Low-carbon CrNiMo gear steel and banded structure control method thereof

• Main Authors: ZHU TIANHAO, YANG SHIZHAO, GAO HUAYAO, ZHOU ZHAN, YU JIE
• Format: Patent
• Language: Chinese; English
• Published: 28.01.2022
• Subjects: ALLOYS; 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; PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OFWROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

The invention discloses low-carbon CrNiMo gear steel and a banded structure control method thereof. The low-carbon CrNiMo gear steel comprises the following chemical components in percentage by weight: 0.14-0.22% of C, 0.17-0.35% of Si, 0.50-0.90% of Mn, 1.50-1.80% of Cr, 1.40-1.70% of Ni, 0.25-0.35% of Mo, 0.020-0.045% of Al, less than or equal to 0.20% of Cu, less than or equal to 0.015% of P, less than or equal to 0.015% of S, less than or equal to 1.5 ppm of [H], less than or equal to 0.035% of As, Sn, Pb, Sb and Bi, 70-150 ppm of [N] and the balance being iron and other inevitable impurities. A manufacturing method comprises the steps of molten steel smelting, die casting steel ingot pouring, forging and heat treatment. According to the invention, molten steel purity is improved by controlling a molten steel refining process; a die casting pouring process and a steel ingot cooling process are improved to relieve composition segregation; by increasing steel ingot forging heating temperature and prolonging