Density-improved powder metallurgical ferritic stainless steels for high-temperature applications

Powder metallurgical (PM) ferritic stainless steels have proven to be an adequate material for the manufacturing of some components exposed to elevated temperatures. This work proposes a new and simple method to obtain PM stainless steels that exhibit reduced oxidation rates at high temperature, using mixes of powders of different particle size and morphology. Addition of gas atomised (ga) powders to traditional water atomised powders (wa) causes two opposite effects that condition the oxidation resistance of the materials: first, they modify the morphology of the porosity reducing the oxidation rate, and second, the additions favour the Mn diffusion and the formation of less protective scales. Mixes of 10% ga and 90% wa powders of the studied ferritic stainless steels have demonstrated to be the optimum material for high-temperature applications. (c) 2007 Elsevier B.V. All rights reserved.