Industrialization of Aluminum Alloy Uniform Solidification Controlled Rheological Die Casting

An efficient and low-cost aluminum alloy uniform solidification control technology, namely, air-cooled stirring rod (ACSR) process, has been developed for preparing large volume semisolid slurry. The semisolid slurry preparation process is connected with the die-casting machine to form multiple integrated intelligent rheological die-casting production lines for the efficient preparation of rheological die-casting of large-scale thin-walled aluminum alloys. At present, the ACSR process can produce 40 kg of large-volume semisolid slurry with a solid phase ratio of 25% to 35% within 30 s. This rheological die-casting process has been industrialized for the preparation of high-quality aluminum alloy large-scale thin-walled parts, such as new energy vehicles and 5G communications. Typical products produced by this process include heat dissipation housings for 5G communications, filter housings, antenna chassis and three-electric structural shell, end cover, and ABS system valve body for new energy vehicles. Compared with traditional die castings, aluminum alloy castings prepared by the new process not only have fine and spherical microstructures, good surface quality, and fewer internal pores but also enjoys more excellent mechanical properties and thermal conductivity.

Semisolid Casting and Die Casting of Al-4.8%Mg-2%Si Alloy

An aluminum alloy, Al–4.8%Mg–2%Si, was cast by die casting and thixocasting, and the properties of the cast specimens were investigated. When the poured molten metal temperature was lower than 640 °C during die casting, it was lower than the liquidus temperature, and the metal became a semisolid slurry in the sleeve of the die casting machine; this fulfills the conditions for rheocasting. A tension test was conducted to investigate the effects of semisolid casting on the mechanical properties of Al–4.8%Mg–2%Si. The ultimate tensile strength and elongation of the ingots cast by die casting and rheocasting were affected by the size of ingot. When the ingot had a circular base of 4.5 mm diameter, the ultimate tensile strength and elongation were excellent; however, when the cross section of the ingot was a square with a side length of 20 mm, the tensile strength and elongation were inferior. The thixocasting was conducted using square ingots with a side length of 20 mm, and the tensile strength and elongation were poor in this case as well. The results of this study demonstrate that semisolid casting cannot improve the mechanical properties of Al–4.8%Mg–2%Si ingots with a high thickness. Semisolid casting cannot produce fine-grained Mg2Si, and the mechanical properties of the material could not be improved by this casting method.

Impingement Density Analysis on Heat Transfer and the Appearance of Edge Cracks in Conventional Slab Using Hydraulic Nozzles

In this work, the fluid dynamics and heat transfer of two hydraulic nozzles used in the secondary cooling of the conventional slab continuous casting machine were analyzed. Impingement density maps, the jet opening angle and heat flux associated with different operating conditions (impingement distance, pressure) were experimentally determined. The opening angle and impingement density footprint were found to vary considerably in shape and magnitude with varying operating pressure and distances. Finally, it was found that when short operating distances are used, a greater heat extraction gradient occurs in the major axis of the impingement footprint, which promotes edge-cracks in the slab in plant.

An automated system development to control the device for supplying slag-forming mixture into mould of CCM

The mechanism of feeding slag-forming mixture (SFM) with a pneumatic drive has a number of disadvantages associated, in particular, with the uneven supply of the mixture into mould. To eliminate the drawbacks, mixture feeding device with an electric drive was designed to eliminate them. In order to ensure control of the SFM feeding process, an automated system has been developed that provides real-time information on the technological process of feeding the mixture into the mould of continuous casting machine, including speed of rotation of screw drive motors and movement of carriage, the level of the mixture in the bunkers and its consumption, temperature of the metal and slag. A software and hardware complex (SCADA-system) has been developed, which makes it possible to analyze the components of the mixture in the “online” mode and take into account the effect of changes in the supply of each of them on its composition. The dependence of the mixture consumption rate on the casting rate has been established, which can be displayed on the screen in the current mode. Application of the SCADA-system made it possible to control the developed SFM feeder both in manual and automatic modes. It was shown that the implementation of the developed automated SFM feeding device in the steelmaking production of Ural Steel, JSC will secure decreasing the SFM consumption by 2.8% and decreasing downtime by 5% due to increasing efficiency of fault detection with a total implementation cost of 200 thous. rubles.

Physical Modeling of Semi-continuous Casting for Developing an Industrial Technology of Producing Ingots From New Deformable Aluminum Alloys

A physical model of a semi-continuous casting unit (SCCU) has been manufactured and tested, designed to develop a technology for casting flat and cylindrical ingots from experimental aluminum alloys for subsequent metal forming. The SCCU includes two induction melting furnaces with a tilting mechanism, a rotary mixer, a metal path system, a vertical casting machine, a jib crane, water supply, power supply, monitoring and control systems. SCCU testing was carried out on six heats of alloy 1580 of the Al-Mg system with the addition of scandium. In the first three ingots the scandium content was 0.05% (wt.). In the second series of three heats ingots with 0.075% (wt.) scandium were cast. The ingots had a high surface quality, did not have casting defects, and there were no inclusions of primary intermetallic compounds Al3(Sc, Zr) in the structure of the ingots. The bottom and runner parts of the ingots were cut off, all faces were milled and subjected to homogenization annealing in a two-stage mode: the first heating at 350 °C, 3 h, the second heating for 1 h to 425 °C, 4 h. Then the billets were hot rolled from 40 to 5 mm, annealed at 380 °C, 1 h, rolled at room temperature to a thickness of 1 mm and annealed at 350 °C, 3 h. After that, tensile mechanical properties were tested. The results of modeling ingot casting were tested in industrial conditions when casting a large ingot with a cross section of 2100×500 mm. A template was cut from the ingot with the dimensions of a billet for rolling, as that obtained from an experimental ingot cast at the SCCU. The billet was subjected to hot and cold rolling according to the conditions used for rolling the experimental ingot. At the same time the modes of heat treatment of sheet semi-finished products were also repeated. The mechanical properties of sheets of alloy 1580 rolled from experimental and industrial ingots practically did not differ. This proves the reliability of casting modes for ingots obtained at the SCCU and tested for casting industrial ingots.

Effect of vacuum system on porous product defects and micro structures on the ADC-12 aluminum material with cold chamber die casting machines

Research on the effect of the vacuum system on porous product defects and microstructure on the ADC-12 aluminum alloy material with cold chamber die casting machine has been carried out. In the injection process in cold chamber die casting, the aluminum material commonly used is namely ADC-12. The ADC-12 aluminum alloy has better resistance to corrosion, is lightweight, has ease of casting, good mechanical properties, and dimensional stability. The purpose of this study is to compare the vacuum system with overflow system using ADC-12 aluminum alloy material with observed parameters are porosity, trapped air pressure, hot spot level, hardness level of Vickers Hardness, XRD analysis, and microstructure analysis with Light Optical Microscope (LOM). The results of the analysis using the Magma flow software, the vacuum system is better than the overflow system in terms of porosity and product yield, which is influenced by the amount of air trapped and the hot spot level. The level of hardness in a product with a vacuum system is better than a product with an overflow system. The average hardness in the vacuum system is 162,235 while in the overflow system is 147,615. Thus, the use of a vacuum system can increase the level of hardness in products by around 9%. With the change in usage from the overflow system to the vacuum system, it shows an increase in dislocation density followed by an increase in lattice strain and a decrease in the level of crystal size of the product.

Improvement the Round Bloom Continuous Casting Technology at JSC “Ural Steel”

The results of assessment of macrostructure and surface quality of round blooms 455 mm in diameter, cast on 4-strand continuous casting machine (CCM) at JSC “Ural Steel” are presented. The analysis of technological casting parameters of round blooms 455 mm in diameter (from steel grade “2”) at bloom caster of JSC “Ural Steel” are completed. Violations in casting temperature and rate parameters, which deteriorate thermal conditions of solidification and quality of continuous casting blooms, have been revealed. The main causes of unsatisfactory bloom quality have been determined, which are the increased overheating of cast metal and irrational secondary cooling mode. The results of the experiment to evaluate the surface temperature dynamics of a round bloom in the secondary cooling zone are presented, which confirmed the inefficiency of the secondary cooling mode for the defect-free bloom formation. As a result of thermal calculations of round blooms solidification of 455 mm in diameter, rational coolant flow rates by secondary cooling sections for bloom caster of JSC “Ural Steel” have been proposed. Optimized secondary cooling parameters provide a softer secondary cooling of the round bloom, which reduces the probability of the surface and internal defects development.

Reconfigurable molds and a fabrication-aware design tool for manufacturing concrete grid structures

The design and manufacturing of concrete elements need to be reconsidered in light of current trends in architectural geometry. Today, there is a movement toward greater customization and adaptability of concrete elements using “reconfigurable formworks” and “additive manufacturing.” Our study approached the issue of fabricating non-standardized concrete elements from the perspective of a “reconfigurable fabrication platform.” Specifically, we developed a method of fabricating geometrically diverse concrete joints by combining flexible pressure-enduring tubes with a rigid mechanism, resulting in an adaptive concrete-casting machine. This platform, which we named “Flexi-node,” can be used in conjunction with a relevant fabrication-aware digital design tool. Users can computationally design and fabricate a great variety of concrete joints using just one mold, with a minimum of material waste and with no distortion from hydrostatic pressure as would typically occur in a fully flexible formwork.

Thermal Fatigue Life Prediction under Temperature Uncertainty for Shot Sleeve of Squeeze Casting Machine

To quantify the influence of temperature uncertainty on thermal fatigue life prediction of a shot sleeve in an injection mechanism, an uncertainty analysis method based on a Kriging surrogate model and Monte Carlo simulation (MCS) was proposed. The training samples of the surrogate model were obtained by a finite element simulation, and the response relationships between input variables, such as pouring and preheating temperature, and target variables, such as strain and stress, were constructed by the Kriging surrogate model. The input variables were sampled by the MCS, and the predicted stress and strain parameters were combined with the modified universal slope equation to predict the thermal fatigue life of the shot sleeve. The statistical characteristics of the predicted life were obtained. The comparative analysis results indicate that the predicted life considering temperature uncertainty is more accurate than the deterministically predicted value.