JPH0428843A - Manufacture of stock for stainless steel extra fine wire - Google Patents

Abstract

PURPOSE:To manufacture stock for a stainless steel extra fine wire having high cleanliness and extremely small disconnection at the time of wire drawing by subjecting stainless steel stock to electron beam melting into an ingot having specified content of O and Al. CONSTITUTION:Stainless steel stock such as SUS316 is irradiated with electron beams in vacuum of about <=10<-3>Torr and is locally subjected to melting treatment at a ultrahigh temp. of about >=2000 deg.C. Thus, O and impurities such as inclusions in the above stainless steel stock are evaporated away. Consequently, the components of the ingot after the melting are regulated to <=20ppm O and <=50ppm Al. In this way, the stock for a stainless steel extra fine wire having high cleanliness of inclusions and having extremely low frequency of disconnection at the time of wire drawing into an extra fine wire can be obtd.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a stainless steel ultrafine wire material that requires high inclusion cleanliness. [Prior art] Stainless steel fine wire is finished to a desired wire diameter by wire drawing, but when producing ultra-fine wire with a wire diameter of about 60 to 80 μm or less, the presence of inclusions can cause wire breakage during wire drawing. Easy to occur. Therefore, materials for stainless steel ultrafine wires are required to have extremely high inclusion cleanliness. For this,
The material is VOD (Vacuum Oxygen Decarbu), which is generally used as a refining method for stainless steel.
oxidation) method and AOD (Argon Oxyg
It is difficult to manufacture using the Vacuum Arc Remel (VAR) method.
tingFurnace) method and ESR (Electro
Special melting methods such as -Slag Remelting Furnace method have been applied. Examples include, for example, Plasticity and Processing, Vol. 19, No. 211 (1978). However, in the VAR method, the melting vacuum degree is 10
-3 to 10 Torr, which makes it impossible to achieve sufficient oxygen reduction and inclusion cleaning.Also, in the ESR method, inclusion cleaning is attempted by the refining effect of molten flux, but it takes a long time. During melting, the composition of the molten flux fluctuates, making it impossible to measure the uniformity of the composition and amount of inclusions. This results in frequent wire breaks due to inclusions during ultra-fine wire drawing, making it difficult to obtain materials of sufficient quality. It has not been done. On the other hand, the electron beam melting method enables impurity elements to be evaporated and removed by melting under ultra-high temperature and high vacuum, which is a characteristic of electron beam irradiation, and it is possible to highly purify and clean the ingot. It is said. However, the conventional electron beam melting method is mainly applied to high melting point metals such as niobium, molybdenum, titanium, etc., and there are very few examples of its application to stainless steel containing 11% or more of chromium. As an example of application to chromium-containing steel, for example, as described in ■ NKK Technical Review 127 (1989) P, 43-P, 52, component evaporation and removal of inclusions progress in electron beam melting of steel. I have confirmed that I will do so. ■ As described in JP-A No. 1-212724, there is only a method of adjusting the component content of alloy steel by adjusting the melting energy and the degree of melting vacuum, and there is no information regarding the removal of inclusions. No knowledge has been shown quantitatively, nor has there been any evidence of application to the production of actual materials. [Problem to be solved by the invention] Since stainless steel ultra-fine wire materials using the VAR method and ESR method cannot be highly cleaned of inclusions, the frequency of wire breakage due to inclusions during ultra-fine wire drawing is reduced. That's difficult. The present invention applies the electron beam melting method to the production of materials for stainless steel ultra-fine wires, and by controlling the composition of the ingot after melting, it is possible to stably produce highly clean steel with extremely few inclusions. An object of the present invention is to provide a material for a stainless steel ultra-fine wire that has extremely few breakages during drawing of the ultra-fine wire due to objects. [Means for Solving the Problems] The present invention applies an electron beam melting method to the production of stainless steel ultrafine wire materials, and also melts the components of the ingot after melting.

[0]≦2
0 ppm, (AI ≦ 50 ppm) This is a method for manufacturing a stainless steel ultrafine wire material. Next, the reason for limiting the composition of the melted ingot in the present invention will be described. Figure 5 shows 5US316 stainless steel. VAR method and ESR for steel
in the ingot melted by the electron beam melting method and the electron beam melting method.

[0]
The relationship between the concentration and the number of inclusions with a size of 2 μm or more is shown. The number of inclusions is 2 μm, which can be measured using an optical microscope.
The above inclusions should be removed for an area of 10 mm or more within the ingot.
This is a value obtained by measuring only oxide inclusions. In Figure 5, the electron beam melting method is the VAR method and the ESR method.
It can be seen that this dissolution method is capable of lowering C0w1 and reduces the number of inclusions compared to the method. Figure 2 shows CAl1) manufactured by electron beam melting method.
The relationship between the (0) concentration in a 5US316 stainless steel ingot that satisfies ≦50 ppm and the amount of wire drawn per wire breakage when an ultrafine wire with a wire diameter of 30 μmφ is manufactured using this ingot is shown. Here, the wire drawing amount per wire breakage is the value obtained by dividing the actual wire drawing amount by the number of wire breaks when drawing a material for ultra-fine wire of 50 kg or more, and the larger this value, the better the wire drawability. This is an indicator that it is in good condition. As shown in Figure 2,
0]≦20ppm, the amount of wire drawing increases rapidly. Figure 3 shows the product manufactured by electron beam melting method.

[0]≦20
The relationship between the (Al) concentration in a 5US316 stainless steel ingot of ppm and the amount of wire drawn per wire breakage when ultrafine wire with a wire diameter of 30 μmφ is manufactured using this ingot is shown in the figure. When AI ≤50ppm"i', the amount of wire drawn increases rapidly. Figure 1 shows 5US316 manufactured by electron beam melting method.
(AI2) and in the stainless steel ingot when ultrafine wire with a wire diameter of 30 μmφ is manufactured from the ingot.

[0] Shows the relationship between the concentration and the amount of wire drawn per wire breakage. In the figure, the O symbol indicates a wire drawing amount of 4.0 kg/1 wire breakage or more, and the Δ symbol indicates a wire drawing amount of 2.
．． 1 to 3, 9 kg/1 disconnection, X mark is 2.0 kg/
Indicates 1 disconnection or less. As shown in Figure 1 [0]
≦20pp■, (i)≦50ppm, wire drawing amount 4
．． Wire drawing with a wire breakage rate of 0 kg/l or higher is possible. The materials used for electron beam melting are VOD method,
Any manufacturing method such as the AOD method may be used. In addition, the inside of the ingot after melting

[0] and [Ajl! ] concentration control is
This is possible by controlling the electron beam melting conditions and the composition of the melting material. As mentioned above, in order to efficiently manufacture ultrafine stainless steel wires with fewer wire breaks, electron beam melting is applied, and
The composition of the ingot after melting

[0]≦20ppm, [Al]≦5
It is necessary to set it to 0 ppm. [Operation] The electron beam melting method generally performs melting under a high degree of vacuum of 10-3 TOrr or less, and since the electron beam itself has a high energy density, the electron beam irradiation part is locally heated to a temperature of 2000°C or more. A high temperature can be obtained. Due to this,
The deoxidation reaction and inclusion removal reaction in electron beam melting of stainless steel are mainly CO degassing reactions, and this reaction is expressed by equation (1), and the reaction equilibrium constant is expressed by equation (2). (C) + [0) −→ Co (g) ・・・・
... (1) log Kl = 10g CP co
/ac'ao)=1160/T+2. OO
3...(2) Here, pco is 00 in the atmosphere.
The partial pressure, ac and ao are the activities of (C) and (0) in the molten steel, and T is the molten steel temperature. According to equations (1) and (2), in order to promote the deoxidation reaction and lower the [03 concentration in the melted ingot, it is necessary to lower the pco, increase the ae, and increase the molten steel temperature. In the inclusion removal reaction, the inclusions dissociate and the

[0]
(1) By promoting the OCO degas reaction , promoted. Further, the number of oxide inclusions in the ingot after melting tends to decrease as the (0) concentration in the ingot decreases. Because the electron beam melting method can achieve higher temperature and higher vacuum conditions than the VAR method,

[0] Both the concentration and the number of inclusions can be reduced. Furthermore, the deoxidation reaction and inclusion removal reaction by the ESR method are determined by the reaction between molten flux and molten steel, and are therefore smaller than the CO degassing reaction. From the above results, as shown in Figure 5, the electron beam melting method
Both the [O] concentration and the number of inclusions can be reduced compared to the AR method and the ESR method. In addition, since the amount of wire drawn per wire breakage during ultra-fine wire drawing depends on the inclusion composition and the number of inclusions, if the inclusion composition is the same, the electron beam melting method with fewer inclusions will reduce wire breakage. This is an effective means for producing extremely small amounts of material for ultra-fine wires. Even in the electron beam melting method, slight variations occur in the concentration and number of inclusions (0) depending on the melting conditions and the composition of the melting material. Therefore, the amount of wire drawn per wire breakage during drawing of ultra-fine wire varies, but as shown in Figure 2,
]≦20ppI11 It is possible to stabilize the amount of wire drawing at a high level by regulating the components after the ingot. Next, the (AI!) concentration in the ingot after melting is a major factor determining the inclusion composition. Figure 4 shows [A!] inside the ingot after melting. ] The relationship between the concentration and the (l□03) concentration in inclusions in the ingot after melting is shown. In addition, (AI!, zO,) in the inclusion
The concentration is a value obtained by measuring the composition of 10 or more inclusions and taking the average value. In the figure, [7/! ] When the concentration exceeds 50 ppm, (Al2zOi
) concentration increases rapidly. (//!z(h
) When the concentration increases, the melting point of the inclusions increases and the malleability of the inclusions during processing decreases, resulting in a decrease in the amount of wire drawn per wire break during ultra-fine wire drawing. Therefore, as shown in FIG. 3, by setting (Af)≦50 ppm, it is possible to stabilize the amount of wire drawn per wire breakage at a high level. [Practical Example] An example in which the method of the present invention is applied to the production of a 5US316 stainless steel ultrafine wire with a wire diameter of 30 μmφ will be described. Table 1 shows the ingot melting method, the composition of the ingot after melting, the number of inclusions of 2 μm or more existing in the ingot, the average (AI!, zOs) concentration of inclusions in the ingot, and the 30 μm φ ultrafine The amount of wire drawn per wire breakage during wire drawing is shown for examples of the present invention and comparative examples. Note that the melting material used was a material manufactured by a vacuum induction melting method. Furthermore, 10 or more inclusions were measured in the ingot after melting. Furthermore, all the steps up to ultra-fine wire drawing of the ingot after melting were the same, and the amount of wire drawn in each case was 500 kg or more. In all of the examples of the present invention, the amount of inclusions is small and the concentration of (Aj!zOz) in the inclusions is also low, so the amount of wire drawn per wire breakage is 4.0 kg or more, which is a very high value. ing. On the other hand, in the comparative example, the amount of wire drawn per wire breakage was as low as 2.0 kg or less, which was a sufficient value because the melting method or the composition in the ingot after melting did not satisfy the conditions for materials for ultra-fine wires. It's not. [Effects of the Invention] As described above, by applying the electron beam melting method to the production of materials for stainless steel ultra-fine wires and by controlling the composition of the ingot after melting, It becomes possible to manufacture materials with extremely low disconnection frequency. This greatly improves the working efficiency of ultra-fine wire drawing, making it possible to improve productivity and significantly reduce manufacturing costs.

[Brief explanation of the drawing]

Figure 1 shows (Af) in the ingot after melting.

Figure 2 shows the relationship between the concentration of [0] and the amount of wire drawn, while Figure 2 shows the relationship between the concentration of (0) in the ingot after melting and the amount of wire drawn.
Figure 4 shows the relationship between the concentration of wire and the amount of wire drawing.
,0. ) Figure 5 shows the relationship between concentrations of the ingot after melting.

[0] It is a diagram showing the influence of the dissolution method on the relationship between the concentration and the number of inclusions. Patent applicant Nippon Steel Corporation

Claims (1)

[Claims] The electron beam melting method is applied to the production of stainless steel ultrafine wire material, and the composition of the ingot after melting is [O]≦20pp.
A method for producing a material for stainless steel ultra-fine wire, characterized in that m, [Al]≦50 ppm.