Description: A series of alloys have been developed as possible replacements for some austenitic stainless steels. These alloys utilized a Mn substitution for Ni and a reduced Cr concentration from the 18% ordinarily found in the AISI 300 series stainless steels to a concentration of 13%. The base system studied was an alloy containing Fe-16%Mn-13%Cr while other elements added included small additions of N, Si and Mo. A range of microstructures was produced from the alloying additions. The base composition had a triplex (fcc, hcp, bcc) structure while the most highly modified compositions were fully austenitic. Mechanical testing included tensile testing and Charpy V-notch testing conducted at various temperatures between -196/sup 0/C to 23/sup 0/C. Excellent combinations of strength and ductility were obtained (40--65 ksi yield strength, 100--125 ksi ultimate strength, 45--75% elongation and 60--80% reduction of area) at room temperature. Upper shelf energies in Charpy V-notch testing were as high as 185 ft-lbs with a ductile-brittle transition temperature (DBTT) of -160/sup 0/C. Analysis of fracture surfaces determined that alloys without interstitials had no transition in the mode of failure between room temperature and liquid nitrogen temperature. Results of an ASTM sensitization corrosion test, where the experimental alloys were compared to 347 stainless steel, indicated that the alloys were not susceptible to intergranular attack.
Date: February 1, 1978
Creator: Haddick, G.T.; Thompson, L.D.; Parker, E.R. & Zackay, V.F.
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