Abstract: Ferrite-austenite stainless steel castings having an improved erosion-corrosion resistance consist by weight percentage of not more than 0.1% of C, 0.2-3% of Si, not more than 2% of Mn, 2.2-4% of Cu, 3-9% of Ni, 20-30% of Cr, 2-6% of Mo, 0.08-0.25% of N, 0.12-0.3% of Sn, at least one of 0-2% of Nb, 0-1% of Ti, 0-2% of Ta, 0-1% of Zr and 0-1.5% of V and remainder of Fe, and are obtained by solution heat treatment at 1,000.degree.-1,150.degree. C in such a manner that Cr- and Ni-equivalents lie within an area represented by the area ABCD shown in FIG. 1 of the accompanying drawings.

Abstract: Disclosed is an improved stainless steel in ferrite-austenite condition caused by solution heat treatment at a temperature of 1000.degree. - 1150.degree. C, composed of by weight percent, carbon up to 0.06%, silicon up to 1.0%, manganese up to 1.5%, nickel from 3.0% to 7.0%, chromium from 21.0% to 28.0%, copper up to 3.0%, molybdenum from 1.0% to 4.0%, boron from 0.0008% to 0.0080%, niobium from 0.08% to 0.7%, titanium from 0% to 0.5%, tantalum from 0% to 0.5%, zirconium from 0% to 0.5%, nitrogen up to 0.1%, and the remainder of iron and an inevitable amount of impurity, with the values of nickel equivalent and chromium equivalent calculated by the following equations:Nickel equivalent = 40(carbon % + nitrogen %) + 3(nickel %) + (copper %) + 2(manganese %)Chromium equivalent = (chromium %) + 5.2(silicon %) + 4.2(molybdenum %) + 4.5(niobium %) + 7.0(titanium %) + 3.0(tantalum %) + 13.