Papers by Keyword: Ingot

Abstract: In this study, 3D numerical simulations were performed to study the effect of Mn on the macrosegregation behaviors of carbon and chromium in a 40 MT steel ingot using Finite Element Modeling (FEM). Two Mn contents of 0 and 5 wt.% were investigated. Thermophysical properties such as specific heat, density and phase fractions were determined using thermodynamic software Thermo-Calc^®. Simulation results indicated that higher Mn content increases the carbon macrosegregation while it tends to lower the one of chromium. Moreover, it changes the solute poor band into rich one in the case of chromium and no bands were obtained for carbon. These results are analyzed in terms of the changes of thermophysical properties, interactions between alloying elements and the change in the primary solidification mode from δ-ferrite to austenite resulting from the increase of Mn concentration.

Abstract: At present, casting and wrought high-strength and light aluminum alloys are widely used in the creation of a number of products and units in mechanical engineering, aviation and space technology. The process of developing alloys includes the formation of initial design data covering the operating conditions, the necessary physical, mechanical and other characteristics of products, and also considers the requirements of manufacturability in their manufacture and ensuring a given structure. To achieve these goals, when smelting aluminum alloys, Al-Mg, Al-Cu, Al-Mn, Al-B, Al-Ti ligatures are used. Despite the widespread use of ligatures, there is no single set of requirements for their quality. However, recent studies in the field of structural heredity in the "charge - melt - cast product" system have shown that the structure of the ligature has a significant hereditary effect on the crystallization process, structure and properties of the modified alloy. In this work, a study of the Al-5Ti-1B master alloy was carried out using synchronous thermal analysis, which made it possible to establish such properties as: the magnitude of the thermal effect, the temperature of its onset, enthalpy, and the crystallization interval. The results obtained make it possible to expand the bank of initial data to improve existing programs for modeling casting processes and to develop new ones.

Abstract: It is noted that the technology for the manufacture of ferrosilicon-magnesium modifiers (crystallization into an ingot in a mold or into a chip on a water-cooled drum) forms their quantitative and qualitative structural differences: the size and distribution of phases, the scatter of the content of elements, etc. The fundamental differences are shown and the features of the distribution of silicon as a base element in ingot and chip modifiers are described. It was found that in ingot modifiers the vast majority of silicon-containing phases are ξ(FeSi) and ζ' (FeSi₂), and with a significantly lower content of pure silicon particles and phases, these are α₁(Fe₃Si) and α₂(Fe₂Si). The picture of the phase structure of the modifier chip has been determined. In it, the 1st mode corresponds to the presence of a set of phases α₁(Fe3Si) and α₂(Fe2Si), and the 2nd mode, as well as in the ingot modifiers ξ (FeSi) and ζ'(FeSi2), but is shifted to the lower boundary of the region their existence. Particles of pure silicon are completely absent in the chip modifier.

Abstract: The authors present the results of evaluating the distribution of plastic properties on the height of a log ingot with the diameter of 145 mm, obtained by means of semi-continuous casting, from the aluminum alloy AD31. The authors study semi-continuous alloys of three manufacturers. One part of ingots was obtained with the use of only primary aluminum, secondary raw materials and secondary raw materials with the addition of primary aluminum. With the purpose of stabilizing the process of presswork the authors define the values of yield stress in the ingot lower and upper parts and study its microstructure. The research was conducted for the ingots without thermal treatment after accelerated homogenization. It is shown that the ingots, produced with the use of primary aluminum only, have less scattered plastic properties in terms of the height. That is why, for the case of press-working the items with thin components, it is reasonable to use the ingots from primary aluminum.

Abstract: The article examines a number of regularities in the production of primary cast ingots of AlSi7Mg, AlSi7MgSr, AlSi11Mg, and AlSi11MgSr. Peculiarities of melting and cast of these alloys, as well as the effect silicon and strontium have on the formation of the shrinkage cavities, have been explored. It has been demonstrated that strontium, when used as a modifier, changes not only the morphology of silicon, but also the nature of solidification and shrinkage of the alloy. Defects formed in the ingots manufactured from near – eutectic AlSi11MgSr alloy have been studied in greater detail.

Abstract: In the present work, the segregation degrees of ferrite and austenite stabilizer alloying elements were analyzed for a high strength steel. For this, samples were taken from the surface and center of the hot-top and the upper section of a 40 MT ingot. The results showed that the positive segregation ratios for all the investigated elements were higher in the ingot center than in the surface with higher values for austenite stabilizer elements. The increase of austenite alloying element stabilizers was accompanied by the change in the primary solidification mode of the austenite phase. The obtained results are in good agreement with the observed presence of austenite, revealed by X-ray diffraction analysis, stabilized by the austenite alloying elements.

Abstract: Optical and electron microscopy are used in the paper to analyze the quality of the cast metal of a 1.53 ton ingot of steel 38ХН3МФАteemed with a cooling feeder head. In addition, the analysis of the metal of hollow forgings produced from ingots with “cooled” and thermally insulated feeders is performed. A metallographic study reveals that if the ingot top is cooled down, it results in an accelerated solidification throughout the entire mass of the ingot; in addition, the thermal centre shifts to the ingot central axial area.

Abstract: A mathematical modeling approach as well as experimental data analysis have made it possible to establish significant factors affecting the relative diameter of the axial porosity zone. The minimal values of this parameter determine if the ingot can be used for the fabrication of rolled steel rods over 300 mm in diameter, because chill extensive axial defects prevent from producing high quality bars of a large diameter. Commercial information analysis and experimental results have enabled to develop a model relating the axial porosity zone dimension, ingot geometry and process parameters of teeming 6.61 ton and 7.0 ton ingots. The improvement of the model obtained has enabled to establish that the axial porosity zone is primarily affected by the following factors: hot top size, slenderness ratio, the H/D ratio and insulation heat capacity. When these parameters are controlled to reduce the relative diameter of the axial porosity zone, the number of shrinkage defects decreases and the quality of large diameter rolled steel becomes better. The proposed ingot geometry improves the direction of the advance of the metal solidification front to the ingot thermal center, located in the hot top. Besides, the solidifying metal is better fed with the hot top melt.

Abstract: A set of Cu-10Ni-1Fe-1Mn alloys were prepared. Electromagnetic casting, DC casting ingot organization, properties and composition distribution of the alloy were studied using Optical Microscope (OM), Scanning Electron Microscopy (SEM), Energy spectrum analysis (EDS), Xray diffraction (XRD), Brinell Hardness Test, and electrochemical tests. The results suggested that homogenization of the Cu-10Ni-1Fe-1Mn alloy changed its properties and distribution of composition. The results also suggest that electromagnetic casting can refine casting organization, homogenize the composition of the alloy, and the casting mechanical performance is superior compared to those of DC casting. However, the composition between Dendritic branch and Dendrites was still not homogeneous. After 1 h of homogenization treatment at 950°C, the ingot composition distribution became more homogeneous, and its stiffness decreased. The tube prepared by squeezing the homogenized ingot, was soaked in 3.5% NaCl solution for 240 h, after which the tube blank surface remained a bright metal luster and XRD analysis indicated that a Cu₂O protective film of high density covered the surface of the tube. The homogenization treatment significantly improved the corrosion resistant properties of the alloy tubes.

Abstract: The paper reports the findings on the effect of various casting methods on the quality and development of primary dendritic structure in large-sized forging ingots of steel 38ХН3МФА. One ingot was teemed as per a conventional teeming method while the other was teemed with an inoculated metal stream. It was established that the dendritic parameter value in the inoculated ingot is much smaller than that in the conventional ingot. Consequently, the solidification process occurs at a higher rate in the inoculated ingot compared with that in the conventional ingot, and this assumption is supported by a more homogeneous dendritic structure. It is demonstrated that disperse inoculants positively affect the structure, physical and chemical homogeneity as well as the mechanical properties of cast metal. This finding is clearly supported by the examination of the forgings made of the conventionally teemed ingot and the one teemed with an inoculated stream. When inoculants were introduced in the metal stream, total chemical heterogeneity increased on the average by 1.2-2 times. It is established that the best results for the inoculation casting method are achieved when 2.4-2.6% inoculants are introduced in the stream. Such quantity of inoculants forms at a distance of 5 meters between the guiding pipe and the hot top.