JPH11131193A - Chisel for refractory crushing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chisel for refractory crushing, excellent in fatigue strength, fatigue failure, wear resistance, etc., particularly at high temp. SOLUTION: This chisel for refractory crushing has a composition consisting of, by weight, 0.20-0.60% C, <0.8% Si, 0.1-2.0% Mn, <=0.020% P, <=0.030% S, 2.0-9.0% Cr, 0.10-6.0% Mo, 0.10-6.0% W, 0.01-2.5% V, and the balance Fe with inevitable impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory crushing chisel which is suitable for crushing refractories such as a tapping ladle and a ladle of a blast furnace, particularly a high temperature refractory.

[0002]

2. Description of the Related Art As shown in FIG. 1, a tapping gutter for a blast furnace has a permanent refractory 2 lined with an irregular refractory 3 inside a permanent refractory 2. Since the slug flows, the irregular-shaped refractory 3 lining the inner surface is worn or chemically deteriorated. Moreover, since the cooling and heating are repeated by switching of tapping etc., this irregular refractory 3 is also deteriorated by this. As shown in FIG. 1, the wear and deterioration are large in the slag line portion 4 and the metal line portion 5, and when the refractory in these portions is thinned, the deteriorated irregular refractory is crushed and dismantled, and then removed. A new irregular refractory 3 is lined inside the gutter 1.

[0003] Crushing of the deteriorated refractory is performed by attaching a chisel 6 to the tip of a breaker of a dismantling device as shown in FIG. 2 and moving the chisel 6 up and down. The chisel 6 is available in various shapes, and the shape of the tip is straight as shown in FIG. 3a, straight from the middle as shown in b, c And a tip having a triangular tip as shown in d (see Japanese Patent Application No. 8-91257).

Conventionally, this refractory crushing chisel has been manufactured according to JIS.
SCM440 (C: 0.38 to 0.43%, Si:
0.15 to 0.35%, Mn: 0.60 to 0.85%,
P, S; ≦ 0030%, Cu: ≦ 0.30%, Ni: ≦
0.25%, Cr: 0.90 to 1.20%, Mo: 0.
15 to 0.30%, the balance being Fe). However, this refractory crushing chisel has a great abrasion when used at a high temperature, and its tip is deformed or bent at the tip as shown in FIG. Time could not be used.

On the other hand, Japanese Patent Application Laid-Open No. 61-213349 discloses that C: 0.20 to 0.85 which is similar to the component composition of the present invention.
%, Si: 2.0% or less (0.80 in case of hot work tool steel)
1.50%), Mn: 0.1-2.0%, P: 0.02
0% or less, S: 0.0030% or less, Cr: 2.0 to 1
5.0%, and Mo: 0.10 to 6.0%, W: 0.
10 to 6.0%, V: one or more of 0.01 to 2.5%, and if necessary, REM:
0.001 to 0.60%, Nb: 0.01 to 1.5%,
Ta: 0.01 to 1.5%, Zr: 0.01 to 1.5
%, Hf: 0.01-1.5%, Ti: 0.01-1.
5%, Sc: 0.001 to 1.5%, Y: 0.001 to
1.5%, Co: 0.01 to 10.0%, Ni: 0.0
1 to 2.0%, Cu: 0.01 to 2.0%, B: 0.0
01 to 0.050%, etc., containing one or more kinds, the balance being composed of Fe and unavoidable impurities, a cold tool,
Alloy tool steel used as a material for hot tools, dies, cutting tools, and the like is disclosed. However, the alloy tool steel disclosed in this publication has a high Si content in hot tool steel and is not intended for a special use such as a chisel for crushing high-temperature refractories.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a refractory crushing chisel particularly excellent in settability, cracking and abrasion resistance at high temperatures.

[0007]

In order to solve the above-mentioned problems, a refractory crushing chisel according to the present invention has a chemical composition of C: 0.20 to 0.60% and Si: 0.8%. , Mn: 0.1 to 2.0%, P: 0.020% or less,
S: 0.030% or less, Cr: 2.0 to 9.0%, M
o: 0.10 to 6.0%, W: 0.10 to 6.0%,
V: 0.01 to 2.5%, and if necessary, N
b: 0.01 to 1.5%, Ta: 0.01 to 1.5%,
Zr: 0.01 to 1.5%, Hf: 0.01 to 1.5
%, Ti: 0.01 to 1.5%, Sc: 0.001 to
1.5%, Y: 0.001 to 1.5%, Ni: 0.01
To 2.0%, Co: 1.0 to 10.0%, Cu: 0.2
5 to 1.0%, B: 0.001 to 0.050%, RE
M: One or more of 0.001 to 0.60% is contained, and the balance is made of Fe and unavoidable impurities.

[0008]

Next, the reasons for limiting the composition of the chisel for refractory crushing of the present invention will be described. C: 0.20 to 0.60% C is an element effective for securing the required strength, hardness and wear resistance as a tool by forming a hard double carbide by combining with a carbide forming element. In order to obtain such an effect, it is necessary to contain 0.20% or more. If contained in a large amount, the wear resistance increases, but the toughness, forgeability and workability decrease, so the content is made 0.60% or less. Si: less than 0.8% Si is an element capable of acting as a deoxidizing agent and promoting the precipitation reaction of carbide by containing the deoxidizing agent in an amount larger than the necessary amount, thereby miniaturizing the carbide. is there. In addition, it is an element effective for improving hardenability, strengthening the matrix, increasing the yield point, preventing surface oxidation at high temperatures, and improving the fatigue limit. However, if it is contained in a large amount, the tool life is shortened due to deterioration of thermal conductivity and toughness.

Mn: 0.1-2.0% Mn is. An element that acts as a desulfurizing and deoxidizing agent to increase the cleanliness of steel and improve hardenability. To obtain such an effect, it must be contained in an amount of 0.10% or more. 2.0%
The following is assumed. P: 0.020% or less P is an element which is an impurity and increases generation of ground flaws. By reducing this content, toughness can be greatly improved, and heat check resistance can be significantly improved. And the anisotropy of the impact value can be considerably reduced, so that 0.020% or less, preferably 0.020% or less.
10% or less.

S: 0.030% or less S is an impurity. Since the occurrence of ground flaws can be suppressed by reducing the S content in steel and the impact value can be increased, the content of S is 0.030% or less. I do. Cr: 2.0 to 9.0% Cr combines with C to form a composite carbide, and is an element effective for enhancing the strength of a tool, particularly high-temperature strength, and improving wear resistance and thermal shock resistance. In order to obtain such an effect, it is necessary to contain 2.0% or more. If the content is too large, toughness and workability are deteriorated. Mo: 0.10-6.0% Mo combines with C to form fine composite carbides, and also forms a solid solution in the matrix to strengthen the matrix, increase the hardness of the heat treatment, and increase the resistance to heat. It is an element effective for improving the wear property. In order to obtain such an effect, it is necessary to contain 0.10% or more. If the content is too large, the toughness is reduced, coarse carbides are increased, and the fatigue properties are reduced. Have a negative effect,
6.0% or less.

W: 0.10-6.0% W combines with C to form fine composite carbides.
It is a solid solution in the matrix, strengthens the matrix, increases the heat treatment hardness, improves the wear resistance, and is an element effective for extending the thermal fatigue life. The content must be 0.10% or more. If the content is too large, the toughness is reduced, the amount of coarse carbides is increased, and the fatigue properties are adversely affected. Therefore, the content is set to 6.0% or less. V: 0.01 to 2.5% V is an element effective to combine with C to form a fine composite carbide, increase heat treatment hardness and improve wear resistance,
In order to obtain such an effect, 0.01% or more is necessary. If the amount is too large, the toughness is reduced, the amount of coarse carbides is increased, and the fatigue properties are adversely affected.
2.5% or less.

Nb: 0.01-1.5%, Ta: 0.0
1 to 1.5%, Zr: 0.01 to 1.5% or less, Hf:
0.01-1.5%, Ti: 0.01-1.5%, S
c: 0.001 to 1.5%, Y: 0.001 to 1.5% Nb, Ta, Zr, Hf, Ti, Sc, and Y all form carbides to increase heat treatment hardness, These elements are effective for improving the wear resistance, and if necessary, these elements are appropriately selected and contained in the above range.

Co: 1.0 to 10.0%, Ni: 0.0
1 to 2.0%, Cu: 0.25 to 1.0%, B: 0.0
01 to 0.050%, REM (total of one or more rare earth elements): 0.001 to 0.60% Co, Ni, Cu, B and REM all strengthen the matrix, An element that enhances impact resistance and heat check resistance. These elements are appropriately selected and contained in the above range. Further, B is an element effective for improving the hardenability of the steel and for fixing N in the steel in the form of BN so as to eliminate the adverse effect of N. Therefore, B is contained in the above range as necessary.

In the chisel for refractory crushing of the present invention, in addition to the above alloying elements, Mg: 0.001 to improve machinability.
0.5%, Ca: 0.002 to 0.01%, Pb: 0.
One or more of 4% or less, Bi: 0.5% or less, and Te: 0.3% or less can be contained.
In addition, N of impurities is 200 ppm or less, and O is 0.003 or less.
0% or less and Al are preferably 0.020% or less.

[0015]

Next, the present invention will be described with reference to examples. After the materials having the chemical component compositions shown in Table 1 below were melted in a vacuum induction melting furnace, they were lumped to obtain ingots. Next, each of the ingots was hot forged and then annealed. The shape (A type) of FIG. 3A and the shape of FIG.
A chisel having the shape b (type B) was prepared. These chisels were heat-treated under the following conditions. Inventive Examples (Nos. 1 to 6) Oil-cooled from 1100 ° C. and quenched, then air-cooled from 570 ° C. and tempered Comparative Example (No. 7, conventional SCM440) 580 after oil-cooled and hardened from 850 ° C. Comparative Example 2 (No. 8, SKD61) Air-cooled from 1025 ° C and quenched, then air-cooled from 600 ° C and tempered Comparative Example 3 (No. 9, SKH51) Oil-cooled from 1220 ° C After quenching, air-cooled from 560 ° C and tempered

[0016]

[Table 1]

Table 2 below shows the normal temperature hardness, toughness, and appearance of the chisel thus produced when used in a temperature range of 450 to 550 ° C. for 2 hours.

[0018]

[Table 2]

From these results, all the chisels of the present invention were slightly worn at the tips even after use at 450 to 550 ° C. for 2 hours, and there was no damage such as cracks or breakage. However, in the chisel (Comparative Example No. 7) manufactured by the conventional SCM440, the A type has a deformation at the tip, and the B type has a bend at the tip (the portion of 60φ). I can no longer do it. In the chisel (Comparative Example No. 8) manufactured with SKD61 which is a comparative hot steel tool steel, heat crack, bending and breakage did not occur. In particular, the tip of the type B was significantly worn. As for the chisel (Comparative Example No. 9) manufactured from SKH51, which is a high-speed steel as a comparative material, the A type has large wear, heat cracks and chips are generated, and the B type has a tip ( (The portion of 60φ) was broken and could not be used halfway.

[0020]

According to the chisel for refractory crushing of the present invention, since the composition of the composition is as described above, even if used at a high temperature, not only those having any shape will not be broken nor sagged, but also have cracking. An excellent effect that there is no occurrence and the amount of wear is small is exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a damaged state of a tapping gutter of a blast furnace.

FIG. 2 is a conceptual diagram showing a state in which a damaged portion of a tapping gutter of a blast furnace is crushed by a chisel.

FIG. 3 is a front view and a bottom view for explaining various chisel shapes.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gutter 2 Permanent refractory 3 Irregular refractory 4 Slug line erosion 5 Metal line erosion 6 Chisel

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiki Shibata 5-3 Tokaicho, Tokai City, Aichi Prefecture Inside Nagoya Works, Nippon Steel Corporation (72) Inventor Shigeru Kanbara 18 Mizobatacho, Sakado City, Saitama Prefecture 5 (72) Inventor Satoru Maejima 1480-1 Tsuruma, Machida-shi, Tokyo Sky Plaza Tsuruma A-1

Claims (4)

[Claims] C. 0.20% by weight (the same applies hereinafter)
0.60%, Si: less than 0.80%, Mn: 0.1 to
2.0%, P: 0.020% or less, S: 0.030% or less, Cr: 2.0 to 9.0%, Mo: 0.10 to 6.0
%, W: 0.10 to 6.0%, V: 0.01 to 2.5
%, The balance being Fe and unavoidable impurities. 2. C: 0.20 to 0.60%, Si: 0.
Less than 80%, Mn: 0.1 to 2.0%, P: 0.020
%, S: 0.030% or less, Cr: 2.0 to 9.0
%, Mo: 0.10 to 6.0%, W: 0.10 to 6.0
%, V: 0.01-2.5%, and Nb: 0.01-
1.5%, Ta: 0.01 to 1.5%, Zr: 0.01
-1.5%, Hf: 0.01-1.5%, Ti: 0.0
1 to 1.5%, Sc: 0.001 to 1.5%, Y: 0.
A chisel for refractory crushing, comprising one or more of 001 to 1.5%, the balance being Fe and unavoidable impurities. 3. C: 0.20 to 0.60%, Si: 0.
Less than 80%, Mn: 0.1 to 2.0%, P: 0.020
%, S: 0.030% or less, Cr: 2.0 to 9.0
%, Mo: 0.10 to 6.0%, W: 0.10 to 6.0
%, V: 0.01 to 2.5%, and Co: 1.0 to 1
0.0%, Ni: 0.01 to 2.0%, Cu: 0.25
１．０1.0%, B: 0.001 to 0.050%, REM:
One or more of 0.001 to 0.60%, balance:
A refractory crushing chisel comprising Fe and inevitable impurities. 4. C: 0.20 to 0.60%, Si: 0.
Less than 80%, Mn: 0.1 to 2.0%, P: 0.020
%, S: 0.030% or less, Cr: 2.0 to 9.0
%, Mo: 0.10 to 6.0%, W: 0.10 to 6.0
%, V: 0.01-2.5%, and Nb: 0.01-
1.5%, Ta: 0.01 to 1.5%, Zr: 0.01
-1.5%, Hf: 0.01-1.5%, Ti: 0.0
1 to 1.5%, Sc: 0.001 to 1.5%, Y: 0.
001-1.5% of one or more kinds, and Co:
1.0 to 10.0%, Ni: 0.01 to 2.0%, C
u: 0.25 to 1.0%, B: 0.001 to 0.050
%, REM: one or more of 0.001 to 0.60%, the balance being Fe and unavoidable impurities.