Producing bellows of austenitic stainless steel, includes transforming single or multilayer sleeve by hydraulic transformation to form bellows, cleaning bellows in environment of e.g. carbon and/or nitrogen atmosphere and hardening

摘要

Producing a bellows made of austenitic stainless steel, comprises transforming a single or multilayer sleeve by hydraulic transformation to form bellows, cleaning the bellows in an environment comprising an inert gas atmosphere containing a carbon and/or nitrogen or a molten salt containing a carbon and/or nitrogen compounds from potassium and/or sodium acetate, and subjecting the bellows to 100-400[deg] C, preferably 200-320[deg] C, by diffusion of carbon and/or nitrogen atoms for hardening of the bellows. An independent claim is also included for a bellows made of austenitic stainless steel with at least one layer, where the surface layer is hardened to a hardness penetration depth of at least 5% of the wall thickness by the incorporation of carbon and/or nitrogen atoms.