The Role of Silicon in Hot Shortness Amelioration of Steel Containing Copper and Tin

Abstract

Hot shortness due to copper and tin in steel is a common industrial problem during the secondary cooling, reheating and hot rolling processes. Silicon is known as a potential element to eliminate hot shortness; however, the effect of single-element silicon on hot shortness and mechanisms involved are not fully understood. The current study aims to determine the Si content needed for a given composition to ameliorate the hot shortness and also to determine the mechanisms. TG, SEM–EDS and XRD were used to study hot shortness behavior of steel containing ~0.3 mass% Cu, ~0.04 mass% Sn and with varying Si-content. It was found that Fe2SiO4 formation at the oxide/steel interface resulting in a reduction of steel oxidation and the enrichment of Cu-rich liquid phase. The mechanisms of silicon eliminating hot shortness were a combination of Fe2SiO4 formation impeding steel oxidation as well as trapping Cu-rich liquid phase into the scale. In the present study, when Si-content is 0.146 mass%, the quantity of Cu-rich liquid phase at the interface was decreased significantly and even no Cu-rich liquid phase was found in the steel with 0.215 mass% Si. Therefore, no less than 0.215 mass% Si was acceptable to alleviate the hot shortness.