Investigation of the high-temperature oxidation behavior of the X30CrNiMnNbN25-12 valve steel.
Internal components of combustion engines, such as valves, are exposed to extreme operating conditions, such as high temperatures, cyclic mechanical loads and corrosive atmospheres. These components must maintain their functional properties and characteristics throughout their estimated useful life. More recently, engines developed for diesel trucks, had combustion chamber volume reduced when compared to older engines (from 16 liters to 12 or 13 liters), reaching pressures of up to 220 bar or higher. These new conditions were necessary to meet the strict environmental regulations for controlling emissions. It is in this context that the X30CrNiMnNbN25-12 valve steel appears, object of study of this work, which was developed as an option to the use of nickel superalloys, with better cost and expected performance superior to that of the previous alloys. The present work will present results of studies on the oxidation mechanism at high temperatures and corrosion. It will also study the formation mechanism of the oxide layer, as well as quantify the phases formed so that the conditions under which this material can be applied will be better understood.