JP6885257B2 - Surface treatment method for metal materials and manufacturing method for metal materials - Google Patents

Description

The present invention relates to a method for surface treatment of a metal material and a method for producing the metal material, which eliminates defects exposed on the surface of the metal material.

Generally, steel sheets (thick plates, thin plates) are manufactured by hot rolling or cold rolling using steel pieces that have undergone processes such as continuous casting, disassembly rolling, and forging. If heating and rolling are performed with defects such as voids and cracks exposed on the surface, the surface properties of the product may deteriorate or cracks may occur.

Therefore, conventionally, the surface of a steel piece (slab) is ground with a grindstone using a grinder to remove defects on the surface of the slab (for example, Patent Document 1). There is also a method for caring for the surface of a steel piece (slab) by cutting the surface of the steel piece (slab) with a milling tool using a machine tool such as Planomira (for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 51-18937 Japanese Unexamined Patent Publication No. 9-108725

The method of polishing the surface of a steel piece by grinding with a grinding machine as in Patent Document 1 is a general and widely used method, but has the following problems. That is, when removing defects, if a pinpoint attempt is made to remove the defects, the defect removing portion becomes concave and adversely affects the rolling quality. Therefore, normally, the surface layer around the defects should also be removed so as not to make a steep slope. To. However, since many defects are present inside the steel material, when the surface layer around the defects is removed, another defect originally existing inside the steel material is exposed to the surface by maintenance. Regarding the technique shown in Patent Document 2, although there is a difference between grinding and cutting, there is also a problem of exposing defects hidden inside. Such a problem occurs not only in steel pieces but also in other metal materials.

Therefore, it is an object of the present invention to provide a surface treatment method for a metal material and a method for producing a metal material, which can eliminate the defects exposed on the surface without exposing new defects on the surface of the metal material.

In order to solve the above problems, the present invention provides the following (1) to (12).

(1) A rotating tool made of a material harder than the metal material is brought into contact with the exposed portion of the defect on the surface of the metal material while rotating with respect to the metal material having the exposed portion of the defect on the surface. The contact portion of the metal material with the rotary tool is plastically flowed by the frictional heat and pressure, and the heated metal powder is supplied to the plastic flow portion, and the rotary tool is rotated while being defective. The metal powder is moved along the distribution of the exposed portion of the metal material, and the moving portion of the rotary tool in the metal material is sequentially plastically flowed while entraining the metal powder to close the exposed portion of the defect of the metal material. Surface treatment method for metal materials.

(2) The method for surface treating a metal material according to (1), wherein the metal powder is supplied in advance to a portion of the surface of the metal material where an exposed portion of a defect exists.

(3) The metal powder is supplied to a portion of the metal material that has been plastically flowed by the rotary tool, and the rotary tool is moved along the distribution of exposed portions of defects while being rotated. The surface treatment method for a metal material according to (1).

(4) The method for surface treating a metal material according to any one of (1) to (3), wherein the rotary tool has a diameter equal to or larger than the short side dimension of the exposed portion of the defect.

(5) Prior to the surface treatment of plastically flowing the metal material by the rotary tool, the exposed portion of the defect on the surface of the metal material before the treatment is marked, and the marked portion of the metal material is plastically flowed by the rotary tool. The method for surface-treating a metal material according to any one of (1) to (4).

(6) The method for surface treating a metal material according to any one of (1) to (5), wherein the metal material is a steel piece that has undergone continuous casting, slabbing rolling, or a forging process.

(7) A process of preparing a material metal material having an exposed portion of a defect on the surface, and
A rotating tool made of a material harder than the material metal material is brought into contact with the exposed portion of the defect on the surface of the material metal material while rotating, and the rotating tool of the material metal material is subjected to frictional heat and pressure generated at that time. The process of plastically flowing the contact part with
The process of supplying heated metal to the plastic flow part, and
The rotary tool is moved along the distribution of the exposed portion of the defect while being rotated, and the moving portion of the rotary tool in the metal material is sequentially plastically flowed while entraining the metal powder. ,
Material A method for manufacturing a metal material, which comprises closing an exposed part of a defect by plastic flow of the metal material.

(8) The step of supplying the heated metal to the plastic flow portion is performed by supplying the metal powder to the portion of the surface of the metal material where the exposed portion of the defect exists in advance. The method for producing a metal material according to (7).

(9) In the step of supplying the heated metal to the plastic flow portion, the rotary tool is rotated while supplying the metal powder to the portion of the metal material that has been plastically flowed by the rotary tool. The method for producing a metal material according to (7), wherein the metal material is moved along the distribution of exposed portions of defects in the state of being kept.

(10) The method for producing a metal material according to any one of (7) to (9), wherein the rotary tool has a diameter equal to or larger than the short side dimension of the exposed portion of the defect.

(11) Prior to the surface treatment of plastically flowing the material metal material by the rotary tool, the exposed portion of the defect on the surface of the material metal material is marked, and the marked portion of the material metal material is plastically flowed by the rotary tool. The method for producing a metal material according to any one of (7) to (10).

(12) The method for producing a metal material according to any one of (7) to (11), wherein the material metal material is a material steel piece that has undergone continuous casting, slabbing rolling, or a forging process.

According to the present invention, a rotating tool made of a material harder than the metal material is brought into contact with the exposed portion of the defect existing on the surface of the metal material before the treatment while rotating, and the frictional heat and pressure generated at that time are used. The contact part of the metal material is plastically flowed, and the heated metal powder is supplied to the plastic flow part, and the rotating tool is moved along the distribution of the exposed part of the defect while being rotated to obtain the metal. While entraining the powder, the moving parts of the rotating tool in the metal material are sequentially plastically flowed to close the exposed parts of the defects, so that the defects exposed on the surface can be eliminated without exposing new defects on the surface of the metal material. it can.

It is sectional drawing which shows typically the steel piece which went through the process such as continuous casting, disassembly rolling, and forging. It is sectional drawing which shows typically the state which removed the oxide scale from the state of FIG. 1 and made into the material steel piece to be used for the surface treatment method of embodiment. It is a figure which shows the procedure of the surface treatment method which concerns on 1st Embodiment of this invention. It is a figure which shows the procedure of the surface treatment method which concerns on 2nd Embodiment of this invention. It is a front view and a bottom view which shows a rotary tool.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view schematically showing a steel piece that has undergone processes such as continuous casting, disassembly rolling, and forging, and FIG. 2 is a surface treatment method of the present embodiment in which the oxide scale is removed from the state of FIG. FIG. 3 is a cross-sectional view schematically showing a state in which the material is a steel piece, FIG. 3 is a diagram showing a procedure of the surface treatment method of the first embodiment, and FIG. Is.

The steel type of the steel piece is not particularly limited, but FIG. 1 shows the case where general high carbon steel is used, and the surface of the steel piece is an oxidation scale called black skin after undergoing processes such as continuous casting, disassembly rolling, and forging. It is a steel piece with black skin having 2. Defect 3 exists inside the steel piece.

From the state of FIG. 1, the oxide scale 2 is removed in advance by machining means such as shot, grinding, and cutting to obtain the material steel piece 1 as shown in FIG. The material steel piece 1 has an exposed portion 3a of defects 3 such as voids and cracks on the surface.

In the present invention, the material steel piece 1 is subjected to surface treatment using plastic flow processing.

First, a first embodiment of the surface treatment method will be described.
The first embodiment of the surface treatment method is carried out according to the procedures (a) to (d) of FIG.
As a preliminary preparation before performing the surface treatment, first, the portion of the exposed portion 3a exposed on the surface of the defect 3 existing in the material steel piece 1 is confirmed and marked. The portion of the exposed portion 3a of the defect 3 can be visually confirmed. In addition, a commonly used penetrant inspection may be performed to bring out the defect 3.

Next, the material steel piece 1 is set in the machine tool. The rotary tool 10 shown in FIG. 5 is attached to the machine tool as a tool. As shown in FIG. 5, the rotary tool 10 has a columnar shape as a whole, and the flange portion at the tip has a truncated cone shape. The rotary tool 10 can tilt its rotating shaft with respect to the material steel piece, and the tilt angle is preferably about 0.3 to 3.0 degrees. The tilting direction is preferably a direction in which the front side floats with respect to the traveling direction of the tool. As the rotary tool 10, a material harder than the material steel piece 1 is used. As the material of the rotary tool 10, for example, cemented carbide (mainly WC), Co alloy, ceramics, cermet and the like can be used. The diameter of the rotary tool 10 is preferably equal to or larger than the dimension on the short side of the exposed portion 3a of the defect 3. In FIG. 5, (a) is a front view and (b) is a bottom view.

Further, the machine tool is equipped with a device for heating the metal powder and supplying the heated metal powder, and the metal powder is heated in advance by this device.

After preparing in this way, first, the preheated metal powder 5 is supplied onto the marking portion 4 (FIG. 3 (a)). As a result, the surface temperature of the material steel piece 1 in that portion rises. The metal powder 5 is preferably made of the same material as the material steel piece 1, but may be made of a different material when heating and scale removal are performed in a later step. The metal powder 5 may have a temperature at which the surface of the material steel piece 1 can be appropriately heated, but is preferably equal to or lower than the transformation point of the supplied metal powder 5. When the metal powder 5 is iron powder, the temperature is preferably 700 ° C. or lower.

Then, the rotary tool 10 is lowered while rotating, and the rotary tool 10 is brought into contact with the end portion of the marking portion 4 where the exposed portion 3a of the defect 3 of the material steel piece 1 exists, and then the rotary tool 10 is brought into contact with the predetermined depth. The rotary tool is buried in the material steel piece 1 for a minute (FIG. 3 (b)). It is preferable that the depth of the rotary tool 10 to be buried is less than the height of the flange of the rotary tool 10, and the bottom surface in the traveling direction is floated from the material steel piece 1. By burying the rotary tool 10 while rotating it in this way, the contact portion of the material steel piece 1 with the rotary tool 10 plastically flows while entraining the metal powder 5 due to the friction and pressure of the rotary tool 10. Since the temperature at which the plastic flow starts in the steel piece is about 800 to 1000 ° C., the peripheral speed of the rotary tool 10 is set so as to reach such a temperature. The peripheral speed of the rotary tool 10 is preferably about 50 to 150 mpm.

After confirming that the contact portion of the material steel piece 1 with the rotary tool 10 has started plastic flow due to the friction and pressure of the rotary tool 10, the rotary tool is rotating along the distribution of the exposed portion 3a of the defect 3. 10 is moved with the metal powder 5 involved (FIG. 3 (c)). The start of plastic flow can be confirmed, for example, by changing the torque of the rotary tool 10.

In this way, the portion of the material steel piece 1 including the exposed portion 3a of the defect 3 is plastically flowed by the rotary tool 10, and the plastic flow portion 6 is formed on the surface portion of the material steel piece 1 after the rotary tool 10 has passed. , The exposed portion 3a of the defect 3 existing in that portion is closed.

Then, as shown in FIG. 3D, after the rotary tool 10 reaches the end of the marking portion 4, the rotary tool 10 is raised to remove the remaining metal powder. By performing such an operation on the exposed portions 3a of all the defects 3, the steel piece 11 in which the exposed portions 3a have disappeared can be obtained.

As described above, the frictional heat and pressure generated by bringing the rotary tool 10 into contact with the material steel piece 1 while rotating the rotating tool 10 causes the steel piece portion in which the exposed portion 3a of the defect 3 exists to be plastically flowed to close the exposed portion 3a. It is possible to eliminate the defects exposed on the surface without exposing new defects as in the case of maintenance by grinding or cutting.

Further, in the case of friction stir welding at room temperature, the required pressure and friction load of the rotary tool 10 may become excessive, but the metal powder heated on the marking portion 4 in which the exposed portion 3a of the defect 3 exists. By supplying 5, the surface temperature of the material steel piece 1 at that portion can be raised, so that plastic flow can be easily performed and the pressure and friction load of the rotary tool 10 can be reduced. Further, the recess of the material steel piece 1 formed during friction stir welding by the rotary tool 10 can be reduced.

Japanese Patent Application Laid-Open No. 2012-40584 describes that the material is heated by high-frequency heating when friction stir welding is performed, but when this is applied, the heating time is added to the processing time. , The processing time becomes long. In addition, energy loss also increases. On the other hand, in the present embodiment, since only the portion to be heated is rapidly heated by supplying the metal powder 5, these problems do not occur.

Next, a second embodiment of the surface treatment method will be described.
The second embodiment of the surface treatment method is carried out according to the procedures (a) to (d) of FIG.
As a preliminary preparation before performing the surface treatment, first, as in the first embodiment, the portion of the exposed portion 3a exposed on the surface of the defect 3 existing in the material steel piece 1 is confirmed and marked.

Next, the material steel piece 1 is set in the machine tool, and the rotary tool 10 is attached to the machine tool as a tool as in the first embodiment. Further, the machine tool is equipped with a device for heating the metal powder and supplying the heated metal powder, and the metal powder is heated in advance by this device. Then, the metal powder can be directly supplied from this device to the friction stir portion via the nozzle.

After preparing in advance in this way, first, the rotary tool 10 is lowered while rotating, and the rotary tool 10 is placed at a position corresponding to the end of the marking portion 4 where the exposed portion 3a of the defect 3 of the material steel piece 1 exists. After contacting, the rotary tool is embedded in the material steel piece 1 by a predetermined depth (FIG. 4 (a)). Similar to the first embodiment, it is preferable that the depth of the rotary tool 10 to be buried is less than the flange height of the rotary tool 10, and the traveling direction side of the bottom surface is floating from the material steel piece 1. By burying the rotary tool 10 while rotating it in this way, the contact portion of the material steel piece 1 with the rotary tool 10 plastically flows due to the friction and pressure of the rotary tool 10. The peripheral speed of the rotary tool 10 is preferably about 50 to 150 mpm, as in the first embodiment.

Next, the supply of the metal powder 5 from the nozzle 7 to the plastic flow portion is started (FIG. 4 (b)). As a result, the metal powder 5 is involved in the plastic flow portion. At this time, since the bottom surface of the rotary tool 10 is floating on the traveling direction side, the metal powder 5 can be easily supplied.

After confirming that the contact portion of the material steel piece 1 with the rotary tool 10 has started plastic flow due to the friction and pressure of the rotary tool 10, the rotary tool rotating along the distribution of the exposed portion 3a of the defect 3. 10 is moved in a state where the metal powder 5 supplied from the nozzle 7 is involved (FIG. 4 (c)). At this time, the nozzle 7 also moves together with the rotary tool 10 so that the metal powder 5 can be supplied to the portion where the plastic flow is always generated.

As a result, as in the first embodiment, the portion of the material steel piece 1 including the exposed portion 3a of the defect 3 is plastically flowed by the rotary tool 10 and becomes the surface portion of the material steel piece 1 after the rotary tool 10 has passed. A plastic flow portion 6 is formed, and the exposed portion 3a of the defect 3 existing in the portion is closed.

Then, as shown in FIG. 4D, after the rotary tool 10 reaches the end of the marking portion 4, the rotary tool 10 is raised to remove the remaining metal powder. By performing such an operation on the exposed portions 3a of all the defects 3, the steel piece 11 in which the exposed portions 3a have disappeared can be obtained.

In the first embodiment, it is necessary to attach the metal powder 5 to the portion of the defect 3 where the exposed portion 3a exists in advance, which increases the labor of the operator and requires that a relatively large amount of the metal powder is attached. On the other hand, in the second embodiment, the metal powder 5 is directly supplied from the nozzle 7 to the exposed portion 3a of the material steel piece 1 while being plastically flowed. It is unnecessary, and the amount of the metal powder 5 may be as long as it is necessary, and the amount of the metal powder 5 can be reduced.

The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the idea of the present invention. For example, in the above embodiment, an example in which a steel piece that has undergone a continuous casting, ingot rolling, or forging process is used as the metal material is shown, but the steel piece is not limited to other metal materials, and an aluminum piece or the like is used. be able to.

Next, examples of the present invention will be described.
Here, as the metal material, a steel piece produced by continuously casting high carbon steel was used. The dimensions of the steel piece were 500 mm in length × 500 mm in width × 250 mm in thickness. The oxide scale layer formed on the surface of this steel piece is removed by machining in advance to obtain a material steel piece, and the exposed portion exposed on the surface of the defect existing in the material steel piece is visually confirmed. Marked.

Next, the material steel piece was set in the machine tool, and as a rotary tool, a cemented carbide (90WC-9Co) having a size of 25 mmφ × 70 mm was attached so that the rotation axis was slanted. Metal powder preheated to 500 ° C. (iron powder whose component standard is equivalent to a high carbon material) was supplied from the metal powder supply device to the marking portion where the exposed portion of the defect exists. Next, the rotary tool is lowered while rotating at 900 rpm, and the rotary tool is brought into contact with the position corresponding to the end of the marking portion where the exposed portion of the defect of the material steel piece is present. It was buried in a piece of steel. In this state, after confirming that the plastic flow of the material steel piece was started from the change in the torque of the rotary tool, the rotary tool was moved at a speed of 60 mm / min along the distribution of the exposed portion of the defect. Then, the rotary tool was moved to the end of the exposed portion of the defect and then raised.

After that, as a result of removing the steel piece and observing the surface-treated part, it was confirmed that the exposed part of the defect was closed and no new defect was exposed.

1 Material steel piece (material metal material)
2 Oxidation scale 3 Defects 3a Exposed part 4 Marking part 5 Metal powder 6 Plastic flow part 7 Nozzle 10 Rotating tool 11 Steel piece after surface treatment

Claims (12)

A rotating tool made of a material harder than the metal material is brought into contact with the exposed portion of the defect on the surface of the metal material while rotating the metal material having the exposed portion of the defect on the surface, and the frictional heat generated at that time. A state in which the contact portion of the metal material with the rotary tool is plastically flowed by the pressure and pressure, and the metal powder heated to a temperature below the transformation point is supplied to the plastic flow portion, and the rotary tool is rotated. While moving along the distribution of the exposed portion of the defect as it is, while entraining the metal powder, the moving portion of the rotating tool in the metal material is sequentially plastically flowed to close the exposed portion of the defect of the metal material. A characteristic surface treatment method for metal materials. The method for surface treating a metal material according to claim 1, wherein the metal powder is supplied in advance to a portion of the surface of the metal material where an exposed portion of a defect exists. A claim characterized in that the metal powder is supplied to a portion of the metal material that has been plastically flowed by the rotary tool, and the rotary tool is moved along the distribution of exposed portions of defects while being rotated. Item 2. The method for surface treating a metal material according to Item 1. The method for surface-treating a metal material according to any one of claims 1 to 3, wherein the rotary tool has a diameter equal to or larger than the short side dimension of the exposed portion of the defect. Prior to the surface treatment of plastically flowing the metal material by the rotary tool, the exposed portion of the defect on the surface of the metal material before the treatment is marked, and the marked portion of the metal material is plastically flowed by the rotary tool. The method for surface treating a metal material according to any one of claims 1 to 4. The metal material, continuous casting or blooming, through the forging process, the steel strip der having an oxide scale on the surface is, prior to the process of the plastic flow, to remove the oxide scale on the surface of the steel strip The method for surface-treating a metal material according to any one of claims 1 to 5, wherein defects are exposed. The process of preparing a metal material with exposed parts on the surface and
A rotating tool made of a material harder than the material metal material is brought into contact with the exposed portion of the defect on the surface of the material metal material while rotating, and the rotating tool of the material metal material is subjected to frictional heat and pressure generated at that time. The process of plastically flowing the contact part with
The process of supplying metal powder heated to a temperature below the transformation point to the plastic flow part, and
The rotary tool is moved along the distribution of the exposed portion of the defect while being rotated, and the moving portion of the rotary tool in the material metal material is sequentially plastically flowed while entraining the metal powder. And
Material A method for manufacturing a metal material, which comprises closing an exposed part of a defect by plastic flow of the metal material. In the step of supplying the metal powder heated to a temperature below the transformation point to the plastic flow portion, the metal powder is supplied in advance to the portion where the defect exposed portion on the surface of the metal material exists. The method for producing a metal material according to claim 7, wherein the method is performed by the above. In the step of supplying the metal powder heated to a temperature below the transformation point to the plastic flow portion, the metal powder is supplied to the portion of the material metal material that has been plastically flowed by the rotary tool. The method for producing a metal material according to claim 7, wherein the rotary tool is moved along the distribution of exposed portions of defects while being rotated. The method for manufacturing a metal material according to any one of claims 7 to 9, wherein the rotary tool has a diameter equal to or larger than the short side dimension of the exposed portion of the defect. Prior to the surface treatment of plastically flowing the material metal material by the rotary tool, the exposed portion of the defect on the surface of the material metal material is marked, and the marked portion of the material metal material is plastically flowed by the rotary tool. The method for producing a metal material according to any one of claims 7 to 10. The material metal material, continuous casting or blooming, through the forging process, material steel strip der having an oxide scale on the surface is, the performed prior to the step of plastically flow, oxidation of the surface of the material steel strip The method for producing a metal material according to any one of claims 7 to 11, further comprising a step of removing scale to expose defects.

Images