Duplex stainless steel is produced through multi-stage steelmaking and forming process route. Scrap steel and alloying additions are initially melted in an electric arc furnace (EAF). The molten steel is then transferred to an AOD converter (argon oxygen decarburization), where the principal metallurgical process is performed. Here, dissolved gases are removed from the molten steel and the final composition fixed by additions of key alloying elements. The steel is then transported to the ladle furnace where the inclusions can be modified. Finally, the molten steel is ready to be cast, either as individual ingots or continuously cast blooms.
The solid steel ingots or blooms are then transformed into bars, firstly being reheated and then forged and/or rolled to the desired diameter. Solution annealing is a heat treatment that ensures the internal structure of the bar is consistent, after which the bar is quenched. To present a consistent surface finish, bars will then be mechanically ‘peeled’ to remove the as-produced surface.
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