Abstract: This invention relates to a steel composition comprising, expressed in percentages by weight: 0.25-0.35% C, 24-28% Cr, 10-15% Ni, 3-6% Mn, 1.75-2.50% Nb, 0.50-0.70% N, 0-0.30% Si, provided that C+N≧0.8%, the rest consisting mainly of iron and unavoidable impurities. The invention further relates to a method for making said compositions and valves produced from said compositions or using said method and exhibiting excellent mechanical strength and oxidation resistance at temperatures between 800 and 900° C.

Abstract: The invention concerns a high specification non-magnetic stainless steel which is corrosion resistant in physiological media and which can be produced at atmospheric pressure, characterized in that its composition in % by weight is as follows: Mn 15% to 24% Ti ≦0.020% Cr 15% to 20% Al ≦0.020% Mo 2.5% to 4% S ≦0.0020% N 0.6% to 0.85% B ≦0.020% V 0.1% to 0.5% Nb + Ta ≦0.5% C ≦0.06% Co ≦0.5% Ni ≦0.25% Cu ≦0.5% silica ≦0.25% and from 0 to 0.5% of each of elements Cu, Co and of the sum Nb+Ta, the remainder being constituted by iron and impurities, and in that its composition satisfies the following conditions: (%Cr)+2.5(%Mo)≦27  (I) (%Cr)+3.3(%Mo)≧26  (II); and Log(%N)+0.0605(%N)=−1.3+[125(%V)+80(%Nb)+52(%Cr)+19(%Mn)]×10−3−[4.