The determination of the gradient and thermal stresses for the heating of type 18-10 stainless steel ingots

Abstract

The aim of this paper is to determine the gradient and thermal stresses depending on the heating rates, based on parameters resulted from industrial studies, for the purpose of optimizing the heating of type 18-10 stainless steel ingots, considering the cases where the heating is required starting from the cold state. If the heating for the plastic deformation processing is to begin from the cold state, the determination of the heating rate up to the temperature of 700 – 800 ºC must be done with extreme care, as this is in fact the most conducive period to the formation of defects. Having analysed the existing domestic and foreign situation, the heating process for this type of steel raises difficult issues and differs from one company to another, relying mostly on their own accumulated experience. Despite the fact that, practically, the possibility of increasing the heating rate has been demonstrated, it is restrained by the fear of achieving an insufficient section heating and of the destruction of steel's tightness during the initial heating period. For these reasons we have taken the step of the analytical review of the gradient variation, as well as of the thermal stresses during the preheating period.