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Parametric Optimization for Producing Semi-Solid A383 Alloy using Cooling Slope Casting Process

Rao M. S., Khandelwal Himandshu, Kumar M., Kumar A.

Archives of Foundry Engineering

2023

Vol. 23, iss. 1

43--52

Cooling slope casting is a simple technique to produce semi-solid feedstock with a non-dendritic structure. The cooling slope technique depends on various parameters like slope length, slope angle, pouring temperature etc, that has been investigated in the present study. This work presents an extensive study to comprehend the combined effect of slope angle, slope length, pouring temperature, on hardness and microstructure of A383 alloy. Response Surface Methodology was adopted for design of experiments with varying process parameters i.e. slope angle between 15o to 60o, slope length between 400 to 700 mm, and pouring temperature between 560 oC to 600 oC. The response factor hardness was analysed using ANOVA to understand the effect of input parameters and their interactions. The hardness was found to be increasing with increased slope length and pouring temperature; and decreased with slope angle. The empirical relation for response with parameters were established using the regression analysis and are incorporated in an optimization model. The optimum hardness with non-dendritic structure of A383 alloy was obtained at 27o slope angle, 596.5 mm slope length and 596 oC pouring temperature. The results were successfully verified by confirmation experiment, which shows around 2% deviation from the predicted hardness (87.11 BHN).

Producing thixotropic semi-solid A356 alloy: microstructure formation x forming behaviour

Robert M. H., Zoqui E. J., Tanabe F., Motegi T.

Journal of Achievements in Materials and Manufacturing Engineering

2007

Vol. 20, nr 1-2

19-26

Purpose: The work discuss the phenomena involved in the formation of the microstructure of semi-solid thixotropic alloy A356 produced by different techniques and the relation between microstructure and forming behaviour of the material. Design/methodology/approach: Thixotropic slurries of A356 alloy were produced from liquid and from solid conditions; in the first case either by stimulating nucleation rate or crystal multiplication during solid growth; in the second case by recrystallization and partial melting of deformed structures. Flow behaviour was analysed by viscosity measurements or by flow ability in forging operations. Findings: Results show that different production techniques activate different mechanisms, leading to distinct structure features in the semi-solid slurry, and, as consequence, in its forming characteristics. Techniques which promote formation of isolate globules of primary phase, like those involving nucleation stimulation and recrystallization, result in a semi-solid with better flowing behaviour. On the other hand, techniques based on crystal multiplication during growth lead to more interconnected globules in the slurry and poorer forming behaviour. Research limitations/implications: Semi-solid processing is suitable only for alloys with appropriate liquid fraction x temperature relation. Practical implications: the konowledge of the phenomena involved in the formation of thixotropic metallic slurries produced by different techniques, and their consequences in the material structure and flow behaviour, allow the decision of the adequate slurry production method for a specific application, in order to take the best advantage of the semi-solid technology. Originality/value: The analysis of the relation between production process x flow behaviour of semi-solid thixotropic A 356 is original.