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Duplex stainless steel has been widely used in chemical industry, oil and gas industry, power plants, and aerospace industry. Since it contains austenite and ferrite in nearly equal proportions which can suppress grain growth at a high temperature, many duplex stainless steels with fine grained microstructures show superplastic behavior. Therefore, by using superplastic blow forming technology, it is possible to form a complex shape in one piece with least amount of waste during machining. The present study constructs an analysis model to predict biaxial blow forming behavior of duplex steel from results of uniaxial and biaxial tests. The experimental results show a complex configuration of aerospace component was successfully manufactured by blow forming of a sheet of stainless steel.

In this paper, manufacturing of launcher structural components with superplastic forming (SPF) and solid state welding technologies is presented with several examples. Some of high strength aerospace alloys, like aluminum, titanium and superalloys, are known to have superplasticity so that complex shapes of aerospace components can be produced with this technology. A combination of superplastic forming and solid state welding processes produces lighter and stiffer components than one manufactured with conventional machining and welding. Solid state welding is an attractive method to weld materials without melting where mechanical properties are important since the welding interface is homogeneous without liquid phases.