Powder Metallurgical Duplex Austenitic-Ferritic Stainless Steels from Prealloyed and Mixed Powders

Abstract

To date little work has been done on powder metallurgical duplex austenitic-ferritic stainless steels. In the present work the manufacture of this type of steel from prealloyed and mixed powders is studied together with the possibility of obtaining duplex compositions of other than 50% ferrite-50% austenite. Mechanical properties, microstructure, and dimensional behaviour of the sintered powders are investigated. Studies on powders sintered at the higher experimental sintering temperature of 1250°C show that there is little difference found between the properties of materials obtained from prealloyed and mixed powders when they contain the same percentages of ferrite and austenite. The strength of duplex stainless steel derived from mixed powders increases with the ferrite content and the dimensional change on sintering is found to be lower for mixed powders than for the prealloyed material. It has been found, however, that a low sintering temperature (1120°C) can cause heterogeneous microstructures and poor mechanical properties in these materials. PM/0621