JP2013000865A - Wire for wire saw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost of wire for a wire saw while maintaining the strength, etc. thereof.SOLUTION: Wire for a wire saw having a wire diameter of ≤0.16 mm and a tensile strength of 3,300-3,800 MPa is obtained by applying patenting and wire drawing processes to a wire rod containing 0.68-0.75 mass% of C, 0.10-0.50 mass% of Si, 0.30-0.90 mass% of Mn, ≤0.025 mass% of P, ≤0.025 mass% of S, ≤0.2 mass% of Cu, and the remainder consisting of Fe and unavoidable impurities. The obtained wire contains less amount of carbon in comparison with conventional high-carbon wire, and so raw material cost can be suppressed. Since the wire contains less amount of carbon and is improved in processability, wire breakage in a wire drawing process is reduced to improve the yield, and a patenting process prior to finish drawing can be applied to the wire having a larger diameter and smaller length, thus allowing a processing cost to be reduced.

Description

  The present invention relates to a wire used in a wire saw as a cutting device suitable for cutting a hard material such as a silicon ingot.

A wire saw is known as a cutting device used for cutting hard materials such as cutting silicon wafers from silicon ingots.
A wire saw winds a large number of wire saw wires between a plurality of rolls, causes the wire to travel at a high speed by rotating the roll, and presses a material to be cut such as a silicon ingot while supplying abrasive grains to the traveling wire. Therefore, it is a mechanism for cutting.

As described above, since the material to be cut is pressed against the traveling wire and cut, the size of the cutting allowance of the material to be cut depends on the size of the diameter of the wire.
Therefore, the yield at the time of cutting | disconnection improves, so that a wire is reduced in diameter. For this reason, there is a demand for wire diameter reduction.

  Further, as the tension is applied to the wire, the vibration of the wire is suppressed and the cut surface of the material to be cut is less likely to be uneven, and the surface accuracy of the cut surface is improved. For this reason, there is a demand for higher wire tension.

  On the other hand, the thinner the wire, the lower its strength and the risk of breakage. Moreover, if a high tension is applied to the wire, the risk of disconnection further increases.

  Therefore, conventionally, as disclosed in Patent Documents 1 and 2, as a wire saw wire, the carbon content is 0.80% by mass or more, having a high strength capable of withstanding a reduction in diameter and an increase in tension. It was common to use a wire.

JP 2001-225257 A JP-A-7-136923

  However, since the high carbon wire used as the raw material of the high carbon wire is expensive, there is a problem that the raw material cost of the wire for the wire saw increases.

  In addition, since the high carbon wire has poor workability, it must already be made considerably thinner before the final wire drawing process, but the patenting process before the wire drawing process has been made much thinner. When it is applied to the wire, the processing cost (manufacturing cost) increases because of its large length.

  Furthermore, since the high carbon wire has poor workability, it is often disconnected during the wire drawing process, resulting in poor yield. Therefore, there is a problem that the manufacturing cost increases from the viewpoint of yield.

  Therefore, the problem to be solved by the present invention is to reduce the cost while maintaining the strength of the wire saw wire.

In order to solve the above-described problems, the wire for a wire saw of the present invention includes 0.68 to 0.75% by mass of C (carbon), 0.10 to 0.50% by mass of Si (silicon), and 0.0. 30 to 0.90 mass% Mn (manganese), 0.025 mass% or less P (phosphorus), 0.025 mass% or less S (sulfur), and 0.2 mass% or less Cu (copper) ), With the balance being Fe (iron) and inevitable impurities, which is obtained by patenting and wire drawing.
Further, the wire saw wire of the present invention has a wire diameter of 0.16 mm or less and a tensile strength of 3300 to 3800 MPa.

  Since the wire for wire saw of the present invention has less carbon content than the conventional wire having 0.80% by mass or more, the cost of raw materials can be reduced.

  In addition, because the carbon content is low, the workability is improved, and since the patenting process before the wire drawing process can be performed in a larger diameter state, that is, in a shorter length state than before, the processing amount can be reduced, Reduction of processing cost can also be realized.

  Similarly, since the workability is improved, there is little disconnection in the wire drawing process, the yield is improved, and the manufacturing cost can be reduced.

Schematic of manufacturing process for wire saw wire

  With reference to FIG. 1, the outline of the manufacturing process of the wire for wire saws of embodiment is demonstrated. The wire saw wire according to the embodiment is manufactured from the wire by wire drawing.

First, a wire having a wire diameter of 4.0 to 6.0 mm is prepared at S ₀ .
As this wire, 0.68 to 0.75 mass% C, 0.10 to 0.50 mass% Si, 0.30 to 0.90 mass% Mn, and 0.025 mass% or less P, 0.025% by mass or less of S, and 0.2% by mass or less of Cu, and the remaining part of 100% by mass of Fe and inevitable impurities are used.
Compared with the case where a wire is manufactured from a wire containing 0.80% by mass or more of C as in the conventional case, the raw material cost is low because the carbon content is small.
In addition, the scale shall be removed suitably by pickling this wire beforehand.

Here, if C is less than 0.68% by mass, the strength of the wire becomes insufficient, and if it exceeds 0.75% by mass, the toughness of the wire is lowered and the material cost increases, so the ratio is limited to the above. From the balance of strength and toughness of the wire, 0.68 to 0.75% by mass is more preferable.
In addition, Si used as a deoxidizer during melting and refining of steel has the effect of improving the strength of the steel by solid solution in ferrite, so if it is less than 0.10% by mass, the wire becomes insufficient in strength. When it exceeds .50 mass%, the toughness decreases, so the ratio is limited to the above.
Similarly, if Mn used as a deoxidizer during melting and refining is less than 0.30% by mass, it is less than the minimum amount required for the deoxidizer, and if it exceeds 0.90% by mass, Since the site is easy to generate and the disconnection at the time of wire drawing increases, it is limited to the above ratio.
P and S segregated as impurities at the austenite grain boundary and the pearlite block grain boundary are limited to the above ratio because the toughness of the wire is lowered when it exceeds 0.025 mass%.

Next, in S _1, the the wire eg dry wire drawing machine, to TEMPORARY drawing the wire diameter 0.5 to 1.5 mm.
Further in S _2, it performs patenting treatment by heating and rapidly cooling the drawn and wire rod.
In S ₃ , the patented wire is plated in the order of Cu (copper) and Zn (zinc) by electroplating, and then subjected to diffusion treatment in a diffusion fluidized bed furnace to thereby perform brass (brass) plating. Apply.
Since the carbon content of the wire is small and the processability is high, the wire diameter of the wire before final drawing may be 0.5 to 1.5 mm, which is larger than the conventional wire diameter. Therefore, the length of the wire at the time of the patenting process and the plating process can be made shorter than before, and the processing amount can be reduced.

Finally, in S ₄ , the brass-plated wire rod is subjected to finish drawing (secondary drawing) to a wire diameter of 0.16 mm or less, preferably 0.12 to 0.15 mm, for example, by a wet wire drawing machine. A wire saw wire is completed.
Since the carbon content of the wire is low and the workability is high, the wire is not broken even in the wire drawing process, and the yield is improved.

Here, the degree of work hardening or the like can be adjusted by adjusting the surface area reduction rate of the wire in the finish wire drawing.
As a result, the tensile strength of the finished wire saw wire becomes 3300 to 3800 MPa, and the twist value in the twist test (the number of times until the wire breaks when both ends of the wire are gripped and twisted. The distance between chucks is adjusted so that the wire diameter is 100 D when the wire diameter is D.) is 25 times or more and the elongation is 2.0% or more.

If the tensile strength is less than 3300 MPa, a high tension is applied to the wire due to the above-described demand for improving the surface accuracy of the material to be cut. If the tensile strength exceeds 3800 MPa, the toughness of the wire is reduced and the wire is broken. This is limited to the above range.
Further, if the twist value is less than 25 times, it is difficult to withstand the tension in the torsional direction generated in the wire when the material to be cut with a wire saw is cut, and disconnection is likely to occur. Therefore, the twist value is limited to the above range.
Further, if the elongation is less than 2.0%, it is considered that there is a certain amount of tension fluctuation at the time of cutting with a wire saw, and the toughness that can withstand the fluctuation cannot be secured. Therefore, the elongation is limited to the above range.

Hereinafter, examples of the present invention and comparative examples will be given to further clarify the contents of the invention.
First, wire rods A to E having a composition shown in Table 1 and having a wire diameter of 5.5 mm were prepared. Each numerical value in the table indicates mass%. Compositions other than those shown in Table 1 are composed of iron and inevitable impurities.

Next, as described in the embodiment, the wire rods A to E are subjected to primary wire drawing, patenting treatment, brass plating treatment, finish wire drawing (secondary wire drawing), and a wire diameter of 0.15 mm. Wires of Examples 1 to 6 and Comparative Examples 1 to 5 were produced.
Here, the true strain and the like were adjusted by adjusting the area reduction rate of the final wire drawing and changing the plating wire diameter.
The results are shown in Table 2. The disconnection rate in the table is represented by an index based on Comparative Example 3.
As shown in Table 2, it was found that the wire of the example had less disconnection than the wire of the comparative example.

  The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the embodiments and examples described above, and is intended to include any modifications and variations within the scope and meaning equivalent to the terms of the claims.

Claims (3)

0.68 to 0.75 mass% C, 0.10 to 0.50 mass% Si, 0.30 to 0.90 mass% Mn, 0.025 mass% or less P, 0 0.025 mass% or less of S and 0.2 mass% or less of Cu, and the balance is obtained by patenting and wire drawing of a wire consisting of Fe and inevitable impurities,
The wire diameter is 0.16 mm or less,
A wire saw wire having a tensile strength of 3300 to 3800 MPa.   The wire for a wire saw according to claim 1, wherein a twist value in the twist test is 25 times or more.   The wire for a wire saw according to claim 1 or 2, wherein the elongation is 2.0% or more.

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