Production method of toughness nodular cast iron

Abstract

The invention relates to a production method of toughness nodular cast iron, which includes four steps of: mixing and smelting raw materials, performing metamorphic modification, performing modification and tempering, and performing tempering thermal treatment. In the invention, on one hand, by means of rare earth, the nodular cast iron which has uniform and continuous distribution and high hardness and is not reduced in ductility, is produced, wherein the structural strength and toughness of the nodular cast iron work piece are greatly improved; on the other hand, through metamorphic treatment, anti-fatigue performance and wear resistance of the nodular cast iron work piece are comprehensively improved; besides, by means of the casting method, defects, such as internal stress concentration, cracks and sand holes, in the nodular cast iron work piece are reduced effectively, thus improving the quality and structural strength of the nodular cast iron work piece.

Description

technical field [0001] The invention relates to a production method of strong ductile ductile iron, which belongs to the technical field of casting processing. Background technique [0002] The furnace charge for the production of ductile iron is generally composed of newborn iron, returned ductile iron and ferroalloy. Scrap steel is rarely used in the furnace charge. In some factories, a small amount of scrap steel is added to the furnace charge to purify the molten iron and improve the purity of the molten iron. The mechanical properties of scrap steel in the charge are generally 0-10% by weight, which reduces the carbon content in molten iron, thereby reducing the carbon-silicon equivalent of cast iron, affecting the spheroidization rate and spheroidization grade of graphite, and resulting in The service performance and service life of ductile iron castings are greatly affected. At the same time, although the current ductile iron processing technology can meet the needs o...

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Problems solved by technology

[0002] The furnace charge for the production of ductile iron is generally composed of newborn iron, returned ductile iron and ferroalloy. Scrap steel is rarely used in the furnace charge. In some factories, a small amount of scrap steel is added to the furnace charge to purify the molten iron and improve the purity of the molten iron. The mechanical properties of scrap steel in the charge are generally 0-10% by weight, which reduces the carbon content in molten iron, thereby reducing the carbon-silicon equivalent of cast iron, affecting the spheroidization rate and spheroidization grade of graphite, and resulting in The service performance and service life of ductile iron castings are greatly affected. At the same time, although the current ductile iron processing technology can meet the needs of workpiece processing operations to a certain extent, the production cost is relatively high and the casting process is complicated, which leads to the current ductile iron processing technology. Cast iron workpieces have poor casting precision, low molding efficiency, and defects such as pores and cracks are likely to remain inside the casting after molding. Therefore, it is urgent to develop a new nodular cast iron and its matching casting process to meet actual production needs

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