Papers by Keyword: Ingot

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Authors: Bin Zhang, Craig Shaber
Abstract: Based on sequentially coupled CFD and FEM models, aluminum alloy rolling ingot thermal stress simulations have been conducted in order to understand start-up phase cold cracking phenomena and optimize tooling designs for 520×2120 mm rolling ingot casting on Wagstaff® Epsilon™ Ingot Tooling. In the CFD model, ingot surface temperature dependant and water flow rate dependant water boiling curves are applied. Thermal boundary conditions for the complex water intrusion phenomena under the ingot butt have been attempted. Temperature dependant elastic-plastic materials constitutive relationship has been employed in the transient thermal stress FEM model. Results of thermal stress development at ingot surface and inside the ingot are presented; Connection of cold cracking (ingot butt quarter and center cracks) with near surface stress development at the ingot butt is shown and the effect of water intrusion under the ingot butt on the butt stress development is also discussed. The predicted temperatures are validated against temperatures measured from cast-in thermocouples at strategic locations in field ingots in order to obtain realistic thermal boundary conditions. The predicted butt curl is also verified through field observation and measurement.
196
Authors: Young Seon Lee, Y.C. Kwon, Yong Nam Kwon, Jung Hwan Lee, S.W. Lee, N.S. Kim
Abstract: Internal voids have to be eliminated for defect-free in some open die forging. The FEM analysis is performed to investigate the overlap defect of cast ingots during cogging stage. The measured flow stress data were used to simulate the cogging process of cast ingot using the practical material properties. Also the numerical analysis of void closure is performed by using the DEFORMTM-3D. The calculated results of void closure behavior are compared with the measured results before and after upsetting, which are scanned by the X-ray scanner. From this result, the criteria for deformation amounts effect on the void closure were estimated into effective strain of 0.6 by the comparison of practical experiment and numerical analysis.
69
Authors: Boris V. Ovsyannikov, Viktor M. Zamyatin
Abstract: Microstructure and composition of elements in phases of homogenized ingots in aluminum alloys of various alloying systems: Al-Mg-Mn-Si, Al-Mg-Si-Cu, and Al-Zn-Mg-Cu, were examined using a method of scanning electronic microscopy and X-ray microanalysis. Besides basic alloying elements of magnesium, zinc, copper, silicon, and manganese, alloy composition contained additional alloying elements, including zirconium and scandium. Presence of intermetallic compounds of various chemical composition insoluble during ingot homogenization was found in microstructure of examined samples. It is found that zirconium and scandium are jointly present in composition of some intermetallic compounds containing additional alloying elements of alloys.
1002
Authors: Boris V. Ovsyannikov
Abstract: Recently significant successes have been achieved in the field of grain refinement by means of such additives as the titanium, zirconium, scandium, AlTiB and AlTiC. However, introduction of grain refining additives results to a number of negative effects. These effects can be divided into four basic groups: 1. Reduction of high-strength alloy casting properties. 2. Defects of structure. 3. Intermetallic and oxide inclusions. 4. Decrease in mechanical and fatigue properties of the semis made of ingots with fine grain.
143
Authors: Hyoung Jae Kim, Do Yeon Kim, Sang Jik Lee, Hae Do Jeong, Hon Jong Choi
Abstract: Diamond abrasive coated wires are core tools for precision multi-wire sawing of mono-crystal ingots for substrate manufacturing, especially for hard materials applications such as SiC, GaN, sapphire and silicon. However, repeated contact by reciprocation motion of wire makes it difficult to design optimized utilization of diamond wires since it makes temporal change in cutting performance due to gradual wear of abrasives. In this paper, the cutting performance of wires are examined based on experimental results with wires having different concentration. The results indicated that the concentration of diamond abrasives have strong relationship with cutting performance and wires with low concentration showed higher material removal characteristics.
549
Authors: Chao Wang, Zhen Rui Li, Yong Ji Niu, Shi Feng Shi, Ning An
Abstract: The causes and the influence factors of the defects of center porosity and secondary pipe of the casting superalloy ingot are briefly introduced, and the study on the principle and technical characters of grain refinement technology with dynamic methods carried out. The mechanism, working parameter and the test result of the typical application methods including the technologies of vibration of ultrasonic, the vibration of mould, the stir of mould and oscillation in the riser were investigated in detail. By comparing the advantages and disadvantages of different methods and also according to the practical production situation of our company, the most appropriate one for improving the defects of center porosity and secondary pipe is proposed.
526
Authors: D.V. Rutskii, N.A. Zyuban, S.B. Gamanyuk
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.
962
Authors: N.K. Tolochko, A.A. Andrushevich, Yu.A. Shienok
Abstract: Novel semisolid casting technique allowing producing the cast composites with highly homogeneous structure is suggested. In according with this technique specially prepared metal bil-lets containing reinforcing nanoparticles are subjected to partial melting and compacting and fol-lowing solidifying. Some model systems were used in order to demonstrate the potential possibili-ties of this technique in principle.
425
Authors: Oleg E. Markov, Natalia A. Rudenko, Igor A. Grachov, Aleksandar Ristovski, Vladimir Radojičić
Abstract: A stress-strain state and a resize of an axial defect during upsetting have been investigated in the article. Theoretical research based on a FEM has been conducted. The upsetting of cylindrical steel workpieces which had the axial defect equal to 10 % of the workpiece diameter has been simulated. Upsetting has been carried out by flat, concave-conical and convex plates (solid or with hole). The result of the studies showed that the main influence on the workpiece shape had a ratio of dimensions. The maximal closure of the axial defect provides upsetting by concave-conical solid plates. Upsetting by flat plates does not provide the closure of axial defects. Convex plates provide the uniform stress-strain state along the workpiece cross section. The hole in the plates increases the non-uniformity of strain distribution and also does not provide the axial defects closure.
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