INGOT MAKING METHOD FOR ALLOY STEEL CONTAINING NIOBIUM

• Main Authors: MAENO SHIGEO, KODAMA HIDEYO, MORISADA TOKIO, AKAHORI KIMIHIKO
• Format: Patent
• Language: English
• Published: 11.05.1983
• Subjects: ALLOYS; CASTING; CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; POWDER METALLURGY; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PURPOSE:To eliminate the presence of Nb eutectic carbide during ingot making by casting molten metal of alloy steel contg. Nb, gathering the Nb eutectic carbide formed at that time near the central part in the radial direction of a mold, allowing the eutectic carbide to float upward and making the ingot while moving said carbide to the riser part of the cast ingot. CONSTITUTION:A melt of alloy steel contg., by weight %, 9-12Cr, and 0.02- 0.15 Nb is cast in a mold, and a cast ingot having <=1 ratio H/D between the height H of the body of the cast ingot and the diameter D in the position of roughly 1/2 the height of the body of the cast ingot is produced. The Nb eutectic carbide formed in this time is gathered near the central part in the radial direction of the mold to allow the eutectic carbide to float in the upper part of a cas ingot. Solidifying of the cast ingot is progressed while said carbide is moved to the riser part of the ingot. Then the eutectic carbide of Nb does not exist in the ingot and the cast ingot suitable for production of large-sized castings such as turbine roller shafts or the like is obtained.