Bismuth-containing inoculating agent for cast iron and preparation method of inoculating agent

Abstract

The invention discloses a bismuth-containing inoculating agent for cast iron and a preparation method of the inoculating agent. The inoculating agent comprises, by weight percentage, 60-70% of silicon, 1-5% of bismuth, 1-3% of calcium, 1-5% of aluminum, 2-7% of a mixed rare earth metal element, and 20-30% of iron. The bismuth-containing inoculating agent for the cast iron can be applied to variousgray iron casting production processes; by adding in the bismuth element, iron phosphide eutectic is decreased and decomposed, the reverse chill effect of a casting is inhibited, the fracture surfacesensitivity of the casting after inoculating is lowered, the graphite form is changed, the rate of spheroidization is increased, and the ferrite content in a casting matrix structure is remarkably increased; by adding in the rare earth metal element, the effects of evolving molten iron, increasing the supercooling degree, and promoting pearlite forming and refining crystalline grains are achieved; and by controlling the content of aluminum and calcium, aluminum and calcium oxide in the molten iron is within a reasonable content range, inoculating interference of the aluminum and calcium oxideon other elements is prevented, and the mechanical performance and the easy-to-machine performance of the casting are effectively improved.

Description

technical field [0001] The invention relates to a bismuth-containing inoculant for cast iron and a preparation method thereof, belonging to the technical field of casting. Background technique [0002] Cast iron is an iron-carbon alloy with a carbon content greater than 2.1%. It is obtained by remelting cast iron (part of steelmaking pig iron) in a furnace, adding ferroalloy, scrap steel, and returned iron to adjust the composition. The difference from pig iron is that cast iron is secondary processing, mostly processed into cast iron. Iron castings have excellent castability and can be made into complex parts, and generally have good machinability. In addition, it has the characteristics of good wear resistance and shock absorption, and low price. [0003] At present, the following measures are often taken to improve the performance of gray cast iron: [0004] (1) Reasonable selection of chemical composition [0005] The carbon content of gray cast iron is mostly 2.6% t...

AI Technical Summary

Problems solved by technology

[0012] The existing inoculation treatment has the following disadvantages: 1. The composition of the mechanically mixed inoculant is uneven, there is component segregation, and the performance of the produced castings is inconsistent; 2. The actual use effect of the mixed inoculant is often not as good as the effect of using a single inoculant Obviously, the due effect of the elements in the inoculant cannot be played well; 3. The inoculation effect of the higher calcium and aluminum content on the molten iron is poor, and the calcium and aluminum have a strong reducing effect, and the sulfur in the molten iron React with oxygen to form oxide slag, affecting the quality of molten iron