Influence of boron and oxygen on the microstructure and mechanical properties of high-strength Ti66Nb13Cu8Ni6.8Al6.2 alloys

The influence of boron additions and different oxygen contamination levels on the microstructure and the mechanical properties in the Ti_66?xNb₁₃Cu₈Ni_6.8Al_6.2B_x (0 ? x ? 1) system were investigated. The alloys were prepared by levitation copper mould casting as rods with a diameter of 5 mm using different grades of starting elements. The alloy without boron exhibits a maximum compressive stress of more than 2500 MPa, associated with a compressive strain of more than 30%. The ultimate tensile stress is ～1075 MPa with a maximum elongation of 1.6%. Increased oxygen content leads to a rise of yield strength due to solid solution hardening. Boron additions promote grain refinement and reinforce the interdendritic phase compound by forming needle-like TiB precipitates. This change in microstructure increases the yield stress and the Young’s modulus and lowers the plastic strain. The microstructure was analysed in terms of the boron content by means of scanning electron microscopy, Auger electron spectroscopy and transmission electron microscopy. The presented mechanical properties are compared with the compression and tensile properties of the commercially available Ti6Al4V ELI (ELI = extra low interstitial) alloy.     

Advances in Thermal Spray Coatings for Gas Turbines and Energy Generation: A Review

Functional coatings are widely used in energy generation equipment in industries such as renewables, oil and gas, propulsion engines, and gas turbines. Intelligent thermal spray processing is vital in many of these areas for efficient manufacturing. Advanced thermal spray coating applications include thermal management, wear, oxidation, corrosion resistance, sealing systems, vibration and sound absorbance, and component repair. This paper reviews the current status of materials, equipment, processing, and properties’ aspects for key coatings in the energy industry, especially the developments in large-scale gas turbines. In addition to the most recent industrial advances in thermal spray technologies, future technical needs are also highlighted.     

Artificial Intelligence System Approach for Optimization of Drilling Parameters of Glass-Carbon Fiber/Polymer Composites

Silicon - In recent times, the study on machining characteristics of combined (hybrid) fiber polymer composites has drawn a remarkable research attention because of its emerging industrial...     

ECSC research into weldability carried out in the last ten years

Abstract

The paper illustrates the research carried out with ECSC financial support in the decade 1976–86 by various laboratories and institutes in countries belonging to the European Community, in the field of the welding and weldability of different steels.

The industrial impact of the research is underlined, particularly with regard to the possibility of making greater use of the characteristics of modern steels, in order to achieve improved quality, productivity and economy in welded constructions.

The importance of each piece of research for the study of heat affected zones (HAZs) and of fusion zone behaviour in welded joints is illustrated, and further research now in progress is also mentioned.

Finally, attention is drawn to the need to promote, through the appropriate development of European standards and regulations and by the drawing up of suitable guidelines for designers, users and manufacturers, knowledge of the possibilities of new steels in order to achieve further development and competitiveness in welded steel constructions.     

Corrosion behaviour of 304LN activated tungsten inert gas and flux-cored arc weld metals

Activated tungsten inert gas (A-TIG) and flux-cored arc (FCA) weld metals were prepared using 304LN stainless steel plate. The weld metals were thermally aged at 923, 973 and 1023?K for 100?h to study the decomposition of initial δ-ferrite in A-TIG (～10 ferrite number (FN)) and FCA (～5 FN) weld metals into secondary phases like M₂₃C₆ carbides, χ and σ. Ferrite number is the measurement of δ-ferrite based on the principle of magnetic property using ferritescope. Preliminary microstructural studies revealed the formation of carbides in FCA weld metals aged at 923?K for 100?h, which was correlated with higher carbon content (0.04?wt-%), and also ageing at higher temperature transformed δ-ferrite into χ/σ phases. However, A-TIG weld metals showed the transformation of δ-ferrite mainly into χ/σ phases. The δ-ferrite transformation kinetics was found to be sluggish in A-TIG weld metals compared to FCA weld metals. This difference was attributed to the difference in the carbon contents of A-TIG and FCA welds. Activated tungsten inert gas weld metals showed better uniform and pitting corrosion resistance compared to FCA weld metals in as-deposited and thermally aged conditions. Presence of higher amount of initial δ-ferrite content in A-TIG weld metal helped diffusion of minor alloying elements like sulphur and phosphorous into it, thereby reducing their microsegregation at the δ/γ interface boundaries and subsequent pitting corrosion attack. Thus, A-TIG welding process was found to be superior compared to FCA welding process.     

Characterisation of microstructural damage due to corrosion fatigue in AISI type 316 LN stainless steels with different nitrogen contents

Corrosion fatigue (CF) behaviour of AISI type 316 LN stainless steels (SS) with three different nitrogen contents was evaluated in a boiling aqueous solution of 5?M NaCl+0·15?M Na₂SO₄+2·5?ml?l^?1 HCl at a stress ratio of 0·5 and a frequency of 0·1?Hz. After the CF tests, the specimens were observed under a field emission gun scanning electron microscope (FEG-SEM) as well as an atomic force microscope (AFM) to understand the deformation mechanism which led to the failure. Slip character could be explained based on the surface deformation features observed using FEG-SEM and AFM. A slip irreversibility relation has been proposed which when applied could explain the CF behaviour of these steels with varying nitrogen contents. Increase in the nitrogen content increased the slip reversibility up to 0·14?wt-% nitrogen; however, further increase in nitrogen content had no beneficial effect on the slip reversibility.     

A Study of the Electrode Potential of Nickel in Accelerated Corrosion Test Media

Potential measurements are reported on bright, semi-bright and Watts-type nickel electrodeposits in a number of electrolytes simulating accelerated corrosion test media, both on open circuit and when anodically polarized. The changes in the potentials with time have been recorded in some cases over a period of several days. The appearance of the deposits has been found to alter with polarization. In some cases, the value of the potential has been found to depend in a surprising manner on agitation, and tentative deductions are made from this phenomenon. Results obtained with different deposits and electrolytes are compared.     

Is LRP2 Involved in Leptin Transport over the Blood-Brain Barrier and Development of Obesity?

The mechanisms underlying the transport of leptin into the brain are still largely unclear. While the leptin receptor has been implicated in the transport process, recent evidence has suggested an additional role of LRP2 (megalin). To evaluate the function of LRP2 for leptin transport across the blood-brain barrier (BBB), we developed a novel leptin-luciferase fusion protein (pLG), which stimulated leptin signaling and was transported in an in vitro BBB model based on porcine endothelial cells. The LRP inhibitor RAP did not affect leptin transport, arguing against a role of LRP2. In line with this, the selective deletion of LRP2 in brain endothelial cells and epithelial cells of the choroid plexus did not influence bodyweight, body composition, food intake, or energy expenditure of mice. These findings suggest that LRP2 at the BBB is not involved in the transport of leptin into the brain, nor in the development of obesity as has previously been described.     

Ytterbium (III) oxide reinforced novel TeO2–B2O3–V2O5 glass system: Synthesis and optical,structural, physical and thermal properties

Different samples of xTeO₂.(25-y)B₂O₃.zV₂O₅.yYb₂O₃ (or TBVY) new glass material were synthesized by the classical melt-quenching method. Structural, optical, physical, and thermal analyses of the synthesized glasses were performed in addition to Monte Carlo simulation to test radiation shielding properties. The results showed that increasing ratios of Yb₂O₃ (y = 0.0, 0.5, 1.0, and 1.5 mol%) produced monotonic density values of the synthesized glasses ranging from 4.70058 g cm^?3 to 5.01038 g cm^?3. XRD and FTIR analyses were used to confirm the glass structure of all samples. Optical transmittance and absorption parameters varied almost monotonically with increasing ratios of Yb₂O₃ indicating the ability to predict and control these properties using Yb₂O₃ additive. Furthermore, simulated radiation interaction parameters, such as attenuation coefficients and half-value layer, exhibited well-behaved dependence on the concentration ratio of the Yb₂O₃ additive. This approach to glass material synthesis demonstrate the useful synergetic effect of combining structural, optical, and radiation characteristics.