JPH0860308A - Stainless steel material excellent in wire drawability - Google Patents

Abstract

PURPOSE: To produce a stainless steel material capable of being superiorly wiredrawn into an extra fine wire while reducing refining cost. CONSTITUTION: This stainless steel material has a composition consisting of <=0.15% C, <=1.0% Si, <=2.0% Mn, 7-30% Ni, 15-25% Cr, <=0.05% P, <=0.03% S, and the balance essentially Fe. Moreover, the inclusions existing in the steel are multiple inclusions containing CaO formed by the addition of Ca to the steel, and further, the total content of O in the steel is controlled to 40-100ppm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stainless steel material having excellent wire drawability.

[0002]

2. Description of the Related Art Conventionally, in order to miniaturize or miniaturize various wire nets, filters and springs for precision equipment, a stainless steel wire rod having a wire diameter of 1 mm or less, for example, about 50 μm is used as a constituent wire rod.

Usually, these wire rods for wire mesh and springs are manufactured by wire drawing. However, in the case of extra fine wires having a wire diameter of 1 mm or less, the wire breakage is caused by inclusions present in the steel during wire drawing. However, there was a problem that it was difficult to satisfactorily perform wire drawing.

Therefore, when manufacturing such an ultrafine wire, generally, after performing ordinary atmospheric refining, ESR, VA
The reality is that remelting and refining of R, etc. is performed to make the steel cleaner, reduce inclusions, and make it finer. However, when such special refining is performed, naturally, there arises a problem that the manufacturing cost becomes high.

[0005]

The invention of the present application has been made in view of such circumstances, and an object of the invention is to provide a stainless steel material capable of excellent wire drawing only by performing ordinary atmospheric refining. To do. Thus, in the stainless steel material of the present invention, the inclusions present in the steel are composite inclusions containing CaO, and the total amount of O in the steel is 4
It is regulated to 0 to 100 ppm (Claim 1).

Another invention of the present application is characterized in that, in claim 1, the total amount of Ca in the steel is regulated to 10 to 20 ppm (claim 2).

Still another invention of the present application is characterized in that, in claim 1 or 2, the total amount of Al in the steel is restricted to 30 ppm or less (claim 3).

Still another invention of the present application is the method according to claim 1, 2 or 3, wherein the steel composition is C: ≤ 0.15% by weight% and S.
i: ≤ 1.0%, Mn: ≤ 2.0%, Ni: 7-30
%, Cr: 15 to 25%, P: ≤ 0.05%, S: ≤
It is characterized in that the composition is 0.03% and the balance substantially consists of Fe (claim 4).

[0009]

As described above, according to the first aspect of the invention, the inclusions in the steel are composite inclusions containing CaO. Generally, the morphology of inclusions present in stainless steel is A
l ₂ O ₃ —Cr ₂ O ₃ —MgO is the main component, which is hard, and when a stainless steel material containing such inclusions is drawn, it is possible to draw extra fine wires of 1 mm or less, for example, about 50 μm. If it is attempted to obtain it by working, the particle size ratio of the inclusions to the wire diameter becomes large, that is, the ratio of the inclusions in the cross section becomes large, and disconnection is likely to occur from such inclusions at the time of wire drawing.

However, when the inclusion is a composite inclusion containing CaO according to the present invention, the inclusion can have a low melting point and can be softened. Form of composite inclusions containing CaO produced by Ca addition is, for example CaO-SiO ₂ -A
L ₂ O ₃ —Cr ₂ O ₃ —MnO—MgO is the main constituent, and thus inclusions in this form are likely to migrate into the slag during refining, have a low melting point and are soft in the steel, and are plastic. It is abundant and easily extends in the rolling direction during rolling. That is, the diameter of the inclusion in the direction perpendicular to the wire drawing direction is smaller than the wire diameter of the wire, and it is less likely to be the starting point of disconnection.

Incidentally, according to the present invention, the diameter of the inclusion (diameter in the direction perpendicular to the drawing direction) can be set to 1/3 or less of the wire diameter when drawing an ultrafine wire of 50 μm,
Wire breakage during wire drawing can be prevented, and good wire drawing can be performed. Has been confirmed by the present inventors).

According to the present invention, the total amount of O in steel is 40 to 100.
It is characterized by limiting to ppm. Here, the total amount of O is regulated to 100 ppm or less because when the total amount of O is larger than this, the total amount of inclusions increases and the inclusions increase in size and become hard.

On the other hand, the total amount of O is set to 40 ppm or more for the following reason. In general, it is considered that the smaller the amount of O, the smaller the amount of inclusions and the finer the particles, which is desirable. However, if the amount of O becomes less than a certain level, the components in the refractory material of the furnace during melting of steel, such as Al ₂ O ₃
It was found that Al and Mg dissociate into Al + O and Mg + O, respectively, and as a result Al and Mg in the steel increase, which contribute to the structure of the inclusions and harden the inclusions.

In other words, it has been found that it is desirable to set the total amount of O to a certain level (40 ppm or more) in order to prevent this. Here, a more desirable amount of O is 50 to 70 ppm.

The amount of O in the steel is related to the basicity (CaO / SiO ₂ ratio) in the slag during steel making, and by adjusting the basicity to 1.6 to 2.0, the The amount of O can be controlled to the above amount.

As described above, according to the present invention, the inclusions in the steel are C
This is a composite inclusion containing aO, and for that purpose, the total amount of Ca should be 10 ppm or more (claim 2). By doing so, the inclusions in the steel can be effectively made into composite inclusions containing CaO. Meanwhile C
If a is added in excess of 20 ppm, the total amount of inclusions will be too large, which will rather bring about inconvenient results.

On the other hand, it has been confirmed that the total amount of Al should be 30 ppm or less. The amount of Al is 30
This is because the inclusions become harder and the total amount increases when the content exceeds ppm.

The present invention has the following chemical composition: C: ≤0.
15%, Si: ≤ 1.0%, Mn: ≤ 2.0%, Ni:
7 to 30%, Cr: 15 to 25%, P: ≤0.05%,
It can be suitably applied to stainless steel having a composition of S: ≤ 0.03% and the balance substantially consisting of Fe.

Here, C solid-dissolves in the matrix to strengthen the matrix, but if it is more than 0.15%, the corrosion resistance is impaired.
15% or less. Si is added as a deoxidizing agent, but if it is too much, ferrite is likely to be formed, so 1.0% or less is preferable. Mn is added as a deoxidizing material and a desulfurizing material, but if it is too much, the workability and corrosion resistance decrease, so 2.0
It is better to be less than or equal to%. Since P deteriorates the corrosion resistance,
It is better to set it to 0.05% or less. Since S impairs hot workability, it is desirable that the amount is as small as possible, and the upper limit is preferably 0.03% or less.

Ni is an austenite stabilizing element,
It is a main element for improving corrosion resistance by using stainless steel as an austenite layer, and it is preferable to set it to 7% or more. However, if the amount is more than necessary, the cost will be high, so it is preferable to set it to 30% or less.

Cr is a component necessary for improving the corrosion resistance, and it is preferable to contain Cr in an amount of 15% or more. However, if it is contained in a large amount, ferrite is generated, so the content is preferably 25% or less.

[0022]

【Example】

[Table 1]

Austenitic stainless steel having the chemical composition shown in Table 1 was melted in an electric arc furnace and an AOD furnace. At this time, the basicity (CaO / SiO ₂ ratio) of the slag was 1.8.
Was melted. This was formed into a billet and then rolled into a wire rod to obtain a wire drawing material having a diameter of 5.5 mm.

Next, solution heat treatment, pickling and film formation treatment were performed, and wire drawing up to 50 μm was carried out to check the workability. The results are shown in Table 2 together with the composition of inclusions in the steel and the maximum diameter in the direction perpendicular to the wire drawing direction.

[0025]

[Table 2]

As can be seen from these results, O is 40 to 1
Regulated to 00 ppm, especially 50 to 70 ppm, and Ca
No. which regulated Al to 10 to 20 ppm and Al to 30 ppm or less. For Nos. 1, 3 and 5, the inclusion composition is a composite inclusion containing CaO. For these, the maximum diameter of the inclusions in the direction perpendicular to the wire drawing direction is 16 μm or less, that is, 1/3 of the wire diameter. The following values are all 50μ
Although the wire drawing could be performed up to m, the other wire could not be drawn satisfactorily because a wire breakage occurred during the wire drawing.

Next, a fatigue test was conducted on each of the test materials to examine the fatigue resistance, and the results shown in Table 2 were obtained. As can be seen from this result, No. The fatigue resistance of Nos. 1, 3 and 5 was also good.

The embodiment of the present invention has been described in detail above, but this is merely an example, and the present invention can be configured in a form in which various modifications are made without departing from the spirit of the present invention.

[0029]

As described above, according to the present invention, the inclusions in the steel can be made into a complex inclusion containing CaO and having a low melting point and a high degree of flexibility. Can effectively prevent disconnection due to objects, 1 mm
Even the following ultrafine wire can be drawn satisfactorily and at a low refining cost.

Claims (4)

[Claims] 1. The inclusions present in the steel are composite inclusions containing CaO, and the total amount of O in the steel is 40 to 1.
Stainless steel material with excellent wire drawability, which is regulated to 00 ppm. 2. The stainless steel material having excellent wire drawability according to claim 1, wherein the total amount of Ca in the steel is restricted to 10 to 20 ppm. 3. The stainless steel material having excellent wire drawability according to claim 1 or 2, wherein the total amount of Al in the steel is regulated to 30 ppm or less. 4. The steel composition according to claim 1, wherein the steel composition is C: ≦ 0.15%, Si: ≦ 1.0%, and Mn:% by weight.
≦ 2.0%, Ni: 7-30%, Cr: 15-25%,
P: ≤0.05%, S: ≤0.03%, the balance substantially F
A stainless steel material having excellent wire drawability, characterized by having a composition of e.