| 摘要 |
1,134,110. Producing steel. COMPAGNIE DES ATELIERS ET FORGES DE LA LOIRE (ST. CHAMOND-FIRMINY-ST. ETIENNE-JACOBHOLTZER. Dec.1, 1965 [Dec.24, 1964; Feb.17, 1965; March 26, 1965; April 5, 1965; Oct. 7, 1965], No.51039/65. Heading C7D. An oxidized mild steel melt, prepared in a steel making furnace or converter at a temperature above 1600‹ C. e. g. where oxygen is blown into the melt and containing a maximum of 0À03% C, is vacuum decarburized in a ladle or whilst being poured from ladle to ladle to reduce the maximum C content to 0À012% prior to final casting e. g. in an ingot mould. Any excess O is removed from the steel with a deoxidizer e. g. Al and/or Si (as Fe-Si) at the end of the vacuum treatment during which alloying additions may be also made e.g. Cr (as Fe-Cr, Si-Cr or CrO 3 ). The initial steel may be a plain carbon or an alloy steel e. g. containing Ni or Co. The steel melt contains at least 0À08% O when Ni, Co or other Group 8 metal is less than 1%, or at least 0À055% O when Ni, Co or other Group 8 metal is 1% or more. For final steels with low P and S content, the initial steel is prepared in an electric furnace. The steelcontaining vessel may be filled with CO diluted with a neutral gas. Oxygen may be introduced into the melt during the vacuum treatment in the form of a blown oxidizing gas e. g. using a hollow stopper-rod and/or an oxide or a carbonate e. g. as lump or powder form. For 3À1% Si steels, the final ingots may be normalized at 850‹ C, cold rolled in two stages with intermediate anneal in dry H 2 at 925‹ C, and re-annealed in dry H 2 at 117‹ C. to obtain a cube-on-edge structure. |
