Effect Of Vanadium Addition Research Articles

Effect of vanadium addition on the microstructure and mechanical properties of low carbon micro-alloyed powder metallurgy steels

Abstract In the present experimental work, the effects of vanadium additions on the microstructures and mechanical properties of powder metallurgy (PM) steel and microalloyed powder metallurgy (PM) steels were investigated. The microstructures of the PM steel and microalloyed PM steels were characterized by optic microscope, SEM and EDS. Experimental results showed that vanadium microalloyed steels can be produced by PM technology. The addition of vanadium limits grain growth during austenitization prior to air cooling and increases the strength in the sintered conditions. By limiting austenite grain growth, the precipitates result in significant improvement in strength.

Micro-alloyed steels for forgings: effect of nano-precipitation on mechanical properties

The aim of the present paper deals with the production of heavy steel forgings of micro-alloyed steels. Improvements of mechanical properties of forgings up to level by sheets, strips and tubes have been achieved by mean of application of micro-alloying elements and thermo-mechanical treatments. The effect of vanadium addition has been assessed by means of metallurgical modelling step followed by a laboratory demonstration phase by means of ingot manufacturing. Heat treatment has been designed aimed to achieve the desired target tensile properties. Results show that ASTM A694 F70 grade requirements can be fulfilled by 0.15% V addition and a proper heat treatment in a ferrite-pearlite microstructure, representative of a forged component.

Effect of Vanadium Addition on the Strength of API X100 Linepipe Steel

Effect of Vanadium Addition on the Strength of API X100 Linepipe Steel

Micro-alloyed steels for forgings: effect of nano-precipitation on mechanical properties

The aim of the present paper deals with the production of heavy steel forgings of micro-alloyed steels. Improvements of mechanical properties of forgings up to level by sheets, strips and tubes have been achieved by mean of application of micro-alloying elements and thermo-mechanical treatments. The effect of vanadium addition has been assessed by means of metallurgical modelling step followed by a laboratory demonstration phase by means of ingot manufacturing. Heat treatment has been designed aimed to achieve the desired target tensile properties. Results show that ASTM A694 F70 grade requirements can be fulfilled by 0.15% V addition and a proper heat treatment in a ferrite-pearlite microstructure, representative of a forged component.

Effects of Vanadium Addition on Microstructure and Tribological Performance of Bainite Hardfacing Coatings

New hardfacing coatings with different vanadium (V) additions were prepared by surfacing technology. The microstructures of the hardfacing coatings were analyzed by field emission scanning electron microscope equipped with energy dispersive X-ray spectrometry and examined by transmission electron microscope. The hardness and wear resistances of the hardfacing coatings were measured. Worn debris were collected at the end of wear test and analyzed. The precipitation temperature of the phases in the hardfacing coatings and the mass fraction of MC carbide were calculated by Jmatpro software. The experimental results show that, the hardfacing coating mainly consists of granular bainite. No significant change in the size of linear martensite-austenite (M-A) islands is observed with the increase of V addition, while the size of massive M-A islands is decreased. The wear resistance of the hardfacing coating reaches a maximum level with V content of 0.14 wt.%. The calculated results show that, the mass fraction of MC carbide is increased with the increase of V content. Based on calculation following two-dimensional mismatch theory, MC carbide is a heterogeneous nucleus of the ferrite resulting refined ferrite in the hardfacing coating.

Oxidative dehydrogenation of 1-butene over vanadium modified bismuth molybdate catalyst: an insight into mechanism

The effect of vanadium addition on the performance of bismuth molybdate catalysts has been discussed. The mechanism of oxygen mobility on the prepared catalysts is proposed.

Vanadium-doped TiO2 anatase nanostructures: the role of V in solid solution formation and its effect on the optical properties

A facile and environmentally friendly synthesis approach for the production of vanadium doped titanium dioxide (VxTi1−xO2) nanostructures was demonstrated via hydrothermal decomposition of vanadium and titanium peroxo-complexes. The effect of vanadium addition on the structural and morphological properties of VxTi1−xO2 nanocrystals was investigated by X-ray diffraction (XRD) and electron microscopy techniques. XRD analysis showed that all VxTi1−xO2 samples presented only the TiO2 anatase crystalline phase and, despite the different amounts of vanadium ions, the single crystalline nature was preserved. Increasing V contents resulted in morphological evolution, from anisotropic to isotropic structures. X-ray absorption spectroscopy (XAS) and electron energy loss spectroscopy (EELS) have been employed for investigating the atomic composition and configuration of these nanostructures. XAS measurements at the K-edges (for V and Ti) revealed that V ions occupy the Ti4+-site, which confirms the doping effect. Furthermore, high-angle annular dark-field (HAADF) imaging, combined with EELS mapping, indicated that the vanadium ions were homogeneously distributed in the structure without any kind of segregation. These morphological and compositional modifications upon vanadium addition led to evolution of the TiO2 optical properties.

Effect of vanadium addition on the creep resistance of 18Cr9Ni3CuNbN austenitic stainless heat resistant steel

The effect of vanadium addition on the creep property of niobium-containing 18Cr–9Ni austenitic heat-resistant steel was studied. After solution treatment, the MX precipitates of vanadium-free steel contained Nb only. On the contrary, high Nb and low V contents were detected from the MX precipitates in the steel with 0.3wt% of vanadium. Vanadium-rich MX carbo-nitride was not observed in the matrix and at the grain boundaries after solution treatment. The vanadium precipitated as a form of Z-phase during early-stage creep deformation was attributed to the improvement in creep strength at 700°C with applied stress higher than 150MPa. And metallic Cu precipitates were confirmed in the nanometer scale using TEM and EDS technique. The Cu precipitates are believed to contribute to the strengthening of austenitic heat resistant steel independently. The precipitation behavior is discussed using transmission electron microscopy and thermo-kinetics simulation technique.

Effects of vanadium addition on microstructure, mechanical properties and wear resistance of Ni-Hard4 white cast iron

Ni-Hard4 white cast iron is commonly used in applications requiring excellent abrasion resistance as in the mining and mineral ore processing industry. In this study, the effects of vanadium on the microstructure, mechanical properties and wear-resistance of Ni-Hard4 white cast iron were investigated. This study was conducted in six laboratory-made alloys with different vanadium contents. The microstructure of the samples was characterized using the optical microscopy, the scanning electron microscopy, and the energy dispersive X-ray spectrometry. The impact energy, hardness and wear resistance of the samples were determined. The results indicated that with an increase in vanadium concentration, the chromium carbides were refined, and the volume fraction of carbides was decreased. After increasing the vanadium content by 2%, the microstructure of Ni-Hard4 white cast iron became finer and the hardness and wear resistance were improved without reduction of fracture toughness. The result of on-line service (AG Mill) showed that the wear resistance of Ni-Hard4 white cast iron was modified by 2%, and vanadium liners were 40% better than the basic Ni-Hard4.

Effect of vanadium addition on the microstructure and mechanical properties of the ODS ferritic steels

In this work, the effects of vanadium addition in the range of 0.3–3% (in weight percent) for an oxide dispersion strengthened reduced activation ferritic (ODS RAF) steel were investigated. Samples of the V-modified steel have been prepared using elemental (Fe, Cr, W, Ti) and Y2O3 powders with the nominal composition of Fe–14Cr–2W–0.3Ti–0.3Y2O3. Consolidated and heat treated samples were investigated using Scanning Electron Microscopy and Scanning Transmission Electron Microscopy equipped with Electron Energy Loss Spectroscopy detector. Hardness and Charpy impact tests (KLST specimens) were also performed. The microstructure investigations revealed numerous particles of the size up to 0.5μm. They are primarily Ti–Cr–V oxides located at the grain boundaries and inside the grains. These particles increase hardness and significantly reduce fracture resistance of the ODS RAF alloys developed here. However, it should be noted that the 0.3% V-ODS steel has unexpectedly the lowest transition temperature of about 282K and that the 1–3% V-ODS steels, in spite of the transition temperature about 373K, exhibit almost two times higher the lower shelf energy values in comparison with the 0.3% V-ODS and 0% V-ODS steels.

Effect of Vanadium Addition on Reliability and Microstructure of BaTiO3-Based Multilayer Ceramic Capacitors

The vanadium distribution in multilayer ceramic capacitors (MLCCs), sintered under a reducing atmosphere, was investigated using scanning transmission electron microscopy–electron energy loss spectroscopy (STEM–EELS), and insulation resistance degradation was analyzed using impedance spectroscopy in highly accelerated lifetime tests to clarify the effects of vanadium on both the electrical properties and microstructure of MLCCs. Vanadium mitigated insulation resistance degradation and increased the reliability of MLCCs. Moreover, vanadium content increased and insulation resistance at the ceramic/electrode interface decreased slowly. This change in dynamics directly resulted in an improved lifetime of MLCCs. The results of STEM–EELS analysis showed that vanadium distributed along the grain boundary and grain boundary junction, but substituted into BaTiO3 at the ceramic/electrode interface. Therefore, it is considered that vanadium substitution at the ceramic/electrode interface improves the reliability of MLCCs.

Effect of Vanadium Addition on Reliability and Microstructure of BaTiO3-Based Multilayer Ceramic Capacitors

Effect of Vanadium Addition on Reliability and Microstructure of BaTiO₃-Based Multilayer Ceramic Capacitors

2-2-2 Ni-Al酸化物系触媒のCO選択メタン化反応におけるバナジウム添加効果と耐久性(2-2 天然ガス科学,Session 2 天然ガス・メタンハイグレート等)

2-2-2 Ni-Al酸化物系触媒のCO選択メタン化反応におけるバナジウム添加効果と耐久性(2-2 天然ガス科学,Session 2 天然ガス・メタンハイグレート等)

Effect of Vanadium Addition to Aluminum and Aluminum Grain Refined by Titanium on their Chemical Corrosion Rate in Acidic Solution, HCL, at Different Temperatures

The paper presents the effect of vanadium addition to aluminum and aluminum grain refined by titanium on the micron level, in the range from 0.005 wt % to 0.236 wt %, on their corrosion resistance in acidic solution, HCl, at three different temperatures namely: 25 °C, 40 °C and 60 °C. It was found that the corrosion rate was slightly increased by the addition of any percentage of vanadium at 25 °C. Furthermore, it was found that the corrosion rate increased with the increase of temperature at any percentage of vanadium addition in the case of both aluminum and aluminum grain refined by titanium. However it was found that addition of vanadium at any percentage to either aluminum or aluminum+ titanium, resulted in decrease of the corrosion rate i.e. improvement in their corrosion resistance in acidic solution at 40 °C and 60 °C. The maximum achieved reduction in corrosion rate was 77 % at 40 °C and 0.148 wt % vanadium addition.

Preparation, heat treatment and photoluminescence properties of V-doped ZnO–SiO2–B2O3 glasses

Four glasses in ZnO–SiO2–B2O3 ternary system were prepared by the melt quenching method with the objective of optimizing sub-nanosecond emission over the UV region of zinc borosilicate glasses used in superfast scintillators. The effect of vanadium addition and heat treatment on phase formation, microstructure and photoluminescence properties of the glasses was characterized by means of DTA, XRD, SEM and fluorescence spectrophotometer. Vanadium contributed to the near-band-edge emission in two ways, by introducing donor levels in the energy band of ZnO particles and by facilitating the precipitation of ZnO and willemite crystals. Furthermore, nucleation of willemite and zinc oxide phases, which are both the origins of the intense emission bands in the UV region, was facilitated with increasing either the time or temperature of heat treatments. Photoluminescence spectra showed the elimination of the visible emission band which is favorable in scintillating glasses.

Model for Predicting Phase Transformation and Yield Strength of Vanadium Microalloyed Carbon Steels

An integrated model for predicting recrystallization, phase transformation and yield strength of vanadium-microalloyed carbon steel (V-steel) is developed. Two effects of vanadium addition on recrystallization are assumed: one is the solute-drag effect on mobility of grain boundary, the other is pinning-effect on austenite grain growth due to vanadium carbide (VC) precipitate in austenite. The austenite grain size is considered as the control variable for nucleation density in grain corner, grain boundary, and grain interior during phase transformation. Thermodynamic data for transformation including para-equilibrium of carbon concentration and driving force were calculated using ThermoCalc software. The vanadium addition leads to α/γ-interphase VC precipitation in ferrite, which accelerates the diffusion rate of carbon in austenite at α/γ interface and increases nucleation sites for intragranular ferrite transformation. In consequence, the ferrite fraction and grain size are increased. Brandt model27) is conducted to predict pearlite transformation. The lamellar spacing is considered as a function of carbon concentration and undercooling. The alloying elements, ferrite and pearlite fractions, ferrite grain size, and lamellar spacing were taken into account for predicting strength of V-free steels. Modified Ashby-Orowan equation is then used to calculate the VC precipitation strengthening of V-steels. Using this model the calculated results obtained are in good agreement with experimental results.

Effect of Vanadium Addition at a Rate of 0.1% on the Mechanical Characteristics, Microstructure, and Microhardness of Al-Cu Casted Alloys

Due to essential need of Al-Cu alloys in different applications such as aerospace and automotive industries, and the mechanical characteristics of Al-Cu alloys being weak; the effect of vanadium addition at a rate of 0.1% on the mechanical behavior, microhardness, and microstructure have been investigated. The effect of upsetting process -cold work- on the microstructure, microhardness has been also investigated. Three set of alloys namely; Al, Al-9%Cu, and Al-9%Cu-0.1%V were prepared. The specimens for microstructure, microhardness and compression tests were machined. The mechanical tests were performed to investigate the effect of vanadium addition and the effect of upsetting process. It was found that the 0.1% vanadium addition resulted in grain refinement of Al-9% Cu alloys of about 32.3 %, furthermore, and extra refining resulted after upsetting process by 44.2 %. On the other hand, the microhardness of Al-9%Cu enhanced by 54.1 %, and the valuable result was a 422.8 % enhancement in the microhardness of Al-9%Cu-0.1%V alloy after upsetting process compared to pure Al.

Effects of Vanadium Addition on Formation of Carbides of High Carbon High Speed Steel

Effects of Vanadium Addition on Formation of Carbides of High Carbon High Speed Steel

Interfacial reactions in the Sn-(Ag)/(Ni,V) couples and phase equilibria of the Sn-Ni-V system at the Sn-Rich corner

Ni-7wt.%V is commonly used as the barrier layer material in the under-bump metallurgy in the microelectronic industry. Although interfacial reactions between various solders with the nickel substrate have been investigated intensively, the effects of vanadium addition upon the solder/(Ni,V) interfacial reactions have not been studied. Sn/(Ni,V) and Sn-Ag/(Ni,V) interfacial reactions at 250°C were investigated in this study using the reaction couple technique. The vanadium contents of the (Ni,V) substrates examined in this study are 3 wt.%, 5 wt.%, 7 wt.%, and 12 wt.% and the reaction time is 12 h. The results indicate that when the vanadium contents in the (Ni,V) substrate are 5 wt.% and higher, the Sn/(Ni,V) and Sn-Ag/(Ni,V) interfacial reactions are different from those in the solder/Ni couples. Besides the Ni3Sn4 phase as commonly formed in the reaction with Ni substrate, a new ternary T phase has been found, and the reaction path is L/Ni3Sn4/T/(Ni,V). A 250°C Sn-Ni-V isothermal section is proposed based on the three constituent binary systems and limited experimental results obtained in this study. The reaction path is illustrated with the proposed Sn-Ni-V isothermal section. No stable ternary Sn-Ni-V phase is found from the phase equilibria study, and the new T phase is likely a metastable phase.

Catalytic synthesis of methanethiol from hydrogen sulfide and carbon monoxide over vanadium-based catalysts

The direct synthesis of methanethiol, CH 3SH, from CO and H 2S was investigated using sulfided vanadium catalysts based on TiO 2 and Al 2O 3. These catalysts yield high activity and selectivity to methanethiol at an optimized temperature of 615 K. Carbonyl sulfide and hydrogen are predominant products below 615 K, whereas above this temperature methane becomes the preferred product. Methanethiol is formed by hydrogenation of COS, via surface thioformic acid and methylthiolate intermediates. Water produced in this reaction step is rapidly converted into CO 2 and H 2S by COS hydrolysis. Titania was found to be a good catalyst for methanethiol formation. The effect of vanadium addition was to increase CO and H 2S conversion at the expense of methanethiol selectivity. High activities and selectivities to methanethiol were obtained using a sulfided vanadium catalyst supported on Al 2O 3. The TiO 2, V 2O 5/TiO 2 and V 2O 5/Al 2O 3 catalysts have been characterized by temperature programmed sulfidation (TPS). TPS profiles suggest a role of V 2O 5 in the sulfur exchange reactions taking place in the reaction network of H 2S and CO.