Optimizing the Conditions of Metal Solidification with Vibration

Vibration treatment of solidifying metals results in improvement in the ingot structure. There is a need to study this process not only because of the practical potential of vibration treatment but also due to the lack of understanding the process. An important practical challenge is to find optimal conditions for liquid metal processing. In this paper, the authors consider a solidification process in the particular case of a cylindrical chill mold with vibration as a solution of the Stefan problem. An integral value of mechanical stresses in the melt during solidification is considered as an efficiency criterion of vibration treatment. A dependence of this value on the vibration frequency and amplitude is obtained through solving the Stefan problem numerically. The solution allows one to find the optimal vibration frequency and amplitude. We verified the numerical solution with experimental data obtained upon vibration treatment of aluminum melt under different conditions. The experimentally found optimal conditions for metal processing were similar to those proposed in theory, i.e., a vibration frequency of about 60 Hz and an amplitude of about 0.5 mm.

Inclusion cleanliness in metallic alloys

The inclusion cleanliness remains an issue of great concern in liquid metal processing which has been addressed in a full session of the last Matériaux Conference held in November 2018 in Strasbourg, France. A special issue of the Metallurgical Research & Technology journal gathers most of the papers of this session which are divided into two sub-sections: on the one hand the analysis and characterization techniques of the inclusions are addressed and on the other hand the modelling methods to simulate the behavior of single particle or a population of inclusions are discussed.