lessons are being implemented in the refurbished and new CANDU plants. CANDU^a is a registered trademark of Atomic Energy of Canada Limited.

关键词： CANDU feeder degradation wall thinning cracking FAC.

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Analysis of Material Loss Behavior According to Long-Term Experiments on LDIE-FAC Multiple Degradation of Carbon Steel Materials

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World Journal of Nuclear Science and Technology 2022年第1期12卷 1-10页

作者： Kyeong Mo Hwang Dong Jin Lee Hun Yun Seung Chang Yoo Ji Hyeon Kim SI Business Department KEPCO E&C Gimcheon-si Korea Nuclear Engineering Department UNIST Ulsan-si Korea

Recently, damage caused by liquid droplet impingement erosion (LDIE) in addition to flow-accelerated corrosion (FAC) has frequently occurred in the secondary side steam piping of nuclear power plants, and the damage-occurring frequency is expected to increase as their operating years’ increase. In order to scrutinize its causes, therefore, an experimental study was conducted to understand how the behavior of LDIE-FAC multiple degradation changes when the piping of nuclear power plants is operated for a long time. Experimental results show that more magnetite was formed on the surface of the carbon steel specimen than on the low-alloy steel specimen, and that the rate of magnetite formation and extinction reached equilibrium due to the complex action of liquid droplet impingement erosion and flow-accelerated corrosion after a certain period of time. Furthermore, it was confirmed at the beginning of the experiment that A106 Gr.B specimen has more mass loss than A335 P22 specimen. After a certain period of time, however, the mass loss tends to be the opposite. This is presumed to have resulted from the magnetite formed on the surface playing a role in suppressing liquid droplet impingement erosion. In addition, it was confirmed that the amount of erosion linearly increases under the conditions in which the formation and extinction of magnetite reach equilibrium.

关键词： Liquid Droplet Impingement Erosion (LDIE) Flow-Accelerated Corrosion (FAC) Multiple Degradations ToSPACE wall thinning Magnetite

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