JP3096876B2 - Manufacturing method of foil material for metal carrier with excellent corrosion resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for stably producing a high temperature resistant material for automobiles by a continuous casting method with a good yield.

[0002]

2. Description of the Related Art Ceramic honeycombs have been used in automobile exhaust gas purifiers. However, by replacing the honeycombs with heat-resistant stainless steel foil, the thickness of the honeycomb wall can be reduced, and ventilation can be achieved. For example, Japanese Patent Application Laid-Open Nos. 50-92286 and 51-52 can improve engine performance and save expensive catalytic precious metals by reducing resistance and heat capacity.
No. 48473, No. 56-96726, and No. 57-7
As disclosed in Japanese Patent Publication No. 1898, there has been proposed a technique in which this honeycomb body is made of an Fe—Cr—Al-based heat-resistant metal foil.

At this time, attention is paid to oxidation resistance and adhesion of an oxide film as properties required for the alloy foil. Therefore, the material is generally excellent in oxidation resistance and film adhesion. Based on Fe-Cr-Al-based alloys, which have been secretly used as high-temperature parts for heating wires and heating appliances, activated alumina (γ-Al ₂ O ₃ etc.) ) Is used.

[0004] Each of the techniques disclosed in the above publications proposes the addition of Y as a means for improving the oxidation resistance of the material. However, since Y is an extremely expensive element, the catalyst carrier is made of ceramic. The range of use is limited in order to reduce the cost merit obtained by using metal.

On the other hand, Japanese Patent Application Laid-Open No. 58-177337 discloses a Fe—Cr—Al alloy containing 0.002 to 0.05% by weight of La, C in order to mainly prevent peeling of an oxide film.
An alloy containing a rare earth element up to a total amount of 0.06% by weight containing e, Nd, and Pr has been proposed. In this case, an alloy in which the total of the rare earth elements exceeds 0.06% by weight is an ordinary steel. It cannot be worked in the hot working process.

Japanese Patent Application Laid-Open No. 63-45351 discloses that the addition of Y is expensive in alloys based on the Fe—Cr—Al system.
Lanthanoid containing 0.05 to 0.2% by weight
It has been proposed to add in the range of 0% by weight.

This is because Ce causes a decrease in hot workability due to the addition of a lanthanoid. Further, Ce has an effect of lowering the oxidation resistance. This is based on the finding that hot working becomes possible and acid resistance is improved.

[0008] However, lanthanoids are chemically active elements and are difficult to separate from each other due to their similar chemical properties, so that substantially pure La is less expensive than Y. However, it is still very expensive for so-called misch metal, which is a common mixture of lanthanoids. Similarly,
Separation and removal of Ce alone cannot avoid a rise in price.

Therefore, Japanese Patent Application Laid-Open No. Hei 2-254136 and No. 3
In Japanese Patent No. 170642, in order to prevent the deterioration of hot workability due to Ce, which is a main component of steel to which misch metal is added, P is added to steel and present as Ce and high melting point phosphide in steel. A method of preventing a decrease in hot workability by performing the method is disclosed.

[0010]

SUMMARY OF THE INVENTION Conventionally, high concentration [Al]
Since the high Cr material containing Cr does not contain a rare earth element, no defects such as cracks during casting or hot rolling were generated.

On the other hand, C contained in the metal carrier material
When e and Y are concentrated at the crystal grain boundaries, defects due to grain boundary embrittlement occur.

Further, even if measures are taken to fix excessive rare earth elements by adding [P] in order to prevent embrittlement due to enrichment of Ce at the grain boundaries, the amount of segregation in the slab is reduced. The addition of [P] alone does not provide a sufficient improvement because it varies depending on the location inside.

Further, it is possible to add [P] excessively in consideration of the dispersion of the segregation of the Ce element. However, if an excessive concentration of [P] is added, rare earth necessary for oxidation resistance is required. It is expected that elements will be fixed,
Since the [P] element is an element that lowers the toughness of the steel sheet, it is desirable that the addition concentration be reduced as much as possible. Therefore, it is difficult to add more [P] than necessary from the viewpoint of the properties of the steel sheet.

The present invention relates to a method for stably producing a metal carrier foil material by continuous casting while preventing the occurrence of defects in the production of the metal carrier material.

[0015]

According to the present invention, the main components in the product are [Al] = 4.5-6.5%, [Cr] = 13-
When casting a metal carrier material of 25%, rare earth element = 0.06 to 0.15% by continuous casting, the casting speed is in the range of 0.2 to 1.0 m / min, and Casting is performed with the discharge angle set in the range of 40 ° downward from horizontal, and the conditions for adding the rare earth element into the molten steel in the mold by the alloy addition method in the mold are as follows:
This is a method for continuously casting a foil material for a metal carrier, characterized by being controlled within the range of the formula.

[0016]

## EQU2 ## 0.2 ≦ α ≦ 1.0 m (1)

Α = addition rate (m / s) for adding necessary rare earth element amount × 1550 ° C. melting time when immersing the wire in molten steel (sec)

[0018]

The present invention will be described together with the following operation. 1 and 2 are views showing a state where a rare earth element is added by a wire addition method in a mold according to the present invention.

FIG. 1 shows the state of diffusion of rare earth elements in a mold during casting by continuous casting using the alloy addition method in a mold.
FIG. 2 shows a concentration distribution in a slab cast by the present method.

FIG. 3 and FIG. 4 show that when the wire containing the rare earth element to be added into the mold is melted at a position shallower than the condition of the present invention, the surface of the cast slab is rare earth. It is a figure explaining that an element concentrates.

That is, FIG. 3 shows, as a comparison, the product of the rate of addition of the wire and the melting time is 0.1 mm when continuous casting is performed by simply adding a rare earth element into a mold as in the prior art.
FIG. 4 is a view for explaining that the wire containing the added rare earth element is concentrated in the meniscus portion in the mold when the ratio is less than 2, and shows the diffusion state of elements in the slab at the time of casting. 3 shows a cross section of a cast slab manufactured by the method of FIG.

Further, FIGS. 5 and 6 show that when the wire containing the rare earth element to be added into the mold is melted at a position deeper than the condition of the present invention, the rare earth element is added to the surface of the slab. It is a figure explaining that although the concentration can be prevented, the added wire remains undissolved in the mold.

That is, FIG. 5 shows a case where a rare-earth element is simply added into a mold and continuous casting is performed as in the conventional case. This diagram explains that the wire containing the rare earth element does not completely melt in the mold and remains as a wire shape in the cast slab, and the diffusion of elements in the slab during casting FIG. 6 is a cross-sectional view of a slab manufactured by the method of FIG.

The main component in the mold is [Al] = 4.5-4.5.
Supplying 6.5%, [Cr] = 13-25% of base molten steel,
Further, the rare earth element concentration is supplied to the mold by a wire addition method so that the rare earth element concentration becomes 0.06 to 0.15%.

It is necessary to set the discharge angle of the immersion nozzle used for the casting in a range from horizontal to 40 ° downward, because the [Al] concentration in the molten steel for the metal carrier is 5 °.
%, And when the molten steel is discharged upward at a horizontal angle or more, the viscosity stabilizing substance in the CC powder used for continuous casting reacts excessively with the SiO ₂ molten steel. Is not stable, and white smoke is generated due to the reaction with Na ₂ O in the powder to deteriorate the workability of casting.

On the other hand, when the discharge angle is directed downward below 40 °, the supply of molten steel to the meniscus in the mold is extremely reduced, so that the temperature of the meniscus becomes low.

As a result, it becomes impossible to supply heat required to melt the wire added into the mold, and the wire is not melted.

Therefore, it is desirable to set the discharge angle of the immersion nozzle in a range from horizontal to 40 ° downward.

Further, the casting speed is increased from 0.2 to 1.0 m /
casting in the range of 0.2 min / min
In the case of the following speed, the supply amount of the molten steel becomes extremely small, so that the temperature of the molten steel in the mold becomes too low, and unmelting of the wire occurs.

On the other hand, when the casting speed is increased to 1.0 m / min or more, although the molten steel temperature in the meniscus portion necessary for melting the wire can be secured, the unit consumption of the continuous casting powder decreases, so that the This is because it becomes impossible to ensure the thickness of the molten layer of the powder, and white smoke is generated due to the reaction between the raw powder and the molten steel.

Further, in the present invention, the rare earth element is added to the mold by a wire addition method, and the addition is performed under the condition shown by the formula (1).

[0032]

## EQU3 ## 0.2m ≦ α ≦ 1.0m (1)

Α: rate of addition for adding the required concentration (m / s) × melting time in molten steel at 1550 ° C. (s)

This is because a rare earth element necessary for producing a foil material for a metal carrier is added by adding an alloy in a mold, and further, the concentration of the element on the surface of the slab is reduced in order to prevent cracking of the slab. It is effective to add a wire at a high speed and dissolve it at a deep position in the mold in order to reduce the formation.

However, the molten steel for casting of the metal carrier foil material is a stainless steel molten steel containing a high concentration of [Cr], so that the liquidus temperature is extremely low. As a result, the molten steel temperature during casting is extremely low.

As a result, the temperature of the molten steel in the mold during casting becomes extremely low. Therefore, even if a wire is added at a high speed in an attempt to suppress the concentration of elements on the surface of the slab, the wire reaches a deep position in the mold. Undissolution occurs.

Therefore, in order to prevent the additive element from being concentrated on the slab surface while preventing the undissolved element, it is necessary to dissolve the additive element within the range represented by the formula (1).

This is because when the metal is melted at a distance of 0.2 m from the meniscus, the added rare earth element is concentrated in the meniscus portion, so that powder alteration and slab cracks occur due to concentration on the slab surface layer. .

On the other hand, if the length is more than 1.0 m from the meniscus, the molten steel is added to a position where the temperature of the molten steel becomes low due to heat removal from the mold, and as a result, the added wire is not melted.

When casting is performed according to the present invention, it is possible to stably produce a steel sheet containing a rare earth element which is brittle at high temperatures in the raw material components.

[0041]

Example 1 A slab for a metal carrier was manufactured by continuous casting using a continuous casting mold having an internal space having a horizontal cross section of 250 × 980 mm.

In the casting, [Al] = 5% as mother molten steel,
[Cr] = Use molten steel containing 20% uniformly.
Casting was performed at a casting speed of 0.4 m / min using an immersion nozzle having an immersion nozzle angle of 10 ° downward with respect to the horizontal, and a rare earth element was further added by an in-mold alloy addition method.

The wire to be added contained [Y] as a rare earth element, and was further added at a rate of 2 m / min using a wire whose periphery was covered with 0.2 mm of iron.

FIG. 3 shows the state of diffusion of the rare earth element in the casting mold at the time of casting, FIG. 4 shows the concentration distribution in the slab obtained by casting, and FIG. 9B shows the rare earth element from the slab surface. However, when casting was performed by this method, the wire added in the mold was dissolved in the vicinity of the meniscus, so that the rare earth element became a slab concentrated on the slab surface part .

As a result, there were frequent occurrences of net cracks in the slab and surface defects during hot rolling. Therefore, about 1550
4 seconds as a result of measuring the melting time by immersion in molten steel
complete dissolution at c, so that the product of the addition rate is 13 cm
Became clear.

Therefore, according to the present invention, the material for coating the wire was changed to 0.4 mm, and the melting time in molten steel at 1550 ° C. was secured for 10 seconds, and the casting was performed so that the product with the addition rate was 33 cm. FIG. 1 shows the state of diffusion of the rare earth element in the casting mold during casting, FIG. 2 shows the concentration distribution in the slab obtained by casting, and FIG. 9A shows the degree of segregation of the rare earth element from the slab surface. Shows, by performing the casting in this method, the segregation degree of the slab surface portion is reduced to 0.9, further,
A slab having an internal segregation degree of 1.1 could be cast by continuous casting.

As a result, it was possible to prevent a slab crack from the casting to the hot rolling step and a surface defect of the hot rolled sheet, and to manufacture a steel sheet for a metal carrier satisfying the properties of the steel sheet.

[0048]

Example 2 Using a continuous casting mold having an internal space with a horizontal cross section of 250 × 980 mm, a slab for a metal carrier was produced by continuous casting.

In the casting, [Al] = 5% as mother molten steel,
A molten steel containing uniformly [Cr] = 20% and [P] = 0.05% is used, and an immersion nozzle having an immersion nozzle angle of 10 ° downward with respect to the horizontal is used.
Casting was performed at a casting speed of 4 m / min, and a rare earth element was further added by an in-mold alloy addition method.

The wire to be added is Ce as a rare earth element.
Was added at a rate of 2 m / min using a wire whose periphery was covered with 0.6 mm iron.

FIG. 5 shows the state of diffusion of the rare earth element in the casting mold at the time of casting, and FIG. 6 shows the concentration distribution in the slab obtained by casting. Since the wire is melted at a deep position in the mold, the concentration of rare earth elements on the slab surface can be prevented, but unmelted wire coating material remains in the slab, causing slab defects. I have.

Then, as a result of performing an immersion experiment on the present wire in molten steel at 1550 ° C., the melting time was 40 seconds.
c, and as a result, the product of the addition rate and the addition rate was found to be 130 cm.

Therefore, in accordance with the present invention, the coating material of the wire was changed to 0.4 mm, the melting time in molten steel at 1550 ° C. was secured for 10 sec, and casting was performed so that the product of the addition rate and the addition speed was 33 cm. .

FIG. 1 shows the diffusion state of the rare earth element in the casting mold at the time of casting, FIG. 2 shows the concentration distribution in the slab obtained by casting, and FIG. 9 (a) shows the rare earth element from the slab surface. The segregation degree of the slab was reduced to 0.9 by performing the casting according to the present method, and further, a slab having an internal segregation degree of 1.1 could be cast by continuous casting. .

As a result, it was possible to prevent a slab crack from the casting to the hot rolling step and a surface defect of the hot rolled sheet, and to produce a steel sheet for a metal carrier satisfying the properties of the steel sheet.

[0056]

Example 3 Using a continuous casting mold having an internal space with a horizontal cross section of 250 × 980 mm, a slab for a metal carrier was produced by continuous casting.

In the casting, [Al] = 5% as the base molten steel,
[Cr] = Use molten steel containing 20% uniformly.
Casting was performed at a casting speed of 0.6 m / min by using an immersion nozzle having an immersion nozzle angle of 45 ° downward with respect to the horizontal, and a rare earth element was further added by an in-mold alloy addition method.

The wire to be added contains [Y] as a rare earth element. Further, the wire was previously measured for melting time, and as a result, it was confirmed that the wire was melted at 1550 ° C. for 3 seconds. Used and added at an addition speed of 8 m / min.

FIG. 7 shows the state of diffusion of the rare earth element in the casting mold during casting, and FIG. 8 shows the concentration distribution in the cast slab obtained by casting. , The temperature of the molten steel dropped extremely, so that the added wire was not melted.

FIG. 7 shows that the angle of the immersion nozzle is
Explain that when casting with the temperature set downward at more than °, the wire added in the mold cannot be completely melted and remains in the slab because the temperature of molten steel in the mold is low. FIG. 8 shows the state of diffusion of elements in the slab during casting.
FIG. 8 is a sectional view of a slab manufactured by the method of FIG. 7.

Therefore, according to the present invention, casting was carried out with the discharge angle of the immersion nozzle set downward at 20 °.

FIG. 1 shows the state of diffusion of the rare earth element in the casting mold during casting, FIG. 2 shows the concentration distribution in the slab obtained by casting, and FIG. 7 shows the degree of segregation of the rare earth element from the slab surface. By performing the casting according to the present method, the degree of segregation at the surface of the slab was reduced to 0.9, and a slab having an inner degree of segregation of 1.1 could be cast by continuous casting.

As a result, it was possible to prevent a slab crack from the casting to the hot rolling step and a surface defect of the hot rolled sheet, and to produce a steel sheet for a metal carrier satisfying the properties of the steel sheet.

[0064]

According to the steel sheet for a metal carrier and the method for producing the same according to the present invention, it is possible to stably cast a foil material for a metal carrier which prevents segregation of rare earth elements on the surface of a slab. .

[Brief description of the drawings]

FIG. 1 is an explanatory view of adding a core of a rare earth element into a slab according to the present invention, showing the diffusion state of elements in the slab during continuous casting.

FIG. 2 is a sectional view of a slab produced by the method of FIG. 1;

FIG. 3 is a view for explaining that a rare earth element is concentrated on a surface portion of a slab.

FIG. 4 is a sectional view of a slab manufactured by the method of FIG. 3;

FIG. 5 is a view for explaining that an added wire remains undissolved in a mold.

FIG. 6 is a sectional view of a cast piece manufactured by the method of FIG. 5;

FIG. 7 is an explanatory view showing the state of diffusion of a rare earth element in a mold during casting.

FIG. 8 is a sectional view of a slab manufactured by the method of FIG. 7;

FIG. 9 is a diagram showing a segregation degree of a rare earth element in a plate thickness direction in a metal carrier slab cast by the present method. Here, (a) shows the degree of segregation in a slab cast by the present invention, and (b) shows, as a comparison, the degree of segregation in a slab cast by a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Immersion nozzle 2 Guide pipe 3 Wire 4 Rare earth element low concentration area in mold 5 Rare earth element high concentration area in mold 6 Mother molten steel in ingot 7 Mold 8 Unmelted wire

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI B22D 11/103 B22D 11/103 B 11/20 11/20 A (72) Inventor Tomohiro Furuta 1-1-1 Tobata-cho, Tobata-ku, Kitakyushu-shi No. Nippon Steel Corporation Yawata Works (56) References JP-A-2-303605 (JP, A) JP-A-2-254136 (JP, A) JP-A-3-170642 (JP, A) JP-A-3-134137 (JP, A) JP-A-5-140766 (JP, A) JP-A-1-115455 (JP, A) JP-A-62-290857 (JP, A) JP-A-6-93386 ( JP, A) JP-A-6-170498 (JP, A) JP-A-5-237599 (JP, A) JP-A-3-177542 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , (DB name) B22D 11/108 B01J 35/04 301 B22D 11/00 B22D 11/10 330 B22D 11/103 B22D 11/20

Claims (1)

(57) [Claims] The main component of the product is [Al] = 4.5
6.5%, [Cr] = 13 to 25%, rare earth element = 0.
When casting a metal carrier material of 0.6 to 0.15% by continuous casting, the casting speed is 0.2 to 1.0 m / m.
In the range of in, further, casting is performed by setting the discharge angle of the immersion nozzle in a range of 40 ° downward from horizontal.
A continuous casting method for a foil material for a metal carrier, characterized in that the addition conditions for adding a rare earth element to molten steel in a mold by the alloy addition method in a mold are controlled within the range of formula (1). 0.2 ≦ α ≦ 1.0 m (1) α = addition rate for adding the required amount of rare earth element (m /
s) Melting time for immersing the wire in molten steel at 1550 ° C (sec)