Influence of Galfan coating on tensile properties, microstructure and dislocation densities of CRS 1018 steel Einfluss der Galfan-Beschichtung auf die Zugfestigkeitseigenschaften, das Gefüge und die Versetzungsdichte von CRS 1018-Stahl

In the present work, zinc-6 % aluminium alloy, Galfan, is coated through the hot dipping technique on tensile bars made from cold rolled CRS 1018 steel to study the influence of Galfan coating on tensile properties of mild steel. The tensile results indicate that Galfan coating prepared by the hot dipping process reduces the ultimate tensile strength and yield strength of the substrate, whereas the elongation at failure is significantly increased. The microstructure of the as-rolled, hot-dipping coated, and other comparing specimens is observed by optical microscopy. Nano indentation is used to evaluate the variation of dislocation densities in the tested specimens. The analyses of the hardness-depth curves obtained from the nano indentation testing implies that the dislocation density of the coated steel might be lower than that of the uncoated specimen. The thermal energy received by the steel substrate during the heating stage of the hot-dipping process should be responsible for the recovery of the substrate, which leads to the reduction in dislocation densities and the arrangement of the dislocations into lower-energy configurations. As a result, the Galfan coating increases the elongation at failure considerably with a moderate decrease in strengths.