JPH05195137A - Production of electric conductive roll - Google Patents

Abstract

PURPOSE:To produce an electric conductive roll for galvanizing, etc., excellent in corrosion and wear resistances. CONSTITUTION:Cr-Ni alloy powder consisting of, by weight, 40.0-50.0% Cr, 0.1-10.0%, in total, of one or more among Nb, Ta, V, Ti and Al, <=10.0% Mo, <=2.0% Si, <=2.0 Mn, <=2.0% Fe, <=0.2% C and the balance Ni with impurities is compacted into the shape of at least the surface of an electric conductive roll and the resulting compact is sintered to produce an electric conductive roll.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energizing roll used as an energizing roll for electrogalvanizing equipment, and particularly for producing an energizing roll for electrogalvanizing which is excellent in corrosion resistance. The present invention relates to a manufacturing method of.

[0002]

2. Description of the Related Art Electrogalvanized steel sheets have advantages such as better workability, less plating amount, and smoother surface than hot-dip galvanized steel sheets. It is used in a wide range of applications such as equipment, steel furniture, kitchen appliances, and building materials.

Such an electrogalvanized steel sheet is a cold-rolled steel sheet or a hot-rolled steel sheet used as an original plate to clean and activate its surface by degreasing and pickling, and then the original plate in a plating bath containing zinc ions. Manufactured by electroplating zinc with the cathode used as a cathode.

Conventionally, the material of the current-carrying roll used in the electrogalvanizing equipment having such an electroplating process is austenite depending on the plating conditions such as plating bath solution composition, hydrogen index (pH) and current density. Various materials having excellent corrosion resistance have been used, including system stainless steel (SUS 316 and the like) to Ni-based alloys.

[0005]

However, all of the conventional energizing roll materials for electrogalvanizing have a Vickers hardness (Hv) of less than 250, which causes a problem in corrosion resistance.

[0006] For example, in the current-carrying roll made of SUS316 as described above, the surface of the current-carrying roll is scratched by corrosion due to the plating bath solution and wear caused by contact with the steel strip after being used for about 7 days under a certain plating condition. There is a problem in that it is likely to occur, which causes transfer to the surface of the steel strip and causes a flaw, which impairs the quality of the product.

Therefore, it has been necessary to re-polish the surface of the energizing roll within a short period of time so as not to impair the quality of the product. Further, in the case of the current-carrying roll made of a Ni-based alloy as well, the re-polishing of the roll is required for about 20 days, so that the electrogalvanizing work is interrupted.

Therefore, it has been desired to further improve the material of the current-carrying roll in order to improve the operating rate of the electrogalvanizing equipment and reduce the maintenance load of the roll.

[0009] Therefore, as a result of further investigation and research for the purpose of further improving the material of the energizing roll used in the electrogalvanizing equipment, as a result, it is possible to easily obtain a high hardness by the age hardening treatment and to withstand the energization resistance. N with excellent corrosivity
The inventors have found an i-Cr-based alloy and have developed a technique for producing an energizing roll for electrogalvanizing or the like by casting or forging using such a Ni-Cr-based alloy. Since a Cr-based alloy has a large Cr content, it may cause segregation of Cr during casting, and such segregation may cause pitting corrosion, resulting in a decrease in corrosion wear resistance. Therefore, there is a problem to solve such a problem.

[0010]

A method of manufacturing a current-carrying roll for electrogalvanizing or the like according to the present invention is Cr: 40.0.
˜50.0% by weight, total of one kind or two or more kinds selected from Nb, Ta, V, Ti and Al: 0.1 to 1
0.0 wt%, Mo: 10.0 wt% or less, Si: 2.
0% by weight or less, Mn: 2.0% by weight or less, Fe: 2.0
Wt% or less, C: 0.2 wt% or less, the powder of the Cr-Ni-based alloy consisting of the balance Ni and impurities at least on the surface of the energizing roll (a part or all of the surface of the energizing roll, or a part or the whole of the energizing roll, etc.). ) Shape
The present invention is characterized in that it is configured to sinter, and the configuration of the invention relating to the method for manufacturing the current-carrying roll is a means for solving the above-mentioned conventional problems.

Next, the main components of the alloy powder constituting at least the surface (a part or all of the surface, a part or all of the roll, etc.) of the current-carrying roll manufactured by the present invention and the ratio of the components will be described in detail below. To do.

Nb, Ta, V, Ti, Al: The alloy powder used in the method for producing the current-carrying roll according to the present invention is
Due to the high Cr content, nitrogen is likely to be picked up during melting in the air or during powder production. As a result, corrosion resistance may be deteriorated, so denitrification and nitrogen fixation are necessary. For this purpose, the N content in the impurities is more preferably 0.2% by weight or less and , Nb, Ta,
One kind or two or more kinds selected from V, Ti and Al are to be contained in a total amount of 0.1% by weight or more. However, if the content of these exceeds 10.0% by weight, the effect is saturated, so the content was made 10.0% by weight or less.

Mo: Mo is an element effective for improving the resistance to galvanic corrosion against galvanic bath, so an appropriate amount is added. In this case, even if the content exceeds 10.0% by weight, the effect is not so much improved, and since it is an expensive element, the cost is rather increased. Therefore, the content is set to 10.0% by weight or less.

Si, Mn, Fe: Si, Mn, and Fe are not elements that are positively added, but if the content of each is 2.0 wt% or less, the characteristics of the current-carrying roll are not significantly impaired. Each of them may be contained up to 2.0% by weight.

C: C is not an element that is positively added, but the hardness increases as the C content increases. But,
Since the electrical corrosion resistance to the plating bath solution deteriorates, it is desirable to suppress the content thereof, and the content may be up to 0.2% by weight or less.

Cr, Ni: Cr and Ni are elements which form an age-hardenable austenite + ferrite matrix, and therefore Cr: 40.0-5.
A combination of 0.0 wt% and Ni: 40.0 to 50.0 wt% is preferable, but in consideration of mixing of impurities, Cr: 40.0 to 50.0 wt%, balance: : Ni and impurities. And, more desirably, Cr + N
i: 85 to 98% by weight is preferable. Also, Cr, N
At the same time, i is an element that improves resistance to galvanic corrosion with respect to the plating bath solution, and Cr and Ni were used as the basic elements of the alloy powder in order to obtain such characteristics.

Then, an alloy powder for producing a current-carrying roll is produced by performing gas atomization using, for example, an inert gas on the molten alloy having the above chemical composition. At this time, the grain size of the alloy powder is fine. If it is too large, impurities such as oxygen and nitrogen are easily mixed in, and the corrosion wear resistance is reduced. Therefore, it is better to set it to 45 μm or more, but the particle size becomes coarse. If it is too much, component segregation is likely to occur, causing pitting corrosion to occur, so it is more desirable to set it to 350 μm or less.

The method of manufacturing the energizing roll according to the present invention is
It is characterized in that the powder of the above Cr-Ni based alloy is molded and sintered into at least the shape of its surface, and a part or the whole of the width of the current-carrying roll is molded using the above alloy powder. In the case of sintering, the main part of the roll is made of, for example, relatively inexpensive high-strength low-alloy steel or heat-resistant steel, and the alloy powder is placed on part or all of the outer peripheral part of the main part of the roll. A structure manufactured by molding and sintering is also included, and further, after the alloy powder is molded and sintered into a sleeve shape, the sleeve and the main part of the roll are fitted to each other to form a current-carrying roll. Some include

[0019]

EXAMPLE A cylindrical roll base made of JIS SUS304 is concentrically arranged in the center of a cylindrical capsule made of JIS S45C, and then an annular space formed between the cylindrical capsule and the cylindrical roll base. Is filled with alloy powder having a particle size of 150 μm or less produced by gas atomization and having chemical components shown in symbols A to E of Table 1, and degassed to remove gas components present in the gaps of the alloy powder. After that, the holes were sealed, hot isostatic pressing (HIP) treatment of 1150 ° C × 5Hr was performed to form and sinter into a roll shape, and then rough processing was performed, then 800 ° C × 3hr. After subjecting to age hardening treatment and finishing, it was subjected to an actual machine test in an electrogalvanizing line. The surface hardness (Vickers hardness) of each of the rolls A to E was examined before starting the actual machine test. The results are also shown in Table 1.

For comparison, the electric current rolls cast and molded with the chemical components indicated by the symbols F to H in Table 1 were examined for surface hardness and subjected to actual machine tests.

The actual machine test was continuously performed for 10 days, and the maximum amount of corrosive wear in the central portion of the roll after the actual machine test was examined.

[0022]

[Table 1]

As shown in Table 1, each of the current-carrying rolls A to D made by powder metallurgy of the present invention has a surface hardness higher than that of the current-carrying rolls F, G, H made of the Ni-based alloy or stainless steel of the comparative examples. It is clear that it is large, the amount of corrosive wear is small, and it has excellent resistance to corrosive wear.

Further, the current-carrying roll E made of powder metallurgy of the comparative example also has a large surface hardness, a small amount of corrosive wear and excellent resistance to corrosive wear. Corrosion wear resistance is not improved compared to C, and it only increases the cost, so M
It is clear that the o content need not be unnecessarily increased.

[0025]

As described above, according to the method for producing a current-carrying roll of the present invention, Cr: 40 ° to 50.0% by weight, one selected from Nb, Ta, V, Ti and Al, or Total of two or more kinds: 0.1 to 10.0% by weight,
Mo: 10.0% by weight or less, Si: 2.0% by weight or less,
Mn: 2.0 wt% or less, Fe: 2.0 wt% or less,
C: 0.2% by weight or less, Cr-Ni based alloy powder consisting of balance Ni and impurities is formed and sintered into at least the shape of the surface of the current-carrying roll, so corrosion resistance against plating bath liquid The resistance is remarkably excellent, and since segregation does not occur as compared with the energizing roll manufactured by the casting method, the corrosion wear resistance is further improved. Therefore, since it is possible to reduce the frequency of exchanging the energizing rolls, it is possible to improve the operating rate of the plating equipment and also reduce the maintenance load of the energizing rolls. By forming only the surface of the roll from the molded / sintered body of the above-mentioned alloy powder, the cost can be reduced and a remarkably excellent effect is brought about.

Claims (3)

[Claims] 1. Cr: 40.0-50.0% by weight, Nb,
1 or 2 selected from Ta, V, Ti and Al
Total of seeds or more: 0.1 to 10.0% by weight, Mo: 10.
0 wt% or less, Si: 2.0 wt% or less, Mn: 2.0 wt% or less, Fe: 2.0 wt% or less, C: 0.2 wt%
Hereinafter, a method for producing a current-carrying roll, characterized by molding and sintering powder of a Cr-Ni-based alloy consisting of balance Ni and impurities into at least the shape of the surface of the current-carrying roll. 2. The grain size of the powder of Cr-Ni based alloy is 350.
The method for producing a current-carrying roll according to claim 1, having a thickness of not more than μm. 3. The method for producing an energizing roll according to claim 1, wherein the N content in the impurities is 0.2% by weight or less.