Austenitic Manganese Alloyed Stainless Steel: the AISI 200 Series. I

A detailed account is given of the metallurgical aspects of the Mn-alloyed stainless steel AISI 200 series to encourage its increased use. The Mn is an austenite promoting element in Fe--Mn and Fe--Cr--Mn systems. Nitrogen also has 30-fold the austenite forming capacity of Ni, and can be introduced via ferrochrome or ferromanganese. The Mn is also a ferrite former, and promotes Mn sub 23 C sub 6 , Mn sub 3 C, Mn sub 5 C sub 2 and Mn sub 7 C sub 3 formation. The carbides formed mainly at the crystal boundaries can be dissolved by heat treatment. Mechanical properties and corrosion resistance, together with typical applications, are also described.--R.H.