Improved Ferritic–Austenitic Stainless Steel

Abstract

For the efficient operation of chemical process plant it is of paramount importance to ensure as far as possible that the periods of closurefor maintenance and repair are minimised.The arduous conditions encountered in many chemical plants as a result of progressive trends towards. higher yields, etc., have therefore highlighted the need for greater strength and pitting resistance than can be obtained in conventional austenitic stainless steels. This paper describes the development of ferritic/austenitic high chromium duplex cast stainless steels and demonstrates how, by addition of nitrogen and close control of composition, certain inherent drawbacks of duplex alloys can be overcome. The nitro gen-containing steel has an attractive combination of mechanical properties, corrosion resistance, ductility, weldability and castability, and has received application in a wide range of aggressive environments.