JPH0790465B2 - Method of manufacturing wire for cut wire - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a wire for high strength cut wire used for shot balls such as shot blast, and more specifically, a wire for cut wire having Vickers hardness Hv = 750 or more obtained by wire drawing. Manufacturing method.

[0002]

2. Description of the Related Art A cut wire is used as a shot ball for shot blasting performed to introduce a compressive residual stress to the surface of a material after being rounded. Japanese Patent Application Laid-Open No. 02-190
There are shot balls manufactured by cutting a steel wire as disclosed in Japanese Patent No. 266, shot balls made of ceramics, shot balls produced by an atomizing method, and the like.

Since a shot ball made of ceramic is easily cracked, there is a problem that when the strength of the material used for shot is high, the material shot by the cracked shot ball is damaged. Shot ball by atomizing method,
It is difficult to adjust the strength, and even if a high-strength shot ball is obtained, the Vickers hardness is only about 500. For this reason, the shot of the high-strength material has a problem that sufficient compressive residual stress cannot be introduced into the material.

On the other hand, a shot ball manufactured from a steel wire has a low strength so far. Therefore, when it is used for a high-strength material shot, there is a problem that a compressive residual stress introduced after the shot is low.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a wire for a high strength cut wire which has a high Vickers hardness and a long life, which is suitable for shots of a high strength material.

[0006]

The present invention is based on C in weight percent:
0.90 to 1.10%, Si: 0.4% or less, Mn:
0.5% or less, Cr: 0.10 to 0.30%, Al:
The strength after final patenting was 13% using a high carbon steel wire consisting of 0.050% or less and the balance iron and unavoidable impurities.
5 or more and less than 145 kgf / mm ² and then, by drawing, processing with a true strain of 3.0 to 3.10 to make the diameter 0.4 mmφ or more and less than 0.8 mmφ and the Vickers hardness Hv = 750 or more and less than 800. A method for manufacturing a wire for a cut wire, comprising:

The present invention further provides a high carbon steel having the above components.
Use a line to increase the strength after final patenting to 145 or more 1
It is less than 55 kgf / mm ^2, and after that, it is drawn to a true strain of 3.10 to 3.30 and a diameter of 0.
4 or more and less than 0.8 mmφ and Vickers hardness Hv = 800
850 or more and 850 or less, and the strength after final patenting is 140 or more and 150 kgf / mm ² or less, and then the strain is 3.00 to 3.20 by true strain, and the diameter is 0.8 to 1.0 mmφ. And a Vickers hardness Hv of 750 or more and 800 or less.

[0008]

The reason for limiting the steel composition of the present invention is as follows. In the usual patenting process, even in the case of 0.8% of the eutectoid component, pro-eutectoid ferrite precipitates along the former austenite grain boundaries, and this pro-eutectoid ferrite causes ductility after wire drawing. The present inventors have found that C is an economical and effective strengthening element,
It is also an effective element for reducing the amount of this proeutectoid cementite precipitate.

Therefore, in the case of manufacturing a cut wire having a diameter of 0.4 mmφ or more and less than 0.8 mmφ and a Vickers hardness of 750 or more and less than 800, when the C content is less than 0.90%, the Vickers hardness is Hv = 750. Since the above cannot be obtained, the C content is set to 0.90% or more. Further, when the C content exceeds 1.10%, it is difficult to suppress the precipitation of pro-eutectoid cementite and the life of the cut wire is remarkably reduced, so the C content is set to 1.10% or less.

In the case of producing a wire for a cut wire having a diameter of 0.4 or more and less than 0.8 mmφ and a Vickers hardness of 800 or more and 850 or less, when the C content is less than 0.95%,
Since the Vickers hardness cannot obtain Hv = 800 or more, the C content is 0.95% or more. In addition, the amount of C is 1.
When it is added in excess of 10%, it is difficult to suppress the precipitation of pro-eutectoid cementite and the life of the cut wire is remarkably reduced, so the C content is set to 1.10% or less.

When manufacturing a wire for a cut wire having a diameter of 0.8 or more and less than 1.0 mmφ and a Vickers hardness of 750 or more and 800 or less, when the C content is less than 0.95%, the Vickers hardness is Hv = 800 or more. Therefore, the C content is set to 0.95% or more. In addition, the amount of C is 1.1
When it is added in an amount of more than 0%, it is difficult to suppress the precipitation of pro-eutectoid cementite and the life of the cut wire is remarkably reduced, so the C content is set to 1.10% or less.

Si is an element necessary for deoxidizing steel, so when the content thereof is too small, the deoxidizing effect becomes insufficient. In addition, Si dissolves in the ferrite phase in pearlite formed after heat treatment to increase the strength after patenting, but on the other hand, it reduces the ductility of ferrite and reduces the ductility of ultrafine wire after drawing, so 0.4% or less. And

As for Mn, it is desirable to add a small amount of Mn in order to secure the hardenability of steel. However, a large amount of M
The addition of n causes segregation and causes a supercooled structure such as bainite and martensite during patenting and impairs the subsequent wire drawability, so the content is made 0.5% or less.

In the case of the hyper-eutectoid steel as in the present invention, a cementite network is likely to occur in the microstructure after patenting, and a cementite having a thickness is likely to precipitate. In order to achieve high strength and high ductility in this steel, it is necessary to make pearlite fine and to eliminate the cementite network and thick cementite as described above. Cr has an effect of suppressing the appearance of such an abnormal portion of cementite and further refining pearlite. However, addition of a large amount increases the dislocation density in the ferrite after heat treatment, and therefore significantly impairs the ductility of the ultrafine wire after drawing. Therefore, the amount of Cr added is set to 0.10% or more, which is expected to have the effect, and the dislocation density in the ferrite is increased to 0.30 without impairing the ductility.
% Or less.

Like the conventional ultra-fine steel wire, the S content is 0.020% or less in order to secure the ductility, and P also impairs the ductility of the wire like S, so the content is 0.020% or less. Is desirable.

Al as a cause of reducing the ductility of the ultrafine wire
The ₂ O _3, Al ₂ O _3, such as MgO-Al ₂ O ₃ is present in the non-ductile inclusions mainly. Therefore, in the present invention, in order to avoid a decrease in ductility due to non-ductile inclusions, Al
The content is 0.050% or less.

The reasons for limiting the manufacturing method of the present invention are as follows. The diameter shown in the method of the present invention is 0.4 mm or more.
In the case of manufacturing a cut wire having a diameter of less than 8 mmφ and a Vickers hardness of 750 or more and 800 or less, it is difficult to set the Vickers hardness of 750 or more when the strength is 135 kgf / mm ² or less in the final LP. Also, the tensile strength is 1
If it is more than 45 kgf / mm ² , the Vickers hardness exceeds Hv = 800, so the tensile strength is 135 kg.
f / mm ² or more and 145 kgf / mm ² or less.

By repeatedly drawing the wire adjusted to have a constant strength range, the wire is processed to have a diameter of 0.4 mmφ or more and 0.8 mmφ or less. At this time, when the processing amount is 3.0 or less in true strain, the Vickers hardness Hv
= 750 or more wires cannot be obtained. In addition, since Vickers hardness exceeds 800 when processing with a true strain of 3.10 or more, the amount of drawing processing is set to 3.0 or more and 3.10 or less with a true strain.

Diameter of 0.4 to 0.8 mm shown in the method of the present invention
In the case of manufacturing a cut wire having a Vickers hardness of less than 800 and a Vickers hardness of 800 or more and 850 or less, it is difficult to set the Vickers hardness of 800 or more when the strength at the final LP is 145 kgf / mm ² or less. Also, the tensile strength is 1
When it is 50kgf / mm ² or more, the Vickers hardness exceeds Hv = 850, so the tensile strength is 145kg.
f / mm ² or more and 150 kgf / mm ² or less.

The wire adjusted to this constant strength range is repeatedly drawn to obtain 0.4 mm
Process φ to 0.8mmφ. At this time, when the working amount is 3.10 or less in true strain, a wire with Vickers hardness Hv = 800 or more cannot be obtained. Further, if the work is carried out at a true strain of 3.30 or more, the Vickers hardness exceeds 850, and the life of the shot grains is remarkably shortened.
It is set to 0 or more and 3.30 or less.

Diameter of 0.8 to 1.0 mm shown in the method of the present invention
If the cut wire has a Vickers hardness of 750 or more and 800 or less, the strength of the final LP is 14 or less.
When it is 0 kgf / mm ² or less, the Vickers hardness is 7
It is difficult to set it to 50 or more. Also, the tensile strength is 150
If it is more than kgf / mm ² , the shot grain life will be significantly reduced, so the tensile strength will be 140 kgf / mm ²
Above 150kgf / mm ² below.

By repeatedly drawing the wire adjusted to have a constant strength range, the wire is processed to 0.4 mmφ or more and 0.8 mmφ or less. At this time, when the processing amount is 3.00 or less in true strain, the Vickers hardness Hv
= 750 or more wires cannot be obtained. Further, if the true strain is processed to 3.20 or more, the Vickers hardness exceeds 800, and the life of the shot grains is remarkably reduced. Therefore, the drawing amount is 3.00 to 3.20 in true strain. To do.

Since the material of the present invention is hyper-eutectoid steel, defective portions are likely to occur in the structure obtained by the wire diameter after hot rolling. This defective portion becomes a source of microcracks in the drawing process. However, it is difficult to reduce the occurrence of microcracks by improving the structure because the steel of the present invention is a hypereutectoid steel. The present inventors use a drawing die of 8 ° to 12 ° with reference to 10 ° for drawing,
I found that this problem could be solved easily.

Generally, high carbon steel wire is drawn by
The drawing angle of 12 ° to 16 ° is used, based on the approach angle of 14 ° at which the drawing force is most reduced. However, in this case, since tensile stress acts on the central portion, fine cracks are easily generated in the central portion.

Therefore, in order to more easily carry out the drawing process without fine cracks, it is desirable to use a drawing die of 8 ° to 12 ° on the basis of 10 ° at which sufficient compressive stress works up to the central portion. Further, by reducing the approach angle of the die used in the drawing process, it is possible to reduce the occurrence of internal defects in the drawing process and realize a shot ball with a longer life.

If the cutting length of these wires is less than 1 time the wire diameter, it becomes difficult to cut, and the cutting length of the wire is set to 1
More than double. Further, when the cutting length exceeds twice the wire diameter, the life of the shot particles is remarkably reduced, so it is desirable to set the cutting length to twice the wire diameter or less.

[0027]

EXAMPLE A cut wire was manufactured according to the present invention by using the steel having the components shown in Table 1. 1 to 4 are according to the first aspect of the present invention method, 5 to 7 are according to the third aspect of the present invention method, 8 to 10
Is according to the method of the present invention, the chemical composition and manufacturing method of the steel used are adjusted according to the present invention. Also,
In Invention Examples 1, 2, 5, 7, 8, and 9, dies having an approach angle of 14 ° are used in the final drawing process.

Reference numerals 11 to 15 are according to the comparative example and have the following differences. Comparative Example 11 is a level in which the C content and the Cr content are different among the chemical components of the steel used in the present invention method.

In Comparative Example 12, the amount of Cr is different among the chemical compositions of the steel used in the present invention. In Comparative Example 13, the area reduction rate in the final drawing is higher than that of the method of the present invention as compared with the method of the present invention. In Comparative Example 14, the area reduction rate in the final drawing is lower than that of the method of the present invention as compared with the method of the present invention. In Comparative Example 15, the cutting length of the cut wire is different from that of the method of the present invention. Steels having the components shown in Table 1 were manufactured by hot rolling to have a diameter of 5.5 mm, and this was drawn into a wire having the final LP wire diameter shown in Table 1. By applying the LP treatment shown in Table 1 to this wire,
The wire has the tensile strength shown in Table 1. 1 according to the present invention
In all of 10 to 10, the strength is adjusted within the range of the method of the present invention. After that, in the example of the present invention, the approach angle is set to 10
The angle of approach is 1 in the comparative example.
Drawing was performed using a 4 ° die.

After the drawing process, the wire was cut by a cutting machine and the hardness was measured. Further, in order to examine the life of the cut wire, continuous shots were carried out for 1000 hours, and the amount of wear of the shot particles was determined by the weight% of the weight of the initial shot particles minus the weight of shot particles of a predetermined size or more after the shot.

As shown in Table 1, by using the examples of the present invention, a cut wire having a Vickers hardness Hv of 750 or more and an excellent life can be obtained. Further, by setting the approach angle to 10 ° during the drawing process, a cut wire with a longer life can be obtained. On the other hand, Comparative Example 11
Then, as shown in Table 1, Vickers hardness Hv = 750.
You can't get more.

Also in Comparative Example 12, as shown in Table 1, the Vickers hardness Hv = 750 or more cannot be obtained. Comparative Example 13 has a higher surface reduction rate in the final drawing process than the method of the present invention, so that a Vickers hardness of Hv = 750 or more is obtained, but the wear rate of the cut wire is large and the life of the cut wire is short. Has become. Comparative Example 14
Since the area reduction ratio in the final drawing process is lower than that of the method of the present invention, Vickers hardness Hv = 750 or more is not obtained. In Comparative Example 15, since the cut length of the cut wire is longer than that of the method of the present invention, it can be seen that the wear rate of the cut wire is large and the life is shortened. In addition, in Table 1
The definition of "life" of the cut wire of
It The wear rate of 10% or more as the life of the shot ball
Then, in continuous use after that, worn-out particles
Such as residual stresses that increase and are introduced into the material being shot
Efficiency is reduced. Due to the increase in crushed particles,
Increases the damage of the placed material. From this,
It is necessary to replace or sort shot grains in a predetermined time
Become. Here, the time until the wear rate of 10% is reached
Think of it as life. The wear rate was calculated by the following formula. A = test shot particle overall weight B = 1000 hours after the test wire diameter × 0.9 or more particles when produced in wire drawing Weight attrition rate = (A-B) / A × 100

[0033]

[Table 1]

[0034]

When a shot ball for shot blasting is manufactured using the steel of the present invention, the Vickers hardness Hv
It is possible to obtain a high-strength shot ball of 750 or more.

Claims (6)

[Claims] 1. C: 0.90 to 1.10% by weight,
Si: 0.4% or less, Mn: 0.5% or less, Cr: 0.
10-0.30%, Al: 0.050% or less, using a high carbon steel wire consisting of balance iron and unavoidable impurities, the strength after final patenting is set to 135 or more and less than 145 kgf / mm ² , and then drawing Due to true strain 3.0 ~
Processed 3.10, diameter 0.4mmφ or more 0.8mmφ
And a Vickers hardness of Hv = 750 or more and less than 800, and a method for producing a wire for a cut wire. 2. A high carbon steel wire having the composition according to claim 1.
The use, the strength after the final patenting 145 or 15
Less than 5 kgf / mm ² , and then the true strain of 3.10 to 3.30 is processed by drawing process, and the diameter is 0.4.
A method for producing a wire for a cut wire, wherein the wire has a Vickers hardness Hv of 800 mm or more and less than 0.8 mmφ and 800 or more. 3. A high carbon steel wire having the composition according to claim 1.
The use, the strength after the final patenting 140 or 15
0 kgf / mm ² or less, and then, by drawing, 3.00 to 3.20 with true strain, diameter 0.8
A method for manufacturing a wire for a cut wire, wherein the wire has a Vickers hardness Hv of 750 or more and less than or equal to 750 and 800 and less than 1.0 mmφ. 4. The die approach angle for drawing is
The method for manufacturing a wire for a cut wire according to claim 1, wherein a die of 8 ° to 12 ° is used. 5. The die approach angle for drawing is
The method for manufacturing a wire for a cut wire according to claim 2, wherein a die of 8 ° to 12 ° is used. 6. The die approach angle for drawing is
The method for manufacturing a wire for a cut wire according to claim 2, wherein a die of 8 ° to 12 ° is used.