Failure Analysis And High Temperature Resistance Technology Of Ring Furnace Internal Cover

Ring Furnace is an advanced equipment in oriented silicon steel produce, which is used for annealing silicon steel at high temperature. Internal cover is one of the key equipment. The main role of the internal cover is to provide protective atmosphere for steel to isolate oxygen atmosphere. This furnace can produce high-quality products with low energy consumption and high efficiency. But during the use, failure often occurred on the top of the cover and the barrel. The cost of the cover is high, and the failure of the cover will cause big accident because of the hydrogen leak. So it is very important to use the cover safely and prolong it’s service life. In this paper, the cover has been optimized through two aspects of material and structure. Failure of the internal cover were analyzed through microstructure before and after the service. According to the using conditions of internal cover to determine the material characteristics, we choose31OS stainless steel to replace YUS701. High temperature behavior of310S stainless steel were studied. The results show that the high temperature creep rupture strength can reach the using requirement. Since the outside of the cover connect with the oxygen atmosphere and suffer from serious oxidation, in order to increase high temperature oxidation resistance of310S, different gradient aluminum coating were formed on it by electro-arc spray and thermal diffusion with different temperature. Slight oxidation was attempted at1050℃. The results show that the middle of the diffusion zone is intermetallic compound layer which can improve the oxidation resistance of the coating. After slight oxidation, the outer rich aluminum layer can grow into a continuous and firm protective Al2O3scale.