Low-temperature nodular cast iron material for fire hydrant and preparation method thereof

Abstract

The invention relates to high-performance low-temperature resistant nodular cast iron for a fire hydrant and a preparation method thereof, and belongs to the technical field of cast alloys. A high-performance low-temperature resistant nodular cast iron alloy for the fire hydrant comprises the following chemical components in percentage by weight: 3.6-3.9% of C, 1.9-2.3% of Si, Mn less than 0.2%, P less than 0.04%, S less than 0.015%, Cu less than 0.05%, Cr less than 0.04%, Sb less than 0.003%, residual Mg of 0.040-0.045%, 0.01-0.02% of RE, and the balance of Fe. The preparation method comprises the steps of: (1) smelting; (2) spheroidizing, inoculation and pouring; and (3) casting aftertreatment. The spherifying grade of the nodular cast iron prepared by the preparation method is 1-2 grade; the spherifying rate is not lower than 95%; the ferrite content is not lower than 95%; the tensile strength is not lower than 400 MPa; the yield strength is not lower than 240 MPa; the ductility is not lower than 18%; and the low-temperature (20-40 DEG C) shock resistance is not lower than 17 J. The produced fire hydrant casting is better in mechanical performance, can satisfy normal working demands under low-temperature environment, and is prominent in beneficial effects.

Description

technical field [0001] The invention relates to a high-performance low-temperature-resistant ductile iron material for a fire hydrant and a preparation method thereof, belonging to the technical field of casting alloys. Background technique [0002] Ductile cast iron is a cast iron material with spherical graphite obtained through inoculation and spheroidization. It has excellent mechanical properties, processing properties, wear resistance, shock absorption properties and low production costs. Its comprehensive properties are similar to steel. Because of its excellent performance, it is successfully used to cast parts with complex stress, high strength, toughness and wear resistance, such as auto parts, cast iron pipe fittings, wind power parts, machine tool parts, engine crankshafts, etc. However, the disadvantage of ordinary nodular cast iron is that it has poor low-temperature impact resistance, so it is subject to certain restrictions in terms of application to workpiec...

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Problems solved by technology

The material of traditional fire hydrant accessories is generally made of gray cast iron HT200. In a low temperature environment, especially for cities in the northern cold regions, the performance of the material used is affected by the low temperature, which will make outdoor fire hydrants, especially above-ground outdoor fire hydrants, prone to accidents. Brittle cracking creates safety hazards for urban fire protection

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