The invention relates to a method for making a thin finished product to be formed by deformation that combines strength with resistance to a highly corrosive environment. The method comprises forming a sheet of stainless steel with a microstructure consisting predominantly of ferrite, austenite, martensite or a mixture thereof, with a thickness of less than 3 mm, to a three dimensional semi finished product, treating said semi finished product with a nitrogen-containing atmosphere at a temperature of between 1000° C. and 1200° C. during a time and under a nitrogen pressure, sufficient to saturate the product through the thickness with a nitrogen content between a lower limit of 0.3 wt % and an upper limit that is provided by the beginning of nitride separation, cooling down said product at such a rate and nitrogen pressure that nitride separation is avoided, and subsequently machining the nitrogen saturated semi- finished product to the finished product. The invention further relates to a rotary shaving assembly prepared by the method of the invention.