JPS6050144A - Alloy cast iron - Google Patents

Abstract

PURPOSE:To provide a alloy cast iron having the higher resistance to corrosion with a molten Al alloy than the conventional FC cast iron and other cast iron by adding the alkali metal salt of titanic acid and boron compd. and further Al to the molten cast iron. CONSTITUTION:The alkali metal salt of titanic acid (e.g.; lithium titaniate) and boron compd. (e.g.; borax) and further Al are added to the molten cast iron used thus far and the molten metal discharge from a melting device is cast to cast a cast iron alloy. The melting temp. in this stage is 1,550-1,800 deg.C, the tapping temp. is 1,500-1,650 deg.C and the casting temp. is 1,450-1,600 deg.C, which are higher than in ordinary conditions. The amt. of the alkali metal salt of titanic acid to be used in this stage is 1.5-10%, more particularly about 2.0-7.0% with respect to the FC component. The amt. of boron compd. to be added is about 0.5-3kg to 120kg molten cast iron. The content of C in the alloy cast iron is 2.5-4.0wt%, more particularly 3.0-3.8wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new composite alloy cast iron, and more particularly to a composite alloy cast iron made by adding an alkali metal titanate and a boron compound or further aluminum to molten cast iron.

The alloy cast iron of the present invention was discovered in the process of material research for special alloy cast iron that has heat resistance and corrosion resistance, and is an alloy cast iron that has particularly high durability against molten aluminum.

Conventionally, equipment for low-pressure casting and die-casting of nonferrous light metal alloys such as aluminum base metals, zinc alloys, magnesium alloys, and tin alloys, such as stalks, crucibles, thermal lightning protection tubes, and automatic heating ladles, etc. Ordinary cast iron with FC20-25 is used.

However, these ordinary cast irons suffer from a large amount of corrosion loss against, for example, molten aluminum, and cannot withstand long-term use. In addition, the quality of aluminum castings is degraded due to the contamination of iron and carbon components.

In view of the above facts, the present inventor has carried out a series of research into new materials to replace these ordinary cast irons, and has conducted research on conventionally known materials such as ductile cast iron, Mieburnite cast iron, and high aluminum cast iron (Kralfer cast iron, Alsilon cast iron). We have created a stalk for aluminum low-pressure casting from special cast iron, and conducted actual operations to investigate the problem.
Compared to the lifespan of ~6 days, the lifespan only increased by about 2 to 3 times.

Therefore, based on cast iron, it was necessary to improve the constitution of cast iron composite alloy cast iron.The present invention was completed by developing a new idea without being bound by the common sense of conventional casting engineering. In other words, by adding alkali gold titanate B salt to molten cast iron, it is possible to stably obtain a material that is much more resistant to corrosion against molten aluminum base metal than conventional FC cast iron or other cast irons. By setting the optimum blending ratio of and the appropriate range of R for the temperature conditions during cast iron manufacturing, composite alloy cast iron made by adding 1% aluminum to the molten cast iron containing alkali metal titanates can be made into cast iron as described above. By adjusting the optimal blending ratio, aluminum addition ratio, and optimal temperature range during composite alloy cast iron production, we have found that simply adding alkali metal titanate to molten cast iron can be effective and produce even better materials. found.

As a result of further research based on the above-mentioned new fruit, the inventor of the present invention found that when adding the above-mentioned alkali metal titanate or aluminum together with the above-mentioned alkali metal titanate to molten cast iron, when a boron compound is further coexisted, the desired product can be obtained. It was discovered that the structure of alloyed cast iron becomes more dense, and as a result, corrosion resistance and heat resistance are further improved, and the present invention has now been completed.

The alloy cast iron of the present invention will be explained below based on its manufacturing method.

In the present invention, an alkali metal titanate and a boron compound, or further aluminum are added to the molten cast iron.

The molten cast iron used in this case can be the one that has been conventionally used, such as fresh pig iron or partially used iron if necessary, and melting steel, ash, limestone, and a silicon source into the molten metal. It is molten cast iron. These components are appropriately mixed in consideration of the composition of the target alloyed cast iron to be obtained. A preferred composition is that the resulting cast iron alloy contains C: 2.5 to 4.0% by weight (hereinafter simply referred to as %), Si: 2.0 to 4%,
0%, Ti: 0.05 to 1%, C
:2.5~4.0, Si:2.2~3.8%, Cr20,2~2%, Mn:0.1~2%, Ti:0.05~
1%. The composition is such that Ai2: 1.5 to 4.0%. Preferred silicon sources include ferrosilicon, ferrochrome, and ferromanganese.

In the present invention, an alkali metal titanate and a boron element compound are added to the molten cast iron, or aluminum is further added, and the molten metal coming out of the melting device is poured to produce an alloy. The melting temperature at this time is 1550-1800℃,
Tapping temperature is 1500-1650℃, casting humidity 1450℃
~1600°C, preferably about 150Q~1600°C, which is higher than normal conditions.

The alkali metal titanate used in this case may be in the form of powder or lll, and examples of preferable examples include lithium titanate, sodium titanate, and potassium titanate, and salts of rubidium and cesium are suitable for practical use. It is hard to say that it is particularly preferable. The amount of the alkali metal titanate added is about 1.5 to 10%, preferably about 2.0 to 7.0%, based on the FC content. In addition, boron compounds include sodium borate (borax), boric acid strength,
Preferred examples include boric anhydride, ferroboron, etc., and the amount of these added is 0.0 to 120k of steel material (1.
It is about 5 to 3 kg.

The apparatus for producing cast iron and composite alloy cast iron of the present invention can be used not only for cubelas, which have been used for a long time, but also for electric melting furnaces, and in the case of cubelas, they are used in the form of lumps to prevent the scattering of alkali metal titanates. It is preferable.

The element C in the composite alloy cast iron used in the present invention is 2
．． The carbon ratio is preferably 3.0 to 3.8%. If the carbon content exceeds 4.0%, the alloyed cast iron becomes too hard, making post-processing such as cutting difficult, and becomes brittle, causing cracks to form during thermal shock when used in molten aluminum, for example. There is a fear. Furthermore, below 2.5%, the alloy cast iron structure becomes dominated by ferrite (pure iron), and ferrite tends to react with aluminum to form aluminum ferrite, resulting in it being leached into the molten aluminum. It becomes easy to corrode. Further, the content of Si is 2.0 to 4.0 mfi%, preferably 2.2 to 3.8 mfi%. Si is 4.0
%, the structure of the alloyed cast iron becomes a structure of graphite and ferrite 1 to 1 to 100% due to the properties of the graphitization-promoting element contained in 3i, and the ferrite becomes susceptible to corrosion as described above.

Furthermore, due to segregation, Sl tends to exist alone, and if it is eluted into the molten aluminum, it may cause foaming, which is generally referred to as foaming.

Moreover, if it is less than 2%, the heat resistance deteriorates, and for example, the heat resistance becomes a problem when used in molten aluminum.

T1 added from the alkali metal titanate is in the range of 0.05 to 1% by weight in Cubola operation.

It is generally known that corrosive gases such as oxygen gas or halogen gas enter the alloy cast iron through the platform graphite. Therefore, long mra and/or graphite in which these m fibers are connected can easily allow corrosive gases to enter, causing corrosion or cracks. Therefore,
Graphite fibers need to be refined into flakes, and Ti is very effective as a graphite refining agent, so that alloyed cast iron with good corrosion resistance can be obtained.

In addition, the presence of 0.2% to 2% by weight of C and/or 0.1% to 2% by weight of Mn as graphite stabilizing elements improves corrosion resistance, and also improves the heat resistance of alloyed cast iron. Therefore, it is preferable that ΔQ exists in the range of 1.5 to 4.0%.
Regarding aluminum, if more than 4.0% is added, the segregation of ΔQ or the flow of alloyed cast iron rB molten water will become poor, and for example, when casting a stalk, it may cause the production of cast moldings with insufficient cavities. .

Therefore, in order to improve the corrosion resistance against molten aluminum, it is necessary to make the composite alloy cast iron structure into a cementite base with the molecular formula Fe5C, which shows no reactivity with aluminum, but a completely cementite base is also hard. Because it is brittle, the cracks mentioned above become a problem. Therefore, a layered structure of cementite and ferrite that has both toughness,
It is necessary to have a pearlite structure. This pearlite structure also has as much cementite as possible to create a dense structure, which leads to improved corrosion resistance. In the present invention, this pearlite base can be obtained by particularly forming the above-mentioned specific structure.

The cast iron and composite alloy cast iron thus obtained were used to make stalks for low-pressure casting of aluminum alloys, and a durability test was conducted on them. As a result, they did not erode at all during continuous operation for 66 to 80 days and maintained their original shape. achieved an astonishing record. This fact cannot be compared with conventionally known cast irons such as ductile cast iron, Mieburnite cast iron, high aluminum cast iron, etc., such as Silar cast iron, Kralfer cast iron, Alsilon cast iron, and even T1 cast iron with Ti added. It is a high-performance one.

One of the reasons why the cast iron and composite alloy cast iron of the present invention have such excellent heat resistance and corrosion resistance is that in addition to the effect of reducing galvanic corrosion due to the synergistic effect of additives, the water flowability for molten metal is extremely low. It is thought that this is the case, but it is not yet clear.

The cast iron and composite alloy cast iron of the present invention have excellent heat resistance and durability against various alloy metals such as copper, tin, nickel, zinc, and lead, as well as crucibles and stalks for aluminum alloy casting. It is also useful as a material for these various molten metal objects. Furthermore, since this cast iron and composite alloy cast iron have good mechanical properties, they can be expected to have great utility and economical effects.

Hereinafter, the present invention will be specifically explained with reference to Examples.

However, in the following examples, parts indicate parts by weight.

Example 1 The blending amount at the time of charging into the Cubola furnace was 60 parts
30 parts of Shinryu, 15 parts of coke, and 10 parts of limestone.To this amount, 5 parts of potassium titanate and 0.6 parts of bentonite are mixed with water, molded into a lump, dried, and combined with the above mixture. Added to the top of the furnace. The melting conditions in the cupola are such that the melting temperature is from 1550℃ to 1800℃,
The hot water temperature is 1580°C. The thus obtained molten metal was placed in a forehearth, 1 to thulium part of boric acid was added to 100 parts of the molten metal, and cast at a pouring temperature of 1520°C.

Example 2 The blended amounts at the time of charging into the Cubola furnace were 60 parts of steel, 30 parts of new metal, 10 parts of waste pig iron, 15 parts of ferrosilicon, 13 parts of coke, and 10 parts of limestone. 0.7 part of bentonite was kneaded with water, formed into a lump, dried, and added to the top of the furnace together with the above blend.

The cupola melting conditions were the same as in Example 1. Also, 2.5 parts of ferroboron (for 9100 parts of Fe) was used in place of 1 part to silium of boric acid.

Example 3 It was carried out in the same manner as in Example 1. The blending amount is 60 parts of steel,
40 parts of new technology, 15 parts of coke, 2.5 parts of waste iron, 10 parts of ferrosilicon, 2 parts of ferrochrome, 2 parts of ferroboron,
5 parts of lithium titanate and 0.6 parts of bentoti (F
e9100 copies).

Example 4 A part of the molten metal produced in Example 1 was taken into the forehearth, and molten metal 1
00 parts, 5 parts of pure aluminum, which had been previously melted in a separate furnace, was added and cast into a mold.

Example 5 A portion of the molten metal produced in Example 2 was taken and cast by adding 3 parts of fused aluminum to 100 parts of the molten metal.

Example 6 The molten metal produced in Example 3 was taken into the forehearth and ? ? J thirst 10
To 0 parts, 4 parts of pure aluminum, which had been previously melted in a separate furnace, was added and cast.

Stokes for low-pressure casting of aluminum alloys were prototyped using Examples 1 to 6. The 1,000 ω of this stalk was measured in advance. On the other hand, a stalk of Fe12 was cast for use in a comparative example. This stroke was 30.2 ka. Continuous operation tests were conducted on the heat resistance, durability, and corrosion resistance of the cast iron and FC stalk of the present invention by using aluminum alloy casting operations in a low-pressure casting apparatus.

The results are shown in Table 1.

Supplementary Procedures 1 [: Book (inside) April 1977 6I1 1981 Patent Application No. 155827 +j26 Name of invention Alloy cast iron 3, sleeve 11 yo: Relationship with Ba case Patent applicant Otsuka Chemicals Co., Ltd. 4, Agent SP-Machicho 2 (), Higashi-ku, Osaka 10 II < Tsuru [Le 1
1., 11.06-2(X(-0!■(generation)(652)
'l Patent Attorney 3 Waza Eiji"""'x 5. Specification of the number of [1 i J,: Voluntary 6 Increasing expression flj] of the amendment order ZJ) Invention, i14 Detailed Explanation Section 8 Amendment Contents Correction Contents 1. 8-B-11, page 6, line 6, ``2°5-4-0'' is corrected to ``2°5-4.0''.

(that's all)

Claims (1)

[Claims] ■ An alloy cast iron made by adding an alkali metal titanate and a boron compound to molten cast iron. ■ Composite alloy cast iron made by adding alkali gold titanate, boron compounds, and aluminum to molten cast iron.