High-strength and high-temperature resistance nodular cast iron, and casting technology of nodular cast iron pipe

Abstract

The invention relates to a high-strength and high-temperature resistance nodular cast iron. The high-strength and high-temperature resistance nodular cast iron comprises, by weight, 10-25% of foundryreturn, 10-25% of primary iron, 0.1-1% of iron-nickel alloy, 0.5-3.5% of manganese-iron alloy, 1-7.5% of tungsten-molybdenum alloy, 1-3.5% of a carburant, 1.1-3.6% of a modifier, 1-3% of a spheroidizer, 1-3% of an inoculant, 0.5-2% of rare earth, and the balance of scrap steel. The casting method includes the following steps: raw material melting, modifying tempering, ladle pretreatment, temperingcasting and modifying heat treatment. Rare earth elements are used to improve the distribution uniformity of the metallographic structure in nodular cast iron in order to improve the hardness of thenodular cast iron without lowering the elongation and toughness, modifying and tempering treatments are performed to comprehensively improve the fatigue resistance and the wear resistance of a spheroidal graphite cast iron workpiece, and a casting technology of the nodular cast iron can effectively reduce the internal stress concentration, cracks, small holes and other defects of the nodular castiron workpiece and improve the product quality and the structural strength of the nodular cast iron workpiece.

Description

technical field [0001] The invention relates to a casting process of high-strength and high-temperature-resistant ductile iron and ductile iron pipe fittings, belonging to the technical field of casting processing. Background technique [0002] At present, cast iron pipe fittings are often produced with ductile iron as the base material. Although it can effectively meet the needs of use, it is also found in use that cast iron pipe fittings processed through traditional ductile iron formula and casting technology have pipe wear resistance on the one hand. , Structural strength, structural toughness, high temperature resistance and thermal expansion resistance are relatively poor. On the other hand, it also leads to low efficiency in pipe casting operations, and defects such as trachoma, cracks and stress concentration are prone to exist inside cast iron pipes, which seriously It affects the reliability and service life of cast iron pipe fittings. Therefore, in response to thi...

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Problems solved by technology

[0002] At present, cast iron pipe fittings are often produced with ductile iron as the base material. Although it can effectively meet the needs of use, it is also found in use that cast iron pipe fittings processed through traditional ductile iron formula and casting technology have pipe wear resistance on the one hand. , Structural strength, structural toughness, high temperature resistance and thermal expansion resistance are relatively poor. On the other hand, it also leads to low efficiency of pipe casting operations, and defects such as trachoma, cracks and stress concentration are prone to exist inside cast iron pipes, which seriously It affects the reliability and service life of cast iron pipe fittings. Therefore, in response to this problem, it is urgent to develop a new ductile iron for cast iron pipe fittings and its matching casting process to meet the needs of actual production and use.

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