JPH07300946A - Deformed bar steel with high adhesion and high strength, and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain the sufficient adhesive strength by forming a deformed bar steel or a linear raw material, to which knot rolling is performed, into the complete round at an area reduction ratio, at which the knots by the hot rolling are left, and thereafter, performing hardening, tempering and heating. CONSTITUTION:A deformed bar steel or a linear raw material, to which knot rolling is applied so as to have a spiral projection by hot rolling in the periphery thereof, is formed into the complete round at an area reduction ratio, at which the knots are left at the original height of the knots formed by the hot rolling, and heating is performed. As components of the raw material, C: 0.1-0.6% by weight, Si: 0.15-2.00 by weight, Mn: 0.6-2.00% by weight, and Cr: 0.6% by weight or less are included, and (the residual part is composed of iron and obligatory impurity, and the bar steel or the linear material is formed at 5-50mm of diameter. This steel bar or the linear material is heated at 93ON/mm<2> or more of tensile strength and at 785N/mm<2> or more of yield point. Consequently, welding is facilitated, and the working efficiency is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to civil engineering. Reinforcing bar for building concrete, main bar and auxiliary bar as steel material for prestressing / concrete, other ground anchors, etc., which are used by rolling screw processing or cross wire welding, and which require adhesive strength with concrete The present invention relates to high strength bar steel.

[0002]

2. Description of the Related Art A conventional deformed steel bar for concrete is shown in FIG.
As in the hot-pressure deformed steel bar 1, a steel bar is used in which the protrusions 11 are provided at regular intervals on the surface of the steel bar by hot rolling to increase the adhesion strength to concrete.

However, these deformed steel bars as hot-rolled have high protrusions and high concrete adhesion, but have poor roundness due to hot-rolling, and a gap between the upper and lower rolling rolls is taken. 2 ribs 12 in the rolling direction
If it is rolled, it is difficult to perform thread rolling on the end, and the weldability is poor due to poor contact between the electrodes during cross wire welding. However, there are drawbacks such as difficulty in handling continuous feed by the feed roller. In particular, for high-strength deformed steel bars such as heat-treated prestressed steel for concrete, if the roundness is poor due to the high hardness of the steel material, thread rolling cannot be performed as it is. I had to carry out thread rolling.

[0004]

SUMMARY OF THE INVENTION Therefore, according to the present invention, a hot-rolled deformed steel bar deformed by hot rolling with knots is further lightly drawn to improve the circularity of the cross section of the concrete steel bar. It is an object of the present invention to provide a high-adhesion, high-strength deformed steel bar that is improved, facilitates secondary processing such as thread rolling, and has improved welding workability during execution.

[0005]

In order to achieve the above-mentioned object, the present invention provides a method of forming a bar-rolled deformed bar steel for concrete or a raw material of a wire rod having a spiral projection on the outer diameter by hot rolling. (EN) Provided is a high-adhesion, high-strength deformed steel bar, which is obtained by performing true circle processing with a reduction in area such that the original height of the rolled node remains, and then performing heat treatment such as quenching and tempering.

C: 0.1 to 0.6% by weight, S
i: 0.15 to 2.00%, Mn: 0.6 to 2.00
%, Cr: facilities remainder comprising 0.6% or less in a steel bar or wire rod 5~50mm diameter consisting of iron and inevitable impurities, tensile strength 930N / mm ² or more, the heat treatment the yield point 785N / mm ² or more The above-mentioned high adhesion /
Provide high-strength deformed steel bar.

[0007]

In the structure of the present invention, the deformed bar steel for concrete or the wire rod having the spiral projection on the outer diameter by the hot rolling is used, but the roundness is poor in the hot rolling as it is. This is because, since the material already has a knot, it is possible to reduce the subsequent steps and easily obtain a deformed steel bar having high concrete adhesion. Further, how much of the height of the hot rolled knots is left is determined by the reference diameter of the deformed steel bar, the height of the knots and the inner diameter of the die, but in order to obtain a high concrete adhesion, the roundness is achieved. It is desirable to keep the height of the hot-rolled node as high as possible by limiting the processing to the minimum reduction ratio. The present invention is based on the results of experiments.
It is desirable to form a perfect circle with a surface reduction rate that remains 40% or more of the original knot height. Further, heat treatment such as quenching and tempering is for obtaining a required mechanical strength.

The reasons for limiting the components of the material of the deformed steel bar are as follows. C by weight ratio is 0.1 to 0.6
%, Because the required strength cannot be obtained by quenching at 0.1% or less, and the toughness decreases at 0.6% or more. Further, Si is an effective component for reducing high temperature relaxation, and the Si content is 0.15 to 2.00.
%, The effect of reducing the high temperature relaxation cannot be obtained at 0.15% or less, and the toughness decreases at 2.00% or more. The reason why the Mn content is set to 0.6 to 2.00% is to improve the hardenability. If the Mn content is 0.6% or less, the effect is insufficient, and if it is 2.00% or more, the retained austenite after quenching increases. Because. Cr increases the hardenability and increases the tempering resistance, but a Cr amount of 0.6% or more is economically disadvantageous, and the required properties can be obtained without adding Cr in a small diameter steel bar. .

The size is limited to a diameter of 5 to 50 mm because it is a range generally used as a high-strength deformed steel bar for concrete. The strength tensile strength 930N / mm ² or more, is to obtain a strength required for the prestressing steel bars to heat treatment yield point 785N / mm ² or more.

[0010]

EXAMPLES An example of the present invention will be specifically described below. FIG. 2 is a view showing a manufacturing process of the high-adhesion / high-strength deformed steel bar (hereinafter simply referred to as high-strength deformed steel bar) of the present invention. In FIG. 2, the material used is a hot rolled deformed steel bar or wire rod (hereinafter simply referred to as hot pressed deformed steel bar) having the shape shown in FIG. 8 that is wound in a coil shape, and is passed through a multi-roll straightening machine in the next descaling step. Surface scale is removed.
Next, in the drawing step, drawing is performed cold by a predetermined round die. Then, in the quenching step, the material is continuously heated to the quenching temperature by the high frequency induction heating means or the direct energizing means, and quenched by water cooling. Then, in the tempering step, similarly, the material is continuously heated to the tempering temperature by the high frequency induction heating means or the direct energizing means, tempered, and rapidly cooled. Then, in the processing step, the wire rod is coiled, and the rod material is cut in a straight line to a fixed length, screwed, and the like, and is shipped as a finished product through an inspection step.

In the present embodiment, JIS3 having as a material a node of a spiral protrusion having a shape shown in FIG.
Nominal diameter D10 specified in 112 with a nominal diameter of 9.53 mm
The heat-pressure deformed steel bar of was used. Table 1 shows the chemical composition of the hot pressed deformed steel bar.

[0012]

[Table 1]

The cross-sectional shape is shown in FIG. That is, in FIG. 3, the body diameter of the steel bar is 8.85 to 8.90 φm.
m, the height of the rib was 0.36 to 0.38 mm, and the height of the joint was 0.58 to 0.63 mm.

This hot-rolled deformed steel bar was manufactured to have an inner diameter of 9.10 mmφ.
Cold drawing was performed using a No. circular die. The cross section of the steel bar after drawing is shown in FIG. As shown in the figure, the diameter of the body is the same as the material, but the height of the rib 12 is 0.24 to 0.2.
8 mm, 63-78% of the original height, and the height of the joint 11 is 0.25-0.30 mm, which is 4 of the original height.
It became 0-52%. The appearance is shown in FIG. As shown in the figure, the drawn deformed steel bar 2 has nodes 11 and ribs 12 whose vertices are slightly flat. As a result, the height of the knots was lowered and the adhesive strength of concrete was slightly reduced compared to the hot-press deformed steel bar.
The roundness is improved and the thread rolling property is improved.

The adhesion strength test of the drawn bar-shaped deformed steel bar with concrete was carried out based on "method (plan) of Japan Concrete Institute". The test piece is shown in FIG. In the figure, a test piece 4 has a deformed steel bar 7 as a test material arranged at the center of a 10 cm cubic concrete cube 5 and has a winding diameter of 8 cm and a spiral pitch a = 4 cm of 6 mm.
Reinforcing rods 6 having a diameter of φ (the end portion was horizontally set to 1.5 windings and 0.5 windings were discarded) were arranged. In addition, the concrete was made horizontal (bars are horizontally arranged) and the quality of the concrete was as follows. Material age 28 days Curing condition 14 to 24 ° C Underwater curing Concrete strength σc 300 ± 30 kgf / cm ² slump 8 ± 2 cm. The test was performed by using a 30t tensile tester by the method shown in FIG. In the figure, the specimen 4 was placed on the pedestal 41 of the fixed portion of the tensile tester via the spherical seat 42 and the washer 43, and a pulling force was applied to the test deformed steel bar 7 by the clamp 44 in the direction of arrow P. Then, the slip amount of the test deformed steel bar 7 is measured by the dial gauge 45, and the XY recorder 4 is supplied through the amplifier 46.
The relationship between the amount of slip and the pulling force was recorded according to 7.

The test results are shown in FIG. 7 and Table 2. Figure 7
, The vertical axis represents the pulling force (KN) and the horizontal axis represents the slip amount (m
m) is shown. Curve A is a hot-rolled deformed steel bar as it is rolled, curve B is a drawn deformed steel bar of the present invention, and curve C is a comparative material of 9.2 mm urbon (10 φ grooved drawn material, urbon is a registered trademark of High Frequency Refining Co., Ltd. ) Shows the drawing force-slip diagram. Table 2 shows the slip amount of 0.05 m from the result of FIG.
m, 0.1 mm, 0.25 mm, the average value and the maximum adhesive force are displayed. From the results in Table 2 and Fig. 7, when hot-rolled and deformed steel bars were drawn, the maximum adhesive force decreased from 36.8KN to 26.5KN due to the decrease in the height of the nodes, but it was still better than the comparative material Urubon. The wearing power is great,
Adhesive strength sufficient for use was obtained.

[0017]

[Table 2]

Next, the drawn out deformed steel bar was heat-treated using a continuous quenching and tempering device 30 shown in FIG. In FIG. 10, the material W of the drawn deformed steel bar is continuously sent out through a pinch roll 31, a vertical straightening roll 32, a horizontal straightening roll 33, and a pinch roll 34, and a quenching high-frequency induction heating coil 35. At 920
Heated to a quenching temperature of ° C, water cooled jacket 36
Is quenched and quenched. Then, after being heated to a tempering temperature of 370 to 380 ° C. by a high frequency induction heating coil 37 for tempering, it is rapidly cooled by a water cooling jacket 38 and sent out by a pinch roll 39.

Table 3 shows the mechanical properties of the deformed steel bars after the heat treatment. Mechanical strength is improved by heat treatment, and both non-grooved bar steel and grooved bar steel are JIS
G3109 standard yield point load, tensile load, elongation at break,
I am satisfied with the aperture.

[0020]

[Table 3]

This deformed steel bar product was subjected to a thread rolling test using an RL23 type rolling machine manufactured by High Frequency Heat Smelting Co., Ltd. The results are shown in Table 4. For both the non-grooved deformed bar steel and the grooved deformed bar steel, the results satisfying the standard value of JIS B 0221 were obtained. Although the roundness was poor and the thread rolling could not be performed with the hot-press deformed steel bar material, the product of this example could be thread-rolled without any problems.

[0022]

[Table 4]

Next, this deformed steel bar was head-pressed into a shape as shown in FIG. 9 using an FP11 type forging machine manufactured by High Frequency Heat Smelting Co., Ltd., and a tensile test was conducted. The results are shown in Table 5.
All of them showed the specified tensile strength, and all of them were normally fractured in the base metal part. Therefore, it was shown that the head forming process can also be performed under normal conditions.

[0024]

[Table 5]

In this embodiment, the deformed bar steel of D10 standard of JIS G 3112 is shown, but it goes without saying that it can be applied to D6 to 51 of the same standard.

[0026]

As described above, according to the present invention, the knots and ribs of the hot-rolled deformed bar steel having a poor roundness are crushed by the drawing process to improve the roundness. As it is, the roundness is poor and the thread rolling process can be performed without screw cutting, which improves the defect and facilitates the thread rolling process. Also, the contact of the electrodes during cross wire welding is good. As a result, welding becomes easier, handling at the site is improved, and work efficiency is improved. Further, it is difficult to straighten the coil material with a straightening roll when the hot rolled material is used as a straight material, and the handling becomes easy.

Furthermore, it is desirable that the adhesive force of the concrete can be maintained at a value sufficient for use by leaving the knot of 40% or more of the height of the spiral projection of the original knot of the hot rolled material.

The weight ratio of the components of the raw material is C: 0.1.
0.6%, Si: 0.15 to 2.00%, Mn: 0.6
~ 2.00%, Cr: 0.6% or less, and if the balance is limited to iron and unavoidable impurities, the strength of the standard value can be easily obtained, so the safety of using high-strength deformed bar steel increases. .

Further, since the hot-press deformed steel bar material can be used as it is, there is an advantage that mass production is easy.

[Brief description of drawings]

FIG. 1 is an external view of a high-adhesion / high-strength deformed steel bar according to an embodiment of the present invention.

FIG. 2 is a manufacturing process diagram of an example of the present invention.

FIG. 3 is a cross-sectional view of a hot-press deformed steel bar material according to an embodiment of the present invention.

FIG. 4 is a sectional view of a deformed steel bar drawn by a die according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view of a concrete adhesive strength test specimen of an example of the present invention.

FIG. 6 is a conceptual diagram of a test apparatus for a concrete adhesion strength test according to an example of the present invention.

FIG. 7 is a graph showing test results of a concrete adhesion strength test of an example of the present invention.

FIG. 8 is an external view of a hot-rolled deformed steel bar as a raw material.

FIG. 9 is a view showing the shape of head forging of a high-adhesion / high-strength deformed steel bar according to an example of the present invention.

FIG. 10 is a conceptual diagram of a continuous quenching and tempering device used in an example of the present invention.

[Explanation of symbols]

 1 Hot-rolled deformed steel bar material 2 Draw-deformed deformed steel bar 4 Specimen for bond strength test 5 Concrete cube 6 Rebar 7 Test steel bar 11 Section 12 Rib 30 Continuous quenching / tempering device 31 Feed roller 32 Horizontal roll straightener 33 Vertical roll straightening Machine 34 Feed roller 35 High frequency heating coil 36 Water cooling jacket 37 High frequency heating coil 38 Water cooling jacket 39 Feed roller 41 Cradle 42 Spherical washer 44 Clamp 45 Dial gauge 46 Amplifier 47 XY recorder

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C21D 9/00 H 9352-4K 9/28 A C22C 38/00 301 Y 38/18

Claims (2)

[Claims] 1. A material for a bar-shaped deformed steel bar for concrete or a wire rod having a spiral projection on its outer diameter by hot rolling after being rounded at a surface reduction rate such that the hot-rolled nodes remain. High-adhesion, high-strength deformed steel bar characterized by being subjected to quenching and tempering heat treatment. 2. A weight ratio of C: 0.1 to 0.6%, Si:
0.15-2.00%, Mn: 0.6-2.00%, C
r: A steel rod or wire rod having a diameter of 5 to 50 mm, which contains 0.6% or less and the balance is iron and inevitable impurities, and has a tensile strength of 93.
High adhesion according to claim 1, characterized in that the heat treatment is performed at 0 N / mm ² or more and at a yield point of 785 N / mm ² or more.
High strength bar steel.