JPS6250432A - Alloy for electrically conductive roll for electroplating - Google Patents

Abstract

PURPOSE:To obtain the titled alloy having superior corrosion and wear resistances and giving a roll from which metal stuck to the surface of the body during plating is easily stripped by adding prescribed amounts of C, Si, Mn, Ni, Cr and W to Co and restricting the amount of Fe as an impurity. CONSTITUTION:This alloy for an electrically conductive roll for electroplating consists of, by weight, 0.2-3% C, <=2% Si, <=2% Mn, <=5% Ni, 20-35% Cr, 2-15% W, <=10% Fe as an impurity and the balance Co. The alloy has superior corrosion and wear resistances in a corrosive environment contg. a plating soln. The alloy is hardly plated and metal for plating has low bonding strength to the alloy. When the alloy is used, the troublesome frequent exchange of a roll and large polishing expenses for regenerating the roll are considerably reduced, stable continuous plating operation is maintained and the quality of a plated product is improved and stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a current-carrying roll alloy for electroplating that has excellent corrosion resistance, abrasion resistance, etc., and has good peelability of plated metal adhering to the surface of the body.

[Conventional technology]

In addition to the specified current conductivity, the current-carrying roll in electroplating equipment such as continuous electrogalvanizing has corrosion resistance to a plating bath (usually pH 1 to 2), which is a strong acidic liquid, and the ability of the steel plate to be plated to pass continuously through the plating bath. It is necessary to have abrasion resistance that can withstand contact with (threaded plate material).

In addition, during use, the current-carrying roll becomes a cathode like the steel plate to be plated, and the surface of its body is also plated with zinc or other plating metal, so the adhering plated metal must be removed from the surface of the body. No.

This is because if a plating operation is performed with the plating metal attached to the surface of the body, the surface of the steel plate to be plated that comes into contact with the body will be scratched, and the quality of the plating will be impaired.

The adhering plating metal is removed by rubbing a grindstone or the like on the surface of the body, so the surface of the body is required to have abrasive wear resistance against sliding contact with the grindstone or the like.

Conventionally, rolls with body parts made of a nickel-based alloy "Hastelloy C" or an alloy such as SUS 316, a high nickel stainless steel, have been used as current-carrying rolls for electroplating.

[Problem to be solved]

However, the above-mentioned conventional current-carrying roll has advantages and disadvantages in terms of corrosion resistance, abrasion resistance, etc., and also has a problem in removing the plated metal adhering to the surface of its body.

In other words, the current-carrying roll whose body material is made of the nickel-based alloy "Hastelloy C" has no problems in terms of corrosion resistance, but has a low hardness of about 25 to 30 Hs and does not have sufficient wear resistance. In particular, the abutting portion of the edge of the plated steel plate is susceptible to scratches.

The flaws are transferred to the surface of the steel plate to be plated, causing deterioration in plating quality. In addition, plating metal is extremely likely to adhere to the surface of the body, and in order to remove it, the surface of the body must be constantly rubbed strongly with a grindstone, etc., making the surface of the body easy to scratch and wear out. easy.

On the other hand, the hardness of energized rolls whose body is made of SUS 316/stainless steel is as low as 20 to 25 Hs, which is poor in abrasion resistance, and the plated metal easily adheres to the surface of the body. There are problems similar to those of the current-carrying roll made of Hastelloy C, and in addition, problems remain in terms of corrosion resistance to plating baths.

For this reason, in conventional energized rolls, wear and deterioration of the roll body surface progresses rapidly, and polishing is required to repair the body surface in a short period of time, for example, every one month, and therefore, frequently. In addition to being forced to replace the rolls and suspend operations to do so, they are also forced to incur a large cost burden for re-polishing the rolls.

The present invention aims to provide an improved current-carrying roll alloy for electroplating in order to solve the above-mentioned problems.

[Means and effects for solving the problems] The current-carrying roll alloy for electroplating of the present invention contains C: 0.2 to 3%, Si
: 2% or less, Mn: 2% or less, Ni: 5% or less, Cr:
20-35%, w: 2-15%, impurity Fe: 1
0% or less, and the remainder essentially consists of Co.

The current-carrying roll made of the alloy of the present invention has excellent corrosion resistance against plating baths and also has excellent wear resistance in the corrosive environment (hereinafter also referred to as "corrosion wear resistance"). Moreover, even if plated metal adheres to the surface of the body, the adhesion to the surface of the body is weak, so it can be easily removed with a grindstone, etc., and therefore the surface of the body will not be scratched or worn by the grindstone. The amount generated is also extremely small.

Note that the corrosion resistance and corrosion abrasion resistance of the electroplating roll and the difficulty in peeling off and removing the plated metal adhering to it are surface-related problems, so it is not necessary to apply the present alloy to the entire roll body. . That is, the core of the roll body can be made of a different material, and a coating layer (surface layer) made of the alloy of the present invention can be formed on the surface of the core by, for example, overlay welding, thereby producing an energized roll. The composition of the alloy of the present invention was determined taking such points into consideration.

The reasons for limiting the components of the alloy of the present invention will be explained below.

C: 0.2-3% The presence of C is unfavorable from the viewpoint of corrosion resistance, but on the other hand, it combines with Cr, W, etc. and forms carbides, increasing hardness and contributing to improving wear resistance. do. In the present invention, corrosion resistance is addressed by elements such as Co, W, and Cr, and from the viewpoint of wear resistance, at least 0.2% of Cl is contained. As the amount of C increases, hardness increases and wear resistance improves, but when it exceeds 3%, the effect is saturated and the material becomes brittle, weldability deteriorates and cracks occur during weld overlay. It becomes more likely to occur. Therefore, the upper limit is set at 3%.

Si: 2% or less Si is added as a deoxidizing agent during alloy manufacturing.

The amount need not exceed 2%.

Mn: 2% or less Mn performs a deoxidizing function during alloy melting. Its amount up to 2% is sufficient.

Cr: 20-35% Cr greatly improves wear resistance by being dispersed and precipitated in the matrix as chromium carbide.

In addition, Cr has a low corrosion dissolution rate in the plating solution, and forms a matrix together with Co, Ni, l''e, etc., and forms a dense and strong protective film, resulting in passivation. at least 20%
of Cr is required. The effect increases as the amount of Cr increases, but if it exceeds 35%, the material becomes brittle and problems arise in weldability, so the upper limit is set at 35%.

Ni: 5% or less Ni is effective in improving corrosion resistance, and also has the effect of strengthening the Co base and increasing wear resistance. For this purpose, an amount of up to 5% is sufficient, preferably 0.1 to 5%. Even if it is added in an amount exceeding 5%, it is difficult to obtain an effect commensurate with the amount added, which impairs economic efficiency, so the upper limit is set at 5%.

W: 2 to 15% W is dispersed in the Co matrix as tungsten carbide (WC), thereby significantly increasing the hardness and contributing to improving corrosion resistance. To obtain this effect, at least 2% W is required, and the effect increases as the amount of W increases. However, if it exceeds 15%, although there is still an effect of improving hardness, on the other hand, it causes a decrease in electrical conductivity and a decrease in weldability. Further, W is an expensive element, and if it exceeds 15%, no effect commensurate with the cost can be obtained. Therefore, the upper limit is set at 15%.

Fe: 10% or less Fe is not a necessary element in the alloy of the present invention;
It is an impurity element that is allowed to be mixed up to.

The reason why 10% is set as the allowable upper limit is that if it exceeds 10%, Fe
- Corrosion resistance decreases due to the precipitation of intermetallic compounds such as Cr, and in actual use as a current-carrying roll, the densification force of the plating metal to the body surface becomes stronger, making it difficult to peel off and remove. be. Note that if the amount of Fe mixed as an impurity is strictly limited, manufacturing costs will increase due to selection of melted raw materials and removal of Fe in the refining process, but in the alloy of the present invention, Fe is , is not harmful, and is economically advantageous because it is allowed to be mixed in a relatively large amount of 10%.

CO: The remainder Co is a basic component of the alloy of the present invention, which stabilizes the matrix as an austenitic structure and increases its hardness. In addition, Co has a noble ionization tendency, and the corrosive film is dense and highly stable, so it has excellent passivation ability and provides excellent corrosion resistance against plating solutions.

Furthermore, the important point of the present alloy containing CO as a basic component is that
It has good electrical conductivity as a current-carrying roll, and at the same time,
This means that the surface of the body is poorly plated, and even if plated metal adheres to the surface, the adhesion is weak and it easily peels off. Therefore, it has the advantage that scratches and abrasion on the surface of the roll body caused by grinding with a grindstone or the like for removing attached plated metal can be effectively reduced.

By the way, as shown in FIG. 1, the electroplating current-carrying roll basically consists of a hollow cylindrical body (10) that forms the body of the roll, and shaft members (20) that also serve as power supply members fitted to both ends of the hollow cylindrical body (10). As a member. In addition, (31) is a cooling water flow path, which is defined inside the body by a cylinder (30) fitted concentrically in a hollow hole of the body, and is connected to the shaft member (20).
) is in communication with a flow path (21) bored in the hole.

When the alloy of the present invention is applied as a current-carrying roll material, it is sufficient to form only the surface layer (12) of the body with the alloy of the present invention as shown in the figure, and this is also more economical. In order to form the body (1o) having such a multilayer structure, a suitable other material (for example, SU33) is used as the body core (11).
A cylindrical cast or plastic-worked product made of stainless steel such as 04 or carbon steel such as 335C is prepared, and a coating layer forming method such as welding or thermal spraying is applied to the outer peripheral surface of the product. The surface layer portion (12) made of the alloy of the present invention may be formed to have an appropriate layer thickness (for example, 1 to 10 layers). Alternatively, a sleeve (hollow cylindrical body) made of the alloy of the present invention may be manufactured by casting or plastic working, and this may be integrated into the body core (11) by fitting it into the bottom of a pit or by other methods. Methods can also be applied.

〔Example〕

For each alloy having the composition shown in Table 1, a corrosion test, a corrosion wear test, and a weldability test were conducted, and the hardness and plating metal adhesion strength were measured, and the results shown in the right column of the table were obtained.

In the table, fragrance (Na) 1 to 9 are examples of the present invention, 11h101 to
10B is a comparative example. Comparative Examples 11m101-108, m101 is equivalent to SUS 316 which is a conventional material, Ilh102 is an example equivalent to "Hastelloy C" which is a conventional material, and numbers 103 to 108 are examples having a composition similar to the present alloy. However, the content of one of the elements (underlined in the table) deviates from the provisions of the present invention.

Each measurement and test condition is as follows.

CI) Hardness measurement Measure the surface hardness of the sample material using a Shore hardness meter.

[n) Measurement of adhesion strength of plated metal (a) Formation of plated layer After wet polishing (#1000) the surface of the plate-shaped specimen (20w x 30fl) (T), the lead wire ( At the same time, connect the plated surface (A) (
20mm x 20n) was left and masked with resin, and this was used as a cathode, and zinc plating was performed using a zinc plate as an anode.

Plating solution composition: 20g/jl! HzSO 100g
/ I! Naz SO4,150g/l Z
n S 04 (liquid temperature 50°C), current density: 50A
/d rd, distance between electrodes: 3 (Jan (constant), energization time: 50 minutes.

(b) Plating layer peeling test After the above plating, a six-shaped stainless steel plate piece (plate thickness 2 dragons) (P) was adhered to the surface to be plated via epoxy resin as shown in Fig. 2, A curing treatment is performed at 120°c for 1 hour. Then, using a tensile tester, the L-shaped steel plate piece (P)
The protruding piece (Pl) and the support rod (B) previously joined to the back surface of the test piece (T) were broken by chucking, and the peeling status of the plating layer was visually observed, and the breaking load and the plating layer were From the peeling area of , the plating adhesion strength (kg/c++l
).

(II [) Corrosion test After immersing a test piece (20' x 30 L x 5 t, fin) in a galvanizing solution, which is a sulfuric acid acid corrosive solution, for 7 days, the corrosion loss (g/rd h) of the test piece is measured. .

Plating solution composition: 20g/ff HzS 04.1
00g/jl'Na z S Oa, 150g/
l Z n S Os, liquid A = 50°C (IV) Corrosion and wear test A round rod-shaped test piece (15φ x 100L, fl) was rotated at 300 rpm in a galvanizing solution, and 2 pieces of 5GP50 were applied to its surface as a mating material. Press with a load of kg, 7
Measure the weight loss of the specimen due to wear after days of continuous loading. The abrasion loss of each sample material is shown in Comparative Example No. 101 (S U
It is expressed as a weight ratio, with the abrasion loss of S316 (equivalent to S316) being 100.

Plating solution composition: 20g/1H2so 100g/xNa
zsOn, 150 g/l Zn5Oa liquid temperature: 50°C (V) Weldability test Rod-shaped filler metal (cross section 4 dragon φ,
A flat base material (SUS304 equivalent material, preheating temperature 600℃) was welded using TIG welding method.
) to form a build-up layer with a bead length of 100 n and a bead width of 2011 mm.

After the above-mentioned overlay welding, the base material is
The bead was cut in a direction perpendicular to the longitudinal direction of the bead at a total of five locations at equal intervals, and the presence or absence of cracks on the cut end surface of the built-up layer was determined by a liquid penetrant test to evaluate the quality of weldability. In the table, "○" in the "Weldability" column means no cracking, "×"
” means that there is a crack.

As shown in Table 1, the example of the present invention is made of 5US, which is a conventional material.
316 material (scented 101) and "Hastelloy C" (scented 10)
Compared to 2), it can be seen that the adhesion strength of the plated metal is lower and its releasability is better, and from a comprehensive comparison of hardness and abrasion loss, it has about three times or more of the abrasion resistance. Furthermore, the corrosion resistance is equal to or higher than those of these conventional materials, and the weldability is also good. In addition, when looking at comparative grades 103 to 108 having a composition similar to the present alloy, Th103 (insufficient C amount) has low hardness and lacks wear resistance, and Th104 (excessive C amount), Poor weldability (also ll&x105 (insufficient W),
It is inferior to the examples of the present invention in terms of poor wear resistance and corrosion resistance.

Furthermore, m106 (Cr deficient) has low hardness and wear resistance (this is due to the insufficient amount of chromium carbide produced),
On the other hand, in No. 107 (excessive Cr), weldability is poor (and the effect of improving hardness is small despite the large amount of Cr41), and in No. 108, where the amount of Fe exceeds the upper limit, intermetallic compounds such as Cr-Fe are precipitated. Therefore, the corrosion resistance was poor, and both were inferior to the examples of the present invention.

〔Effect of the invention〕

The current-carrying roll alloy of the present invention has excellent corrosion resistance and corrosion wear resistance in the corrosive environment of plating solutions, as well as
Poor plating properties and low adhesion strength of plating metal.

The current-carrying roll for electroplating, which has a surface layer made of the alloy of the present invention, has less corrosion caused by the plating solution and corrosion caused by contact with the steel plate to be plated, and is suitable for grinding with a grindstone or the like to remove plated metal adhering to the surface. Since the occurrence of scratches and abrasion due to application is slight, the smooth and beautiful surface condition is maintained for a long period of time. Therefore, the hassle of conventional roll replacements and the cost of polishing for roll regeneration are significantly reduced, stable continuous plating operations are maintained, and the quality of plated products is improved.
A stabilizing effect can be obtained.

The alloy of the present invention is useful as a current-carrying roll alloy for various types of electroplating, such as tin plating, nickel plating, etc., and is not limited to the above-mentioned zinc plating. It is also useful as a material for zinc rolls, etc., which are guide rolls for passing sheets through.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view showing an example of the layered structure of an energizing roll when the surface layer of the body is formed of the alloy of the present invention, and Fig. 2 CI) and (II) are test pieces related to Examples. It is a perspective explanatory view showing the form of. ! 0: roll body, 11: body core, 12: body surface layer, 'l゛: test piece.

Claims (1)

[Claims] (1) C: 0.2-3%, Si: 2% or less, Mn: 2%
Below, Ni: 5% or less, Cr: 20-35%, W: 2-
A current-carrying roll alloy for electroplating consisting of 15% Fe as an impurity, 10% or less, and the remainder substantially Co.