Abstract: A method for manufacturing a bi-material sleeve is provided. The sleeve includes an annular outer sleeve and an annular inner sleeve bonded to each other. The bottom pouring of the outer sleeve is carried out in a casting space delimited by a wall of a first ingot mold and by an outer upwardly moveable wall of a second ingot mold concentric with the first. The moveable wall of the second ingot mold is raised so as to uncover the skin of the outer sleeve which has solidified thereagainst. The bottom pouring and the solidification of the inner sleeve are carried out in a casting space delimited by said skin and an inner stationary wall of said second ingot mold, the bonding of both sleeves being effected by diffusion between said sleeves. Forging and/or machining of one of said bonded sleeves are optionally carried out. A device for using this method and a sleeve produced by this method are also provided.

Abstract: A method for manufacturing a bi-material sleeve is provided. The sleeve includes an annular outer sleeve and an annular inner sleeve bonded to each other. The bottom pouring of the outer sleeve is carried out in a casting space delimited by a wall of a first ingot mold and by an outer upwardly moveable wall of a second ingot mold concentric with the first. The moveable wall of the second ingot mold is raised so as to uncover the skin of the outer sleeve which has solidified thereagainst. The bottom pouring and the solidification of the inner sleeve are carried out in a casting space delimited by said skin and an inner stationary wall of said second ingot mold, the bonding of both sleeves being effected by diffusion between said sleeves. Forging and/or machining of one of said bonded sleeves are optionally carried out. A device for using this method and a sleeve produced by this method are also provided.

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 steel composition comprising, expressed in weight percentages: 0.25-0.35% of C, 24-28% of Cr. 10-15% of Ni, 3-6% of Mn, 1.75-2.50% of Nb, 0.50-0.70% of N, 0-0.30% of Si, provided that C+N≧0.8%, the rest consisting mainly of iron and unavoidable impurities. The invention also concerns 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.