JPH1112677A - Manufacturing method of extremely low manganese alloy - Google Patents

Abstract

(57) [Problem] To produce an alloy (SUS316L) having a manganese content of 0.05% by weight or less at low cost. The manganese content [Mn] is 0.06 to 0.3.
Using a 0% by weight consumable electrode, the diameter of the ingot to be obtained is D
(Mm) When the degree of vacuum during melting is defined as P (Pa), vacuum arc remelting is performed at a melting speed V (kg / min) satisfying the following expression or the expression. When 0.06 ≦ [Mn] ≦ 0.15, 0.2 ≦ V ≦ {0.0002 ・ D / P ・ ([Mn] −0.05)} + 2.7 ・ ・ ・ ・ 0.15 <[Mn] ≦ 0.30, 0.2 ≦ V ≦ {(0.013・ D / P) +16.7} (0.3- [Mn]) + 0.2 ・ ・ ・ ・

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to alloys such as Fe-based alloys and Ni-based alloys represented by ordinary steel, special steel and stainless steel, wherein the manganese content in the alloy is 0.05.
The present invention relates to a method for producing an extremely low manganese alloy which is required to be not more than% by weight.

[0002]

2. Description of the Related Art In the field of manufacturing semiconductors and liquid crystals, in recent years, the degree of integration has been further increased. For example, in the manufacture of a device called a super LSI, processing of a fine pattern on a submicron unit is required. ing. However, in the above-described VLSI manufacturing process, if minute dust or a small amount of impurity gas adheres to the wiring pattern, the circuit is short-circuited, resulting in a defective product.

[0003] Therefore, the reaction gas used is required to be high in purity and low in fine particles (particles) existing in the gas. For this reason, the pipe material constituting the supply pipe of the reaction gas and its attached members include:
It is required that the generation of particles emitted from the inner surface is as small as possible.

[0004] As a semiconductor manufacturing gas, nitrogen,
In addition to inert gases such as argon, many extremely corrosive gases such as hydrogen chloride and hydrogen bromide are used. For this reason, it is required that the above-mentioned tube material and the material for the attached member have good corrosion resistance and do not generate particles such as metal compounds as corrosion products from the material surface.

As the above-mentioned material, austenitic stainless steel is usually used, and in particular, the amount of nonmetallic inclusions is reduced by regulating the content of impurity elements.
SUS316L is mainly used to reduce the generation of particles emitted from the material surface.

However, among the impurity elements, manganese evaporates during welding during pipe fabrication due to its high vapor pressure, and is deposited in a pipeline downstream of a welded portion or flows as particles to the downstream side to cause contamination. It is easy to be.

[0007] Therefore, if the manganese content can be reduced more than ever before, it will have extremely excellent performance in the following points.

(A) Since the generation of manganese fume during welding is reduced, the amount of generated particles is reduced. (b) Corrosion resistance is improved because the amount of manganese fume adhering to the pipe inner surface is reduced. (c) A beautiful weld bead is obtained. (d) The corrosion resistance of the material itself is improved.

[0009] Incidentally, alloys represented by SUS316L, which are used as materials for the above-mentioned tube material and its attached members, have been conventionally produced mainly by a vacuum remelting process.

That is, it is manufactured by performing primary melting by a vacuum induction melting method and then performing secondary melting by a consumable electrode type vacuum arc remelting method or an electron beam melting method (for example, see Japanese Patent Application Laid-Open No. 7-90472). ).

However, when an alloy having a manganese content of 0.05% by weight or less is to be produced by the above-mentioned vacuum remelting process, a low manganese material, specifically, a consumable electrode which is a material for secondary melting is used. Required that the manganese content be at least less than 0.06% by weight.

The reason is that in order to produce a desired ingot by one-time secondary vacuum melting, a consumable electrode having a manganese content that is qualitatively low in accordance with the manganese content of the ingot to be obtained is used. However, in this case, manganese hardly decreases in ordinary vacuum arc remelting.

Therefore, it is necessary to produce a low manganese material having a manganese content of at least less than 0.06% by weight in the above-mentioned primary dissolution, and for that purpose, a high-grade material having a low manganese content is used as a raw material to be subjected to the primary dissolution. It is necessary to use expensive ones. If high-quality raw materials are not used, it is necessary to perform a costly special demanganese treatment at the time of the first melting. For this reason, there has been a problem that the manufacturing cost of the product is significantly increased.

As a method of controlling the manganese content in remelting under vacuum, there is a method of controlling the degree of vacuum in order to change the amount of manganese evaporated from the molten alloy during melting (Japanese Patent Publication No. 7-081711). Reference). However, the publication states that the manganese content is 0.05% by weight.
No specific method for producing an extremely low manganese alloy at low cost is described below.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to eliminate the need for using high-quality raw materials having a low manganese content in the primary dissolution, and It is possible to produce an ingot with a manganese content of 0.05% by weight or less using an electrode having a relatively high manganese content, which can be easily produced without performing a costly special demanganese treatment. It is an object of the present invention to provide a method for producing an extremely low manganese alloy.

[0016]

The gist of the present invention resides in the following method for producing an extremely low manganese alloy.

A method for producing an extremely low manganese alloy having a manganese content of 0.05% by weight or less by using a consumable electrode type vacuum melting method, wherein the manganese content [Mn] of the consumable electrode is less than 0.1% by weight. In addition to using those having a melting point of 0.6 to 0.30% by weight and setting the degree of vacuum of the melting furnace to less than 10 Pa, the diameter of the ingot to be obtained is D (mm), and the degree of vacuum during melting is P (Pa). And re-melting at a dissolution rate V (kg / min) satisfying the following equation or the following equation:

When 0.06 ≦ [Mn] ≦ 0.15

[0019]

(Equation 3)

When 0.15 <[Mn] ≦ 0.30

[0021]

(Equation 4)

In the above-mentioned present invention, the manganese content is set to 0.1.
As an inexpensive method for producing extremely low manganese alloys of up to 05% by weight, in the first vacuum melting, a consumable electrode with a relatively high manganese content [Mn] obtained using inexpensive raw materials is used. We focused on a method to make manganese evaporation more active.

Specifically, by adjusting the melting rate V of the consumable electrode according to the degree of vacuum P, the manganese content [Mn] of the consumable electrode to be used, and the diameter D of the ingot to be obtained, the secondary vacuum melting is performed. Is characterized in that manganese evaporation from the molten alloy is promoted to obtain an extremely low manganese alloy having a manganese content of 0.05% by weight or less.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the alloy to be obtained by the method of the present invention will be described.
It is an Fe-based alloy or Ni-based alloy typified by ordinary steel, special steel and stainless steel of not more than 05% by weight, and the content of components other than manganese is not particularly restricted.

An important feature of the method of the present invention is that when a consumable electrode having a relatively high manganese content [Mn] obtained by using an inexpensive raw material in the primary vacuum melting is redissolved in the second vacuum, Degree of vacuum P (Pa), diameter D of ingot to be obtained
By adjusting the dissolution rate V (kg / min) of the consumable electrode in accordance with (mm) and the manganese content [Mn] (% by weight) of the consumable electrode, the evaporation of manganese from the molten alloy is promoted to 0. It is to obtain an ingot having a manganese content of 0.05% by weight or less.

At this time, while the degree of vacuum of the melting furnace is set to less than 10 Pa, it is necessary to use a consumable electrode having a manganese content [Mn] of 0.06 to 0.30% by weight.
In addition, the dissolution rate V (kg / min) of the consumable electrode needs to be set to a value that satisfies the above expression or the expression according to the manganese content [Mn].

Here, it is necessary to set the degree of vacuum of the melting furnace to less than 10 Pa for the following reason.

That is, manganese is an element having a high vapor pressure and easily evaporates under vacuum. The evaporation rate depends on the difference between the degree of vacuum in the furnace and the manganese vapor pressure. The smaller the difference, in other words, the lower the degree of vacuum in the furnace, the slower the evaporation rate. It takes too long to dissolve because it is too slow and is not industrial. If the degree of vacuum is 10 Pa or more, there is a risk that glow discharge will occur, and it will be difficult to redissolve itself. Therefore, in the present invention, the degree of vacuum of the melting furnace is set to less than 10 Pa.

The consumable electrode has a manganese content [Mn].
Must be 0.06 to 0.30% by weight, and the dissolution rate V must be set to the above equation or a value satisfying the above equation. These are based on the results of the basic experiments described below.

Using a vacuum arc remelting furnace (VAR furnace), SU with various manganese contents [Mn] (% by weight) was used.
Made of S316L consumable electrode, diameter D is 500m
m and 800 mm ingot, the degree of vacuum P in the furnace
Was set to 0.3 Pa and 1.0 Pa, and a secondary vacuum arc melting was performed by variously changing the melting rate V (kg / min) of the consumable electrode, and the manganese content of the obtained ingot was investigated.

1 to 3 show the results of the investigation, in which the degree of vacuum P in the furnace during melting, the diameter D of the ingot to be obtained, the manganese content [Mn] of the consumable electrode and the melting rate V were obtained. FIG. 3 is a diagram showing the effect of a given ingot on the manganese content. And in the figure, the manganese content of the obtained ingot was 0.1%.
The case where the content was less than 05% by weight is indicated by a mark “○”, and the case where the content was more than 0.05% by weight was indicated by a mark “▲”.

As is clear from FIGS. 1 to 3, in each case, a consumable electrode having a manganese content [Mn] of 0.30% by weight or less was used, and its dissolution rate V was adjusted to its own manganese content [Mn]. It can be seen that when remelted to a predetermined value or less determined according to the above, an ingot having a manganese content of 0.05% by weight or less can be obtained.

More specifically, the results shown in FIGS. 1 to 3 are put together and the manganese content is 0.05% by weight in consideration of the degree of vacuum P in the furnace during melting and the diameter D of the ingot to be obtained.
When the upper limit of the dissolution rate V of the consumable electrode capable of obtaining the following ingot is represented by an equation, the upper limit is such that the manganese content [Mn] of the consumable electrode is 0.06 to 0.15% by weight. In this case, the value is represented by the following equation. When the manganese content [Mn] of the consumable electrode is more than 0.15% by weight and 0.30% by weight or less, the upper limit of the dissolution rate V is a value represented by the following equation.

[0034]

(Equation 5)

[0035]

(Equation 6)

According to the experimental results shown in FIGS. 1 to 3, the manganese content [Mn] of the consumable electrode was 0.06% by weight.
In the case of, as the value of the degree of vacuum P decreases, the upper limit of the dissolution rate V approaches infinity. However, in actuality, when the ingot quality such as segregation is taken into consideration, the dissolution rate at a dissolution rate V exceeding 20 kg / min is considered. Should be avoided.

In order to promote the evaporation of manganese, a lower dissolution rate V is desirable. However, for example, in order to produce an ingot of 500 kg or more which is generally regarded as industrial, it takes 42 hours or more if the dissolution rate V is less than 0.2 kg / min, which is not practical.

Further, as shown in FIGS. 1 to 3, when the manganese content [Mn] of the consumable electrode is 0.30% by weight,
The upper limit of the dissolution rate V of the consumable electrode capable of obtaining an ingot having a manganese content of 0.05% by weight or less is 0.2 kg /
It can be seen that the value approaches to min.

On the other hand, when the manganese content [Mn] of the consumable electrode is 0.05% by weight or less, there is no manganese pick-up at the time of re-melting. The amount will be less than 0.05% by weight.

From the above, according to the present invention, a consumable electrode having a manganese content [Mn] of 0.06 to 0.30% by weight is used, and the dissolution rate V is set within the above formula or a range satisfying the above formula. It was decided.

[0041]

EXAMPLE Using a vacuum arc remelting furnace (VAR furnace),
Manganese content [Mn] variously different outer diameter 130-69
Using 21 types of consumable electrodes made of SUS316L of 0 mm as a material, the degree of vacuum P during melting and the dissolution rate V of the consumable electrodes
And ingots having different outer diameters D were produced.

Then, a test piece was sampled from the D / 4 position at the center in the longitudinal direction of the obtained ingot, and the manganese content was examined. Based on the results, the manganese content [M
n], the degree of vacuum P during dissolution and the dissolution rate V of the consumable electrode are shown in Table 1.

[0043]

[Table 1]

As shown in Table 1, the ingots of the present invention (Nos. 1 to 14) produced according to the method of the present invention were:
In each case, the manganese content was 0.05% by weight or less.

On the other hand, the ingots of the comparative examples (Nos. 15 to 21) produced under the conditions in which the dissolution rate V of the consumable electrode is out of the range specified in the present invention have a manganese content of any of them. It was 0.06% by weight or more.

[0046]

According to the present invention, the manganese content is set to 0.1.
An extremely low manganese alloy of not more than 05% by weight can be manufactured stably. In addition, a consumable electrode which is a material having a relatively high manganese content can be used, so that the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 The degree of vacuum during melting is 0.3 Pa and the diameter of the ingot is 5
It is a figure which shows the influence which the dissolution rate of a consumable electrode and the manganese content have on the manganese content of an ingot in the case of 00 mm.

FIG. 2 shows that the degree of vacuum during melting is 1 Pa and the diameter of the ingot is 500
It is a figure which shows the influence which the dissolution rate of a consumable electrode and manganese content have on the manganese content of an ingot in the case of mm.

FIG. 3 shows that the degree of vacuum during melting is 1 Pa and the diameter of the ingot is 800
It is a figure which shows the influence which the dissolution rate of a consumable electrode and manganese content have on the manganese content of an ingot in the case of mm.

Claims (1)

[Claims] 1. A method for producing an extremely low manganese alloy having a manganese content of 0.05% by weight or less using a consumable electrode type vacuum melting method, wherein the consumable electrode has a manganese content [Mn]. 0.06 to 0.30% by weight, the degree of vacuum in the melting furnace is set to less than 10 Pa, the diameter of the ingot to be obtained is D (mm), and the degree of vacuum during melting is P (Pa ), Wherein the re-melting is performed at a dissolution rate V (kg / min) that satisfies the following equation or the following equation: When 0.06 ≦ [Mn] ≦ 0.15 0.15 <[Mn] ≦ 0.30