Microstructure Control of Dual-Phase Steels through Hot-Dip Al–Mg–Si Alloy Coating Process

Abstract

This study investigates the γ→α transformation kinetics of Fe–Mn–C dual-phase steels at a temperature above the melting point of an Al–8.2Mg–4.8Si (wt.%) alloy coating formed on their surface by hot-dipping process. Using an experimentally determined time-temperature-transformation (TTT) diagram for a model steel of Fe–1.5Mn–0.1C (wt.%), the volume fraction of martensite is controlled through the intercritical heat treatment incorporated into the hot-dipping process. The microstructural observations confirm that this combined process route makes it possible to fabricate hot-dipped Al alloy-coated dual-phase steels with a controlled microstructure.