PRODUCTION OF HOMOGENEOUS STEEL MATERIAL

• Main Authors: NANUN MICHIHIKO, KUBOTA TAKESHI
• Format: Patent
• Language: English
• Published: 02.08.1982
• Subjects: CHEMISTRY; 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

PURPOSE:To eliminte the segregation of contained elements formed during casting and to form a homogeneous steel material by subjecting an ingot or slab of steel to primary hot working in a specific temp. region then holding the same at above specific temp. CONSTITUTION:An ingot or slab is subjected to primary hot working of >=20% reduction of area in an austenite temp. region of 1,200 deg.C or below or an austenite-ferrite two phase coexistence temp. region between Ar1 temp. and Ac3 temp. Thence, it is reheated to above the primary hot working starting temp. and is held at 1,000 deg.C or above for >=30min. By this treatment, segregation elements diffuse thoroughly. In succession to this, secondary hot working can be accomplished. When the coarse austenite crystal grains of steel are formed by the heating stage, it is possible to restore toughness by holding the ingot for >=30min at 1,000 deg.C after the primary hot working or cooling the ingot after the secondary hot working once to the Ar1 temp. or below, thence again reheating the same to the Ac3 temp.