JPH07138709A - Stainless steel for wire rod horizontal continuous casting excellent in long time castability - Google Patents

Abstract

PURPOSE:To produce a stainless steel for wire rod horizontal continuous casting excellent in longtime castability by specifying the componental compsn. constitut ed of Ni, Cr, C, Si, Mn and iron and the contents of chalcogens such as S, Se and O. CONSTITUTION:A stainless steel for wire rod horizondal continuous casting contg., by weight, <=40% Ni, 13 to 28% Cr. <=0.2% C, <=4% Si and <=10% Mn, and the balance iron is incorporated with 0.004 to 0.020% of one or more kinds of chalcogens among 0.004 to 0.020% S, 0.004 to 0.020% Se and 0.004 to 0.010% O. In this way, the surface tension of this stainless steel is reduced to increase its fluidity. Thus, in a wire rod horizondal continuous casting method for a diameter of about <=12mm of the stainless steel, the rupture of the wire rod in the process is prevented to prevent deterioration in its productivity and yield, thus stable continuous casting is made possible for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stainless steel suitable for producing a wire rod by a horizontal continuous casting method, particularly a wire rod having a diameter of 12 mm or less.

[0002]

2. Description of the Related Art As one method for producing a relatively thin stainless steel wire having a diameter of 12 mm or less, a horizontal continuous wire casting method is known. This is a wire rod horizontal continuous casting machine 1 shown in FIG.
Is a method of directly casting the stainless steel wire 3 by flowing molten steel (molten metal) 2 from the tundish 10 into the mold (mold) 13 through the tapping nozzle 11 and the break ring 12. Reference numeral 14 is a pinch roll, and reference numeral 15 is a gas introduction port 15 for supplying nitrogen gas or an inert gas into the tundish 10.

Conventionally, in the production of stainless steel, it has been common sense to keep the concentrations of sulfur and oxygen as low as possible from the viewpoints of hot workability and corrosion resistance, except for special applications. That is, sulfur combines with other elements (eg, manganese) to form sulfides, which are the starting point for pitting corrosion, while
This is because oxygen deteriorates cleanliness, punching properties and surface properties. Therefore, their concentrations are, specifically, 0.003% by weight or less of sulfur and 0.
It was 002% by weight or less.

[0004]

However, when a wire rod made of stainless steel having the above-mentioned conventional composition is continuously cast by using the above wire rod horizontal continuous casting machine 1, the wire rod will be halfway before reaching the target casting amount. Sometimes it broke. Once the wire rod was broken, the molten steel 2 solidified in the mold 13, and it was impossible to continuously perform continuous casting. Therefore, the molten steel 2 remaining in the tundish 10 must be drained immediately when the wire breaks, which causes a problem that productivity and yield are reduced.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent continuous deterioration of productivity and yield in the horizontal continuous casting method of a wire rod, and continuously cast a stainless steel wire continuously for a long time. It is an object of the present invention to provide a stainless steel for horizontal continuous casting of wire, the composition of which is adjusted so that it is excellent in long-term castability.

[0006]

In order to achieve the above object, the present inventor conducted various investigations on the internal structure and composition of the stainless steel wire 3 produced by the wire rod horizontal continuous casting method, and examined the fracture of the wire rod. The cause has been clarified.

The cause thereof is that the heat removal capability of the mold 13 gradually decreases immediately after the start of casting, the thickness of the solidified shell becomes gradually thin, and it cannot withstand the pulling load and breaks. It has been found that the decrease in heat removal capability occurs because the molten steel 2 cooled by the tapping nozzle 11 has poor fluidity and the molten steel 2 is less likely to wet the mold 13.

Therefore, the present inventor thinks that in order to prevent breakage of the wire during the continuous casting, it is sufficient to lower the surface tension of the molten steel 2 to improve the fluidity. It has been found that it is effective to contain an appropriate amount of chalcogen such as selenium and oxygen, and the present invention has been completed.

That is, according to the present invention, nickel having a concentration of 40 wt% or less, chromium having a concentration of 13 wt% or more and 28 wt% or less, carbon having a concentration of 0.2 wt% or less, carbon having a concentration of 4 wt% or less is used. A stainless steel for horizontal continuous casting of wire, containing silicon and manganese at a concentration of 10% by weight or less, and the balance being iron, wherein sulfur has a concentration of 0.004% by weight or more and 0.020% by weight or less, 0 0.02 when 0.004% by weight or more
Selenium with a concentration of 0% by weight or less, and 0.004% by weight
It is characterized in that it contains one or more chalcogens selected from the chalcogen group consisting of oxygen at a concentration of 0.010% by weight or less in a total amount of 0.004% by weight or more and 0.020% by weight or less. And

Hereinafter, the reasons for setting the concentrations of the above components to the above ranges will be described.

With respect to sulfur (S) and selenium (Se), if their concentrations are less than 0.004% by weight, the fluidity of the molten steel 2 is not sufficient and heat removal ability within a sound range is obtained. On the other hand, when the content exceeds 0.020% by weight, the molten steel 2 is seized with the mold 13 and casting becomes impossible.

Regarding oxygen (O), its concentration is 0.0
This is because if it is less than 04% by weight, the fluidity of the molten steel 2 is not sufficient and the heat removal ability within a sound range cannot be obtained. On the other hand, if it exceeds 0.010% by weight, the molten steel 2
The reason is that it will be seized with the mold 13 and cannot be cast. In the present specification, in the description of the components of stainless steel, oxygen means dissolved oxygen,
It does not contain oxygen in inclusions such as oxides.

The total amount of two or more of sulfur, selenium, and oxygen is 0.020% by weight or less. When the upper limit is exceeded, the molten steel 2 seizes on the mold 13. This is because casting becomes impossible.

Preferably, the concentration of each of sulfur, selenium and oxygen is 0.007% by weight or more and 0.020% by weight or less, and when two or more of them are contained, the total amount is 0. The content is preferably 0.007% by weight or more and 0.020% by weight or less.

With respect to nickel (Ni), the corrosion resistance to non-oxidizing acids such as sulfuric acid and hydrochloric acid shows a saturation tendency at a concentration of 40% by weight, and even if the content exceeds this concentration, the corrosion resistance is further improved. Because I can't expect.

The concentration of chromium (Cr) is 1
If it is less than 3% by weight, sufficient corrosion resistance to non-oxidizing acids such as sulfuric acid and hydrochloric acid cannot be obtained, while if it exceeds 28% by weight, the above corrosion resistance tends to be saturated.

The concentration of carbon (C) is 0.2
This is because if the content exceeds the weight percentage, carbides of chromium are likely to be formed, thereby reducing corrosion resistance.

For silicon (Si), the concentration is 4
This is because if the content exceeds 5% by weight, the high temperature oxidation resistance decreases and hot cracking easily occurs.

This is because the corrosion resistance of manganese (Mn) decreases when the concentration exceeds 10% by weight.

In addition to the above-listed elements, the stainless steel for horizontal continuous casting of wire according to the present invention has a molybdenum (M) (M) content in order to improve corrosion resistance and pitting corrosion resistance.
O), copper (Cu), or other elements may be contained. At that time, the concentration of molybdenum or copper is not particularly limited, but is preferably about 5% by weight or less.

The stainless steel for horizontal continuous casting of wire according to the present invention contains at least one of sulfur, selenium and oxygen among sulfur, selenium, oxygen, nickel, chromium, carbon, silicon and manganese, and chromium. The presence or absence of other elements is irrelevant as long as it contains iron.

[0022]

According to the above means, the stainless steel for continuous horizontal casting of wire according to the present invention has a content of 0.004% by weight or more and 0.0
Sulfur at a concentration of 20 wt% or less, selenium at a concentration of 0.004 wt% or more and 0.020 wt% or less, and 0.00
The total amount of one or more chalcogens selected from the chalcogen group consisting of oxygen at a concentration of 4% by weight or more and 0.010% by weight or less is 0.004% by weight or more and 0.020% by weight.
Since it is contained in the following concentration, the fluidity of the molten steel 2 is just improved and the wettability between the molten steel 2 and the mold 13 is optimized. Therefore, during continuous casting of the stainless steel wire 3, the heat removal ability of the mold 13 is kept within a sound region throughout the continuous casting, the stainless steel wire 3 is prevented from being broken during the continuous casting, and the molten steel 2 and the mold ( It is prevented that casting becomes impossible due to seizure with the mold 13).

Therefore, the stainless steel wire 3 can be stably continuously cast for a long time, the productivity and the yield of the stainless steel wire 3 in the horizontal continuous casting method of the wire can be prevented from being lowered, and the material Uniform stainless steel wire 3
Can be obtained.

In addition to wire rods, there are slabs and billets manufactured by horizontal continuous casting. However, since all of them have a large cross-sectional area and a long mold length, the decrease in heat removal capacity does not lead to breakage. Therefore, the present invention can be said to be a problem peculiar to horizontal continuous casting of wire rods.

[0025]

EXAMPLES Hereinafter, the features of the present invention will be clarified by giving examples and conventional examples. In each of the examples and the conventional examples, the wire rod horizontal continuous casting machine 1 configured as shown in FIG. 1 was used, the target casting amount was set to 550 kg, and the drawing stroke was 20 mm and the drawing speed was 3.0 m / min. A stainless steel wire 3 having a diameter of 10 mm was manufactured. Unless otherwise specified, manufacturing conditions and the like were the same in each example and each conventional example.

The ingredients of the raw material to be the molten steel 2 were adjusted in advance so that the stainless steel wire 3 having a desired composition was cast. In addition, in each example, the value of the heat removal capacity is calculated by using the cooling water temperature difference between the inlet side (the inflow side of the molten steel 2) and the outlet side (the delivery side of the stainless steel wire 3) of the mold 13, the cooling water amount, and the mold 13. The value was calculated from the surface area value.

(Examples 1 to 13) Table 1 shows the composition of each stainless steel wire 3 produced in Examples 1 to 13.

[Table 1]

Table 1 also shows the amount of casting that was continuously performed without breaking in Examples 1 to 13 and the calculated heat removal capacity (value in a stable state). As can be seen from the table, in all the examples, the concentrations of sulfur, selenium, and oxygen contained, and the total amounts thereof were within the respective ranges specified in the present invention, and fracture occurred on the way. The target casting amount of 550 kg could be achieved without any effort.

Further, with respect to Examples 1 to 13, FIGS. 2 to 14 show the changes with time in the heat removal capacity from the start to the end of casting. From those figures, in all the examples, the value of the heat removal ability during casting was good in all the examples (6 ×).
It was found to be within 10 ⁶ to 8 × 10 ⁶ kcal / m ² · hour).

(Conventional Examples 1 to 4) The composition of each of the stainless steel wires 3 produced in Conventional Examples 1 to 4, the amount of casting that was continuously performed before breaking, and the calculated heat removal capacity (stable condition) Values) are also shown in Table 1. Further, with respect to Conventional Examples 1 to 4, FIGS. 15 to 18 show the changes over time in the heat removal ability from the start to the end of casting.

As can be seen from Table 1, in Conventional Example 1, the concentration of sulfur was 0.001% by weight and the concentration of oxygen was 0.002.
The content was wt%, and none of them fell below the lower limit of each range specified in the present invention. No selenium was added. Therefore, when the casting amount reaches 200 kg, the stainless steel wire 3
Has broken. The change with time of the heat removal capability was much lower than the healthy region from the beginning of casting, and gradually decreased as casting proceeded.

In Conventional Example 2, sulfur exceeds the range specified in the present invention, and naturally the total amount of sulfur and oxygen combined also exceeds the range specified in the present invention. Therefore, although the heat removal ability is within a sound region and is proper, the mold 13 and the molten steel 2 are too wet and seizure thereof occurs, and casting is impossible at the initial stage of casting. .

In Conventional Example 3, selenium exceeds the range specified by the present invention, and naturally the total amount of sulfur, selenium and oxygen combined exceeds the range specified by the present invention. Therefore, as in Conventional Example 2, casting became impossible at the early stage of casting.

In Conventional Example 4, the total amount of sulfur, selenium, and oxygen was within the range specified by the present invention, but oxygen exceeded the range specified by the present invention. Therefore, as in Conventional Example 2, casting became impossible at the early stage of casting.

Examples 1 to 13 and Conventional Example 1 described above
From 4, the stainless steel used in the horizontal continuous casting method for wire is
At least one of sulfur, selenium, and oxygen, and 0.004% by weight to 0.02% for sulfur and selenium.
0% by weight, 0.004% by weight to 0.01% for oxygen
The content of 0% by weight, and the total amount of 0.004% by weight or more and 0.020% by weight or less, ensures stable stainless steel without causing breakage during continuous casting. It can be seen that the wire 3 can be continuously cast.

It should be noted that the stainless steel of the present invention is not limited to the above-mentioned examples, and it is sufficient that at least one of sulfur, selenium, and oxygen is contained, and the concentration thereof is For sulfur, 0.
004 wt% to 0.020 wt%, 0.004 wt% to 0.020 wt% for selenium, and 0.004 wt% to 0.010 wt% for oxygen.

When two or more of sulfur, selenium and oxygen are contained, at least one concentration satisfies the above concentration and the total amount is 0.004% by weight or more and 0.020% by weight or less. Needless to say, the effect that the stainless steel wire 3 can be continuously cast stably without causing seizure and breakage can be sufficiently obtained with the concentration.

[0038]

According to the stainless steel of the present invention,
Sulfur at a concentration of 0.004 wt% or more and 0.020 wt% or less, selenium at a concentration of 0.004 wt% or more and 0.020 wt% or less, and 0.01 at 0.004 wt% or more.
The total amount of one or more chalcogens selected from the chalcogen group consisting of oxygen at a concentration of 0% by weight or less is 0.004.
Since it is contained in a concentration of not less than 0.020% by weight and not more than 0.020% by weight, the heat removal capability of the mold is maintained soundly throughout the continuous casting of the stainless steel wire, and the wettability between the molten steel and the mold is also maintained. This is optimal, and it prevents casting failure due to breakage and seizure of the stainless steel wire during continuous casting.

Therefore, the stainless steel wire can be stably continuously cast for a long time, the productivity and the yield of the stainless steel wire can be prevented from being lowered in the horizontal continuous wire casting method, and the material can be made uniform. A stainless steel wire can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a wire rod horizontal continuous casting machine used for manufacturing a wire rod made of stainless steel according to the present invention.

FIG. 2 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Example 1.

FIG. 3 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Example 2.

FIG. 4 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Example 3.

FIG. 5 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Example 4.

FIG. 6 is a characteristic diagram showing changes with time in heat removal capability during continuous casting in Example 5.

FIG. 7 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Example 6.

FIG. 8 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Example 7.

FIG. 9 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Example 8.

FIG. 10 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Example 9.

FIG. 11 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Example 10.

FIG. 12 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Example 11.

FIG. 13 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Example 12.

FIG. 14 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Example 13.

FIG. 15 is a characteristic diagram showing changes over time in heat removal capacity during continuous casting in Conventional Example 1.

FIG. 16 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Conventional Example 2.

FIG. 17 is a characteristic diagram showing changes with time in heat removal capacity during continuous casting in Conventional Example 3.

FIG. 18 is a characteristic diagram showing changes over time in heat removal capacity during continuous casting in Conventional Example 4.

[Explanation of symbols]

 1 wire rod horizontal continuous casting machine 2 molten steel 3 stainless steel wire (wire rod) 10 tundish 11 tapping nozzle 12 break ring 13 mold 14 pinch roll 15 gas inlet

Front Page Continuation (72) Inventor Masato Noda 4-2 Kojima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Nihon Metallurgical Industry Co., Ltd. R & D Headquarters Technical Research Center (72) Takashi Nakatani, Kojima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 4-2 Nihon Metallurgical Industry Co., Ltd.

Claims (1)

[Claims] 1. Nickel having a concentration of 40% by weight or less, 13
Chromium having a concentration of not less than 28% by weight and not more than 28% by weight, carbon having a concentration of not more than 0.2% by weight, silicon having a concentration of 4% by weight or less,
And a stainless steel for horizontal continuous casting of wire, containing manganese at a concentration of 10% by weight or less, and the balance being iron,
Sulfur at a concentration of 0.004 wt% or more and 0.020 wt% or less, selenium at a concentration of 0.004 wt% or more and 0.020 wt% or less, and 0.01 at 0.004 wt% or more.
The total amount of one or more chalcogens selected from the chalcogen group consisting of oxygen at a concentration of 0% by weight or less is 0.004.
A stainless steel for horizontal continuous casting of a wire excellent in long-term castability, which is characterized by containing at a concentration of not less than 0.020% by weight and not more than 0.020% by weight.