The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Keyvan Raeissi - One of the best experts on this subject based on the ideXlab platform.
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effect of current type on microstructure and corrosion resistance of super duplex stainless steel Claddings produced by the gas tungsten arc welding process
Surface & Coatings Technology, 2014Co-Authors: Abbas Eghlimi, Morteza Shamanian, Keyvan RaeissiAbstract:Abstract In this research, super duplex stainless steel filler metals were clad on high strength low alloy steel substrates by the tungsten arc welding process using pulsed and constant currents. To characterize the pulsed current effect, the phase composition and microstructure of the Claddings were compared, and the corrosion behavior of the Claddings was evaluated using cyclic polarization, electrochemical impedance spectroscopy and critical pitting temperature measurements. The results showed that the slower cooling rate of the constant current Cladding led to a higher total reformed austenite content and better corrosion resistance. It was also found that the formation of thermally-activated secondary austenite did not influence the corrosion behavior significantly. The electrochemical impedance spectroscopy indicated that the passive film formed on the pulsed current Cladding was more defective. The constant current Cladding also showed ten degree higher critical pitting temperature than the one which was produced by pulsed current.
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Dilution and Ferrite Number Prediction in Pulsed Current Cladding of Super-Duplex Stainless Steel Using RSM
Journal of Materials Engineering and Performance, 2013Co-Authors: Abbas Eghlimi, Morteza Shamanian, Keyvan RaeissiAbstract:Super-duplex stainless steels have an excellent combination of mechanical properties and corrosion resistance at relatively low temperatures and can be used as a coating to improve the corrosion and wear resistance of low carbon and low alloy steels. Such coatings can be produced using weld Cladding. In this study, pulsed current gas tungsten arc Cladding process was utilized to deposit super-duplex stainless steel on high strength low alloy steel substrates. In such Claddings, it is essential to understand how the dilution affects the composition and ferrite number of super-duplex stainless steel layer in order to be able to estimate its corrosion resistance and mechanical properties. In the current study, the effect of pulsed current gas tungsten arc Cladding process parameters on the dilution and ferrite number of super-duplex stainless steel clad layer was investigated by applying response surface methodology. The validity of the proposed models was investigated by using quadratic regression models and analysis of variance. The results showed an inverse relationship between dilution and ferrite number. They also showed that increasing the heat input decreases the ferrite number. The proposed mathematical models are useful for predicting and controlling the ferrite number within an acceptable range for super-duplex stainless steel Cladding.
Abbas Eghlimi - One of the best experts on this subject based on the ideXlab platform.
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effect of current type on microstructure and corrosion resistance of super duplex stainless steel Claddings produced by the gas tungsten arc welding process
Surface & Coatings Technology, 2014Co-Authors: Abbas Eghlimi, Morteza Shamanian, Keyvan RaeissiAbstract:Abstract In this research, super duplex stainless steel filler metals were clad on high strength low alloy steel substrates by the tungsten arc welding process using pulsed and constant currents. To characterize the pulsed current effect, the phase composition and microstructure of the Claddings were compared, and the corrosion behavior of the Claddings was evaluated using cyclic polarization, electrochemical impedance spectroscopy and critical pitting temperature measurements. The results showed that the slower cooling rate of the constant current Cladding led to a higher total reformed austenite content and better corrosion resistance. It was also found that the formation of thermally-activated secondary austenite did not influence the corrosion behavior significantly. The electrochemical impedance spectroscopy indicated that the passive film formed on the pulsed current Cladding was more defective. The constant current Cladding also showed ten degree higher critical pitting temperature than the one which was produced by pulsed current.
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Dilution and Ferrite Number Prediction in Pulsed Current Cladding of Super-Duplex Stainless Steel Using RSM
Journal of Materials Engineering and Performance, 2013Co-Authors: Abbas Eghlimi, Morteza Shamanian, Keyvan RaeissiAbstract:Super-duplex stainless steels have an excellent combination of mechanical properties and corrosion resistance at relatively low temperatures and can be used as a coating to improve the corrosion and wear resistance of low carbon and low alloy steels. Such coatings can be produced using weld Cladding. In this study, pulsed current gas tungsten arc Cladding process was utilized to deposit super-duplex stainless steel on high strength low alloy steel substrates. In such Claddings, it is essential to understand how the dilution affects the composition and ferrite number of super-duplex stainless steel layer in order to be able to estimate its corrosion resistance and mechanical properties. In the current study, the effect of pulsed current gas tungsten arc Cladding process parameters on the dilution and ferrite number of super-duplex stainless steel clad layer was investigated by applying response surface methodology. The validity of the proposed models was investigated by using quadratic regression models and analysis of variance. The results showed an inverse relationship between dilution and ferrite number. They also showed that increasing the heat input decreases the ferrite number. The proposed mathematical models are useful for predicting and controlling the ferrite number within an acceptable range for super-duplex stainless steel Cladding.
Morteza Shamanian - One of the best experts on this subject based on the ideXlab platform.
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investigation of powder fed laser Cladding of nicr chromium carbides single tracks on titanium aluminide substrate
Optics and Laser Technology, 2019Co-Authors: S E Aghili, Morteza ShamanianAbstract:Abstract In the present study, a Cr3C2 NiCr powder mixture was used to fabricate laser Claddings on a titanium aluminide (TiAl) substrate. The effect of processing parameters, such as laser power (P), powder feeding rate (F) and scanning speed (S), were studied on the geometrical properties (height, width, dilution and wetting angle) of single-line Claddings and their systematic correlation were predicted using the regression analysis method. The results indicated that the clad height showed a linear dependency on the P1.S−1.F0.85 parameter. Similarly, the width, wetting angle and penetration depth depicted a linear dependency on the P1.S−1.F−0.7, P0.8.S−0.7.F1 and P0.75.S0.5.F−1 parameters, respectively, while the dependency on dilution was S0.8.F−0.8. High values of the correlation coefficient were observed for all empirical dependencies. Finally, a processing window was developed for the laser Cladding of the Cr3C2 NiCr powder mixture on the TiAl substrate. The microstructure analysis of the optimal Cladding showed that the microstructure was covered with different chromium carbides (Cr3C2, Cr7C3 and Cr23C6), together with the Ni(Cr) solid solution. The microhardness of the optimal clad was found to be around 820 HV, which was higher than that of the titanium aluminide substrate (320 HV).
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effect of current type on microstructure and corrosion resistance of super duplex stainless steel Claddings produced by the gas tungsten arc welding process
Surface & Coatings Technology, 2014Co-Authors: Abbas Eghlimi, Morteza Shamanian, Keyvan RaeissiAbstract:Abstract In this research, super duplex stainless steel filler metals were clad on high strength low alloy steel substrates by the tungsten arc welding process using pulsed and constant currents. To characterize the pulsed current effect, the phase composition and microstructure of the Claddings were compared, and the corrosion behavior of the Claddings was evaluated using cyclic polarization, electrochemical impedance spectroscopy and critical pitting temperature measurements. The results showed that the slower cooling rate of the constant current Cladding led to a higher total reformed austenite content and better corrosion resistance. It was also found that the formation of thermally-activated secondary austenite did not influence the corrosion behavior significantly. The electrochemical impedance spectroscopy indicated that the passive film formed on the pulsed current Cladding was more defective. The constant current Cladding also showed ten degree higher critical pitting temperature than the one which was produced by pulsed current.
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Dilution and Ferrite Number Prediction in Pulsed Current Cladding of Super-Duplex Stainless Steel Using RSM
Journal of Materials Engineering and Performance, 2013Co-Authors: Abbas Eghlimi, Morteza Shamanian, Keyvan RaeissiAbstract:Super-duplex stainless steels have an excellent combination of mechanical properties and corrosion resistance at relatively low temperatures and can be used as a coating to improve the corrosion and wear resistance of low carbon and low alloy steels. Such coatings can be produced using weld Cladding. In this study, pulsed current gas tungsten arc Cladding process was utilized to deposit super-duplex stainless steel on high strength low alloy steel substrates. In such Claddings, it is essential to understand how the dilution affects the composition and ferrite number of super-duplex stainless steel layer in order to be able to estimate its corrosion resistance and mechanical properties. In the current study, the effect of pulsed current gas tungsten arc Cladding process parameters on the dilution and ferrite number of super-duplex stainless steel clad layer was investigated by applying response surface methodology. The validity of the proposed models was investigated by using quadratic regression models and analysis of variance. The results showed an inverse relationship between dilution and ferrite number. They also showed that increasing the heat input decreases the ferrite number. The proposed mathematical models are useful for predicting and controlling the ferrite number within an acceptable range for super-duplex stainless steel Cladding.
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effect of pulse current on microstructure and wear resistance of stellite6 tungsten carbide Claddings produced by tungsten inert gas process
Surface & Coatings Technology, 2011Co-Authors: F Madadi, Morteza Shamanian, F AshrafizadehAbstract:In this paper, the tungsten inert gas (TIG) surfacing process was carried out in two, pulse and constant current modes to produce Stellite/WC composite Claddings. To evaluate the coating, phase composition, microstructure, hardness and wear behavior of the clad layers were investigated. The results showed that the microstructure of the Cladding was composed of a hypoeutectic structure (γ + (γ + WC)). The added WC was completely melted into the weld pool and the resolidified structure contained α-Co, σ-CoCr and some types of carbides. It was indicated that the use of pulsed current leads to a decrease in dilution and formation of a finer microstructure having higher hardness. Several significantly different solidified microstructures were characterized by dendrites, eutectics and faceted dendrites in the Claddings. The faceted dendrites contained the majority of W as well as Cr and Co while the matrix had higher Cr and Co content. The presence of faceted dendrites caused improvement in wear behavior of Claddings, with more WC content introduced, more faceted dendrites was obtained.
Toyoshi Fuketa - One of the best experts on this subject based on the ideXlab platform.
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investigation of hydride rim effect on failure of zircaloy 4 Cladding with tube burst test
Journal of Nuclear Science and Technology, 2005Co-Authors: Fumihisa Nagase, Toyoshi FuketaAbstract:To promote a better understanding of failure behavior of high burnup PWR fuel rods during reactivity initiated accidents (RIAs), tube burst tests have been performed with artificially hydrided Zircaloy-4 specimens at room temperature and at 620 K. Pressurization rate was increased to a maximum of 3.4 GPa/s in order to simulate rapid pellet/Cladding mechanical interaction (PCMI) that occurs in high burnup fuel rods during a pulse-irradiation in the Nuclear Safety Research Reactor (NSRR). Hydrogen content in the specimens ranged from 150 to 1,050 ppm. Hydrides were accumulated in the Cladding periphery and formed ‘hydride rim’ (radially-localized hydride layer) as observed in high burnup PWR fuel Claddings. The hydrided Cladding tubes failed with an axial crack at the room temperature tests. Brittle fracture appeared in the hydride rim, and failure morphology was similar to that observed in the NSRR experiments. The hydrides rim obviously reduced burst pressure and residual hoop strain at the tests. The res...
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effect of pre hydriding on thermal shock resistance of zircaloy 4 Cladding under simulated loss of coolant accident conditions
Journal of Nuclear Science and Technology, 2004Co-Authors: Fumihisa Nagase, Toyoshi FuketaAbstract:Experiments simulating loss-of-coolant accident (LOCA) conditions were performed to evaluate the effect of pre-hydriding on the thermal-shock resistance of oxidized Zircaloy-4 Cladding. Test rods fabricated with 580-mm long Claddings were isothermally oxidized at temperatures ranging from 1,220 to 1,530 K in steam and then were quenched with flooding water. Both artificially hydrided (400 to 600ppm) and non-hydrided Claddings were subjected to these tests. Since Cladding fracture on quenching primarily depends on the amount of oxidation, the fracture threshold was evaluated in terms of “equivalent Cladding reacted (ECR).” Under an axially unrestrained condition, the fracture threshold is about 56% ECR, and the influence of pre-hydriding is not observed. The fracture threshold is decreased by restraining the test rods on quenching, and it is more remarkable in pre-hydrided Claddings than in non-hydrided Claddings. Consequently, the fracture threshold was about 20% ECR and 10% ECR for non-hydrided and pre-h...
Shigeharu Ukai - One of the best experts on this subject based on the ideXlab platform.
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production and properties of nano scale oxide dispersion strengthened ods 9cr martensitic steel Claddings
Isij International, 2003Co-Authors: Shigeharu Ukai, Masayuki Fujiwara, Takeji Kaito, Satoshi Ohtsuka, Tsuyoshi Narita, Toshimi KobayashiAbstract:The 9Cr-ODS martensitic steel Claddings were developed by cold-rolling and subsequent heat-treatment. The standard chemical composition is Fe-0.13C-9Cr-2W-0.2Ti-0.35Y 2 O 3 . The substantially elongated grains formed by cold-rolling turned out to be into equi-axied grains by ferrite to austenite phase transformation at the final heat-treatment. The produced Claddings have the tempered martensitic structure and excess oxygen of 0.060 mass%. The superior tensile and creep rupture strength were shown in the produced Cladding, compared with conventional ferritic (PNC-FMS) and even austenitic (PNC316) Claddings at higher temperature and extended time. The strength improvement is attributed to finely distributed nano-scale complex oxide. The coarser ferrite grains produced by slow cooling make further improvement in the tensile and creep rupture strength beyond those of tempered martensite at high temperature and longer testing time. The higher excess oxygen content of 0.137 mass% prevents fine distribution of the oxide particles that lead to inferior high temperature tensile and creep strength.
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development of 9cr ods martensitic steel Claddings for fuel pins by means of ferrite to austenite phase transformation
Journal of Nuclear Science and Technology, 2002Co-Authors: Shigeharu Ukai, Takanari Okuda, Masayuki Fujiwara, Shunji Mizuta, Toshimi KobayashiAbstract:For use as fuel Cladding of liquid metal fast reactors, Fe-0.12C-9Cr-2W ODS martensitic steel Claddings were developed by cold-rolling under the softened ferrite phase induced by slow cooling from austenite phase, subsequently by ferrite to austenite phase transformation to break up substantially elongated grains produced by cold-rolling at the final heat-treatment. The produced Claddings showed noticeable improvement in tensile and creep rupture strength that are considerably superior to PNC-FMS and even austenitic PNC316 at higher temperature and extended time to rupture. The strength improvement is mainly attributed to titanium addition in ODS martensitic steels through its reduction of Y2O3 particle size and shortening inter-particles spacing. The behavior of oxide particle size reduction is associated with stoichiometry between Y2O3 and TiO2.
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development of oxide dispersion strengthened ferritic steels for fbr core application i improvement of mechanical properties by recrystallization processing
Journal of Nuclear Science and Technology, 1997Co-Authors: Shigeharu Ukai, Toshio Nishida, Hirokazu Okada, Takanari Okuda, Masayuki Fujiwara, Kazutaka AsabeAbstract:As to an oxide dispersion strengthened (ODs) ferritic steel Cladding as the promising candidate for long-life core materials of the fast reactors, previously fabricated Claddings had inferior internal creep rupture strength in hoop direction and inferior formability due to less ductility. Those unexpected features of ODs Claddings are substantially ascribed to the needle-like grain structure excessively elongated along the forming direction. Controlling the grain morphology by applying the recrystallization method to ODs ferritic steel made possible to improve those inferior features. The ranges of Y2O3 and excessive oxygen contents for possibly cold-rolling and recrystallization were revealed, and the effects of extruded temperature and deformation texture on recrystallization characteristics were evaluated. The recrystallized ODs ferritic steel showed superior internal creep rupture strength and ductility. It was demonstrated from those results that cold-rolling manufacturing of ODs Cladding at room tem...
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tube manufacturing and mechanical properties of oxide dispersion strengthened ferritic steel
Journal of Nuclear Materials, 1993Co-Authors: Shigeharu Ukai, Toshio Nishida, Hirokazu Okada, Masayuki Fujiwara, M Harada, M Inoue, S Nomura, S Shikakura, Kazutaka AsabeAbstract:Abstract In order to apply the ODS ferritic steels for the prospective Cladding materials of advanced fast breeder reactors, fabrication tests of thin-walled Cladding tubes were carried out from a viewpoint of future industrial manufacturing. The manufactured Claddings within the specification limit exhibited a superior high temperature strength and sufficient Charpy impact properties. The degradation of creep rupture strength in the bi-axial direction, as compared with the uni-axial direction, is mainly attributed to the grain boundary fracture mode within the elongated bamboo grain structure.
