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Li G.,Shanghai Key Laboratory for Engineering Materials Evaluation | Fang K.,Shanghai Key Laboratory for Engineering Materials Evaluation | Yang W.,Shanghai Key Laboratory for Engineering Materials Evaluation | Zhang M.,Nuclear Electric Ltd | Sun Z.,Nuclear Electric Ltd
Key Engineering Materials | Year: 2011

The microstructures and mechanical properties of a dissimilar metal weld A508/52M/316L used in the primary water system of pressurized water reactor (PWR) nuclear power plants were investigated. The weld exhibits complicated microstructures, with significant change around the interfaces A508/52M and 52M/316L. The variations of main elements in 52M weld metal are greater than those in the A508 and 316L, with significant changes in the zones closed to the interfaces. The bulk 52M weld metal has higher and more uneven hardness than both of the base metals A508 and 316L. The HAZ of A508 exhibits the highest hardness value in the weld. The area around the A508/52M interface is the most weak part for stress corrosion cracking (SCC) resistance of the weld in simulated PWR primary water at 290°C. SCC was only found in the specimens tested at +200mV(SHE) but not in those tested at both -780mV and E corr (about -500mV).


Li G.F.,Shanghai Key Laboratory for Engineering Materials Evaluation | Li G.J.,Shanghai Key Laboratory for Engineering Materials Evaluation | Peng J.,Shanghai Key Laboratory for Engineering Materials Evaluation | Zhang M.L.,Nuclear Electric Ltd | Sun Z.Y.,Nuclear Electric Ltd
Applied Mechanics and Materials | Year: 2014

The mechanical behaviors of dissimilar metal weld SA508-52M-316L in several environments were investigated by using tensile tests with smooth specimens, focusing on the behavior of SA508-52M weld part during slow strain rates testing (SSRT) at 290°C in nitrogen gas and in simulated primary water at different electrode potentials. The mechanical properties at room temperature of main materials were obtained first. When tested at 290°C, the weld exhibited characteristics of dynamic strain ageing (DSA), which was more significant when strain rate was decreased from 1x10-6 (1/s) to 3.1 x10-7 (1/s). When tested in the water at the potentials from -720 to +200mV(SHE), SA508-52M specimens showed the mechanical behaviors almost the same as that in nitrogen gas, with ductile failure happened in the 52M bulk weld metal. When the potential was raised to +300 and +400mV(SHE), brittle failure of stress corrosion cracking (SCC) took place around the interface, causing the significant drop of elongation and reduction in area. © (2014) Trans Tech Publications, Switzerland. All Rights Reserved.


Li G.,Shanghai Key Laboratory for Engineering Materials Evaluation | Fang K.,Shanghai Key Laboratory for Engineering Materials Evaluation | Peng J.,Shanghai Key Laboratory for Engineering Materials Evaluation | Yang W.,Shanghai Key Laboratory for Engineering Materials Evaluation | And 2 more authors.
Jinshu Xuebao/Acta Metallurgica Sinica | Year: 2011

The stress corrosion cracking (SCC) behavior of advanced dissimilar metal weld A508/52M/316L in simulated primary water environments of pressurized water reactor (PWR) at 290 _ was investigated by means of slow strain rate testing (SSRT). The tests were performed at various applied electrode potentials which correspond to the electrochemical conditions of the weld in various water environments, from low potentials with ideal water chemistry to high potentials with oxygen-contaminated water chemistry. The weld exhibits complicated microstructure and chemical composition distributions, especially, significant changes appear around the A508/52M interface and the 52M/316L interface. For tensile specimens in SSRT, sharp notches were machined at important and typical places, i. e., at the two interfaces and in the bulk parts of the low alloy steel, Ni base weld metal and stainless steel of the weld. Results showed that the specimens always failed in bulk zone of the Ni base weld metal with ductile appearances when tested in the potential range from -780 mV to -300 mV (vs SHE). When electrode potential was raised into the range from -200 mV to +200 mV which corresponds to oxygen-contaminated water chemistry, the weld exhibits significant SCC. The area around the A508/52M interface is the weakest place, transgranular stress corrosion cracking (TGSCC) happened both along the interface and in A508 heat affected zone (HAZ), intergranular stress corrosion cracking (IGSCC) occurred in the Ni base weld metal close to the interface. The cracking mechanism and the engineering practical significance were discussed. © Copyright.


Li G.F.,Shanghai Key Laboratory for Engineering Materials Evaluation | Yuan Y.F.,Shanghai Key Laboratory for Engineering Materials Evaluation | Lu X.,Shanghai Key Laboratory for Engineering Materials Evaluation
Procedia Engineering | Year: 2015

The microstructure and stress corrosion cracking (SCC) in simulated primary water at 290 °C of a dissimilar metal weld 16MND5/309L/308L/Z2CND18-12N made in China were studied for reliability and lifetime assessment and management of relevant pressurized water reactor (PWR) nuclear power plants. Results of microstructure characterization showed that the base metal of the low alloy steel (LAS) 16MND5 was upper-bainitic and stainless steel (SS) Z2CND18-12N was equiaxial austenitic grains, the bulk weld metal of SS 308L was austenite with dendritic structures plus δ-ferrite islands. The interfaces areas around 16MND5/309L and 308L/Z2CND18-12N exhibited apparent fusion lines with complicated microstructure/chemical composition changes, especially the former. The area between the 16MND5 base metal and the bulk weld metal was made up of three parts, that is, the heat-affect zone of 16MND5, fusion line and transition zone. There was a thin martensitic layer along the fusion line, which possessed the highest micro-hardness among the weld. The transition zone was an austenitic layer within which Cr% and Ni% changed significantly. SCC test results showed that this area around 16MND5/309L was the most susceptible to SCC among the weld. Both intergranular and transgranular SCC occurred in this area when tested in at high electrode potential which is mainly related to bad water chemistry with high oxygen contamination. The crack mechanism and the significance in engineering are discussed. © 2015 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.


Lu Q.-S.,Fudan University | Sun L.-H.,Fudan University | Yang Z.-G.,Fudan University | Li X.-H.,Shanghai Key Laboratory for Engineering Materials Evaluation | And 2 more authors.
Composites Part A: Applied Science and Manufacturing | Year: 2010

In order to obtain an optimal PU based polyester fabric composites orienting to applications, the composites with different ratios of bi-component PU adhesive and different structural inorganic fillers were fabricated and characterized thermally and mechanically, and the mechanisms were theoretically discussed in details; in particular, the tensile performances with different loading directions have also been studied. In the present approach, the ratios of bi-component PU adhesive, the fillers as well as the loading directions were comprehensively investigated and optimized to get the best tensile performance under constraint of the thermal properties. All the results of tensile testing have been explained by the proposed "crack propagation and encountering mechanism" which can identify the strengths of interfaces, matrixes and fibers and describe the initiation and propagation of the cracks inside the composites. © 2010 Elsevier Ltd. All rights reserved.


Hu X.,East China University of Science and Technology | Bao H.,East China University of Science and Technology | Wang P.,Shanghai Key Laboratory for Engineering Materials Evaluation | Jin S.,Shanghai Key Laboratory for Engineering Materials Evaluation | Gu Z.,Shanghai Key Laboratory for Engineering Materials Evaluation
Polymer International | Year: 2012

Flake-like polyaniline with various thicknesses was prepared by cationic emulsion polymerization of aniline monomer in the presence of cetyltrimethylammonium bromide (CTAB). The morphology of polyaniline with uniform and smooth flake-like structure was observed using field-emission scanning electron microscopy and transmission electron microscopy. The lamellar complex of (CTA) 2S 2O 8, acting as a reactive soft template for the formation of polyaniline, was investigated using low-angle X-ray diffraction. The soft template provides an expanding space for the growth of polyaniline, in which the oxidization of aniline monomers can construct effectively a flake-like structure. The concentration of CTAB plays an important role in adjusting the d-spacing of the soft template. Crystallization and composition of polyaniline were characterized using X-ray diffraction and Fourier transform infrared spectroscopy. The X-ray diffraction pattern has a sharp peak at 2θ = 6.4° (d-spacing = 13.7 Å), showing that polyaniline has a solid-state ordering structure and high degree of crystallization. Doping and dispersive experiments were also included in the study. © 2012 Society of Chemical Industry.


Yang W.,Shanghai Research Institute of Materials | Yang W.,Shanghai Key Laboratory for Engineering Materials Evaluation | Li G.,Shanghai Research Institute of Materials | Li G.,Shanghai Key Laboratory for Engineering Materials Evaluation | And 4 more authors.
Chinese Journal of Mechanical Engineering (English Edition) | Year: 2010

Stress corrosion cracking (SCC) of stainless steels and Ni-based alloys in high temperature water coolant is one of the key problems affecting the safe operation of nuclear power plants (NPPs). The nitrogen-added stainless steel is a kind of possible candidate materials for mitigating SCC since reducing the carbon content and adding nitrogen to offset the loss in strength caused by the decrease in carbon content can mitigate the problem of sensitization. However, the reports of SCC of nitrogen-added stainless steels in high temperature water are few available. The effects of applied potential and sensitization treatment on the SCC of a newly developed nitrogen-containing stainless steel (SS) 316LN in high temperature water doped with chloride at 250°C were studied by using slow strain rate tests (SSRTs). The SSRT results are compared with our data previously published for 316 SS without nitrogen and 304NG SS with nitrogen, and the possible mechanism affecting the SCC behaviors of the studied steels is also discussed based on SSRT and microstucture analysis results. The susceptibility to cracking of 316LN SS normally increases with increasing potential. The susceptibility to SCC of 316LN SS was less than that of 316 SS and 304NG SS. Sensitization treatment at 700°C for 30 h showed little effect on the SCC of 316LN SS and significant effect on the SCC of 316 SS. The predominant cracking mode for the 316LN SS in both annealed state and the state after the sensitization treatment was transgranular. The presented conditions of mitigating stress corrosion cracking are some useful information for the safe use of 316LN SS in NPPs. © 2010 Chinese Journal of Mechanical Engineering.


Zhai L.,University of Shanghai for Science and Technology | Zhou H.,University of Shanghai for Science and Technology | Li X.,Shanghai Key Laboratory for Engineering Materials Evaluation | Gu Z.,Shanghai Key Laboratory for Engineering Materials Evaluation | Chen L.,Shanghai Institute of Space Power Sources
Corrosion Science and Protection Technology | Year: 2014

A novel etching process of indium tin oxide (ITO) transparent electrode and its etching effect were reported. Etching liquid was made up of FeCl3 solution with various pH as functional component, PEG10000 as medium, and gas phase SiO2 as thixotropic agent. ITO etching experiments were carried out by screen printing method. The influence of different etching conditions on ITO electrode volume resistivity was studied. The result shows that the optimal etching condition is etching at 80 °C for 90 min in a solution with pH 1.67. The change of composition and morphology of ITO electrode was characterized by EDS and AFM respectively.


Gu Z.-M.,Shanghai Key Laboratory for Engineering Materials Evaluation | Li X.-H.,Shanghai Key Laboratory for Engineering Materials Evaluation | Hu X.-X.,East China University of Science and Technology | Bao H.,East China University of Science and Technology
Gongneng Cailiao/Journal of Functional Materials | Year: 2013

Synthesized graphite oxide(GO)/multi-wall carbon nanotubes(MWNTs) hybrid material with good conductive performance. The hydrogen bonding between GO layers in the hybrid material was subsided when the content of MWNTs was increased, and interlayer spacing of GO was enlarged proved by IR, Raman spectra and X-ray diffraction. The intersecting surface and surface images of hybrid material were observed by SEM, it showed that the original heaped GO layer-structure happened to exfoliate when MWNTs inserted, and MWNTs had a good dispersion in hybrid material. When the ration of GO and MWNTs charged 1:4 from 1:1, the conductivity increased by 5 orders of magnitude.


Li G.F.,Shanghai Key Laboratory for Engineering Materials Evaluation
Advanced Materials Research | Year: 2014

The effects of soil type of Shanghai and electrode potential from cathodic protection point on near-neutral pH stress corrosion cracking (SCC) behavior of pipeline steel X60 has been investigated for structural integrity assessment. The SCC behavior was evaluated through slow strain rate tests (SSRT) at various electrode potentials in three solutions containing different typical soils. Results showed that the SCC susceptibility generally increased with decreasing electrode potential in all the three environments, with quick increase happening in the range from -1500 to -700mV(SCE). It is suggested that hydrogen induced cracking should dominate the SCC at low potentials. In cathodic potential range, the rank of the SCC susceptibility for soil type was Near-city soil > Cyan-purple soil > Cyan-yellow soil. In anodic potential range, SCC susceptibility curves mixed each other in the three solutions. © (2014) Trans Tech Publications, Switzerland.

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