Study the Thermodynamic Behaviour of Inclusions in High Heat Input Welding Steel
DOI:
https://doi.org/10.24425/afe.2026.158022Abstract
Investigation on the thermodynamic precipitation behavior of inclusions is a prerequisite for achieving the fine and dispersed distribution of inclusions in steel. To clarify the influence of cooling rate on the formation pathway, precipitation pathway evolution and precipitation conditions of complex inclusions in EH40 ship plate steel, this paper systematically investigates the precipitation behavior of inclusions by combining FactSage with the Won-Thomas microsegregation model. The results show that Mg is the key element promoting the transformation of Al2O3 to spinel-type composite oxides; it is difficult to form stable Al-Ti composite oxides directly between Al2O3 and Ti2O3, and Ti mainly enters the composite inclusion system with the participation of Mg. Al, Mg and Ti all segregate and enrich in the interdendritic residual liquid phase during solidification, and local supersaturation promotes oxide precipitation. Al2O3 satisfies the precipitation condition at the early stage of solidification, while Ti3O5 and Ti2O3 reach their precipitation conditions at similar stages. This study provides important theoretical guidance for regulating the modification process of inclusions in steel.
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