Development of a new 12%Cr-steel for tubes and pipes in power plants with steam temperatures up to 650°C

Abstract

Today, newly developed 9% Cr-steels, such as T/P911 and T/P92, are used for power plants with advanced steam parameters, thanks to their high creep rupture strength values. They show an increase of creep values by around 10 to 25 %, compared with T/P91. Nevertheless, their range of use is limited for high temperature because their oxidation resistance is lower than that of the classical 12%Cr-steels, such as X20CrMoV12-1 or the austenitic steels. In order to meet higher design parameters, a new steel, named VM12, has been developed by Vallourec and Mannesmann Tubes (V&M). The aim was to keep the high creep level of the T/P92 together with improvement of the steam oxidation resistance to fit with design steam temperature up to 650°C.