JP2003112217A - Method for removing oxidized film on surface of metallic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a removing method of an oxidized film on the surface of a metallic material by which the oxidized film which is generated on the surface of the metallic material at heat treatment which is performed as the pretreatment of various metallic materials is removed efficiently and surely in the rolling or the wiredrawing stage of the various metallic materials. SOLUTION: This method is a removing method of the oxidized film on the surface of the metallic material in which, by blasting metallic particles of only polygonal particles or the polygonal particles and approximately spherical particles which are mixed at a proper mixing ratio to the surface of the metallic material of a stainless steel sheet, an electrical steel sheet, a steel bar or a wire rod, the oxidized film on the surface of the metallic material is removed.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is capable of efficiently and reliably removing an oxide film formed on the surface of a metal material during a heat treatment carried out as a pretreatment for various metal materials in a rolling or drawing process of various metal materials. The present invention relates to a method for removing an oxide film on the surface of a metal material. In addition, in this specification, the term "rolling" includes "pulling" in a steel bar or a wire rod.

[0002]

2. Description of the Related Art Generally, a metal product such as a metal plate, bar or wire is hot-rolled after a cast slab is heat-treated in a heating furnace, and the hot-rolled material is further annealed in an annealing furnace. After being heat-treated, it is further cold-rolled to obtain a desired metal material product. By the way, an oxide film (so-called scale) is generated on the surface of each metal material during heat treatment in the heating furnace or the annealing furnace, and if hot rolling or cold rolling is performed as it is, it is caused by the presence of foreign matter called an oxide film. As a result, the surface of the metal material is scratched during the rolling, resulting in defective products. Therefore, in the manufacturing process of the metal material product,
Efficient and reliable removal of the oxide film on the surface of the metal material is the most important for managing the production yield of the final metal material product.

Conventionally, as a method for removing this oxide film, a slight amount of mechanical deformation is given by pulling the steel product having the oxide film while applying a little twist, for example, by varying the degree of plastic deformation of each part of the steel product. A method of peeling and removing the oxide film, a method of forcibly peeling and removing the oxide film by rubbing the steel surface with a brush, a method of washing the steel surface with an acidic liquid and chemically peeling and removing the oxide film, and further above. There was a method of combining ~.

[0004]

In the above-mentioned conventional methods (1) to (5), the removal of the oxide film on the surface of the steel material is actually insufficient in terms of both efficiency and degree of removal and cannot be reliably removed. The defect rate at which the steel material was scratched during the hot or cold rolling process was high. Further, if the defect occurrence rate is high, there is a problem that the labor of the inspecting person for inspecting this becomes great. In order to solve these problems, it is necessary to reduce the line speed in the above oxide film removal process and perform sufficient peeling removal work to reduce the defect occurrence rate, but then the line speed of the entire process will decrease in this part. There was a problem that it would end up.

Further, whenever the composition ratio of the steel product changes, the properties and shape of the oxide film also change greatly,
Since the removal rate of the surface oxide film also fluctuates greatly, there is a problem that special management is required to cope with these fluctuations.

[0006] The polygonal particles do not have the completely same shape but have irregular shapes such as sand and stone. The spherical particles are not limited to perfect spheres, but may be egg-shaped, somewhat elliptical spheres or ellipsoidal spheres.

[0007]

The present invention provides a method for removing an oxide film on a surface of a metal material, wherein the metal material is any of a stainless steel plate, an electromagnetic steel plate, a steel bar or a wire rod, and Then, the oxide film on the surface of the metal material is removed by spraying only polygonal particles or metal particles in which polygonal particles and substantially spherical particles are mixed at an appropriate mixing ratio.

Thus, by spraying only the polygonal particles or the mixed metal particles of the polygonal particles and the substantially spherical particles, the line speed is increased while the surface roughness of the metal material such as the stainless steel plate is almost the same. The processing efficiency of the process can be improved.

[0009] Preferably, the step of spraying the particles is
It is performed before the cold rolling process or the hot rolling process of the stainless steel plate. This prevents the surface of the metal material from being scratched by the presence of the oxide film in the rolling process (including the rod and wire drawing process).

Preferably, the appropriate mixing ratio of the polygonal particles and the spherical particles is such that the polygonal particles are about 30% by weight or more of the whole mixed metal particles. As a result, the presence of the polygonal particles can improve the removal efficiency of the oxide film and increase the line speed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, a stainless steel plate slab 1A, which is one of the steel materials after casting, is first sent to a heating furnace 2 and subjected to heat treatment. The particles 4 are sprayed, and the oxide film (also referred to as scale) 5 formed on the surface of the particles by the heat treatment in the heating furnace 2 is removed. Next, this stainless steel plate 1B is hot-rolled by hot rolling rolls 6 to become hot-rolled stainless steel plate 1C, which is sent to an annealing furnace 7 and subjected to annealing heat treatment.
Subsequently, the stainless steel plate 1C is sprayed with the metal particles 4 by the injector 3B as in the oxide film removing treatment, and the oxide film 5 formed on the surface thereof is removed by the annealing heat treatment in the annealing furnace 7. Further, cold rolling is performed by the cold rolling roll 8. The cold-rolled stainless steel plate 1D is heat-treated and annealed again in the annealing furnace 9, and then pickled by the pickling device 10 to remove the oxide film 5 regenerated on the surface thereof by the annealing heat treatment in the annealing furnace 9. The final stainless steel plate 1E is completed.

In FIG. 1, the first oxide film removal treatment immediately after the stainless steel plate 1A leaves the heating furnace 2 may not be performed in some cases, and the stainless steel plate 1C leaving the first annealing furnace 7 is Although only the oxide film removal treatment by the injector 3B is performed, mechanical deformation treatment, brush rubbing treatment, or the like may be performed in combination, and similarly, the final annealing furnace 9 is used.
The stainless steel plate 1D that has been exposed is only pickled, but of course it may be further subjected to an oxide film removal treatment, a mechanical deformation treatment, a brush rubbing treatment, and the like. Further, the stainless steel plate 1C exiting the injector 3B may be directly shipped as a product of the hot rolled steel plate 1C without being sent to the cold rolling roll 8.

In the above oxide film removal treatment, the injector 3
The metal particles 4 are sprayed by A and 3B and sprayed on the heat-treated stainless steel plate 1B and the annealed stainless steel plate 1C to remove the oxide film 5 on the surfaces of these steel plates 1B and 1C. According to this, the removal rate of the oxide film 5 can be improved as compared with the conventional method of applying mechanical deformation, rubbing with a brush or the like, or washing with an acidic liquid.

In the present invention, the stainless steel plate 1 (1
A ... 1E) is not limited to this, and may be an electromagnetic steel plate, a steel bar, or a wire rod. As the shape of the metal particles 4, only the polygonal particles or a mixture of the polygonal particles and the substantially spherical particles in an appropriate ratio is used and sprayed. The proper mixing ratio is such that, in the polygonal particles and the spherical particles, the polygonal particles are about 30% by weight or more of the whole mixed metal particles. The polygonal particles and the spherical particles have outer diameters of approximately 0.
It is 2 mm to 0.7 mm. The hardness of the polygonal particles and the spherical particles is 400 to 500 Hv.

[0015]

Example 1 In Example 1 (Table 1 and FIG. 2), first, as shown in Table 1, polygonal particles and spherical particles (particle size: 0. 4 mm,
Desirably 0.2 to 0.7 mm, particle hardness 450H
v, preferably about 400 to 500 Hv), the mixing ratio of the metal particles is changed within the range of 0 to 100% (five kinds of experimental examples ae), and the particle spraying density (kg / m). ² ) The oxide film removal rate (%) was investigated for the case where particles were sprayed while appropriately changing. The results are shown in Table 1 and FIG. The composition of the spherical and polygonal particles is based on iron and has at least C 0.1.
~ 1.2%, Si 0.1-1.2%, Mn 0.1-
1.2%, and this composition is the same in the following examples.

[0016]

[Table 1]

According to Table 1 and FIG. 2, among the metal particles,
It can be seen that the surface oxide film removal rate improves as the particle spraying density increases and the polygonal particle mixing ratio increases. That is, the polygonal particles have a higher oxide film removal performance than the spherical particles. Also, the oxide film removal performance is
It can be seen that when the total amount is only polygonal particles (experiment e), the improvement is about twice as much as when only spherical particles are used.

[0018]

Example 2 In Example 2 (Tables 2 to 4), a mixture of polygonal particles and spherical particles having different mixing ratios was sprayed onto the surface of the stainless steel plate 1 to form a steel plate. 1
Changes in surface roughness and line speed were tested.

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

In particular, Table 2 shows the distribution ratio (%) of both particles corresponding to the change in the particle size of polygonal particles and spherical particles sprayed on a stainless steel plate (hereinafter,% is% based on weight). Show). In Table 2, "sieving size" means
It is a mesh size of a standard sieve for distributing particles. For example, in the mesh size of 355 to 425 μm, it means that 35.6% of polygonal particles as a whole have passed through the sieve. "Means approximately the particle size. According to this, it can be seen that the particle size is distributed in the range of 0.1 to 0.6 mm, but is centered at about 0.3 to 0.5 mm.

Table 3 shows the obtained surface roughness (μm) of the stainless steel plate corresponding to five kinds of changes in the mixing ratio of polygonal particles and spherical particles (experiments ae). In the table, Ra is the arithmetic surface roughness (Ra = 1 / L · ∫ | f (x)
| Dx; where L is the length of the measured surface and the integral is from 0 to L)), and Ry is the maximum height between the maximum roughness point and the minimum roughness point of the surface, Rz Is the average roughness of 10 points in total, 5 points from the maximum value and 5 points from the minimum value.

From Table 3, it was found that as the proportion of polygonal particles increases, the surface roughness of the stainless steel plate is almost the same as when the proportion of polygonal particles is zero. Therefore, in the present invention, under the condition that the surface roughness of the stainless steel plate can be maintained below a predetermined value, mixed metal particles obtained by mixing polygonal particles with spherical particles or particles having only polygonal metal particles are used as the surface of the stainless steel plate. It has been found that it is possible to improve the removal rate of the oxide film, in other words, to increase the line speed, by spraying on.

Further, Table 4 shows the surface treatment line speed (m / mi) of the stainless steel plate 1 corresponding to five kinds of changes in the mixing ratio of polygonal particles and spherical particles (experiments ae).
n), surface roughness (μm) and oxide film removal rate (%), and for comparison, a conventional method (providing mechanical deformation)
Similar results with or and (rubbing in addition to mechanical deformation). In Table 4, Ra (μm) is the same as that shown in Table 3, and Rmax (μm) is the same as Ry (μm) in Table 3. These symbols also apply to Tables 5 and 6 below.

According to Table 4, the line speed (m / mi
It can be seen that n) is improved as the mixing ratio of the polygonal particles is increased, and during this time, the surface roughness Ra is 3.7 to 4.3 (μm) and R is the same as in the case of Table 3.
The max is in the range of 45 to 46 (μm) and is almost the same. That is, when the mixing ratio of the polygonal particles is 30%, the line speed is 1.2 times or more compared to when the mixing ratio of the polygonal particles is zero, and similarly, the mixing ratio of the polygonal particles is 50%. , 70% and 100%, the line speed is improved to 1.4 times or more, 1.6 times or more, and about 2 times, respectively. During this period, the surface oxide film removal rate increased to 100 even though the line speed was increased.
% Can be maintained. Therefore, in order to obtain the maximum line speed, it suffices to adopt the spraying of only polygonal particles,
Further, if it is desired to suppress the surface roughness of the stainless steel plate as much as possible, the mixing ratio of polygonal particles in the mixed particles may be reduced although the line speed is slightly decreased. It is judged that a mixing ratio of the polygonal particles of 30% or more is practical.

Further, the conventional method shown in Table 4, that is, the method in which the spraying of particles is not adopted (the method of giving mechanical deformation), or (the method of rubbing with a brush in addition to mechanical deformation)
According to the combined use method, if the line speed is forcibly increased, the surface roughness is almost the same, but the surface oxide film removal rate decreases, that is, the oxide film remains on the stainless steel plate surface. I understand.

[0028]

Example 3 In Example 3 (Table 5), oxidation was performed in each of three types of experiments a, b, and c in which the mixing ratio of polygonal particles and spherical particles was changed with respect to the surface of the electromagnetic steel sheet. Sufficient line speed (m to achieve 100% film removal rate)
/ Min) (that is, if the line speed is smaller than this, an oxide film removal rate of 100% can be achieved) and the surface roughness Ra (μm) and Rmax (μm) at that time are investigated. Further, for comparison, similar results are shown by the conventional method and the combination thereof (mechanical deformation and rubbing with a brush).

[0029]

[Table 5]

According to Table 5, the maximum line speed that can achieve the oxide film removal rate of 100% is improved as the mixing ratio of polygonal particles is increased, and that the ratio of polygonal particles is increased and the line speed is increased. It can be seen that the surface roughness is almost the same even when is increased. That is, when the mixing ratio of polygonal particles becomes 50%, the line speed becomes 4
It can be increased to 0 (m / min). On the other hand, in the above-mentioned conventional method and the combined method (rubbing with a brush in addition to mechanical deformation), if the line speed is gradually increased at the same level as in Experimental Examples a, b, and c, the oxide film removal rate will decrease. I understand.

[0031]

Example 4 In Example 4 (Table 6), the wire rod was used in each of three experiments a, d, and e in which the mixing ratio of polygonal particles and spherical particles was changed with respect to the surface of the metal wire rod. Line speed of surface treatment of 80, 100, and 120
The surface roughness (μm) and the oxide film removal rate (%) in the case of changing to three types (m / min) (however, in the case of only the experimental example a, only 80 (m / min) this time), For comparison, similar results are shown with the conventional method (providing mechanical deformation) or and in combination (mechanical deformation plus rubbing with a brush).

[0032]

[Table 6]

According to Table 6, under the condition that the mixing ratio of polygonal particles and spherical particles is constant, even if the line speed is increased, the surface roughness and the oxide film removal rate are almost the same, so a large line speed is set. It turns out that it can be adopted. Even if the mixing ratio of polygonal particles is increased, the surface roughness is almost the same, so the mixing ratio of polygonal particles is 100%.
It can be seen that the oxide film removal rate can be 100%. On the other hand, in the conventional method, the line speed is the experimental example a,
When substantially equal to d and e, the oxide film removal rate is generally lower than that of the examples of the present invention, and the oxide film removal rate is improved as the line speed is slower. Rubbing with a brush in addition to mechanical deformation)
It can be seen that the oxide film removal rate is better than that of the conventional method (only by applying mechanical deformation).

[0034]

According to the present invention, by using only polygonal particles or metal particles obtained by mixing polygonal particles and substantially spherical particles in an appropriate mixing ratio, a stainless steel plate, an electromagnetic steel plate, a steel bar or a wire rod is prepared. By performing the oxide film removal treatment, the line speed can be increased and the treatment efficiency of the process can be improved while the surface roughness of the metal material such as the stainless steel plate remains substantially the same.

Since the oxide film removal treatment is performed before the hot or cold rolling process, the presence of the oxide film in the rolling process (including the rod and wire drawing process) may damage the surface of the metal material. There is no such thing.

The polygonal particles are about 3% of the total of the mixed metal particles.
Since it is 0% by weight or more, the presence of polygonal particles causes
It is possible to improve the removal efficiency of the oxide film and increase the line speed.

[Brief description of drawings]

FIG. 1 is a process schematic diagram illustrating one embodiment of a method for removing an oxide film on a steel surface according to the present invention.

FIG. 2 is a diagram showing a relationship between a spray density and a surface oxide film removal rate when metal particles are sprayed on a stainless steel plate in the process of FIG.

[Explanation of symbols]

1A, 1B, 1C, 1D, 1E ... Stainless steel plate 2 ... Heating furnace 3A, 3B ... Injector 4 ... Metal particles 5 ... oxide film 6 ... Cold rolling roll 7, 9 ... Annealing furnace 8 ... Hot rolling roll 10 ... Pickling equipment

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masaaki Kato             4 of 412 Nunowari, Minami-Shibata Town, Tokai City, Aichi Prefecture               IKK Shot Co., Ltd.

Claims (3)

[Claims] 1. A method for removing an oxide film on a surface of a metal material, wherein the metal material is any one of a stainless steel plate, an electromagnetic steel plate, a steel bar or a wire rod, and only polygonal particles are formed on the surface of the metal material, or A method for removing an oxide film on a surface of a metal material, comprising: spraying metal particles obtained by mixing polygonal particles and substantially spherical particles at an appropriate mixing ratio to remove the oxide film on the surface of the metal material. 2. The method according to claim 1, wherein the step of spraying the particles is performed before the cold rolling step or the hot rolling step of the stainless steel plate. 3. The method according to claim 1 or 2, wherein when the polygonal particles and the substantially spherical particles are mixed, the proper mixing ratio is about 30 when the polygonal particles are mixed with the entire mixed metal particles.
The above method, which is at least wt%.