Failure of a new batch feeded furnace

Case A batch feeded furnace had been heated from the outside (Inconel 600) up to 800°C inner temperature. After operating for only two months, the furnace in which sulfur- and phosphorus containing substances were heated, failed.
Wrong choice of material, the choice of material was based on oxidation resistance. Above 650°C Nickel alloys combined with sulfur will result in low melting phases consisting of nickel Sulphide (Ni3S2).
Advice  Choose an appropriate material, suitable for this process.