JPH10204561A - Conductive roll for plating, and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive roll for plating, having long and stable regrinding life, and its production. SOLUTION: An alloy powder, which has a composition consisting of, by mass, <=0.01% C, <=2% Si, 18-35% Cr, 8-15% Mo, 3-10% (Nb+Ta), <=1.0% Al, <=1.0% Ti, <=0.02% N, <=0.02% O, and the balance Ni with inevitable impurities and satisfying the relation of (Cr+Mo+Nb+Ta)<=40%, is used. This alloy powder is compacted at least into the shape of the surface of conductive roll, sintered, and subjected to working for high density, by which the porosity of the resultant sintered compact is regulated to <=0.10%. At this time, as the above compacting, sintering, and working for high density, any of hot isostatic pressing treatment (HIP treatment), (HIP treatment + forging), and constrained hot forging is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroplating roll for continuously electroplating metals and alloys such as zinc, tin and lead on the surface of a metal material such as a steel plate.

[0002]

2. Description of the Related Art As a technique for continuously plating the surface of a steel sheet, for example, as shown in FIG. 1, a plating bath vessel 1 is filled with a metal plating solution, for example, a galvanizing solution 2. Rolls 3 and 4 for transporting the steel sheet 5 are immersed in the plating solution 2. This roll 3,
The steel plate 5 is conveyed in the direction of the arrow as shown by the rotation of 4 in the direction of the arrow. When the steel sheet is transported, a zinc electrode 6 is provided in the galvanizing solution 2 so as to face the steel sheet 5 to serve as a positive electrode, and the steel sheet 5 is used as a negative electrode via the rolls 3 or 4 to energize the surface of the steel sheet 5. A technique for continuously forming a zinc film on a substrate is widely known.

[0003] The properties required of such rolls 3 and 4 (current-carrying rolls) include high corrosion resistance, low electrical resistance, abrasion resistance, abrasiveness and the like. Therefore, as the material of the energizing roll conventionally used in such an electroplating facility, depending on plating conditions such as a plating bath composition, a hydrogen index (pH), and a current density, a range from austenitic stainless steel to a Ni-based alloy is used. Various types of alloys having excellent corrosion resistance were used, and were manufactured into energized rolls by casting or forging.

[0004] By the way, it is difficult to avoid casting segregation in castings and forgings during the casting of the material. In a current-carrying roll manufactured using this material, this segregated portion causes uneven wear during use, and this is transferred to the surface of the plated steel sheet, resulting in a roughened product. In order to prevent such deterioration in the quality of the plated product, it is necessary to interrupt the plating operation, remove the energizing roll, and re-grind (refurbish) the surface of the energizing roll. For this reason, if the life between remodeling is short, productivity is remarkably impaired, and the life of the roll is also shortened.

In order to reduce the occurrence of uneven wear caused by such segregation in casting, for example, Japanese Patent Application Laid-Open No. 5-195137 discloses a method of forming and sintering a powder of a Cr—Ni base alloy into a shape of the surface of a current-carrying roll. A method for manufacturing an energizing roll is disclosed. According to this technology, the occurrence of flake wear due to casting segregation can be reduced, but since it is a two-phase alloy system containing δ ferrite, a stable long machining life cannot be obtained due to preferential corrosion of the ferrite phase. Was.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to use a sintered alloy powder product for plating having a stable and long re-polishing life. An object of the present invention is to provide an energizing roll and a manufacturing method thereof.

[0007]

Means for Solving the Problems In order to achieve the above object, a current-carrying roll for plating according to the present invention comprises (1)
C: 0.01% or less, Si: 2% or less, Cr: 18 to
35%, Mo: 8 to 15%, (Nb + Ta): 3 to 10
%, Al: 1.0% or less, Ti: 1.0% or less, N:
An alloy powder comprising 0.02% or less, O: 0.02% or less, the balance being Ni and unavoidable impurities, and satisfying the relationship of (Cr + Mo + Nb + Ta) ≦ 40% is formed and sintered into at least the shape of the surface of the current-carrying roll. , A porosity of 0.
It is characterized by being 10% or less.

The method for producing a current-carrying roll for plating according to the present invention is characterized in that (2) the alloy powder is subjected to high-temperature hydrostatic pressure treatment to form, sinter, and densify at least the shape of the surface of the current-carrying roll; The ratio is set to 0.10% or less. (3) The alloy powder is subjected to high-temperature hydrostatic pressure treatment to form and sinter at least the shape of the surface of a current-carrying roll, and then to be densified by hot forging to reduce the porosity to 0.10% or less. It is characterized by the following. Further, (4) the above alloy powder is subjected to confined hot forging after canning, thereby forming, sintering, and densifying at least the shape of the surface of the current-carrying roll to reduce the porosity to 0.10% or less. I do.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the main components of the alloy powder constituting at least the surface (part or all of the surface of the current-carrying roll, or part or all of the current-carrying roll) of the current-carrying roll for plating of the present invention, The reason for limiting the content will be described. C: 0.01% or less, N: 0.02% or less C and N tend to preferentially precipitate as carbonitrides at austenite crystal grain boundaries. Precipitates, and significantly impairs corrosion resistance. Therefore, the upper limits of the contents are set to 0.01% for C and 0.02% for N, respectively.

Si: 2% or less Si is an effective element as a deoxidizing element of the molten metal, and is effective in reducing the oxygen content of the powder and improving the fluidity of the molten metal to produce a stable powder. . However, if it is contained excessively, the nozzle is likely to be clogged when the molten metal is sprayed, and the powder shape is irregular, which hinders stable work during high-temperature hydrostatic pressure treatment (HIP treatment). Therefore, the upper limit of the Si content is set to 2%.

Cr: 18-35% Cr is a basic element mainly for improving the overall corrosion resistance of the alloy, and the lower limit of the content is set to 18% for improving the overall corrosion resistance. Is required at least 18%. If the Cr content exceeds 35%, precipitation of the σ phase becomes remarkable, so that the alloy becomes embrittled remarkably, and δ
Mo, Nb effective for pitting corrosion resistance due to appearance of ferrite
Since the addition amount of Cr cannot be secured, the upper limit of the Cr content is set to 35% to prevent this.

Mo: 8 to 15% Mo is a basic element for improving the pitting corrosion resistance of the alloy, and 8% or more is necessary to obtain the effect. However, if the content exceeds 15%, the effect of improving the pitting corrosion resistance is not further improved, so the upper limit of the content is set to 15%. (Nb + Ta): 3 to 10% Nb and Ta are elements that fix C and N and improve the overall corrosion resistance of the alloy. Therefore (Nb +
Although 3% or more is contained as Ta), (Nb + Ta)
If the content exceeds 10%, the effect is saturated and no improvement occurs, and the grindability at the time of reshaping is impaired. Therefore, the upper limit of the content is set to 10%.

Al: 1.0% or less, Ti: 1.0% or less Al and Ti are effective elements for deoxidation and denitrification of molten metal, respectively. Therefore, the upper limit of the content is 1.
0%. O: 0.02% or less O mainly exists as an oxide film on the surface of the powder, and in the alloy after sintering and solidification of the powder, this oxide is distributed in a network along the old powder grain boundaries. When used as a current-carrying roll, the periphery of the oxide is preferentially corroded, impairing the corrosion resistance of the alloy. If the O content exceeds 0.02%, the corrosion resistance of the alloy is significantly deteriorated. Therefore, the upper limit of the O content is set to 0.02%.

(Cr + Mo + Nb + Ta): 40% or less The individual effects of Cr, Mo, Nb, and Ta are as described above. However, when the value of (Cr + Mo + Nb + Ta) increases, the loss due to corrosion particularly during pulsed current application decreases. But (C
When the value of (r + Mo + Nb + Ta) exceeds 40%, a ferrite phase appears in the alloy, and this ferrite phase preferentially corrodes during use of the current-carrying roll, thereby causing skin roughness. Further, the corroded surface has a white color, and it is difficult to discriminate it from a zinc sowing accident occurring during galvanizing work, which is inconvenient in operation. Therefore, the total content of (Cr + Mo + Nb + Ta) is limited to 40% or less.

The alloy powder constituting at least the surface of the current-carrying roll for plating according to the present invention contains the above-mentioned components, and the balance consists of Ni and unavoidable impurities. The alloy powder is a spherical powder that can easily obtain a high powder packing density when canned, and has a powder particle size of 1000 μm or less and an apparent density of 4.5 g.
/ Cm ² or more and a tap filling density of 5.5 g / cm ² or more. As a result, the powder filling rate at the time of canning, which is desirable for producing a current-carrying roll for plating, is 70%.
% Or more can be secured.

The alloy powder is filled in a capsule forming at least the surface of the energizing roll for plating (part or all of the surface of the energizing roll, or part or all of the energizing roll, etc.), and degassed and sealed. The powder filling is then sintered and densified to reduce the porosity of the sintered body to 0.10% or less. Here, the porosity is an area ratio occupied by the cross section of the pores existing in the sintered body in the cross section of the sintered body. The porosity of the sintered body is reduced to 0.10% because the porosity of the sintered body is increased since the porosity remaining in the sintered body is large, and when the porosity is a high value exceeding 0.10%, the corrosion of the sintered body is accelerated.
It is necessary to:

In the method for producing a current-carrying roll for plating according to the present invention, the sintered body is densified by performing densification processing simultaneously with or after molding and sintering. The following method is preferable as a method for increasing the density. In other words, any one of hot forging after high-temperature isostatic processing (HIP processing) as the first embodiment, hot forging after high-temperature isostatic processing (HIP processing) as the second embodiment, and constrained hot forging after canning as the third embodiment. That way.

In the first embodiment, it is preferable to apply a hydrostatic pressure of 1000 kgf / cm ² or more to the powder filling at a temperature of 1000 ° C. or more by using a high-temperature isostatic press (HIP). Thereby, the alloy powder in the capsule is sintered and densified, and the porosity of the sintered body is reduced to 0.1.
0% or less. In a second embodiment, a high-temperature isostatic press (HIP) is used to apply a hydrostatic pressure of 500 kgf / cm ² or more to the powder-filled body at a temperature of 800 ° C. or more, followed by a forging process with a forging ratio of 4 or more. Is preferably added. Thereby, the alloy powder in the capsule can be sintered, and the porosity of the sintered body can be increased to 0.10% or less.

In a third embodiment, the powder filling is 9
It is preferable to heat to a temperature of 00 ° C. or higher, and to apply a forging with a forging ratio of 8 or higher to this by constrained rotary forging using a mold. Thereby, the alloy powder in the capsule is sintered and densified, and the porosity of the sintered body can be reduced to 0.10% or less. The energizing roll for plating and the method of manufacturing the same according to the present invention are characterized in that the alloy powder is formed into at least the surface shape, sintered, and densified. When molding using the above alloy powder, or the main part of the roll is composed of, for example, relatively inexpensive high-strength low-alloy steel or corrosion-resistant steel, and part or all of the outer peripheral part of the main part of the roll is formed. Also included are those produced by forming, sintering, and densifying the above alloy powder. Further, a structure in which the alloy powder is formed into a sleeve shape, sintered and densified, and then the sleeve and the main part of the roll are fitted to form a current-carrying roll is also included.

[0020]

EXAMPLE A particle size 50 having a chemical composition shown in alloys 1 to 5 in Table 1 was obtained by a gas atomization method using argon.
A spherical alloy powder of 0 μm or less was obtained. Using the alloy powder, high-density processing was performed by HIP, HIP + forging, and forging.

[0021]

[Table 1]

(High Density by HIP) A cylindrical roll base made of SUS304 is concentrically disposed at the center of a hollow cylindrical capsule made of mild steel, and the hollow cylindrical capsule made of mild steel and the cylindrical roll base are formed. An annular space formed between the alloy powders is filled with the alloy powder, gas components present in the gaps between the alloy powders are removed, and then sealed to form a powder filler. 1 by hydrostatic press
5 hours of H under the conditions of 200 ° C. and 1000 kgf / cm ²
IP processing was performed to form, sinter, and increase the density of the roll. (High Density by HIP + Forging) The powder filling body manufactured in the same manner as in the case of the high density by HIP is subjected to HIP treatment at 800 ° C. and 500 kgf / cm ² for 5 hours by hot isostatic pressing to be rolled. After being formed and sintered into a shape, it was further heated to 1100 ° C. and forged by a hot press at a forging ratio of 4 to increase the density. (High Density by Forging) A powder filling manufactured in the same manner as in the case of high density by HIP is heated to 900 ° C., and the powder filling is subjected to a forging ratio of 8 by a constrained rotary forging method using a tapered anvil. Densification was achieved by adding forging.

The test material manufactured as described above is subjected to finish processing, and the outer diameter of the roll body is 360 mm and the length is 1700.
mm test rolls were manufactured and subjected to actual machine tests in an electrogalvanizing line. The actual machine test was performed continuously for 150 hours, and the state of corrosion of the roll body was observed. For some of the test rolls, the amount of wear of the roll per 10,000 t of the plating treatment of the steel sheet, the roll surface roughness at the time of rework, and the amount of rework per one run were measured.

Further, a test piece was taken from a position corresponding to the surface of the roll body, the state of carbonitride precipitation was observed, and the porosity was measured. The porosity was measured at a magnification of 400 times with a real
This was performed for 0 mm ² . For comparison, Table 6 shows alloys 6-
Test rolls (comparative examples 1 to 13) were prepared in the same manner as in the example of the present invention for an alloy powder having a chemical composition shown as No. 13.
8) was manufactured and tested. For Comparative Examples 1 to 8, densification by HIP was performed as densification processing.

The other manufacturing conditions were the same as those of the embodiment. The test roll (Comparative Example 9) made of Alloy 2 with only the HIP processing temperature in the method of densification by HIP at 750 ° C. and the pressure alone were 450 kgf / cm
Test rolls made of alloy 3 as ² (Comparative Example 1
0), the porosity is out of the range of the invention.
The test was also performed on a casting roll made of Alloy 14 and a forging roll made of Alloy 15.

Table 2 shows the results of the above tests.

[0027]

[Table 2]

As can be seen from Table 2, in the embodiment of the present invention, no remarkable corrosion marks such as avatar-like corrosion and pit-like corrosion are generated even after the actual test for 150 hours, and harmful corrosion products are not produced. No surface adhesion was observed and a good surface condition was exhibited. In the example, a casting roll (Comparative Example 11) was used.
And a smaller amount of wear than the forged roll (Comparative Example 12), indicating excellent wear resistance. In the examples, a casting roll (Comparative Example 11) and a forging roll (Comparative Example 12) were used.
As compared with the above, since the erosion mark of the avatar-like or pit-like locally deep corrosion is hard to occur, the surface roughness Rmax at the time of remodeling is small,
Therefore, the amount of modification to be deleted in one modification is small.

[0029]

As described above, the current-carrying roll for plating according to the present invention is unlikely to produce locally deep corrosion marks such as avatar-like corrosion and pit-like corrosion on the roll surface during use. It requires a small amount and has excellent wear resistance, so it has a long and stable remodeling life. Furthermore, since there is no adhesion of harmful corrosion products, it is possible to provide a current-carrying roll for plating that is easy to operate and economical, for example, it is easy to discriminate it from a zinc dusting accident. Further, the method for producing a current-carrying roll for plating according to the present invention provides a method for producing a current-carrying roll for plating having the above-described excellent characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a roll apparatus for electroplating.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plating bath container 2 Galvanizing solution 3 Roll (Electric roll) 4 Roll (Electric roll) 5 Steel plate 6 Zinc electrode

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tatsuya Tomioka 2-7 Meitoku-cho, Nakagawa-ku, Nagoya City, Aichi Prefecture (72) Inventor Tateo Hisada 2-34 Karasaki-cho, Tokoname City, Aichi Prefecture

Claims (4)

[Claims] 1. Mass%, C: 0.01% or less, Si: 2% or less, Cr: 18 to 35%, Mo: 8 to 15%, (Nb + Ta): 3 to 10%, Al: 1. 0% or less, Ti: 1.0% or less, N: 0.02% or less, O: 0.02% or less, the balance consisting of Ni and unavoidable impurities, and satisfies the relationship of (Cr + Mo + Nb + Ta) ≦ 40%. The alloy powder is formed, sintered, and densified to at least the shape of the surface of the current-carrying roll to reduce the porosity to 0.
A current-carrying roll for plating, characterized in that the content is 10% or less. 2. A plating method comprising subjecting the alloy powder to high-temperature hydrostatic pressure treatment to form, sinter, and increase the density of at least the surface of a current-carrying roll to reduce the porosity to 0.10% or less. Manufacturing method of energizing roll for use. 3. The alloy powder is subjected to high-temperature hydrostatic pressure treatment to form and sinter at least the shape of the surface of a current-carrying roll, and then to high-density by hot forging to reduce the porosity to 0.10% or less. A method for producing a current-carrying roll for plating, characterized in that: 4. A porosity of at least 0.10% by forming, sintering, and densifying at least the shape of a current-carrying roll by constraining hot forging after canning of the alloy powder. Method for producing a conductive roll for plating.