JPH06330233A - Corrosion resistant and wear resistant alloy for molten aluminum - Google Patents

Abstract

PURPOSE:To obtain a corrosion resistant and wear resistant alloy having excellent corrosion resistance to molten aluminum contg. activated Al atoms by specifying the compsn. constituted of C, Si, Mn, Ni, Cr, Mo, W, V and Fe. CONSTITUTION:This alloy is a corrosion resistant and wear resistant alloy for molten aluminum contg., by weight, 1.5 to 3.0% C, 0.5 to 2.0% Si, 0.5 to 2.0% Mn, <=0.1% Ni, 3.0 to 7.0% Cr, 1.0 to 5.0% Mo, 1.0 to 5.0% W and 1.0 to 6.0%. V and furthermore contg., at need, 1.0 to 10% Co, and the balance substantial Fe and shows excellent high temp. hardness and corrosion resistance at a using temp. of about 650 to 700 deg.C, i.e., the Al melting temp. In this alloy, the penetration of Fe atoms into Al is suppressed by prescribed content of Si, the content of Ni forming solid solution with Al is controlled, and, furthermore, high hardness carbides having low wettability for Al such as Cr, Mo, W and V are formed, so that excellent characteristics are shown.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion-resistant and wear-resistant alloy used for members that come into contact with molten aluminum or its alloy.

[0002]

2. Description of the Related Art In order to improve the corrosion resistance of a steel sheet, a surface-treated steel sheet having a surface of the steel sheet plated with molten aluminum and its alloy (hereinafter, simply referred to as aluminum) is manufactured. After the surface of the steel sheet is activated, the steel sheet is immersed in a plating bath of molten aluminum for plating.

A sink roll for supporting the steel plate in a rotating state is installed in the plating bath. The roll is required to have not only wear resistance but also corrosion resistance to corrosive molten aluminum. Conventionally, Cr-containing cast iron or stainless steel has been used as such roll material.

[0004]

However, the melting temperature of aluminum in the plating bath is 650 to 700 ° C.
Since the Al atoms are activated, there is a problem that the roll surface is significantly damaged, the corrosion rate is high, and the life is short. This is because the activated Al atom easily diffuses on the roll surface, and the Al solid solution formed by this easily falls off from the matrix.

The present invention has been made in view of the above problems, and an object thereof is to provide a corrosion-resistant and wear-resistant alloy having excellent corrosion resistance against molten aluminum.

[0006]

The present invention has the following features to attain the object mentioned above. That is, the corrosion-resisting and wear-resisting alloy according to claim 1 of the present invention has a chemical composition of wt.
: 1.5-3.0%, Si: 0.5-2.0%, M
n: 0.5 to 2.0%, Ni: 0.1% or less, C
r: 3.0 to 7.0%, Mo: 1.0 to 5.0%, W
: 1.0 to 5.0%, V: 1.0 to 6.0%, and the balance substantially Fe.

The corrosion-resistant and wear-resistant alloy according to claim 2 of the present invention has a chemical composition of wt% and C: 1.5 to 3.0%.
Si: 0.5-2.0%, Mn: 0.5-2.0%, N
i: 0.1% or less, Cr: 3.0 to 7.0%, M
o: 1.0 to 5.0%, W: 1.0 to 5.0%, V
: 1.0 to 6.0% Co: 1.0 to 10% and the balance substantially Fe.

[0008]

The chemical composition of the corrosion resistant and wear resistant alloy of the present invention is limited for the following reasons. The unit is% by weight. C: 1.5 to 3.0% C mainly combines with Fe, Cr, Mo, W and V to form a carbide. This carbide not only improves wear resistance but also exhibits low wettability with respect to molten aluminum and suppresses corrosion by molten aluminum. If it is less than 1.5%, the amount of carbides generated during casting is small, and remarkable corrosion resistance cannot be expected. On the other hand, if it exceeds 3.0%, the amount of carbide produced becomes excessive and the material becomes brittle.

Si: 0.5 to 2.0% Since Si is stably associated with Fe atoms, it is possible to prevent Fe atoms from melting into molten aluminum. If it is less than 0.5%, such action is insufficient and the flowability of molten metal during casting is deteriorated. On the other hand, if it exceeds 2.0%, the above-mentioned action is improved, but the material becomes brittle.

Mn: 0.5-2.0% Mn combines with S to form MnS and suppresses embrittlement of the material due to S. If it is less than 0.5%, such an effect is insufficient, while if it exceeds 2.0%, the hardness becomes too high and it becomes brittle. Ni: 0.1% or less Since Ni does not form a carbide, it does not have the effect of suppressing the erosion of molten aluminum and the effect of suppressing the penetration of Fe atoms into the molten aluminum. Further, since a solid solution is formed with Al, the diffusion rate of Al is improved. Therefore, Ni
The smaller the value, the better. With the material of the present invention, the content is limited to 0.1% or less.

Cr: 3.0 to 7.0% Cr combines with C and other carbide-forming elements to precipitate carbides in the matrix, effectively reducing wettability with molten aluminum. The free energy of formation of Cr carbide is Fe
Since it is lower than that of carbide (Fe ₃ C), the amount of Cr / Fe carbide produced is large, and Fe in molten aluminum is
Can be suppressed. If it is less than 3.0%, the effect is insufficient, while if it exceeds 7.0%, the amount of coarse eutectic Cr carbide becomes excessive, and the corrosion resistance to aluminum is rather lowered. Further, crystallization of VC carbide, which has a greater erosion suppressing effect, is suppressed.

Mo: 1.0 to 5.0% Mo combines with C to form Mo ₂ C carbide, which effectively reduces wettability with molten aluminum. Further, high hardness can be maintained even in a high temperature use environment, which contributes to improvement of wear resistance. If it is less than 1.0%, this action is insufficient, while if it exceeds 5.0%, the amount of carbides becomes excessive and the material becomes brittle.

W: 1.0 to 5.0% W combines with C and other carbide forming elements to form carbides, effectively reducing the wettability with molten aluminum. Further, the presence of W carbide makes it possible to maintain the high temperature hardness, which contributes to the improvement of wear resistance. If it is less than 1.0%, the effect is insufficient, while if it exceeds 5.0%, the material becomes brittle and macrosegregation easily occurs in centrifugal force casting, which impairs the uniformity of the material.

V: 1.0 to 6.0% V combines with C to form V carbide and effectively lowers wettability with molten aluminum. Further, the presence of the V carbide makes it possible to maintain the high temperature hardness and contributes to the improvement of wear resistance. If it is less than 1.0%, such an effect is insufficient, while if it exceeds 6.0%, the material becomes brittle and macrosegregation easily occurs in centrifugal force casting.

Co: 1.0 to 10.0% Co combines with C to form Co carbide and increases the solid solubility of other carbide forming elements in the matrix. Therefore 65
In a use atmosphere of 0 to 700 ° C., high temperature hardness is maintained and wear resistance is effective. If the Co content is less than 1%, the above effect is small, whereas if it exceeds 10%, the effect is saturated and it is economically disadvantageous.

In the alloy of the present invention, in addition to the above alloy components, the balance is substantially Fe. Since P and S make the material brittle, it is preferable that the content is small, and it is preferable to keep the content of P and S at 0.1% or less. The corrosion-resistant and wear-resistant alloy of the present invention is not limited to a sink roll for steel plate plating, and various wear-resistant mechanical members that come into contact with molten aluminum, such as a pumping stalk of molten aluminum in a die casting machine, a plunger sleeve in the injection section, and the like. Of course, it can also be used for a sprue sleeve. The sink roll is usually formed by centrifugally casting a cylindrical or cylindrical roll body with the roll material, and fixing shaft members made of forged steel or Cr-containing cast iron to both ends of the roll body.

[0017]

EXAMPLE An alloy having the chemical composition shown in Table 1 below was melted,
Centrifugal die casting at a casting temperature of 1450 ° C and a die rotation speed of 700 rpm, an outer diameter of 630 mmφ, a wall thickness of 50 mm, and a length of 2
A 000 mm sleeve (roll body) was obtained. Sample No. 1 to 4 are Examples, 6 to 9 are Examples, and No. 5,
No. Reference numeral 10 is a conventional example (high Cr cast iron).

[0018]

[Table 1]

From the sleeve, a test piece (20 mm × 2
0 mm × 20 mm) was sampled, and the surface hardness was measured, and in order to investigate the corrosion resistance to molten aluminum, this was immersed in a molten aluminum alloy (Al-1 wt% Si) held at 680 ° C. in a graphite crucible, Hold for 48 hours. Then, the sample was taken out and the damage depth on the sample surface was measured. The results are shown in Table 2 together with the surface hardness.

[0020]

[Table 2]

From Table 2, No. 1-4 and 6-
It is presumed that No. 9 has higher hardness than Conventional Examples 5 and 10 and has excellent wear resistance. In addition, the corrosion resistance was scarcely eroded, and the maximum erosion depth was 0.1 mm or less. On the other hand, in the conventional example, all six surfaces were damaged, and the maximum erosion depth was 3 mm. FIG. 1 shows 10
The hardness at 0 ° C. to 800 ° C. is the same as that of the example No. 1
Alloy of Comparative Example No. 10 is a graph of high temperature hardness measurement results comparing 10 alloys. From this graph, it is understood that the alloy of the present invention has higher hardness at any temperature than the comparative alloy. That is, the melting temperature of aluminum is 650
It maintains high-temperature hardness at operating temperatures of up to 700 ° C and thus exhibits wear resistance.

[0022]

As described above, the corrosion-resistant and wear-resistant alloy for molten aluminum of the present invention contains Si in an amount of 0.5 to 2.0% to suppress the penetration of Fe atoms into molten aluminum. The content of Ni forming a solid solution is suppressed to 0.1% or less, and a predetermined amount of Cr, Mo,
Since W and V were contained to form a high hardness carbide having low wettability with respect to molten aluminum, not only wear resistance due to the high hardness carbide but also excellent corrosion resistance against molten aluminum could be ensured. .

[Brief description of drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
It is a contrast graph of hardness at 00 ° C.

Claims (2)

[Claims] 1. The chemical composition, in% by weight, is C: 1.5-.
3.0%, Si: 0.5 to 2.0%, Mn: 0.5 to
2.0%, Ni: 0.1% or less, Cr: 3.0 to
7.0%, Mo: 1.0 to 5.0%, W: 1.0 to
A corrosion-resistant and wear-resistant alloy for molten aluminum, characterized in that 5.0%, V: 1.0 to 6.0% and the balance substantially Fe. 2. The chemical composition in% by weight, C: 1.5-.
3.0%, Si: 0.5 to 2.0%, Mn: 0.5 to
2.0%, Ni: 0.1% or less, Cr: 3.0 to
7.0%, Mo: 1.0 to 5.0%, W: 1.0 to
5.0%, V: 1.0 to 6.0% Co: 1.0 to 1
Corrosion-resistant wear-resistant alloy for molten aluminum, characterized in that 0% and the balance consist essentially of Fe.