JPH0681073A - Conductive roll alloy for electroplating - Google Patents

Abstract

PURPOSE:To obtain an allay capable of obtaining high hardness and excellent in corrosion and wear resistances as well by incorporating specified amounts of Nb, Ta, V or the like as well as Mo into an Ni-Cr allay having a matrix mixed with austenite and ferrite. CONSTITUTION:This conductive roll alloy for electroplating has a compsn. of, by weight, 40.0 to 50.0% Ni, 40.0 to 50.0% Cr, <=10. 0% Mo, each 2.0% Si, Mn and Fe, <=0.2% C and 0.1 to 3.0% of one or more kinds among Nb, Ta, V, Ti and Al with inevitable impurities such as N. Preferably, the content of NifCr is regulated to 85 to 98%. Furthermore, for preventing the formation of CrN compounds drastically deteriorating its toughness and ductility, the content of N is regulated to <=2 and >=0.1% of one or more kinds among Nb, Ta, V, Ti and Al are incorporated therein, but, in the case, their content is >3.0%, its touoghness and ductility as well as workability deteriorate. Mo improves its conducting corrosion resistance, because the improving effect therewith is not so shown and it rises the cost in the case of >l0.0%, it is regulated to <=10.0%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a galvanizing roll alloy for electroplating, which is used as a galvanizing roll for electrogalvanizing equipment and is particularly excellent in corrosion resistance.

[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 electrogalvanized steel sheet is prepared by degreasing and pickling the surface of the cold-rolled steel sheet or hot-rolled steel sheet to clean and activate it, and then in a plating bath containing zinc ions. Is 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 the composition of the plating bath solution, the hydrogen index (pH) and the 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 is problematic in corrosion resistance.

[0006] For example, in the current-carrying roll made of SUS316 as described above, the surface of the current-carrying roll has a flaw due to corrosion due to the plating bath solution and wear due to contact with the steel strip after being used for about 7 days under certain plating conditions. There is a problem in that it tends 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, and 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.

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, a high hardness can be easily obtained by the age hardening treatment and the energization resistance can be improved. N with excellent corrosivity
They have found an i-Cr base alloy and have developed a current-carrying roll alloy for electroplating comprising such a Ni-Cr base alloy.

[0010]

The current-carrying roll alloy for electroplating according to the present invention is a Ni alloy having a matrix of austenite and ferrite mixed with age hardening.
A total of 0.1 to 3.0 of one or more selected from Nb, Ta, V, Ti, and Al in a Cr-based alloy.
It is characterized by having an alloy composition of a basic component containing 1% by weight of Mo and 10.0% by weight or less of Mo, and containing other elements and impurities within a range that does not significantly impair the characteristics thereof. Considering that there is also a possibility that the current-carrying roll alloy for electroplating according to the present invention, Ni: 40.0-50.0 wt%, Cr: 40.
0-50.0% by weight, Mo: 10.0% by weight or less, S
i: 2.0 wt% or less, Mn: 2.0 wt% or less, F
e: 2.0 wt% or less, C: 0.2 wt% or less, and a total of one or more selected from Nb, Ta, V, Ti, and Al: 0.1 to 3.0 wt. % Alloy composition and containing unavoidable impurities such as N. More preferably, Ni + Cr is 85
It is characterized in that it is made to be 98% by weight.

The alloy composition of the electroplating roll alloy for electroplating according to the present invention will be described in detail below.

Nb, Ta, V, Ti, Al: Since the current-carrying roll alloy according to the present invention has a high Cr content, nitrogen (N) pickup is likely to occur during melting in the air. As a result, when a CrN compound is produced, it segregates at the grain boundaries and significantly reduces the toughness and ductility of the alloy. Therefore, it is necessary to denitrify and fix nitrogen so that the above CrN compound is not generated. For this purpose, the content of N, which is an unavoidable impurity, is more preferably 0.2% by weight or less and , Nb, Ta, V, Ti, and Al, and one or more selected from the total of 0.1 wt% or more. However, if the content of these is too large, the toughness and ductility of the alloy and the workability are deteriorated, so the content was made 3.0 wt% or less.

Mo: Mo is an element effective for improving the electrical corrosion resistance of the Ni-Cr based alloy to the plating bath solution, and is therefore added in an appropriate amount. In this case, even if it exceeds 10.0% by weight, the effect is not so much improved, and since it is an expensive element, the cost is rather increased.
It was made less than or equal to weight%.

Si, Mn, Fe: Si, Mn, and Fe are not elements that are positively added, but Si is effective as a deoxidizing agent, and Mn is effective as a deoxidizing and desulfurizing agent. If it is in the range of 0.0% by weight or less, the characteristics of the alloy are not significantly impaired, so that up to 2.0% by weight or less as ancillary elements are included in the scope of the invention.

C: C is not an element that is positively added, but the hardness increases as the C content increases. But,
Since the galvanic corrosion resistance of the alloy deteriorates, it is desirable to suppress the content thereof, and up to 0.2 wt% or less is included in the scope of the present invention.

Ni, Cr: Ni and Cr are elements that form an age-hardenable austenite + ferrite matrix, and for this reason, Ni: 40.0-5.
0.0% by weight, Cr: 40.0-50.0% by weight, preferably Ni + Cr: 85-
It is preferably 98% by weight. Further, Ni and Cr are elements that simultaneously improve galvanic corrosion resistance, and in order to obtain such characteristics, Ni and Cr were used as the basic elements of the alloy.

The electroplating roll alloy for electroplating according to the present invention has the above alloy composition and is used at least on the roll surface. That is, in addition to the case where the entire energizing roll is formed from the above alloy and is formed by casting, forging, etc., the alloy of the above components is also excellent in weldability, so that the main part of the roll is relatively inexpensive and high in cost. It is also possible to use high-alloy low-strength steel, heat-resistant steel, or the like, and form the above alloy by welding overlay on the outer peripheral portion of the main portion of this roll. In addition to the weld overlay, it may be manufactured by shrink fitting, thermal spraying, double centrifugal casting, or the like.

[0018]

[Embodiment] Current-carrying rolls (A to H) (outer diameter 310 mm) using alloys having the chemical compositions shown in Table 1 were manufactured, and the current-carrying rolls A to E were subjected to age hardening treatment at 800 ° C x 3 hr. After that, it was subjected to an actual machine test in an electrogalvanizing line. The surface hardness (Vickers hardness) of each roll was examined before starting the actual machine test. The results are also shown in Table 1.

Then, the above-mentioned 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.

[0020]

[Table 1]

As shown in Table 1, all of the current-carrying rolls A to D according to the present invention have a larger surface hardness than the current-carrying rolls F, G, and H made of the Ni-based alloy or stainless steel of the comparative example, and have corrosion. It is clear that the amount of wear is small and the corrosion resistance is excellent. In addition, the current-carrying roll E of the comparative example also has a large surface hardness, a small amount of corrosive wear, and is excellent in anti-corrosion wear resistance. Abrasion is not improved,
It is clear that the Mo content does not have to be unnecessarily increased, since it only increases the cost.

[0022]

As described above, the current-carrying roll alloy for electroplating according to the present invention is Ni: 40.0-5.
0.0% by weight, Cr: 40.0 to 50.0% by weight, M
o: 10.0% by weight or less, Si: 2.0% by weight or less, M
n: 2.0 wt% or less, Fe: 2.0 wt% or less, C:
0.2% by weight or less, and Nb, Ta, V, Ti, Al
Total of 1 or 2 or more selected from: 0.1
Since it has an alloy composition of up to 3.0% by weight and contains inevitable impurities such as N, it is remarkably excellent in corrosion and wear resistance against a plating bath solution, and is therefore superior to this alloy. Since it is possible to reduce the frequency of exchanging the energizing rolls, it is possible to improve the operation rate of the electroplating equipment and also reduce the maintenance load of the energizing rolls. By forming only the surface of the roll from the above alloys, it is possible to achieve cost reduction and other excellent effects.

Claims (2)

[Claims] 1. Ni: 40.0-50.0% by weight, C
r: 40.0 to 50.0 wt%, Mo: 10.0 wt%
Below, Si: 2.0 wt% or less, Mn: 2.0 wt% or less, Fe: 2.0 wt% or less, C: 0.2 wt% or less,
And a total of one or more selected from Nb, Ta, V, Ti, and Al: 0.1 to 3.0% by weight of the alloy composition and containing inevitable impurities such as N. A current-carrying roll alloy for electroplating, which has excellent corrosion resistance and wear resistance. 2. The electroplating roll alloy for electroplating according to claim 1, wherein Ni + Cr is 85 to 98% by weight.