Production of cooking utensils with a prestressed base of constant flatness

The invention relates to a method and a device for the production of pots and pans with a radially prestressed base in which no compressive stresses occur when they are heated during use, such compressive stresses leading to the bulging of the base. The invention is intended to make a decisive improvement in the service properties of pots and pans by ensuring that their base maintains a constant flatness and does not bulge when heated. According to the invention, this is achieved if tensile stresses directed primarily towards the centre of the base are introduced into it. Upon heating, thermal expansion leads to a reduction in these tensile stresses dependent on the temperature, without the occurrence of compressive stresses. For this purpose, one or more zones of the base are heated briefly to temperatures above the high-temperature limit of elasticity of the respective material, expansion being prevented by the unheated areas and the corresponding constraint. As a result, the heated areas are compressed plastically and their shrinkage upon cooling gives rise to the expected tensile stresses.