A heat and corrosion resistant cast austenitic stainless steel alloy which contains less than about 15% nickel. The alloy has a completely austenitic microstructure in an as-cast state, and a creep rupture life exceeding 20,000 hrs at a stress of 35 MPa and a temperature of 850.degree. C., when creep tested in the as-cast state under ASTM E139 test conditions.
 This invention was made with government support under the terms of Contract No. DE-AC05-960R2264 awarded by the U.S. Department of Energy. The government may have certain rights in this invention.