KR100804681B1 - Guide roll used for centrifugal casting and manufacturing method thereof - Google Patents

Abstract

A continuous casting guide roll using centrifugal casting method and a manufacturing method thereof are provided, wherein the continuous casting guide roll satisfies sufficient hardening capability and mechanical properties even at a high temperature and has excellent wear resistance by developing an alloy capable of controlling microstructure such that 5% or less of a ferrite fraction is contained in the alloy. A manufacturing method of a continuous casting guide roll using centrifugal casting method comprises the steps of: (a) preparing molten iron having a composition comprising 11 to 12 wt.% of Cr, 0.12 to 0.15 wt.% of C, 2 to 3 wt.% of Ni, 1 to 1.5 wt.% of Mo, 0.5 to 1 wt.% of Mn, 0.2 to 0.81 wt.% of Si, 0.4 to 0.6 wt.% of Cu, 0.4 to 0.5 wt.% of W, 0.2 to 0.4 wt.% of V, 0.2 to 0.3 wt.% of Nb, 0.05 to 0.2 wt.% of N, and the balance of Fe and other inevitable impurities; (b) injecting the prepared molten iron into a mold of a centrifugal casting machine; (c) rotating the mold until the molten iron is solidified; (d) separating a casting from the mold; and (e) air cooling the casting. The manufacturing method further comprises a step(f) of preheating the mold to a temperature range of 400 to 450 deg.C prior to the step(b). The manufacturing method further comprises a step(g) of heat-treating the casting after performing the step(e).

Description

Guide roll used for Centrifugal casting And Manufacturing Method

1 is a plan view of a continuous casting machine of a typical playing process.

Figure 2 is a cross-sectional view showing a centrifugal caster.

Figure 3 is a block diagram showing an embodiment of a method for producing a playing guide roll using the centrifugal casting method according to the present invention.

Figure 4 is a graph showing the distribution of inclusions according to the rotational speed of the mold.

Figure 5 is a block diagram showing another embodiment of the production guide roll production method using a centrifugal casting method according to the present invention.

6 to 8 are graphs showing the mechanical properties of the Table 1 specimen.

9 is a graph showing the hardness value of the specimen in Table 1.

FIG. 10 is a tissue photograph of Specimen 1 in Table 1. FIG.

111 is a tissue photograph of a specimen in accordance with the present invention (Psalm 3).

** Description of the symbols for the main parts of the drawings **

10: Mold 20: playing guide roll

30: cast 40: continuous casting machine

110: centrifugal mold 120: roller

130: mold 140: motor

150: centrifugal casting machine

Sa ~ Sg: Each step of the method of manufacturing the performance guide roll using the centrifugal casting method

The present invention relates to a performance guide roll using the centrifugal casting method and a method of manufacturing the same. More specifically, by using centrifugal casting method, the performance guide roll for lowering the feride fraction of the performance guide roll for continuous casting machine used in one of the manufacturing processes of steel to 5% or less, improving the mechanical properties and wear resistance, and It relates to a manufacturing method.

In general, the manufacturing process of steel is largely composed of a steel making process, steelmaking process, casting process and rolling process. The iron making process is a process of removing oxygen in iron ore and melting iron ore to produce pig iron, and the steel making process is a process of manufacturing steel by removing impurities of pig iron which has been subjected to the iron making process, and the casting process is a continuous casting machine It is a process of manufacturing intermediate materials, such as slab, bloom, or billet, having a predetermined form of steel in a liquid state while passing, and the rolling process is a process of forming / modifying a steel sheet or a wire to meet the intended use.

On the other hand, the continuous casting machine used in the playing process is shown in FIG.

The continuous casting machine 40 is composed of a mold (10) (Mold) for producing molten steel in a predetermined shape, the play guide roller 20 for guiding the slab 30 passed through the mold.

The playing guide roll of the present invention is a core part of the playing process with the material of the playing guide roller. The playing guide roller is subjected to thermal fatigue in which heating and cooling are repeated by contact with a hot cast steel, and problems such as thermal fatigue crack, hot wear, shape deformation, and fluoride corrosion are generated due to continuous contact with the hot cast steel. . In particular, the playing guide roll is exposed to high temperatures of about 500 ° C. due to the limitation of cooling capacity, and is subjected to thermal fatigue by repeating the high temperature region and the low temperature region by contact of the cooling water for cooling the cast steel. When the slab is stagnated for a predetermined time or more, it must withstand higher temperatures and is required to withstand the load of the slab itself.

Therefore, the material of the guide roller of the continuous casting machine should have a high yield strength even at high temperatures, low thermal expansion, and satisfies all conditions of high hardness, corrosion resistance and ductility. If the requirements are not satisfied, there is a problem in that the thickness variation of the cast steel, the surface quality is lowered, the productivity is lowered, and the production cost is increased by shortening the life of the playing guide roll.

Accordingly, various techniques have been proposed for increasing the life of the performance guide roll while satisfying the characteristics required in the performance guide roll of the continuous casting machine.

In general, martensitic stainless steel is used as a material for the performance guide roll. However, it is difficult to apply the martensitic stainless steel to a large part as a whole. Therefore, welding is used in most steel mills to reduce manufacturing costs. Is used.

Among the methods using welding, a method of coating martensitic stainless steel materials such as 410, 420, and 423 on the basic roll material by overlay molding is widely used.

However, the above-described method by the above-mentioned welding welding method has been pointed out that a problem occurs such that peeling of the base roll material and martensitic stainless steel, surface defects such as beads and cracks are generated, and thus the existing problems cannot be completely solved.

Therefore, the present invention has been made to solve the above problems, the object of the present invention is to develop an alloy that can control the microstructure so that the fraction of the ferrite is 5% or less to achieve sufficient curing ability and mechanical properties even at high temperatures The present invention provides a performance guide roll using a centrifugal casting method which is satisfactory and excellent in wear resistance, and a method of manufacturing the same.

Method for producing a performance guide roll using the centrifugal casting method of the present invention for achieving the above object is a) Cr: 11 ~ 12% by weight, C: 0.12 ~ 0.15% by weight, Ni: 2-3% by weight, Mo: 1 ~ 1.5 wt%, Mn: 0.5-1 wt%, Si: 0.2-0.81 wt%, Cu: 0.4-0.6 wt%, W: 0.4-0.5 wt%, V: 0.2-0.4 wt%, Nb: 0.2-0.3 wt% Preparing a molten metal having a composition of%, N: 0.05 to 0.2% by weight, the balance of Fe and other incurable impurities; b) injecting the prepared melt into a mold of a centrifugal casting machine; c) rotating the mold until solidification of the molten metal is completed; d) separating the mold from the mold; e) air cooling the mold; Characterized in that it comprises a.

In addition, f) before the step b) may further comprise the step of preheating the mold to 400 ~ 450 ℃.

Further, after step e), g) heat treating the mold; It characterized in that it further comprises, the step g) is characterized in that tempering to 400 ~ 450 ℃.

In addition, the injection temperature of the molten metal in the step b) is 1,550 ~ 1,600 ℃, the injection speed is characterized in that 4kg / sec, when the rotational speed of the mold in the step c) 800 ~ 900 rpm, inclusions of 100μm or more More than 95% of the particles are present in the area of 3mm thickness from the inner surface.

In addition, the centrifugal caster is characterized in that the horizontal type.

On the other hand, the playing guide roll of the present invention is Cr: 11-12% by weight, C: 0.12-0.15% by weight, Ni: 2-3% by weight, Mo: 1-1.5% by weight, Mn: 0.5-1% by weight, Si : 0.2 to 0.81 wt%, Cu: 0.4 to 0.6 wt%, W: 0.4 to 0.5 wt%, V: 0.2 to 0.4 wt%, Nb: 0.2 to 0.3 wt%, N: 0.05 to 0.2 wt%, the balance is Fe And other incurable impurities.

In addition, the performance guide roll is characterized in that the martensite phase of 95% by volume or more is formed, the performance guide roll is characterized in that the delta-ferrite phase of volume% or less is formed.

Hereinafter, a method for producing a performance guide roll using the centrifugal casting method according to the present invention having the configuration as described above and a method for manufacturing the same will be described in detail with reference to the accompanying drawings.

First, centrifugal casting is a method of using a centrifugal force of a rotating mold as one of casting methods.

The centrifugal casting method is divided into a horizontal type and a vertical type according to the direction of the rotating axis, and the playing guide roll and the manufacturing method using the centrifugal casting method of the present invention is preferably a horizontal centrifugal casting machine.

2 is a view showing a horizontal centrifugal casting machine 150, the horizontal centrifugal casting machine 150 is a molten steel injection unit for storing and injecting molten steel; A roller 120 rotated by the motor 140; And a centrifugal mold (110) for receiving the molten steel from the molten steel injection unit and placing the molten steel on the roller (120) to manufacture the mold (130) using the centrifugal force by the rotation of the roller (120). The present invention provides a performance guide roll using the centrifugal casting method and a manufacturing method thereof, the centrifugal casting machine 150 is an example of the device that can use the centrifugal casting method is not limited to the components described in FIG. Not surprisingly available.

3 is a block diagram showing an exemplary embodiment of a method for producing a playing guide roll using the centrifugal casting method according to the present invention. Referring to FIG. 3, the method for producing a playing guide roll according to the present invention may include a) molten metal manufacturing step (Sa); b) molten metal injection step (Sb); c) mold rotation step Sc; d) mold separation step (Sd); e) mold air cooling step (Se); Characterized in that it comprises a.

The molten metal manufacturing step (Sa) is 11% to 12% by weight of Cr, 0.12% to 0.15% by weight, 2% to 3% by weight of Ni, 1% to 1.5% by weight of Mo, 0.5% to 1% by weight of Mn, and Si. : 0.2 to 0.81 wt%, Cu: 0.4 to 0.6 wt%, W: 0.4 to 0.5 wt%, V: 0.2 to 0.4 wt%, Nb: 0.2 to 0.3 wt%, N: 0.05 to 0.2 wt%, the balance is Fe And a molten metal having a composition which is other incurable impurities. The alloy will be described later in the experimental results in a composition designed to inhibit the production of delta-ferrite.

The second step, the molten metal injection step (Sb) is a step of injecting the molten metal prepared by the molten metal manufacturing step (Sa) into a mold of a centrifugal casting machine, wherein the injection temperature of the molten metal is 1,550 to 1,600 ° C. It is preferable that the rate of injection into 4kg / sec.

The mold rotation step (Sc) is a step of rotating the mold of the centrifugal caster until the solidification of the injected molten metal is completed, and the rotation speed of the mold is preferably 800 ~ 900 rpm.

Figure 4 is a graph showing the distribution of the inclusions according to the rotational speed of the mold as shown in the distribution of the inclusions having a size of 100μm or more when the rotational speed of the centrifugal casting machine mold is 800 ~ 900 rpm As the distribution area decreases sharply, it can be seen that more than 95% of the inclusions having a thickness of 100 μm or more exist in the 3 mm thickness area from the inner surface. That is, in order to remove impurities of the mold to be produced, the rotation speed of the mold is preferably 800 to 900 rpm.

The mold separating step Sd is a step of separating the mold from the mold when the molten metal is solidified.

The mold air cooling step Se is a step of air cooling the separated mold.

5 is a block diagram showing another embodiment of a method for producing a playing guide roll using the centrifugal casting method according to the present invention f) before the step b) mold preheating step (Sf); And g) heat treatment step (Sg) after step e); An embodiment is further included.

The mold preheating step (Sf) is a step of preheating the mold to 400 ~ 450 ℃ before the injection (Sb), the heat treatment step (Sg) is a heat treatment after the air cooling (Se) step of the mold In the step, the heat treatment is preferably tempered at a temperature of 400 ~ 450 ℃.

The performance guide roll using the centrifugal casting method of the present invention is produced by the method as described above, the performance guide roll produced by the production method is 95% or more martensite phase is formed, 5% or less delta- A ferrite (δ-ferrite) phase is formed.

The following table shows three specimens with different melt contents, and specimen 3 corresponds to the melt composition of the playing guide roll using the centrifugal casting method of the present invention.

TABLE 1

Cr C Ni Mo Mn Si Cu W V Nb N Psalm 1 11.5 0.12 2 0.6 0.95 0.38 0.24 0.4 0.01 0.28 0.01 Psalm 2 10.5 0.15 2.4 One 0.54 0.11 0.07 0.4 0.07 0.27 0.15 Psalm 3 11.2 0.12 2.6 1.3 0.61 0.23 0.57 0.4 0.37 0.21 0.16

The molten metal having three alloy compositions was prepared, and the mold was heated to a temperature of 430 ° C., and then the molten metal was injected into the mold of the centrifugal caster at an injection temperature of 1550 to 1600 ° C. and an injection speed of 4 kg / sec. The rotational speed of the mold was maintained at 800rpm for 3 minutes, and the mold was separated from the mold, cooled to room temperature, and then tempered to a temperature of 450 ° C.

6 to 8 are graphs showing the mechanical properties of the specimens of Table 1, FIG. 6 shows the mechanical characteristics of the specimen 1, FIG. 7 shows the mechanical characteristics of the specimen 2, and FIG. The mechanical properties of Specimen 3 having the alloy composition of the invention are shown.

As shown, the specimen 3 of the present invention showed excellent properties in tensile strength, yield strength and elongation, especially when the tempering temperature is 450 ℃.

Table 2 is a table showing the tensile strength, yield strength and elongation of each specimen at 450 ℃.

TABLE 2

Tensile Strength (MPa) Yield strength (MPa) Elongation (%) Psalm 1 1293 1226 0.83 Psalm 2 1498 1453 2.1 Psalm 3 1592 1385 1.48

9 is a table showing the hardness of each specimen specimen 3 has the most excellent characteristics, in particular, the highest value in the region of the tempering temperature 400 ~ 450 ℃ can be confirmed.

In addition, by obtaining the tissue photograph of each specimen having the alloy composition of Table 1, the area of delta-ferrite, which is visible to the naked eye, was obtained, and the phase fraction of delta-ferrite was obtained. Based on the XRD (X-Ray Diffraction) method, the following equation 1 was used to compensate for the error caused by the reduction of the diffraction intensity due to internal stress, and 100% of the parts except the delta-ferrite and austenite phases were removed. Judging by martensite organization.

[Equation 1]

( V _γ : integral strength of austenite, Iα : integral strength of ferrite, I _γ : integral strength of austenite, K : constant)

Table 3 below shows the percentage of each specimen measured by the method described above.

TABLE 3

　 (%) Delta-ferrite Residual austenite Martensite Psalm 1 16.4 2.7 80.9 Psalm 2 <2 3.8 <94.2 Psalm 3 <1 3.7 <95.3

As confirmed in Table 3, the specimen 3 having the alloy composition of the present invention exhibited a high martensite phase of 95% or more due to a decrease in the production of delta-ferrite, which can be confirmed through the tissue photograph of each specimen.

10 is a tissue photograph of the specimen 1 of Table 1, Figure 11 is a tissue photograph of the specimen according to the present invention (Psalm 4).

In FIG. 10, the delta-ferrite phase can be directly identified, but in FIG. 10, the delta-ferrite phase cannot be identified. In other words, the performance guide roll using the centrifugal casting method of the present invention and the manufacturing method thereof can control the delta-ferrite to produce a performance guide roll having excellent mechanical properties, and by using the centrifugal casting method to reduce the manufacturing cost and increase the productivity .

The present invention is not limited to the above-described embodiments, and the scope of application is not limited, and various modifications can be made without departing from the gist of the present invention as claimed in the claims.

Accordingly, the playing guide roll using the centrifugal casting method of the present invention and the manufacturing method thereof are characterized by adjusting the alloy composition to control the microstructure, satisfying the mechanical properties of high tensile strength and yielding strength, and having a high corrosion resistance, thereby having a playing guide having excellent characteristics. Providing a roll, it is possible to reduce the production cost and increase the productivity in the production of the performance guide roll.

Claims (10)

a) Cr: 11-12% by weight, C: 0.12-0.15% by weight, Ni: 2-3% by weight, Mo: 1-1.5% by weight, Mn: 0.5-1% by weight, Si: 0.2-0.81% by weight, Cu: 0.4-0.6% by weight, W: 0.4-0.5% by weight, V: 0.2-0.4% by weight, Nb: 0.2-0.3% by weight, N: 0.05-0.2% by weight, the balance of Fe and other incurable impurities Preparing a molten metal; b) injecting the prepared melt into a mold of a centrifugal casting machine; c) rotating the mold until solidification of the molten metal is completed; d) separating the mold from the mold; e) air cooling the mold; Method for producing a playing guide roll using the centrifugal casting method comprising a. The method of claim 1, F) before the b) step further comprises the step of preheating the mold to 400 ~ 450 ℃ using the centrifugal casting method. The method of claim 1, G) heat treating the mold after step e); Method for producing a playing guide roll using the centrifugal casting method characterized in that it further comprises. The method of claim 3, wherein The g) step is a performance guide roll manufacturing method using the centrifugal casting method, characterized in that tempering at 400 ~ 450 ℃. The method of claim 1, The injection temperature of the molten metal in the step b) is 1,550 ~ 1,600 ℃, the injection speed production method using the centrifugal casting method, characterized in that the 4kg / sec. The method of claim 1, When the rotational speed of the mold in the step c) is 800 ~ 900 rpm, 95% or more of the inclusions of 100μm or more is present in the 3mm thickness region from the inner surface, characterized in that the playing guide roll manufacturing method using the centrifugal casting method. The method of claim 1, The centrifugal caster is a playing guide roll manufacturing method, characterized in that the horizontal type. Cr: 11-12 wt%, C: 0.12-0.15 wt%, Ni: 2-3 wt%, Mo: 1-1.5 wt%, Mn: 0.5-1 wt%, Si: 0.2-0.81 wt%, Cu: 0.4-0.6% by weight, W: 0.4-0.5% by weight, V: 0.2-0.4% by weight, Nb: 0.2-0.3% by weight, N: 0.05-0.2% by weight, the balance consisting of Fe and other incurable impurities Playing guide roll. The method of claim 8, The playing guide roll is a playing guide roll, characterized in that 95% by volume or more of the martensite phase is formed. The method of claim 8, The playing guide roll is a playing guide roll, characterized in that the delta-ferrite phase of 5% by volume or less is formed.

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