JP2022171223A - γ- STAINLESS STEEL WIRE AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Abstract

To provide a stainless steel wire which has increased workability by maintaining a γ amount remaining on a finished metal wire at a high numerical value, and a practical method for manufacturing the stainless steel wire.SOLUTION: A γ-stainless steel wire is provided, having a composition of, by mass%, C:0.08% or less, Si: 1.00% or less, Mn: 2.00% or less, P:0.045% or less, S:0.030% or less, Ni: 8.0-10.50%, Cr: 18.00-20.00% and the remainder consisting of Fe, and having a wire diameter of 0.08 mm or more and 2.60 mm or less, a tensile strength of 1550 N/mm2 or more and 3500 N/Mm2 or less and a γ amount of 30 vol.% or more and 90 vol.% or less. A method for manufacturing the γ-stainless steel wire comprises: arranging at least two drawing tools back and forth in the wire drawing direction of a γ-stainless steel base wire; and heating and drawing a wire with the latter drawing tool using working heat generated by the wire drawing of the γ-stainless steel with the former drawing tool.SELECTED DRAWING: Figure 4

Description

In the present invention, two drawing jigs (dies) are arranged in the wire drawing direction, and wire drawing is performed by the latter drawing jig using the heat generated by drawing in the former drawing jig. More particularly, the present invention relates to a γ-based stainless steel wire in which an austenite structure is retained and a method for producing the same.

Wire drawing of stainless steel is performed for the purpose of obtaining a desired wire diameter and obtaining a desired strength. The wire diameter is determined by the hole diameter of a jig (die) used in wire drawing. Also, the strength is determined by the degree of processing. The degree of processing is determined by various experiments in advance using a diagram of the relationship between the degree of reduction in the cross-sectional area of the wire diameter due to processing, that is, the rate of area reduction "(1-(d ₁ ² ÷ d ₂ ² )) x 100%" and the strength. We will secure it and utilize it in actual production. That is, the strength is controlled by the area reduction rate.

By the way, a γ-based stainless steel wire undergoes a γ→α' deformation transformation when subjected to working. This γ→α' working transformation is significantly affected by the temperature immediately before being worked, and even if it is subjected to strong working (90% surface loss) by heating at about 150 ° C, it transforms only about 30% of the room temperature working. does not progress and 70% of the volume remains as a γ structure, enabling further processing. Therefore, it is suitable to draw a γ-based stainless steel wire in a heated state of about 150° C. and to hard work the wire.

However, the technical issue that is a practical problem here is the operation of the γ-stainless steel wire, which runs at a high speed of several meters per second. How to raise the temperature in the vicinity of the die BOX to the above-described temperature is the subject of the wire drawing process of the present invention.
It is not so easy to raise the temperature of a γ-stainless steel wire running at a high speed of several meters per second in a short time of 1 second or less, even if it is said to be heated to about 150°C at most.

The inventor of the present invention previously proposed a heating wire drawing method using an induction heating device as a method for heating a stainless steel wire, and was granted a patent (Patent Document 1: Patent 2050506, which describes the content of the invention. Please refer to Japanese Patent Publication No. 07-080008, which is a public notice).
However, the induction heating device (IH), which is essential to implement this invention, is very expensive at 6 million yen per set, and it is not possible to set multiple units of this in front of the dies of each pot of the continuous wire drawing machine. There were many problems in the transition to commercial production because it could not be put into practical use unless it showed a certain level of performance.
As one of the countermeasures, the present inventor developed a heat-resistant lubricating oil method (Patent Document 2: see Japanese Patent Laid-Open No. 2012-81502) and filed an application as a hot wire drawing method using a heat-resistant lubricating oil. In this way, for example, austenitic stainless steel wires with a tensile strength of 2200 N/mm can be obtained (see paragraphs 0022, 0024). However, the invention of Patent Document 2 was experimentally established as well as the invention of Patent Document 1, but there are requirements to be solved, such as the development of a heat-resistant lubricating oil that can adapt to high temperatures of 150 ° C or higher for a long time. There were many problems in the transition to commercial production as in Patent Document 1.
Under these circumstances, at present, a stainless steel wire in which the amount of γ remaining in the finished metal wire is maintained at a high value to improve workability and a practical manufacturing method thereof have not been obtained. .

Japanese Patent Publication No. 07-080008 Japanese Unexamined Patent Application Publication No. 2012-81502

In view of the above circumstances, the present inventors have made intensive studies to solve the above problems. This is an epoch-making invention that can contribute to productivity improvement, cost reduction, and development of new products by extending the processing limit to the maximum extent by leaving a large amount of excellent γ structure. We have succeeded in developing a ``γ-based stainless steel wire'' in which a large amount of such γ-structure remains, and a ``method for producing this γ-based stainless steel wire by wire drawing''. The present invention will be specifically described below.

First, an outline of the "method for producing a γ-based stainless steel wire (having a composition of SUS304)" according to the present invention will be described.
In general, when a metal is processed, the elements move along the surface of the metal's unique crystals, and deformation progresses, accumulating internal stress. do. In addition to these deformation mechanisms, the structure of the γ-based stainless steel wire itself undergoes working, causing γ→α' working transformation and hardening.
The work transformation in this case is remarkably affected by the temperature immediately before the work is performed. Heating at about 200° C. causes almost no change and little improvement in strength. However, since the processing speed of the continuous wire drawing machine is as high as 2 to 8 m/s, it is difficult to set the heating device in the narrow platform of the continuous wire drawing machine.

Therefore, the method of the present invention (hereinafter referred to as "double die heating wire drawing method") has been developed as a completely new technique that is completely different from these countermeasures.
See Figure 1 for "Schematic diagram of double die heating wire drawing method", Figure 2 for "Temperature dependence of drawing and martensite generation", and Figure 3 for "Relationship between working temperature, exemption rate and tensile strength". Then, the outline of the "double die heating wire drawing method" according to the method of the present invention will be described.
It should be noted that FIG. 1 is a schematic diagram showing a specific example for facilitating understanding of the present invention. In FIG. 1, an example of the arrangement of two dies is shown in the upper row, and the heating temperature is shown in the lower row with numerical values, etc., but the intention is that the present invention is specified by the specific numerical values, etc. shown in FIG. Just to be sure, I point out that it is not.
In addition, FIG. 2 shows that the higher the working temperature, the lower the rate of martensite generation, and FIG. 3 shows that the higher the working temperature, the higher the tensile strength can be suppressed. there is

As is clear from the description in FIG. 1, two dies (wire drawing jigs) are arranged at an interval of, for example, 100 mm to 150 mm, and the heat generated by the wire drawing process in the preceding No. 1 die is It can be said that the ideal method is to bring the wire to the No. 2 die in the subsequent stage and heat wire drawing there, preferably to preheat it in the preheating zone before wire drawing in the No. 1 die. .

(preheating)
More specifically, in order to reduce the γ→α' deformation transformation during wire drawing in the No. 1 die in the previous stage, the γ-based stainless steel wire is processed, for example, before entering the No. 1 die. By preheating the wire to about 70°C to 130°C and introducing the preheated wire into the No. 1 die, the γ→α' deformation transformation during passage through the No. 1 die is greatly suppressed, and furthermore, the No. 1 die If the temperature just before entering the No. 2 die in the latter stage can be increased to nearly 200°C, the γ→α' heating transformation can be drastically reduced and the strength improvement can be halved, realizing the ideal heating wire drawing. It can be done.
Direct heating (electricity, heat-resistant lubricating oil, etc.) or indirect heating (hot air, passing through a heating furnace, etc.) can be considered as a preheating method placed in front of the No. 1 die. FIG. 4 shows a state in which 6 sets of double dies are arranged with preheating and arrangement of No. 1 and No. 2 dies as one set of double dies. Incidentally, if the preheating is around 130° C., it is possible to sufficiently raise the temperature even if the linear velocity is high.

(Double-die heating wire drawing method)
The method of the present invention is characterized in that the operation in wire drawing is changed from the conventional "area reduction rate strength control method" to the "heating temperature control method".
This point will be specifically described below.
The wire drawing operation involves passing the wire through a wire drawing jig called a tie, which has a large entrance and a small exit, and matches the diameter of the exit. By this operation, it is possible not only to set the wire diameter to a predetermined diameter, but also to improve the strength by working at the same time as working.
The factor that governs the improvement in strength in this case is the area reduction rate (1-(d ₁ ² ÷ d ₀ ² )) × 100%), which is 25 to 20% in normal room temperature wire drawing from past experiments and results. If this process is repeated until the annihilation area ratio reaches around 85%, the wire cannot withstand further processing and breaks. Even if the wire does not break, internal cracks may occur, resulting in defective products. In many wire manufacturers, each area reduction rate is 20 to 25%, and the total area rate is about 80 to 82% as a work standard. Continuous wire drawing is performed by driving the wiring.
It should be noted that for each wire drawing machine, the same area reduction rate (parallel draft) is adopted for each wire drawing machine, or the drawing force is taken into account and the area reduction rate is gradually reduced (taper draft). It is possible.
After that, the wire is softened by bright annealing, and the same wire drawing is repeated to reduce the wire diameter and increase the strength.

In order to compare with the wire drawing process of the present invention, first, a conventional wire drawing process is shown in FIG. 5 (current wire drawing/annealing process).
For example, when using a rolled rod (material) of 5.5 mmφ to produce a thin wire of 0.90 mmφ, as shown in Fig. 5, two types of continuous wire drawing machines are used, the primary wire drawing and the secondary wire drawing. Primary annealing (bright annealing once) is carried out between wire drawing to produce the target 0.90mmφ. FIG. 6 shows the area reduction rate and strength improvement in this case for a Ni equivalent of 21.9 ^{Note 1} . The strength control of conventional γ-based stainless steel wire is all controlled by the area reduction ratio. to make it better.
Note 1: Ni equivalent is a formula that considers the influence of contained elements on the occurrence of γ → α' deformation transformation, that is, the stability of γ, and is generally called Hirayama's formula. γ is more stable as the Ni equivalent increases.
Hirayama's formula:
Ni equivalent(%)=Ni(%)+0.65Cr(%)+0.98Mo(%)+1.05Mn(%)+0.35Si(%)+12.6C(%)
On the other hand, there are two JIS standards for γ-based stainless wires, JIS G 4309 (stainless steel wire) and JIS G 4314 (stainless steel wire for springs), which are W1, W2, W1/2H and WPA, WPB, respectively. There are 5 strength standards, and the strength standards for intermediate wire processing are the other 4 standards excluding W1. Strength standards are established within the size range. FIG. 7 shows the relationship between JIS standards and wire diameters in an easy-to-understand manner.

FIG. 6 is a diagram showing the relationship between reduction of area and strength. From this figure, the area reduction rate for creating the strength lines of the four standards is obtained, and although it depends on the wire diameter, W2 is obtained at a reduction rate of about 20%, W1/2H at about 40%, and WPA at about 70%. At around 82%, it is possible to produce WPB standard products. However, the production of strength standardized products that depend on the area reduction rate requires a precise response, and there are many types of JIS standard sizes (wire diameters), and the start size and wire drawing process that satisfy all of them are complicated.

In the method of the present invention, the above-mentioned problem of the prior art, that is, the production of strength standard products dependent on the area reduction rate, requires a precise response, and there are many types of JIS standard sizes (wire diameters), and it satisfies all of them. It was developed to solve the problem that the starting size and wire drawing process are complicated, and the work transformation of γ (austenite structure) → α' (martensite structure) is reduced by using the work heat generated by the wire itself. Innovative technology and new product development methods that leave a large amount of γ structure with excellent workability, extend the processing limit to the maximum extent, improve productivity, reduce costs, and contribute to the development of new products. It is proposed.

In other words, γ-based stainless steel wire has the property of undergoing γ→α' processing transformation when it is processed, but this processing transformation is significantly affected by the temperature immediately before processing, and when the temperature is around 200°C, Little working transformation occurs. In other words, the present invention focuses on the fact that the γ structure with excellent workability is maintained and the strength improvement is halved even when subjected to strong working, which occurs only about 1/10 of normal temperature working.

The outline of the present invention will be described below with reference to the drawings. In addition, although the explanation here presents specific numerical values and the like in order to facilitate the understanding of the invention, the present invention is specified by the specific numerical values, means, etc. described here. is not. It should be noted that the present invention is merely the invention specified in the claims, and that the drawings show the invention more specifically.

In the double-die wire drawing method according to the present invention, an ordinary die box is lengthened, and two dies are placed in a die box containing a powdered lubricant with an interval of about 150 mm, as shown in FIG. installed, with a preheat zone in front of it. In the preheating (preheating) zone, the temperature of the wire entering the first die in the die box is raised to about 50°C to 130°C by heating with electric heat, lubricating oil, hot water, or the like.

As a result, the γ→α' working transformation that occurs during wire drawing is reduced as much as possible, and the heat generated by the first die is added to heat the wire to 130 ° C to 250 ° C. Heat drawing is performed with the second die in this state.
FIG. 8 shows the relationship between the area reduction rate of the first die (No. 1 die) and the working heat generation temperature. From this figure, it is possible to obtain the desired processing heat generation temperature by appropriately controlling the area reduction rate of the No. 1 die.

As described above, according to the method of the present invention, the heat generated by the process heat generation (self-heating) generated in wire drawing can be effectively used as it is, so it can be said that it is a very energy-saving heating wire drawing method. Of course, if the development of heat-resistant lubricating oil advances and a lubricating oil with a temperature up to about 150° C. can be produced, this may be utilized. The lower part of FIG. 1 shows the predicted temperature conditions in the preheating zone and double dies. If the preheating temperature exceeds, for example, 100° C., it can be expected that the heat generated in the No. 1 die is added, that is, the wire temperature is about 200° C. before entering the No. 2 die.

Table 1 below shows that a die box (for example, the die set shown in FIG. 1), in which two dies are incorporated in one die box, is placed in a continuous wire drawing machine, and the first die of the double die set is reduced. The area ratio is 20%, the area reduction ratio of the second die is 35%, and the transition of the total area reduction ratio when drawing with a continuous wire drawing machine (6H) is performed with 4 types of start sizes (1.00 mm, 2.00mm, 3.00mm and 5.50mm).

Furthermore, according to the present invention, many merits can be obtained by utilizing a combination of hot wire drawing and normal temperature wire drawing in the wire drawing process. That is, it is possible to change the epoch-making production technology from the strength control by the conventional processing area reduction rate to the strength control by the heating temperature.
Moreover, FIG. 9 shows the tensile strength for each heating temperature in wire drawing up to 0.77 mm (heated wire drawing 6 passes) with a starting size of 5.50 mm in Table 1. This table shows the case where double dies and heating wire drawing are performed in all die boxes. It can be said that it is a wire drawing method with a wide range of applications, such as being able to obtain a wire with an arbitrary finished wire diameter and tensile strength from the wire diameter.
Then, by the method for producing γ-based stainless steel according to the present invention, the mass % described in claims 1 and 2 is C: 0.08% or less, Si: 1.00% or less, Mn: 2.00% Below, P: 0.045% or less, S: 0.030% or less, Ni: 8.0 to 10.50%, Cr: 18.00 to 20.00%, the balance Fe composition (SUS304 composition) having a wire diameter of 0.08 mm or more and 2.60 mm or less, a tensile strength of 1550 N/mm or more and 3500 N/mm or less, and 30 volume% or more, 90 volume% or less, or 40 volume% or more; A γ-based stainless steel wire having a γ content of 70% by volume or less can be produced.

Examples (Examples 1 to 6) of the present invention are described below.
As will be described in detail below, Example 1 is an example relating to a method for producing arbitrary JIS standard strength lines by changing only the heating temperature in the same bus bar, the same double die set continuous machine, and the same area reduction rate. be.
Example 2 is a method of producing a JIS standard product with an arbitrary strength by selecting a heating temperature with an arbitrary double die set using the same bus bar, the same double die set continuous machine, and the same area reduction processing.
Example 3 is an example of a one-operation operation (omitting heat treatment and reducing the number of wire drawing machines) by increasing the area reduction rate.
Example 4 is an example of a method for producing a high-strength wire of piano wire grade from SUS304 by utilizing the hot wire drawing method.
Example 5 is an example of a method for producing a fatigue resistance strength curve.
Example 6 is an example of a method for producing a SUS304 wire having a tensile strength of 1,600 N/mm ² or more and a γ content of 30% or more.

Example 1: Production method of any JIS standard strength wire by changing only the heating temperature in the same busbar, the same double die set continuous drawing machine, and the same area reduction rate Using a double die continuous wire drawing machine (6 tanks) FIG. 10 shows an example of the rate of area reduction, heating temperature, and increase in tensile strength when wire drawing is performed. Experimental results show experimental results at 200°C, 140°C and 80°C.
On the right side of this graph, the scale of the tensile strength is matched with the standard value of the tensile strength for each wire diameter. Looking at FIG. 10, it can be seen that the heating wire drawing temperature to be applied to each standard value in the double die set. As another example, let us consider the case of drawing a wire with a finished wire diameter of 0.77 mm using six sets of double die drawing machines.
From Table 1, it is necessary to prepare a start size of 5.50mm. The four standard strength ranges of 0.77 mm can be read from FIG. 10, and the appropriate heating temperature can be selected by comparing with the JIS standard. In this case, W1/2H of 0.77 mm is drawn at a heating temperature of 200°C, WPA is drawn at 140°C, and WPB is drawn at 80°C. It is possible to be satisfied in spite of this.
As can be seen from this fact, the present invention can be said to be a conversion from the area reduction rate control method that has been practiced even today to the heating temperature control method according to the present invention.

Example 2: Using the same bus bar, the same double die set continuous machine, and the same area reduction process, selecting the heating temperature with an arbitrary double die set to produce a JIS standard product with arbitrary strength This production method is as shown in the figure. 11, the heating temperature is selected for each number of the double die set to secure the target strength. For example, when securing W1/2H, all six sets of 200°C heat wire drawing are employed for wire drawing, and when producing WPB, 200°C heat wire drawing is used as No. 4 double dice set and then No. 5 to No. The double die set of 6 performs normal temperature wire drawing. In this case, only the die after the double die may be used, and the strength may be ensured by processing with a reduction of area of about 20%. Similarly, WPB can be produced by adopting heated wire drawing at 140° C. up to double die set No. 5, and then adopting ordinary temperature wire drawing.

Example 3: One-operation operation by increasing the processing area reduction rate (omitting heat treatment, reducing the number of wire drawing machines)
In general wire drawing work, the wire is passed through a jig called a die, which has a conical hole with a large entrance and a small exit. measure. In this case, in order to express the degree of processing, the degree of reduction in the cross-sectional area of the wire is called each area reduction rate (1-(d ₁ ² ÷ d ₀ ² )) × 100%). Continuous wire drawing is repeated 7 to 8 times. The cross-sectional area reduction rate between the start size and the finished diameter is called the total area reduction rate, and is expressed by ⁽ 1- ₍ d02/ _d82 )) ^x 100%).
There are complicated factors such as the friction problem between the wire and the die, the material, the structure of the wire drawing machine, etc., and it is a secret matter of each manufacturer, but it is a general matter. Generally, each area reduction rate is 20 to 25%, and the total area reduction rate is about 80 to 85%. When further thinning is required, intermediate annealing is performed to soften the wire and then draw again. I do.
In the double die heating wire drawing method according to the present invention, the area reduction rate of the No. 1 die of the double die set in which two dies are set is about 20%. Table 1 shows an example of a pass schedule for a 6H continuous wire drawing machine with 2 dies at 35%. In the case of the double die heating wire drawing method, as shown in Table 1, one set of double dies can be processed with a total area reduction rate of 48%. 10 passes), it will be about 96%, and it will be possible to perform continuous wire drawing in 16 blocks at a reduction rate of 21% in the case of normal room temperature wire drawing, and heavy processing equivalent to processing with two types of wire drawing machines. Moreover, since the wire can be continuously drawn without intermediate annealing, it is possible to significantly streamline production and reduce costs. Moreover, by using the heat generated by the work itself, energy savings and cost reductions can be expected that are incomparable compared to the use of induction heating equipment.

Example 4: A method of producing a high-strength wire of piano wire grade from SUS304 using a hot wire drawing method.
As described above, γ-based stainless steel wire cannot be subjected to heavy working because deformation-induced martensite increases with working. At present, in order to secure the strength of a stainless steel wire comparable to that of a piano wire, it is only possible to change the contained elements by increasing the amount of Mn or the like or decreasing the amount of Ni. Therefore, the hot wire drawing method according to the present invention is used to obtain a strength equivalent to that of a piano wire with pure SUS304.
Now, if we use 5 sets of double dies at a heating temperature of 140°C and wire drawing with a total area reduction of 96%, the tensile strength is only about 1,700 N/ ^mm2 , but there is residual The amount of γ is 70% or more of the total, and the steel is in a state of being able to withstand further heavy working. When the intermediate wire with a total area reduction of 96% at 140°C is processed again with a double die wire drawing machine, as shown in Fig. 12, the tensile strength of the second wire drawing is 2,600 N/ ^mm2 or more. can be obtained.
That is, the strength of conventional SUS304 is up to ^2,400 N/mm ² at most, but by applying the present invention, it is possible to further improve the strength. The strength values are well comparable to the piano wire (WPA) type.
This process is just one example, and there is ample possibility of securing a strength equal to or greater than that of a piano wire by applying the present invention by combining heated wire drawing and normal temperature wire drawing.

Example 5 Production of Fatigue-Resistant Strength Wire When producing a stainless steel wire for a spring, a state containing a large amount of γ structure, that is, a wire drawn by heating to 140° C. to 250° C. is subject to fatigue. It was confirmed in the test that the fatigue strength was more than doubled. This is shown in FIG. The reason why the fatigue strength in the fatigue test is more than doubled is that when fatigue fracture occurs, a crack occurs, and when the tip propagates, the stress at the tip portion causes γ → α' transformation and hardening. This is considered to prevent further propagation and prevent fatigue fracture.
According to the experimental data in the fatigue fracture test, when comparing the room temperature wire drawing and the wire drawing material heated at 140°C, the room temperature wire drawing has higher tensile strength and wire diameter, but the fatigue test results are shown in Fig. 13. As can be seen, the heated wire drawing material is nearly twice as good. From this example, it was confirmed that a fatigue resistance strength wire can be produced by the method for producing a processed drawn wire material according to the present invention.

Example 6: Production of SUS304 wire with tensile strength of 1,600 N/ ^mm2 or more and γ content of 30% or more
In the case of SUS304, when subjected to processing with a total area reduction of 50% or more at room temperature, α' martensite occupies 80% or more of the total volume of the structure, as shown in FIG. In terms of strength, as shown in FIG. 15, it is around 1,500 N/mm ² .
That is, at 1,600 N/mm ² or more, the amount of α' martensite is 80% or more and the amount of austenite is 20% or less in the case of normal temperature wire drawing. ^On the other hand, if the wire is drawn by heating at 140.degree.
That is, it can be said that the product processed by the hot wire drawing method has a high strength of 1,600 N/mm ² or more and contains 75% of γ.
Although Table 2 shows the elements contained in SUS304, SUS304 contains many elements other than the components listed in Table 2, and these elements are γ → α' processing transformation, that is, γ Affects stability. Furthermore, the content of each element has its own allowable range and affects the γ→α' deformation transformation in a complicated manner. There are many studies on the stability of γ, but the most commonly used formula is called Hirayama's formula.
For reference, FIG. 16 and FIG. 17 show the influence of the heated wire drawing on the Ni equivalent. As can be seen from this figure, in the normal temperature wire drawing, the Ni equivalent clearly has an effect on the deformation transformation, but in the case of the hot wire drawing, the effect is reduced at around 200 ° C., reaching 100 N/mm ² . There is only a degree. Also, martensite can be suppressed to about 10%.

According to the present invention, the γ→α' working transformation is reduced, a large amount of γ structure with excellent workability remains, and the working limit is extended to the maximum extent to perform wire drawing, thereby improving productivity and reducing costs. Furthermore, it is possible to provide a method for producing an austenitic stainless steel wire that can contribute to the development of new products.

Outline drawing of the double-die heating wire drawing method Diagram showing temperature dependence of drawing and martensite generation Diagram showing the relationship between heating temperature, tensile strength, and exemption rate Diagram showing double die heating wire drawing process Diagram showing the current wire drawing and annealing process Diagram showing the relationship between exemption rate and intensity Diagram showing the relationship between wire diameter and strength according to JIS standards A diagram showing the relationship between the area reduction rate and the processing heating temperature for the No. 1 die Diagram showing the relationship between heating temperature, tensile strength, and exemption rate Diagram showing an example of producing a JIS standard strength line by changing only the heating temperature in the same bus bar, the same double die set continuous machine, and the same reduction rate processing process. Diagram showing an example of production of any JIS standard strength standard wire by selecting any heating temperature of any double die set in the same bus bar, the same double die set continuous machine, and the same reduction rate processing process. Diagram showing an example of high-strength stainless steel wire production Diagram showing S-N curves (normal wire drawing and heat drawing) Diagram showing the relationship between reduction rate and amount of martensite Diagram showing the relationship between heating temperature, exemption rate, and tensile strength Diagram showing the effect of heat drawing on Ni equivalent (Part 1) Diagram showing the effect of hot wire drawing on Ni equivalent (Part 2)

Claims (12)

% by mass, C: 0.08% or less, Si: 1.00% or less, Mn: 2.00% or less, P: 0.045% or less, S: 0.030% or less, Ni: 8.0 to 10.50%, Cr: 18.00 to 20.00%, and the balance Fe, a wire diameter of 0.08 mm or more and 2.60 mm or less, and a tensile strength of 1550 N/mm ² or more and 3500 N/mm ² and having a γ content of 30% by volume or more and 90% by volume or less. 2. The γ-based stainless steel wire according to claim 1, having a γ content of 40% by volume or more and 70% by volume or less. At least two drawing jigs are arranged in front and behind along the wire drawing direction of the γ-based stainless steel busbar, and the γ-based stainless steel wire is passed through the drawing jig in the previous stage to be drawn, and then drawn in the subsequent stage. A method for manufacturing a γ-based stainless steel wire by performing a plurality of steps of heating and drawing a wire at a predetermined heating temperature set in advance using a drawing jig, the method comprising:
Heated wire drawing by the drawing jig in the latter stage draws the wire at the above-mentioned predetermined heating temperature using the processing heat generated by the drawing of the γ stainless steel wire by the drawing jig in the former stage. The method for producing a γ-based stainless steel wire according to claim 1 or 2, characterized in that: Claim 3, wherein the temperature of the γ stainless steel wire is raised by 100° C. to 250° C. from the temperature before the wire drawing by the former drawing jig by the wire drawing by the former drawing jig. The method for producing the γ-based stainless steel wire according to 1. At least two drawing jigs are arranged in front and behind along the drawing direction of the γ-based stainless steel busbar, and after the γ-based stainless steel wire is passed through the drawing jig in the former stage and wire-drawn, it is drawn in the latter stage. When performing a plurality of steps of heating wire drawing at a predetermined heating temperature with the drawing jig, at least part of the steps is performed before passing the γ-based stainless steel wire through the drawing jig in the previous stage. 5. The method for producing a γ-based stainless steel wire according to claim 3 or 4, further comprising a step of preheating the γ-based stainless steel wire. 6. The method for producing a γ-based stainless steel wire according to claim 5, wherein the step of preheating is a step of raising the temperature of the γ-based stainless steel busbar by 50° C. or higher. The method for producing a γ-based stainless steel wire according to claim 6, wherein the step of preheating is a step of raising the temperature of the γ-based stainless steel busbar by 50°C to 200°C. The γ-based stainless steel busbar heated in the preheating step is passed through the preceding drawing jig to raise the temperature by 100° C. to 250° C. from the temperature before wire drawing by the preceding drawing jig, and this heated state. 8. The γ-based stainless steel wire according to any one of claims 5 to 7, wherein the γ-based stainless steel wire is drawn by passing the γ-based stainless steel busbar through a subsequent drawing jig at a predetermined heating temperature. manufacturing method. A die box containing a drawing jig applied to the method for producing a γ-based stainless steel wire according to any one of claims 3 to 8, wherein the inlet of the γ-based stainless steel bus wire to be drawn. A die box characterized in that a front-stage drawing jig and a rear-stage drawing jig are installed in order from the side to the exit side. A die box containing a drawing jig applied to the method for producing a γ-based stainless steel wire according to any one of claims 5 to 8, wherein the γ-based stainless mother steel wire to be drawn is drawn. A die box characterized in that a preheating means, a front-stage drawing jig, and a rear-stage drawing jig are installed in order from an inlet side to an outlet side. 11. The die box according to claim 10, wherein the preheating means is one or more of direct heating means and/or indirect heating means. 12. The die box according to any one of claims 9 to 11, characterized in that powder lubricant is filled in the area where the former stage drawing jig is installed and the area where the latter stage drawing jig is installed. .

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