JPH06108198A - Material having erosion resistance to molten metal - Google Patents

Abstract

PURPOSE:To provide a mold material hardly eroded by molten metal such as high temp. aluminum. CONSTITUTION:An atomized powder of a steel having a composition consisting of, by weight, <=0.7% C, <=15%, in total, of carbide-forming elements, such as Cr, Mo, V, and W, 0-3% each of Si, Mn, and Ni, and the balance Fe with inevitable impurities is mixed with the grains of hard inorganic compound, such as carbide, boride, and nitride, in the amount of 10-50% of the whole quantity, which is formed at <=1200 deg.C by a powder metallurgical method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material which is unlikely to be corroded by contact with molten metal of high temperature such as aluminum.

[0002]

2. Description of the Related Art Conventionally, as a die material for casting molten aluminum, a hot tool steel material such as SKD61 series and a material whose surface is nitrided have been widely used. For special places, use SUS44 for materials such as SKD61 series.
It is also practiced to fill up the 0C series. Furthermore,
In recent years, heat-resistant materials such as cemented carbide and ceramics have begun to be used.

[0003]

In the hot work tool steel SKD61 series material which is widely used as a mold for aluminum-based molten metal and the material whose surface is subjected to nitriding treatment, a portion contacting with the high-temperature aluminum molten metal is It was not able to withstand melting damage sufficiently. In addition to this, the demand for aluminum parts has recently increased to reduce the weight of automobile parts, etc., and since many of these are large and have complicated shapes, the temperature of the aluminum melt rises and erosion by the mold melt occurs. Is increasing.

For this reason, recently, overlay materials and various surface treatments have begun to be used, but their erosion resistance to high temperature molten aluminum has not been sufficient. Further, ceramics, which have begun to be used as a new material, are difficult to process at present, fragile, and expensive. The present invention is intended to realize a material which has excellent erosion resistance to molten metal such as aluminum and which can be cut without trouble.

[0005]

The aluminum corrosion resistant material of the present invention comprises steel powder and hard inorganic compound particles.
It is formed by the powder metallurgy method at a temperature of 00 ° C. or less.

The above hard inorganic compounds include carbides, nitrides,
Borides and oxides are suitable, for example TiN, W
Examples thereof include N, VN, TiC, WC, VC and Al ₂ O ₃ . In the present invention, one kind or a mixture of plural kinds of these powders having an average particle diameter of 300 μm or less is used.

The steel material for powders described above contains 0.7 wt% or less of C, a total amount of 15% or less of carbide forming elements such as Cr, Mo, V, and W, and Si of O or 3% or less, respectively.
It is composed of Mn and Ni, and the balance Fe and unavoidable impurities, which are pulverized by an atomizing method, and particles having a maximum particle size of 1000 μm and an average particle size of 200 μm or less are selected and used.

[0008]

[Operation] The mold made of the material thus obtained has less abrasion and wear even when it comes into contact with the flow of high temperature molten metal such as aluminum due to the excellent wear resistance of the hard inorganic compound particles, and There is little damage due to thermal shock, and it is possible to cut the mold.

Here, if the average particle size of the hard inorganic compound particles as the raw material is too large, not only the cutting work of the material becomes difficult, but also it becomes difficult to make a mold having a precise dimension, and the material is lacking. Since it becomes easy, the thickness is set to 300 μm or less.

Similarly, the smaller the average particle size of the powder of the hot working tool steel used as the raw material, the higher the toughness by suppressing the growth of crystals in the obtained material, and the hard inorganic compound particles. Is advantageous because the distribution of
The particle size is 0 μm or less and the maximum particle size is 1000 μm.

The ratio of the hard inorganic compound particles in the whole material is related to the melting loss rate of the material due to contact with a high temperature molten metal such as aluminum as shown in FIG. 1, and the amount of the hard inorganic compound particles is Owt%. Compared with those of 10 wt%, the melt loss volume ratio is reduced to 30% or less, and of 20 wt% is reduced to 10% or less, but above 50 wt% the melt loss volume ratio is not increased. Be flat. In addition to this, as the proportion of the hard inorganic compound increases, various properties of the material deteriorate, and the cutting process becomes difficult. Therefore, the ratio of the hard inorganic compound particles is set to 10 to 50 wt%.

The forming temperature of the material by powder metallurgy is
If it is too high, C, N, etc. will diffuse from the hard inorganic compound particles into the steel and the characteristics of the material will be markedly deteriorated.

C maintains excellent hardenability, tempering hardness and high temperature hardness and combines with components such as W, Mo, V and Cr to form a carbide. However, if the amount is too large, the toughness of the material decreases, and cracking particularly due to thermal shock occurs, so the upper limit is made 0.7 wt%.

Carbide-forming elements such as Cr, Mo, V, and W are added to maintain the high temperature strength of the material, but if the addition amount is too large, the toughness decreases, so the total amount is 15 w.
t% or less.

Si, Mn, and Ni are generally added to increase the toughness, but if they are too much, the toughness is lowered or the machinability is deteriorated.
wt%.

[0016]

EXAMPLE Various steels shown in Table 1 were pulverized by gas atomization to obtain powder raw materials having an average particle size of 54 to 150 μm and a maximum particle size of 1000 μm. This is 660m long
m, an outer diameter of 149 mm, and a wall thickness of 1.5 mm were filled, the inside was evacuated and sealed, heated to 1100 ° C., and hot extruded to a diameter of 60 mm. Samples each having a diameter of 30 and a length of 100 mm were cut out from these extruded materials, quenched at 1020 ° C., and tempered at 600 ° C.

[0017]

[Table 1]

These samples were immersed in molten aluminum at 810 ° C. ± 20 ° C. for 10 minutes and then pulled up to 20 ° C.
The results are shown in Table 1 together, which was allowed to cool for a minute and then repeated 18 times (total immersion time was 3 hours) to determine the melt damage property (volume reduction) of each sample by the molten aluminum.

In Examples 1 to 5, the powder raw materials of SKD61, SCM415 and SNC631 in the steel materials shown in Table 1 were mixed with hard inorganic compound particles having the material, size and amount shown in Table 2, and Hot extrusion was carried out by the same method, samples of similar dimensions were cut out, and heat treatment was carried out in the same manner. C of each of these steel materials is 0.7 wt.
%, The carbide forming element is 15 wt% or less, the average particle diameter of the hard inorganic compound particles is 300 μm or less, and the addition amount thereof is 50 wt% or less.

Comparative Example 1 is the same as Example 1 except that the average particle size of the hard inorganic compound particles exceeds 300 μm. In Comparative Example 2, the amount of hard inorganic compound particles added was 5
Same as Examples 3 and 4 except that it exceeds 0 wt%.

Comparative Examples 3 to 7 are steel materials SKH5 in Table 1.
1, SKH57, SPM60, SKD11, and SKS5 gas atomized powders mixed with hard inorganic compound particles having the material, size and amount shown in Table 2.
It is the same as the case of the sample of the material. In all of these steel materials, the amount of C exceeds 0.7 wt%,
In Nos. 5 and 5, the carbide forming element also exceeds 15 wt%.

Table 2 also shows the results of the immersion test for the molten aluminum of the samples of these Examples and Comparative Examples by the same method as that for the above-mentioned steel materials.

According to the results of this immersion test, none of the samples of the examples produced defects or cracks, and the volume reduction was significantly improved as compared with the same steel material to which the hard inorganic compound particles were not added. I was able to confirm the effect.

In the case of Comparative Example 1, although the volume reduction due to the immersion in the molten metal could be improved, fine defects due to the lack of the hard inorganic compound particles were recognized. In the case of Comparative Example 2, compared with Example 4, the improvement effect of the volume reduction due to the immersion in the molten metal was extremely small, but the mechanical strength was largely reduced. In the cases of Comparative Examples 3 to 7, although it was possible to improve the volume reduction due to the molten metal immersion, it was found that the sample itself cracked and could not be used as a mold.

[0025]

As described above, according to the present invention,
While preserving the resistance to thermal shock of hot work tool steels and the advantages that can be cut, which were conventionally used for molds, it was possible to significantly reduce the melting loss due to high-temperature aluminum melt.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the content of hard inorganic compound particles and the erosion volume ratio.

[Table 2]

Claims (1)

[Claims] 1. A steel having a maximum of 0.7 wt% or less C, a total of 15 wt% or less of carbide forming elements, 0 or 3% or less of Si, Mn, and Ni, and the balance of Fe and inevitable impurities. Atomized powder with a particle size of 1000 μm and an average particle size of 200 μm or less has an average particle size of 300.
Hard inorganic compound particles having a particle size of less than or equal to 10
A melt-melting-resistant material obtained by mixing wt% and molding at a temperature of 1200 ° C. or less by a powder metallurgy method.