Pouring Temperature Research Articles

Early-Hydration heat and influencing factor analysis of Large-Volume concrete box girder based on equivalent age

Large-volume concrete box girders are vulnerable to early cracking because of the hydration reaction at early ages. The excessive temperature difference between the core and external surface is the main reason for early cracking. Controlling the temperature field of concrete can reduce the risk of early cracking. Therefore, numerical simulations and tracking tests of a 50-m box girder were conducted. The early-age temperature field was simulated using ABAQUS and the secondary development of the subroutine. Meanwhile, the influences of different construction and curing method parameters were analyzed. The subroutine UMATHT considers the variations of hydration degree, thermal conductivity, and specific heat with equivalent age. The results indicate that the early-age hydration temperature of the box girder follows a general trend of “increasing temperature — continuous high temperature — cooling.” The measured results verify the accuracy of the numerical simulation method. The temperature peak and temperature difference between the core and surface increased with the increase in concrete section size, pouring temperature, and cement dosage. The effects of pouring temperature and cement dosage on the temperature rise and cooling rate were reversed. For every 5 °C decrease in the pouring temperature, the temperature peak of the web also decreased by approximately 5 °C, while the temperature difference between the core and surface of the web decreased by approximately 2 °C. When thermal insulation measures were taken for the box girder's outer formwork, the concrete temperature peak increased slightly, but the temperature difference between the core and surface decreased significantly. When the thickness of the polystyrene foam board reached 1 cm, the temperature difference between the core and web surface could be controlled within 6.1 °C.

Effects of gate cross-section area and vaccum pressure on mold filling in lost foam casting

The lost foam casting process utilizes polymeric foam patterns to produce the metallic components. Foamed polymer patterns are coated with a refractory slury, dried and embedded in unbonded sand. Molten metal is poured directly on the coated polymer. The polymer is thermally decomposed and is gradually replaced by the liquid metal to create the casting after solidification. Expanded polystyrene (EPS) is the most common pattern material used in commercial practice. In this paper, experiments are conducted to examine the filling of an aluminum alloy melt into the molds. The purpose is to observe some parameters such as the gate cross-section area, vaccum pressure, gas gap length, metal pouring temperature in lost foam casting of aluminum. The results indicate that the gate section, metal pouring temperature and vaccum pressure affect directly the mold-filling time.

ANALISA KEGAGALAN INTI CETAKAN JENIS SKD 61 PADA PROSES PELEBURUAN DENGAN CARA DIECASTING

Damage to the surface of the mold core by loss of the nitride layer from the surface hardening process, namely the name of the surface hardening process for the mold core, namely Nitriding on the surface of the metal core type skd61 series in die casting molds. In the die casting process is a process in which a process by melting molten aluminum metal at a pouring temperature of 720 0 C , then the liquid is taken with a ladle inserted into the sleeve cylinder and then pressed by the piston to fill the iron casting cavity so that it forms a casting object called a brake drum. The service life is only 80,000 shoots while the standard uses 160,000 shoots in the sub-section of the steel mold of the casting brake drum product. And to find out the low life time, the cause of the wear is sought, tests are carried out including: analysis of chemical composition, visual, microstructure and hardness

Influence of temperature rising inhibitor on temperature and stress field of mass concrete

As a new type of concrete admixture, concrete temperature rising inhibitor (TRI) can slow down the heat release rate of the initial hydration reaction of concrete. However, due to the lack of a clear feasibility analysis, its application in engineering is limited. In this paper, the thermodynamic parameters of concrete with different TRI are obtained by fitting the experimental data. At the same time, taking the sluice as an example, the influence of TRI on the temperature and stress field of mass concrete is studied by numerical simulation. The results show that when the content of TRI reaches 0.6% of the cementitious material, the temperature and stress peak value are obviously reduced, and the temperature control effect is obvious. Furthermore, the effect of TRI is inversely proportional to structure thickness, and its temperature control effect is more noticeable for mass thin-walled concrete structures. Compared with other temperature control measures, such as lowering the peak value of adiabatic temperature rise and the pouring temperature, the effect of TRI is more effective. It can be used as a means of temperature control in engineering and combined with other measures to put forward a more reasonable and economical temperature control scheme.

Effect of variations in pouring temperature on tensile strength of CuZn cast alloys

The solidification rate of materials affects the properties of the cast product and the pouring temperature also influences the freezing conditions of cast-metal alloys. The propose of this study is to evaluate the tensile strength of cast samples by using five variations of pouring temperatures through permanent molds by a gravity casting process. The results showed that the tensile strength maximum was 443 MPa at 1210 °C, the freezing range affected the tensile properties of cast samples.

Interfacial Microstructure and Shear Strength Improvements of Babbitt–Steel Bimetal Composites Using Sn–Bi Interlayer via Liquid–Solid Casting

To enhance the performance of Babbitt–steel bimetallic composites, bismuth (Bi) was incorporated into the Tin (Sn)-interlayer. Babbitt–steel bimetallic composites were created using the liquid–solid compound casting method in this study. Sn–Bi interlayer alloys with varying levels of Bi (1, 2, 3, and 4 wt.%) were created. The Babbitt-steel bimetallic composite’s bonding strength and interfacial microstructure were examined in relation to Sn-Bi interlayer alloys. The structure of the interface layer at the Babbitt–steel interface’s edge and center are significantly altered when Bi is added to the Sn interlayer. The relatively higher cooling rate near the edge led to the formation of clear unsolved Sn/Sn–Bi interlayers. Otherwise, the Sn–Bi interlayers in the middle were completely dissolved. By increasing the amount of Bi in the Sn–Bi interlayer alloy, the interfacial hardness of Babbitt-steel bimetallic composites increases by increasing Bi content in Sn–Bi interlayer alloy. Babbitt-steel bimetal composites’ shear strength increased to 28.27 MPa by adding Bi to the Sn interlayer using 1 wt.% alloying, with a 10.3% increase when compared with the reference pure Sn interlayer. Future research that aims to improve the production of Babbitt-steel bimetallic composites with high-quality and long-lasting bi-metal bonding ought to take into consideration the ideal pouring temperature, the preheating of the mold, and the addition of a minor amount of Bi (Bi ≤ 1) to the Sn-interlayer.

Stimulation of microstructure and wear properties by pouring temperatures of Al-Si-Al2O3 hypereutectic alloy

The replacement of cast iron by recent developed Al-hypereutectic composites are highly impacted to lower down the cost of production and enhances fuel efficiency. Parts like pistons, engine blocks and cylinder heads, brake plates and rocker arms manufactured from Al-hypereutectic composites can reduce and improve vehicle emissions. The present investigation to make the Al-hypereutectic composites reinforced with 1% Al2O3 using the stir casting method at different pouring temperatures. Addition of Al2O3 in Al-alloy which act as nucleating agent and causes for refinement of grain size and the effect of pouring temperature on microstructure as well as wear properties of composites are reported here. The morphology of primary as well as eutectic silicon was emphasized in this paper. The irregular primary silicon and eutectic silicon shapes are changes to fine globular shape of primary Si and fibrous and regular fine shape of eutectic Si. The study of microstructure-property relations are co-related here by means of changing the pouring temperature of the Al-hypereutectic composites.

Investigation on the effect of Zn interlayer and process parameters optimisation in the production of Al-SS bimetallic castings

The effect of Zn interlayer on the stainless steel insert in the fabrication of Aluminium-Stainless Steel (Al-SS) Bimetallic casting (BmC) is reported. The design of Experiments was conducted with pouring temperature (680°C–730°C), insert preheat temperature (100°C–400°C) and insert thickness (1–3 mm) as influencing process parameters to produce Al-SS BmC. The maximum bond strength of 25.33 MPa was achieved when the experimental conditions were 705°C pouring temperature, 250°C insert temperature and 2 mm insert thickness. Using Response Surface Methodology (RSM), the interaction between the process parameters has been studied and a second-order polynomial equation was derived for maximising the bond strength. The predicted maximum bond strength using RSM for the above experimental conditions is 26.75 MPa. The output of RSM was given to the Genetic Algorithm (GA) to identify the maximum bond strength at forbidden parametric values. The maximum bond strength predicted using GA by interpolation is 26.87 MPa. However, the three process parametric conditions are 707°C, 277°C, and 1.86 mm respectively for achieving the maximum bond strength in the given Al-SS BmC’s. Experimental validation of the above conditions was conducted and the results obtained confirmed the predicted bond strength value using the GA technique. Spiral morphology due to the formation of Zn10Fe3 intermetallics was observed at the Zn-SS interface when the pouring temperature increased to 730°C and this might have led to the reduced bond strength of BmC than the bond strength achieved at 705°C and 707°C. The formation of the Al-rich and Fe-rich solid solutions as reaction layer between Al and SS without the micro gap around 705°C may contribute to the significant increase in bond strength of produced BmC with different insert temperatures and insert thickness.

Pengaruh variasi laju aliran dan preheating cetakan pada investment casting terhadap sifat fisis dan mekanis prototipe aluminium cylinder head engine

This research studies the effect of flow rate on the pouring of molten metal into the mould so that the flow rate into the mould can be controlled. Furthermore, this research studies the effect of mould preheating so that the temperature inside the cavity can be maintained, especially for narrow holes. The process starts with making the engine cylinder head pattern and gating system using a three-dimensional printer with polylactic acid resin. The mould pattern and gating system are combined and coated with a layer of cement plaster, silica sand and kaolin. After the coating is dry, the mould is heated until the mould pattern evaporates and there is no residue. The casting process was carried out at pre-heating moulds of 300 0C and 350 0C and a pouring temperature of 800 0C with pouring speeds of 20, 30, and 40 rpm. The final stage of the research is manufacturing test objects and testing mechanical properties. The results showed that the higher the pouring speed, the less perfect the casting results, especially in the cylinder head fins. The best casting results occurred in the pre-heat condition of the 300 0C mould with a pouring speed of 20 rpm, with a Maximum Tensile Strength of 105 N/mm2, Hardness 53 hardness Brinell test (HBN), Density and Porosity of 2.43 gr/cm3. The material used in this study refers to the reference is A356 Aluminum Alloy.

Effect of process variables and melt treatment conditions during cooling slope semi solid slurry generation process of Al-7Si-0.3 Mg alloy

Simulation studies on semi solid slurry preparation of A356 alloy employing cooling slope technique, with the help of an existing multiphase and multiscale model, are presented here. The constituent phases considered in the multiphase model are the liquid melt of A356 alloy, near spherical primary Al grains, and air. The numerical study features prediction of slurry morphology, for a desired set of process conditions of cooling slope slurry formation technique. In particular, the effects of melt pouring temperature into the slope, slope angle variation and addition of grain refiner and modifier within the melt on the thermophysical and morphological properties of the generated slurry are studied. Attempts are made to gain insight into the transport phenomena of cooling slope slurry generation process, with respect to volume fraction of constituent phases, morphological evolution of solidifying primary Al grains, viscosity distribution, temperature field, velocity field, macro and micro segregation, and isothermal coarsening kinetics of α-Al grains. The efficacy of the multiphase model is validated by performing relevant experiments.

Center Line Globular Structure of Strip Cast Using High Speed Twin Roll Caster

Formation of a centerline globular structure in an aluminum alloy strip cast using a vertical type high-speed twin-roll caster was investigated. The theory that the crystals form at tip of the nozzle and are conveyed to the roll gap was investigated by roll casting using a cooling slope and clad-strip-casting in this study. In high-speed roll casting, the center of the strip thickness is semisolid, and the temperature gradient in the thickness direction is small. The latent heat of the semisolid metal heats the dendrite structure, which is divided by melting. The dendrite structure was divided as in thixocasting, which is the mechanism of formation of a globular crystal form. The zone of the semisolid metal becomes narrow as the roll load increases or the pouring temperature of the molten metal decreases. As result, the zone containing globular crystal structures becomes thinner.

Numerical Simulation of Copper-Aluminum Composite Plate Casting and Rolling Process and Composite Mechanism.

This paper uses ANSYS Workbench platform to simulate the casting and rolling composite process, taking the horizontal type casting and rolling machine as the research object, and conducts the numerical simulation study of copper-aluminum composite solid-liquid casting and rolling heat-flow coupling, mainly to study different walking speed, aluminum pouring temperature, casting and rolling zone length, heat transfer coefficient on the temperature field, liquid phase rate influence law, and use it as a theoretical guide for copper-aluminum solid-liquid casting. The experiments of copper-aluminum solid-liquid casting-rolling composite were carried out to optimize the process parameters and to verify the experiments, so as to prepare a well-bonded copper-aluminum composite plate. The composite mechanism in the preparation of copper-aluminum composite plate was analyzed, and it was clarified that the interfacial layer was formed through four stages: contact between copper and aluminum surfaces, contact surface activation, mutual diffusion of copper and aluminum atoms, and reaction diffusion.

Optimization of centrifugal casting process parameters by Taguchi method to reduce shrinkage porosity ratio of K417 superalloy

The process parameters were optimized by simulation and verification experiments using orthogonal experimental design and the Taguchi method to lessen the tendency of significant shrinkage porosity in the centrifugal cast ring parts of K417 nickel-based superalloy. Advanced Porosity Model (APM) in ProCAST was used to predict the shrinkage porosity of centrifugal castings, and the effects of centrifugal speed, pouring speed, pouring temperature and preheating temperature of the mold were investigated on the shrinkage porosity ratio of the castings. According to the results, the parameter that has the greatest influence on the shrinkage porosity ratio of centrifugal casting is the centrifuge speed, followed by the preheating temperature of the mold, and the pouring temperature and pouring speed have relatively small effects on it. The optimized parameters were proposed as follows: centrifugal speed of 500 r/min, pouring speed of 225 mm/s, pouring temperature of 1400[Formula: see text], and mold preheating temperature of 50[Formula: see text], which could effectively reduce the formation of shrinkage porosity of the K417 centrifugal casting rings.

Substrate stimulating technique for Ni-based single crystal superalloy preparation during direction solidification

The grain selector method is a prevailing technique in the manufacturing process of Ni-based single crystal superalloy, however, it cannot control the orientation of single crystal within an appropriate scope. In this study, a novel technique named substrate stimulating method was proposed and DD32 Ni-based single crystal superalloy was prepared. The microstructure evolution was characterized by EBSD and OM, and the temperature field and temperature gradient distribution were predicted by the finite volume method. With a substrate height of 18 mm, the proportion of grains with deviation angles less than 12° and 8° account for 100 % and 99 % at the entrance of spiral selector, compared with 80 % and 51 % by grain selector method, which makes significance sense for optimizing the orientation of single crystal casting and improving the yield of single crystal casting. The morphology and the orientation of the substrate stimulated grains, which are mainly determined by temperature gradient and melt undercooling, could be optimized by adjusting the substrate height and melt pouring temperature.

Effect of HEA/Al composite interlayer on microstructure and mechanical property of Ti/Mg bimetal composite by solid-liquid compound casting

In this study, HEA/Al composite interlayer was used to fabricate Ti/Mg bimetal composites by solid-liquid compound casting process. The Al layer was prepared on the surface of TC4 alloy by hot dipping, and the FeCoNiCr HEA layer was prepared by magnetron sputtering onto the Al layer. The influence of the HEA layer thickness and pouring temperature on interface evolution was investigated based on SEM observation and thermodynamic analysis. Results indicate that the sluggish diffusion effect of HEA can effectively inhibit the interfacial diffusion between Al and Mg, which is conducive to the formation of solid solution, especially when the thickness of HEA is 800 nm. With the increase of casting temperature from 720 °C to 730 °C, 740°C, and 750 °C, α-Al(Mg), α-Al(Mg)+Al3Mg2, Al3Mg2+Al12Mg17, and Al12Mg17+δ-Mg are formed at the interface of Ti/Mg bimetal, respectively. When the thickness of the HEA layer is 800 nm and the pouring temperature is 720 °C, the bonding strength of the Ti/Mg bimetal can reach the maximum of 93.6 MPa.

Experimental and numerical studies on the influence of centrifugal casting parameters on the solidification structure of Al-Cu alloy

A horizontal centrifugal casting experiment was designed to determine the change in the solidification structure of Al-Cu alloy casting and the underlying variation in temperature, then obtained interface heat transfer coefficient by inverse calculation. The continuous simulation of metal melt filling from the gate to copper mold cavity is realized. The influence of centrifugal speed, pouring temperature, and mold preheating temperature on the solidified structure was analyzed. Simulation results showed that increasing the centrifugal speed mainly enhance the solidification rate of the molten metal and then refined the solidified structure of the Al-Cu alloy. Increasing the pouring temperature and mold preheating temperatures coarsen the grain size of the casting, but the range of change is small.

Melt sampling for hydrogen analysis optimized with the help of computer simulation

This research was carried out in laboratory conditions on a semi-continuous ingot casting machine owned by the Siberian Federal University. The paper compares the results of computer simulation carried out for AK12 alloy solidification process in the PoligonSoft programme. A new original mould is described designed for sampling liquid aluminium and its alloys for hydrogen analysis. The new mould has a larger surface area and walls that are made in the form of a heat exchanger intended for more efficient heat removal. It is shown that, in the commonly used Rensley mould, the melt solidifies in 14 seconds at the metal crystallization rate in the range from the pouring temperature to the solidus temperature of 15 oC/s, while in the case of the new mould these parameters are 12 seconds and 17.5 oC/s, correspondingly. The paper also compares the results of dissolved hydrogen analysis obtained when sampling was done with both the conventional Rensley mould and the new one. It was found that the concentration of hydrogen in the samples taken with the Rensley mould is lower on average by 0.01 cm3/100 g Al than in the samples taken with the new mould. Based on the results of the study, a conclusion was drawn that the proposed mould design delivers an additional advantage when sampling liquid metal. It also helps determine the concentration of dissolved hydrogen in molten aluminium with a higher degree of accuracy.This research was carried out by the Siberian Federal University as part of the governmental assignment for research; Project No. FSRZ-2020-0013.

The relationship between ignition and oxidation of molten magnesium alloys during the cooling process.

Ignition of magnesium alloys during casting processes limits their processability and applications. For identifying the ignition mechanism of magnesium alloys during solidification, a Mg-Al-Zn alloy was solidified with different cooling rates and pouring temperatures. The oxide scale morphologies and thicknesses were identified by SEM and energy dispersive spectrometer. Based on the experimental results, the oxidation kinetics and heat released were calculated and the relationship between oxidation and ignition was discussed in detail. The calculation results indicate that oxide rupture directly induces combustion of the melt. The rupture route of the oxide scale was determined to be buckling cracks according to the experimental and calculation results. Based on the buckling mechanism of the oxide scale, the ignition criterion during solidification was correlated to the pouring temperature, cooling rate and casting modulus. This work reveals the underlying relationship between ignition and casting process parameters, and it helps to develop new technology for inhibiting ignition of molten magnesium alloys.

Study on asymmetry and temperature difference between different strands in 7-outlets tundish

ABSTRACT This paper addresses the problem of temperature difference between the different strands in a 7-outlets tundish of a steel plant by using physical modelling and numerical simulation methods. The problem of large temperature difference between different strands was solved and stability was achieved in the field production process. The parameters such as stagnation time and peak time by each stream were calculated by physical modelling and the optimized parameters based on temperature difference were implemented in the actual production process, which could predict an accurate temperature difference between strands in multi-flow tundish. The average temperature difference between side flow and intermediate flow of tundish was reduced from 15°C to 5°C by reasonable adjustment of flow control device between different strands, which provides basic support for improved billet quality, prevents breakout accident during continuous casting operation, reduces the pouring temperature and ensures the low-temperature rapid casting.

Development of open-porosity magnesium foam produced by investment casting

High-porosity, open-cell AZ91 magnesium alloy foams of two pore sizes were fabricated by means of investment casting technology, using PUR foam patterns. Foam casting variables such as pressure, mould temperature and metal pouring temperature were thoroughly investigated to define the most optimal casting conditions. The mechanical properties of the fabricated foams were measured in compression tests. A potential application for the foams considered is temporary bioresorbable bone implants, therefore the mechanical properties of the foams were compared with those of cancellous bone tissue. Foams with smaller pore size and lower porosity (20 PPI and 80%–87%) exhibited mechanical properties in the lower regions of the cancellous bone property range (Young's modulus 36.5–77.5 MPa), while foams with higher pore size and porosity (10 PPI and ∼90%) were found to have insufficient compression strength (Young's modulus 11.65–23.8), but thickening their walls and lowering their porosity below 90% yielded foams with Young's modulus between 36.5 and 77.5 MPa. Foam fractures were also investigated to determine their collapse mechanism. A series of corrosion tests in stimulated body fluid was carried out to determine their applicability as a biomaterial. The Plasma Electrolytic Oxidation (PEO) process was used in a feasibility study to examine the microstructure and chemical composition of foams with protective coating.