The Research On Effect Of Al Element On Microstucture And Properties Of 310S,316L Steel

310S,316L alloy has been extensively used as ethylene cracking furnace tubes. During running the material is often destroied by high temperature oxidation and corrosion in acid environment. Therefore we attempt to develop the 310S steel with Al element in order to improve the elevated temperature mechanical properties, and attempt to develop the 316L with Al element in order to improve the resistantce corrosion performance as well as do not increase the room-temperature brittleness.The weight percentage of Al in the 310S and 316L alloy was 2,4,6,8 and 10%, respectively. Microstructures and mechanical properties of the steels were investigated via melting the alloy in vacuum arc furnace and solidifing in water-cooling-molds. The results showed that the phase of the steels transformed fromγ-Fe toα. The interconnected chromium carbide transformed to isolated plates with Al content increasing. The Al element dissolved in the matrix phases. When the weight percentage of Al in the 310S and 316L alloy was more than 6%, the alloy stranformed from plastic materials to brittle materials.The anti-oxidant property and mechanical properties of 310S steel at high temperature were studied. It showed that the oxide film on the surface of the alloy mainly consists of Al₂O₃, thus the anti-oxidant property increases. Theσ_0.2 of the alloys increased at first and then decreased with increasing the weight percentage of Al, and the maximum value is in weight percentage of 6%.The uniform corrosion and intercrystalline corrosing of 316L steel in nitric acid was studied. The results showed that the Al element obviously enhanced the alloy corrosion resistantce and the corrosion performance.