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Embodiments provide methods, apparatuses and systems for depositing a thermal insulator coating onto a desired surface of a mold cavity or insert or preform. Embodiments also provide casting methods using a thermal insulator coating.
Uranium Accumulations in Casting Operations
A material sorting system sorts materials utilizing a vision system that implements a machine learning system in order to identify or classify each of the materials, which are then sorted into separate groups based on such an identification or classification determining that the materials are composed of either wrought aluminum or cast aluminum.
One or more embodiments relates to a method of casting a creep-resistant Ni-based superalloy and a homogenization heat treatment for the alloy. The method includes forming a feed stock having Nickel (Ni) and at least one of Chromium (Cr), Cobalt (Co), Aluminum (Al), Titanium (Ti), Niobium (Nb), Iron (Fe), Carbon (C), Manganese (Mn), Molybdenum (Mo), Silicon (Si), Copper (Cu), Phosphorus (P), Sulfur (S) and Boron (B). The method further includes fabricating the creep-resistant Ni-based superalloy in a predetermined shape using the feed stock and at least one process such as vacuum induction melting (VIM), electroslag remelting (ESR) and/or vacuum arc remelting (VAR).
Extending service of Light Water Reactors (LWRs) to beyond 60 years will demand a high integrity of materials and components in reactors. The accurate evaluation and prediction of materials performance under anticipated operation conditions are of particular importance for ensuring the safe operation of nuclear power plants over their extended lifetime. The duplex structure stainless steels including cast austenitic stainless steels (CASS) and welds of austenitic stainless steels are widely used in LWRs. The CASS alloys are mainly used in LWRs primary pressure boundary and for some limited core structural components. The type 308/309 welds are used for welding the reactor components made of 304 and 316 stainless steels and as a cladding layer on the inner surface of reactor pressure vessel. The core support columns made of CF8 CASS in a B and W design PWR are expected to be exposed to a fluence of between 1x10{sup 21} and 1x10{sup 22} n/cm{sup 2}, E>1.0 MeV, and the austenitic stainless steel welds can potentially receive a fluence up to 5x10{sup 22} n/cm{sup 2}, E>1.0 MeV. In addition to the thermal aging effect, the radiation induced fracture toughness in those duplex structure stainless steel components located in the high neutron fluence regions in LWRs hasn't be fully evaluated. Previous studies showed that the spinodal decomposition in the delta ferrite phase in CASS or type 308/309 welds is the primary embrittlement mechanism, and the G-phase precipitates were also identified but with less impact on the reduction of fracture toughness. It is generally agreed that the irradiation induced fracture toughness decrease in CASS and weld steels saturates after 10 dpa (∼1x10{sup 22} n/cm{sup 2}, E>1.0 MeV). Nevertheless, there are not enough high dose data points to confirm the lower bound in measured fracture toughness as the reported doses are limited to 15 dpa. The work in this paper is to present a more comprehensive study on the microstructural evolution in the ferrite phase in a CF3 CASS, and the results provide a scientific basis for extrapolating the change of fracture toughness to a high dose range.
Developing low-cost and durable heat exchangers is critical for next-generation heating, ventilation, air conditioning, and refrigeration systems. The emerging requirement to minimize the total refrigerant charge inventory while ensuring a uniform distribution of refrigerant has led to the deployment of advanced manufacturing strategies. At the same time, corrosion is a longstanding issue for metal components, especially those used in heat exchanger (HX) applications. In this study, Al-Ce-Mg alloy-based HXs have been investigated. The corrosion resistance of HXs prototype manufactured by the casting process has been examined and the potential of a new manufacturing approach has been explored to meet the requirements of emerging needs.
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The stress arising when melt passes through a filter is determined with different positions of the filter in the mold. The compressive strength of the proposed filter is investigated.
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Three new low melting compositions have been developed here based on the ingredients amino-1,2,4-triazolium nitrate, 3,5-diamino-1,2,4-triazolium nitrate and ammonium nitrate, to create the formulation AAD, in addition to mixtures comprising guanidinium 5-amino-tetrazolate and ammonium nitrate in either a 1 : 3 or 1 : 6 mole ratio (GAN13 and GAN16 respectively). The materials melt in the range of 95–100 °C and do not begin to decompose until >195 °C. The formulations are insensitive to impact, spark and friction and were calculated to show promising explosive performance properties (V D =8.78–9.0 km/s, P CJ =28.4–30.6 GPa). HMX mixtures of AAD, GAN13 and GAN16 were also prepared and these materials were characterized with respect to their safety and performance as well.
The effects of nozzle design on dispersed, two-phase flows of the steel-argon system in a slab mold are studied using a water-air model with particle image velocimetry and ultrasound probe velocimetry techniques. Three nozzle designs were tested with the same bore size and different port geometries, including square (S), special bottom design with square ports (U), and circular (C). The meniscus velocities of the liquid increase two- or threefold in two-phase flows regarding one-phase flows using low flow rates of the gas phase. This effect is due to the dragging effects on bubbles by the liquid jets forming two-way coupled flows. Liquid velocities (primary phase) along the narrow face of the mold also are higher for two-phase flows. Flows using nozzle U are less dependent on the effects of the secondary phase (air). The smallest bubble sizes are obtained using nozzle U, which confirms that bubble breakup is dependent on the strain rates of the fluid and dissipation of kinetic energy in the nozzle bottom and port edges. Through dimensionless analysis, it was found that the bubble sizes are inversely proportional to the dissipation rate of the turbulent kinetic energy, ε{sup 0.4}. A simple expression involving ε, surface tension, and density of metal is derived to scale up bubble sizes in water to bubble sizes in steel with different degrees of deoxidation. The validity of water-air models to study steel-argon flows is discussed. Prior works related with experiments to model argon bubbling in steel slab molds under nonwetting conditions are critically reviewed.
No abstract prepared.
According to the calculation results of a 3D thermomechanical-coupled finite-element (FE) model of GCr15 bearing steel bloom during a heavy reduction (HR) process, the variation ranges in the strain rate and strain under HR were described. In addition, the hot deformation behavior of the GCr15 bearing steel was studied over the temperature range from 1023 K to 1573 K (750 °C to 1300 °C) with strain rates of 0.001, 0.01, and 0.1 s{sup −1} in single-pass thermosimulation compression experiments. To ensure the accuracy of the constitutive model, the temperature range was divided into two temperature intervals according to the fully austenitic temperature of GCr15 steel [1173 K (900 °C)]. Two sets of material parameters for the constitutive model were derived based on the true stress–strain curves of the two temperature intervals. A flow stress constitutive model was established using a revised Arrhenius-type constitutive equation, which considers the relationships among the material parameters and true strain. This equation describes dynamic softening during hot compression processes. Considering the effect of glide and climb on the deformation mechanism, the Arrhenius-type constitutive equation was modified by a physically based approach. This model is the most accurate over the temperatures ranging from 1173 K to 1573 K (900 °C to 1300 °C) under HR deformation conditions (ignoring the range from 1273 K to 1573 K (1000 °C to 1300 °C) with a strain rate of 0.1 s{sup −1}). To ensure the convergence of the FE calculation, an approximated method was used to estimate the flow stress at temperatures greater than 1573 K (1300 °C).
The non-uniform friction and thermal stress in the mold are important as causes of the transverse cracks around strand corner. To analyze the stress distribution features around strand corner, a three-dimensional thermo-elastoplastic finite-element mold model with different corner structures (right-angle, big-chamfer, multi-chamfer, and fillet) was established. The temperature field in the mold was indirectly coupled through a three-dimensional fluid flow and heat transfer model. In addition, the non-uniform mold friction stress loaded on the strand surface was calculated through a friction model. The results show that the stress distribution on the shell is similar to the temperature distribution. The stress concentration appears in the strand corner and the lower part of wide face. The friction stress enhances the corner stress around the edge of the air-gap. For chamfered molds, the stress around the corner between the wide face and chamfer face is larger than that between the narrow face and chamfer face. Around the corner region, both the stress peak and the area of the large stress zone of the right-angle strand are the largest, while those of big-chamfered, multi-chamfered, and fillet strands decrease in that order. The stress peak position of the chamfered strands is closer to the mold exit than that of the right-angle strand. Compared with the use of the right-angle mold, the application of chamfered molds is able to reduce the stress concentration around the strand corner.