KR20030087484A - A composition of compacted graphite iron ferrite - Google Patents

Abstract

PURPOSE: A composition for ferritic CGI (compacted graphite iron) cast iron, which improves economic feasibility and physical properties by controlling composing constituents is provided. CONSTITUTION: In a graphite cast iron comprising carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), chromium (Cr), copper (Cu) and magnesium (Mg), the composition for ferritic CGI (compacted graphite iron) cast iron comprises 3.6 to 3.8 wt.% of carbon, 2.3 to 2.7 wt.% of silicon, 0.25 to 0.4 wt.% of manganese, 0.05 wt.% or less of phosphorus, 0.015 wt.% or less of sulfur, 0.05 wt.% or less of chromium, 0.3 to 0.5 wt.% of copper, 0.007 to 0.15 wt.% of magnesium, 0.008 to 0.015 wt.% of lanthanum and a balance of iron.

Description

Ferrite CCI composition {A composition of compacted graphite iron ferrite}

The present invention relates to a ferrite-based CGI (Compacted graphite iron) composition, more specifically, carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), chromium In the graphite cast iron material consisting of (Cr), copper (Cu) and magnesium (Mg), by controlling the content of silicon, sulfur and magnesium, and by adding lanthanum (La), the control of residual magnesium without the use of dedicated equipment The present invention relates to an improved ferrite-based CGI composition which is easy, can be extended in the product injection time of the cast iron melt, and can be easily applied to a general casting site, and has increased toughness by ferrite matrix.

CGI (Compacted graphite iron) cast iron has a microstructure and characteristics in the intermediate position between gray cast iron and spheroidal graphite cast iron, and is characterized by 'worm-like' graphite particles when observed under an optical microscope. Compared with gray cast iron, CGI graphite particles are shorter, rounded in corners, have an aspect ratio of less than 10, and for gray cast iron, the aspect ratio is usually between 50 and 100. , See FIG. 1).

Normally, magnesium is added to make the above-mentioned CGI cast iron. The magnesium in the molten metal disappears at a rate of 0.001% / 5 minutes due to the fading action, so that the final content of magnesium is about 0.008. It was possible to stably produce CGI in the range of 0.018% by weight (see attached figure, FIG. 2).

Therefore, in order to stably control the residual magnesium content, after sampling a certain amount in the molten state by using the equipment of Sinter Cast company in Sweden, predicting the graphite behavior in the molten state by using its own program, the necessary inoculum and magnesium After supplying additionally, the method of injecting into the product after reconfirmation is currently the only manufacturing method that can be applied to mass production.

Due to the dissipation characteristics of magnesium as described above, at least 5 after inoculation of magnesium in the molten metal by using a dedicated device patented by Sinter Cast of Sweden as shown in Fig. It was very difficult to apply it in general casting site because it was troublesome to complete the injection of molten metal into the product within 10 minutes or more, especially in large castings. There was a difficulty, which resulted in the occurrence of significantly higher defects.

Inoculation of magnesium was determined in advance by experimentally predicting the residual amount of magnesium, and after 5 minutes of actual experiment, the desired CGI ash was not produced, and after about 10 minutes, all of the graphite was released into flaky graphite. In addition, in the case of large castings such as diesel engine blocks and heads, the success rate is low as 60% even when injected in the time within the above range, and since the solidification process of the molten metal continues to be slow even after the injection of the product, the productivity is poor, so that the mass production is somewhat applied. There was a problem.

Therefore, the inventor of the present invention, as a result of research efforts to solve the above problems, carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), chromium (Cr), copper ( In graphite cast iron material consisting of Cu) and magnesium (Mg), by controlling the content of silicon, sulfur and magnesium, and adding lanthanum (La), it is easy to control the residual magnesium without using the existing equipment. In addition, by extending the injection time of the molten metal in the product can be easily applied in the general casting site, it was found that the ferritic base can increase the toughness to complete the present invention.

Accordingly, an object of the present invention is to provide a ferritic CGI cast iron composition having improved economic properties and properties by adjusting the components.

1 is an optical microscope tissue photograph before etching of cast iron prepared according to Example 1,

FIG. 2 is a photograph of an optical microscope after etching of cast iron prepared according to Example 1; FIG.

3 is an optical microscope tissue photograph before etching of the cast iron prepared according to Example 2,

4 is an optical micrograph of the cast iron prepared according to Example 2 after etching,

5 is a view simply showing a conventional manufacturing apparatus for graphite cast iron.

The present invention is a graphite cast iron containing carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), chromium (Cr), copper (Cu) and magnesium (Mg), 3.6-3.8 wt% of carbon, 2.3-2.7 wt% of silicon, 0.25-0.4 wt% of manganese, 0.05 wt% or less of phosphorus, 0.015 wt% or less of sulfur, 0.05 wt% or less of chromium, 0.3-0.5 wt% of copper, magnesium 0.007-0.15 A ferritic CGI cast iron composition composed of weight percent, lanthanum from 0.008 to 0.015 weight percent, and residual iron.

The present invention will be described in more detail as follows.

The present invention is to control the content of silicon, sulfur and magnesium, and by adding lanthanum (La), it is easy to control the residual magnesium without using a dedicated equipment, can be easily applied in the general casting site, increased toughness It relates to a ferritic CGI cast iron.

The present invention increases the content of silicon (Si) compared to the prior art, thereby decomposing the known pearlite and not adding tin (Sn) to promote ferrite, and sulfur (s). By limiting the content of compared to the prior art to prevent the production of MnS and MgS compounds to enable the production of stabilized CGI. In addition, unlike the prior art, while the residual amount of magnesium (Mg) is reduced compared to the prior art, it is a characteristic part of the present invention that the production of CGI is made easier by newly adding lanthanum (La). In this case, the amount of lanthanum added is 0.008. ~ 0.015% by weight, if the added amount is less than 0.008% by weight, CGI is difficult to form (unsaturated graphite), and when it exceeds 0.015% by weight, a large number of spheroidal graphite iron is produced due to excessive spheroidization rate, resulting in poor castability. It is done.

Table 1 shows the components and contents of the conventional graphite cast iron and the components and contents of the CGI of the present invention.

The CGI cast iron of the present invention composed of the above components can increase the output by designing a higher explosion pressure than the existing engine as the tensile strength is increased, fuel economy by compactness of the block by increasing the high power and material strength You can expect improvement.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which are not intended to limit the present invention.

Examples 1-2

Based on the results of preliminary experiments on the CGI cast iron composed of the components of Examples 1 to 2 of Table 2 based on the results obtained in a preliminary experiment without using a dedicated apparatus of SinterCast, the content of carbon and Mn, S, P, Cr in the bath were adjusted. After loading the ladle with the rest of the alloying components (Si, Mg, Cu, La), the raw water was injected into the ladle at about 1530 ℃. At this time, lanthanum and Mg are charged in the form of an alloy with the following component ratios. That is, 44.92% by weight of Si, 2.06% by weight of Mg, 0.49% by weight of Ca, 8.85% by weight of La, and 0.20% by weight of Al. Each of the components loaded with the above content is subjected to a melt process. And partly removed so that the residual amount in the final product falls within the content range of each component of the cast iron composition of the present invention. Thereafter, the ladle had a delay time of 10 minutes after the explosion reaction of Mg, and was prepared by injecting the product into a mold.

The physical properties and casting properties of the specimens and the comparative examples prepared based on the composition of the examples were measured. As a result, the tensile strength was increased to 25 kg / ㎜ in Comparative Example 1, 40 ㎏ / ㎜ in Example 1, 42 ㎏ / ㎜ in Example 2, according to the design explosion pressure of Comparative Example 1 is about 160 bar On the contrary, Examples 1 to 2, which are CGI cast iron of the present invention, can be designed up to 180 bar explosion pressure. Therefore, the strength per unit area is increased by about 60% or more, and the elongation is also about 15% by ferriticization (increasing the toughness by about 10% more than the comparative material). Since it is possible to reduce the size, it is possible to reduce the size of the block by about 15% in actual application, which has the advantage of making the block size compact. In addition, compared to Comparative Example 2 in the manufacture of blocks of the same type castability was tested by the method of easy CGIization and reduction of defect rate, etc. As a result, the desired CGI cast iron structure can be obtained without using the existing equipment SinterCast company Compared with the existing method, the melt injection time was extended from about 1 minute to 15 minutes without the addition of additional inoculum treatment.

As described above, according to the present invention, it is easy to control the residual magnesium without using the existing dedicated equipment, and can be easily applied to the general casting site by extending the injection time of the molten metal in the product, and ferrite bases. To increase toughness. Therefore, it is possible to design a high explosion pressure of the engine, thereby increasing the output of the engine, and it is possible to optimize the block size in accordance with the increase in high power and material strength, which can reduce the block size by about 15%. Therefore, the fuel economy can be improved.

Claims (1)

In graphite cast iron containing carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), chromium (Cr), copper (Cu) and magnesium (Mg), carbon 3.6 to 3.8 wt%, silicon 2.3-2.7 wt%, manganese 0.25-0.4 wt%, phosphorus 0.05 wt% or less, sulfur 0.015 wt% or less, chromium 0.05 wt% or less, copper 0.3-0.5 wt%, magnesium 0.007-0.15 wt%, Lanthanum 0.008 to 0.015% by weight of ferritic CGI cast iron composition, characterized in that consisting of.