Estudo do processo corrosivo em liga de aço baixo carbono com revestimentos inorgânicos em forno de tratamento térmico ao ar

Abstract

Heat treatment furnaces contain a refractory lining designed to ensure thermal insulation that maintains the internal temperature of the furnace chamber, in order to guarantee the efficiency of the process. These linings are fragile and, therefore, the components that will undergo treatment are placed in a way that minimizes the impact with the interior of the furnace, or even eliminates direct contact between these components through the use of supports suitable for the process. Some companies use SAE 1020 steel to manufacture the supports, however, this material presents a high corrosive process after being used in repeated thermal cycling processes inside the heat treatment furnace. In this study, the corrosive process of a low-carbon steel with different inorganic coatings was evaluated under conditions of repeated thermal cycling. The corrosion rates were studied in samples without coating and in samples coated by galvanization, max plasma nitriding and oxy plasma nitriding. The results obtained showed that the samples with max plasma nitriding coating presented better performance in reducing the corrosion rate, although their behavior was inferior to that of the sample without coating.