Method for producing mixed matrix structure as-cast spheroidal graphite cast iron

Abstract

The invention discloses a method for producing mixed matrix structure as-cast spheroidal graphite cast iron. A proper smelting technology and proper chemical components are selected for control, wherein an intermediate frequency furnace is used in molten iron smelting for single smelting, and a pig iron and scrap steel recarburization technology is adopted for producing base iron; a sandwich type package is used in a ladle, and the mass percents of Si, Mn, Cu, Ca and Ba in a casting are controlled; and after casting forming is conducted, high-temperature box opening is conducted. By the adoption of the method, the content range of pearlite ranges from 55% to 75%, the content of ferrite ranges from 25% to 45%, the content of cementite is zero, iron phosphide eutectic is in the first level, the graphite spheroidal rate reaches the second level, and the graphite sphere size is in the sixth level. According to the mechanical performance of a casting body of the mixed matrix structure as-cast spheroidal graphite cast iron, the tensile strength of the casting body can be larger than or equal to 600 Mpa, the ductility of the casting body is larger than or equal to 10%, the impact toughness of the casting body is larger than or equal to 25 J/cm<2>, the hardness HB of the casting body ranges from 180-250, and iron is used for replacing steel. In addition, technological processes are simple, control is easy, and the cost is reduced.

Description

technical field [0001] The invention relates to the field of production methods of nodular cast iron, in particular to the field of production of as-cast nodular cast iron with mixed matrix structure. Background technique [0002] In my country's national standards for ductile iron, only QT600-3 and QT900-2 are materials with a mixed matrix structure ductile iron tensile strength greater than 600Mpa, and their elongation is about 3%, and the QT900-2 grade usually needs to heat treat the casting to achieve. However, in the ductile iron produced by my country, some non-standard materials of QT600-10 have been produced. For example, Guangxi Yuchai Machine Parts Manufacturing Co., Ltd. has used this material to manufacture automobile chassis parts, and its tensile strength is greater than 600Mpa. The elongation rate is above 10%. Its strength and elongation are high, and it belongs to high-strength and high-ductility ductile iron materials. [0003] In order to improve the stre...

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Problems solved by technology

[0003] In order to improve the strength and toughness of ductile iron at the same time, expand the application range of ductile iron, and in order to make ductile iron can be used in more important places, many technical solutions for alloying ductile iron have appeared in the production of ductile iron with mixed matrix structure. However, most of these schemes use relatively expensive metals, such as nickel, vanadium, titanium, molybdenum, tin, etc. Although ductile iron with these elements can improve toughness, it is difficult to greatly improve toughness. Make the elongation of ductile iron reach more than 8%, which cannot reach the toughness material, and the production cost cannot be reduced