JPS6046308A - Carbon-contained graphite globule-forming agent for cast iron making - Google Patents

Abstract

PURPOSE:To prevent the generation of slag after globule-forming treatment by using the titled agent, which is made by mixing small amount of C with a solid solution comprising Si, Mg, rare earth elements, Cd, and balance Fe. CONSTITUTION:The titled agent is a solid solution comprising in wt%, 30-70 Si, 1-9.5 Mg, 4 less Ga, 7 or less rare earth elements, 0.5-4 C, and balance Fe, those additive Ca is limited to a small amount to be able to contain C as a substituted, and a part or whole of Si can be substituted by one or more of Ni, Cu, and Mn, if needed. With the use of this globule-forming agent, pinholes and slug-inclusions which are likely to be produced in case iron can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a graphite nodularizing agent used in manufacturing ductile cast iron and the like.

Pig iron, that is, cast iron, which is generally obtained by casting, contains a small amount of carbon and a considerable amount of manganese, sulfur, and phosphorus. White cast iron with a white fracture surface due to the inclusion of iron carbide, a mixture of these,
There is mottled cast iron, etc. All of these cast irons have good wear resistance.

It has the disadvantage that it does not have sufficient corrosion resistance or strength, and cannot be bent. In order to improve these drawbacks, malleable cast iron that is made malleable through heat treatment, tough cast iron that has been treated with copper scraps, and special cast iron that has properties similar to copper have been produced. One type of the above-mentioned special cast iron is cast iron in which graphite is spheroidized for the purpose of improving processing characteristics, cutting characteristics, tensile characteristics, etc., and special cast iron commonly called nodular cast iron. The spheroidal graphite is manufactured by treating graphite with magnesium or the like, and is observed as graphite exhibiting a fine spherical shape in cast iron, and is known to have a smooth outline.

The spheroidizing agent for obtaining the spheroidal graphite usually contains calcium in order to increase the product yield after the spheroidizing treatment.

This calcium tends to be the main cause of slag generated after cast iron is spheroidized, and the generation of slag tends to cause defects such as pinholes and gouges in the cast iron, resulting in defective castings.

The object of the present invention is to obtain a graphite spheroidizing agent that eliminates the drawbacks of the conventional means for obtaining spheroidal graphite, and to obtain cast iron that eliminates the generation of slag caused by calcium. The main focus is Furthermore, the present invention also aims to suppress the decarburization that occurs after the spheroidizing treatment of (2) and to prevent sink marks in cast iron caused by the decarburization.

In order to achieve the above object, the present invention is characterized by obtaining a carbon-containing graphite nodularizing agent for producing cast iron, which is a solid solution consisting of silicon, magnesium, rare earth elements, carbon, and the balance iron, and which contains only a trace amount of calcium. By simply mixing it, it is possible to obtain a cast product that maintains the same mechanical performance as conventional products and does not generate slag.

Hereinafter, the configuration of the present invention will be explained based on various embodiments.

(First Example) Table 1 shows examples of blending of various elements showing the first example of the present invention, where A is the composition of molten cast iron (base metal) and B is added as a graphite nodularizing agent. The alloy composition is shown, and C shows the composition of the molten metal after the spheroidization treatment.

Table 1 (Second Example) Table 2 shows the second example of the present invention, which shows the result of spheroidizing using the same method as in the first example with a slightly different blending ratio. The composition is shown.

Table 2 (Third Example) Table 3 shows the third example of the present invention, and also shows combinations of results obtained by performing spheroidization treatment while changing the blending ratio and treatment conditions.

Table 3: The reaction temperature in each of the above examples is 1500"C to 151"C.
The temperature is 5°C. The spheroidized molten metal is poured into a predetermined mold to obtain a spheroidal graphite cast iron product. On the other hand, in order to compare with each of the above examples, three sets of molten metal having the same composition as those of Examples 1 to 3 were separately prepared, and after reacting with three sets of graphite nodularizing agents shown in Table 4, molds were prepared. A spheroidal graphite cast iron product was obtained by pouring molten metal into the spheroidal graphite cast iron product.

Table 4 Table 5 shows the results of analysis and measurement of the chemical components and mechanical properties of the spheroidal graphite cast irons of Comparative Examples 1 to Comparative Examples III and Examples 1 to 3 obtained as described above. .

The difference between the above-mentioned Examples and Comparative Examples is that the Comparative Examples are conventional methods in which a considerable amount of calcium is mixed, whereas in the Examples according to the present invention, a trace amount of calcium is added and an appropriate amount of carbon is added. It's what I did.

The mechanical properties of the spheroidal graphite cast iron obtained as a result, that is, tensile strength, elongation, and hardness, were largely the same as those of the comparative example, indicating that it was sufficiently durable for practical use. Furthermore, from each of the examples of the present invention, the composition ratio of the carbon-containing graphite spheroidizing agent is 30 to 70% by weight of silicon, 1 to 9.5% by weight of magnesium, 4% by weight or less of calcium, and 7% by weight of calcium.
It has been found that it is suitable to consist of a solid solution consisting of a rare earth element of less than 0.5% by weight, 0.5 to 4% by weight carbon, and the balance iron. According to yet another example, it has been found that similar results can be obtained by replacing part or all of the silicon with at least one element selected from nickel, copper, and manganese.

As explained in detail above, the graphite spheroidizing agent according to the present invention prevents the generation of slabs after spheroidizing treatment by adding a very small amount of calcium and containing carbon instead. It has the great effect of being able to eliminate easy pinholes and slag, as well as providing a carbon-containing graphite nodularizing agent that does not impair the mechanical properties of cast iron products, such as tensile strength, elongation, and hardness. It is extremely useful in manufacturing applications.

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Claims (2)

[Claims] (1) 30-70% weight element and 1-9.5% weight
of magnesium, 4% by weight or less of calcium, 7% by weight or less of rare earth elements, and 0.5 to 4% by weight of carbon.
A carbon-containing graphite spheroidizing agent for producing cast iron, characterized in that it is composed of a solid solution consisting of the remainder iron. (2) A carbon-containing graphite nodularizing agent for producing cast iron according to claim 1, characterized in that part or all of silicon is replaced with at least one element selected from nickel, copper, and manganese. .