The effect of thermal treatment of the melt before crystallization on the structure and properties of castings

Abstract

Purpose: The aim of the proposed research is to investigate the influence of temperature and duration of isothermal melt processing on structural characteristics of castings in connection with technological background of charge metal. Design/methodology/approach: Ferrous and non-ferrous alloys were obtained by remelting a charge with a dispersion-structured structure (which was ensured by highspeed crystallization). Remelting was carried out at different temperatures of overheating of the melt over the liquidus with different isothermal exposure at these temperatures. Experimental castings were crystallized under normal conditions. It was studied a change of structure formation and mechanical characteristics depending on the temperature and duration of thermal treatment of the melt before crystallization. Findings: It is established that isothermal treatment of the melt at the overheating of the liquid metal above a certain equilibrium temperature of the micro-inhomogeneous melt (Te) causes a gradual loss of hereditary characteristics of the original charge metal, increase of the chemical homogeneity of the melt and the formation of crystallization and formation a corresponding change in the mechanical properties of castings. Research limitations/implications: The results can be complemented by studies of the effect of thermal treatment in the temperature range of crystallization. Practical implications: The results can be used to select the optimal heat treatment during remelting and, accordingly, the mechanical properties of the resulting casting. Originality/value: The obtained results testify to the predominant influence of temperature on the dispersion of the cast structure of steels, given the duration of technological operations of preparation and casting of steels in the manufacture of castings in industrial conditions.