JPH07216584A - Conductor roll and ts production - Google Patents

Abstract

PURPOSE:To impart durability combining wear resistance and corrosion resistance to a conductor roll by forming an Ni-Cr-based sintered alloy layer on the outer circumference of a metallic roll base metal. CONSTITUTION:The surface outer circumference of a metallic roll base metal of a carbon steel, an allay steel or a stainless steel is applied with an alloy layer contg., by weight, 30 to 40% Cr, 8 to 25% Mo, <=2% Nb, <=1% Si, <=2% V, <=5% W, <=3% Cu, <=6% Co and 0.05 to 0.5% B, and the balance Ni with inevitable impurities. This alloy layer is diffusedly joined integrally with the roll base metal by hot isotropic pressurizing treatment for the powder. Thus, fine carbides free from microstructural segregation can be formed, by which wear resistance and corrosion resistance sufficient as those of the conductor roll can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductor roll (also referred to as a current-carrying roll) used as a cathode in a continuous electroplating apparatus for thin steel sheets and a method for producing the same.

[0002]

2. Description of the Related Art Electroplating of a thin steel sheet is carried out in a plating solution bath by bringing the steel sheet to be plated into contact with a cathode conductor roll and passing between the anodes.
That is, the conductor roll contacts the plated steel sheet and rotates to convey the plated steel sheet, and
It has the role of holding the plated steel sheet at a predetermined potential. In order to play such a role, the conductor roll must have a) good electrical conductivity. b) It has excellent corrosion resistance. c) It has excellent wear resistance. That performance is required. And as its structure,
Many of them are sleeve rolls.

By the way, the conventional conductor roll is
It has been manufactured and used by using a Ni-based alloy such as Hastelloy C alloy by casting or forging. However, the conventionally used Ni-based alloys have insufficient corrosion resistance and have a problem that they are easily damaged by corrosion and wear due to their low hardness. Furthermore, in the conventional manufacturing methods of casting and forging, there are restrictions on the chemical composition and hardness of the product, and it has been difficult to impart both corrosion resistance and wear resistance to the conductor roll.
In addition, some conductor rolls were made of pure copper and used by plating the surface with Cr. However, pin holes or cracks are likely to occur in the Cr plating layer, and they penetrate through the pin holes or cracks. There is also a problem that the plating solution erodes pure copper and damages it.

[0004]

As described above, the conventional conductor roll is susceptible to damage due to corrosion and wear, and therefore, there is a problem in that the plated steel sheet, which requires high quality, is flawed. In addition, the conductor roll must be replaced in a short cycle, which causes a problem that productivity cannot be improved.

[0005]

[Means for Solving the Problems] Conventionally, in Ni-based alloys, the alloy design was made by suppressing the C content to less than 0.1% by weight. This is because when the C content is increased, N
It is believed that intergranular corrosion occurs due to the formation of carbides with alloy elements such as Cr or Mo in the i-based alloy and the precipitation of these carbides at the grain boundaries.
Further, B segregates at the crystal grain boundaries and strengthens the crystal grain boundaries to improve the creep rupture strength, so B was added in an amount of about 0.03% by weight or less. It was thought that it would cause the deterioration or cracking.

By the way, in a Ni-based alloy for conductor rolls, wear resistance is required in addition to corrosion resistance. Therefore, as a result of research and development in order to solve the problem that both properties must be combined, Ni The base alloy powder material is sintered to the outer periphery of a metal base material such as carbon steel or stainless steel by hot isostatic pressing and diffusion bonding to the base material, that is, integral diffusion bonding 0.6 wt% in the alloy layer obtained by
It has been clarified that the following C and 0.05 to 0.5% by weight of B can be contained, and an alloy layer excellent in corrosion resistance and wear resistance can be obtained.

The present invention is based on such knowledge,
Cr around 30 to 40 wt%, Mo at 8 to 25 wt%, Nb at 2 wt% or less, Si at 1 wt% or less, and V2 wt% on the outer periphery of a metal base material such as carbon steel, alloy steel or stainless steel.
Below, W5% by weight or less, Cu3% by weight or less, C0.6% by weight or less, B0.05-0.5% by weight, a conductor roll provided with a surface layer consisting of the balance Ni and unavoidable impurities, and Cr30-40% by weight %, Mo 8 to 25 wt%, Nb 2 wt% or less, Si 1 wt% or less, V2 wt%
Below, W5 wt% or less, Cu3 wt% or less, C0.6 wt% or less, B0.05-0.5 wt%, the balance Ni-based alloy powder material consisting of Ni and unavoidable impurities, carbon steel,
The present invention relates to a method for manufacturing a conductor roll in which the outer periphery of a metal base material such as alloy steel or stainless steel is integrally diffusion bonded by hot isostatic pressing.

The reasons for limiting the chemical composition of the Ni-based alloy will be described below. Conventionally, the C component is considered to cause intergranular corrosion by forming carbides with alloy elements such as Cr or Mo in a Ni-based alloy when its content is increased, and by precipitating these carbides at grain boundaries. However, the content was suppressed to less than 0.1% by weight.
However, as shown in Table 1, it was clarified that by increasing the C content to form fine carbides, the wear resistance is improved and the corrosion resistance is also improved. If it exceeds 0.6% by weight, the corrosion resistance is adversely affected. Therefore, its content is set to 0.6% by weight or less. The reason why the corrosion resistance is improved by increasing the C content is that the formed carbide has a function of being finely precipitated in the crystal grains without being biased to the crystal grain boundaries.

The Cr component forms a solid solution in the matrix to improve the corrosion resistance and forms fine carbides and intermetallic compounds to contribute to the wear resistance, but the C content is 0.2 to 0.6% by weight. In the alloy (1), some of the Cr precipitates as carbides, so if it is less than 30% by weight, the action on the corrosion resistance of the matrix is insufficient, and if it exceeds 40% by weight, the sinterability of the powder material is adversely affected. In order to affect, the content is 30-40
It was set to% by weight.

The Mo component forms carbides and intermetallic compounds to improve wear resistance. If the content is less than 8% by weight, the above action is insufficient, and if it exceeds 25% by weight, the corrosion resistance deteriorates.
And Component B is effective in improving corrosion resistance and wear resistance. This is because the presence of the B component causes fine precipitation of carbides and intermetallic compounds. However, the effect does not appear at 0.05% by weight or less, and the alloy becomes brittle if it exceeds 0.5% by weight, so the content was made 0.05 to 0.5% by weight.

The Nb component forms carbides and intermetallic compounds to improve wear resistance. However, if the content exceeds 2% by weight, the corrosion resistance deteriorates, so the content was set to 2% by weight or less. The V component forms carbides and intermetallic compounds to improve wear resistance. However, if the content exceeds 2% by weight, the corrosion resistance deteriorates, so the content was made 2% by weight or less.

The W component forms a solid solution in the matrix, improves the hardness of the matrix, forms carbides and intermetallic compounds, and improves the wear resistance, but if the content exceeds 5% by weight, the corrosion resistance increases. Therefore, its content is set to 5% by weight or less. The Si component makes the alloy brittle when its content exceeds 1% by weight, so the content was made 1% by weight or less. The Cu component improves the corrosion resistance, but its effect does not change even if it exceeds 3% by weight, so the content was made 3% by weight or less.

Next, the method for obtaining the alloy layer of the present invention is based on hot isostatic pressing for the following reason. That is,
When the alloy layer of the chemical components shown in the present invention is to be obtained by casting or forging, melting and solidification cause microstructural segregation, coarsening of crystal grains occurs, and sufficient corrosion resistance is obtained. It depends. Further, carbides formed by increasing the C content are precipitated at the crystal grain boundaries, and the state becomes coarse, resulting in insufficient wear resistance and corrosion resistance. Furthermore, B combines with other elements to form borides, which precipitate at grain boundaries, causing embrittlement and cracking.

On the other hand, in the case of hot isostatic pressing, a powder material produced by a gas atomizing method or the like and rapidly cooled is used, and the temperature is 1080.
〜1180 ℃, pressure 500〜2000kgf / cm ² , time 1
Since it is carried out under the condition of 10 hours, there is no melting and solidification process during the treatment, therefore there is no microstructural segregation, and it is possible to form fine carbides, which is excellent in wear resistance and corrosion resistance. Because the alloy layer can be obtained.

[0015]

EXAMPLES Next, the present invention will be described in detail based on its examples. The Ni-based alloy powder materials 1 to 10 of the present invention having the chemical components shown in Tables 1 and 2, the Ni-based alloy powder materials 1 to 9 of the comparative examples, and the Ni-based alloy powder material 2 used conventionally are heated under the following conditions. Sintered metal was manufactured by performing isostatic pressing. Sintering temperature: 1150 ° C Sintering pressure: 1000kgf / cm ² Sintering time: 2 hours

For the purpose of evaluating the corrosion resistance of the above-mentioned sintered metal, distilled water 400 cc + sulfuric acid 236 cc + ferric sulfate 25
Corrosion tests were carried out by immersion in 24 g of boiling solution for 24 hours. In addition, Vickers hardness measurement was performed as an evaluation of the wear resistance. The results are shown in Tables 1 and 2. The evaluation results of the centrifugally cast Ni-based alloy 1 that has been used conventionally are also shown.

[0017]

[Table 1]

[0018]

[Table 2]

From the results shown in Tables 1 and 2, the Ni of the present invention can be obtained.
It is understood that the sintered metal obtained by hot isostatic pressing of the base alloy powder material is a conductor roll alloy layer having both corrosion resistance and wear resistance. Further, Comparative Examples Ni-based alloy powder materials 1 to 9 having chemical components outside the scope of the present invention
It can be seen that the sintered metal of No. 3 has low hardness or poor corrosion resistance.

[0020]

As described above, the conductor roll alloy layer obtained by hot isostatic pressing using the Ni-based alloy powder material of the present invention has corrosion resistance depending on the roll use conditions. And wear resistance can be selected, and by exhibiting excellent characteristics that combine both, excellent effects can be obtained in the field of manufacturing plated steel sheets.

Claims (2)

[Claims] 1. A steel base material made of carbon steel, alloy steel, or stainless steel, having Cr of 30 to 40% by weight and Mo of 8 to 10% by weight on the outer periphery thereof.
25 wt%, Nb2 wt% or less, Si1 wt% or less, V
2% by weight or less, W5% by weight or less, Cu3% by weight or less, C
A conductor roll comprising: a surface layer containing 0.6% by weight or less, B: 0.05 to 0.5% by weight, the balance being Ni and inevitable impurities. 2. Cr of 30-40% by weight, Mo of 8-25% by weight, Nb of 2% by weight or less, Si of 1% by weight or less, V2% by weight or less, W5% by weight or less, Cu3% by weight or less, C0.6.
Wt% or less, B0.05 to 0.5 wt%, the balance Ni-based alloy powder material consisting of Ni and unavoidable impurities, on the outer periphery of the metal base material of carbon steel, alloy steel or stainless steel, hot etc. A method of manufacturing a conductor roll, characterized by integrally diffusion-bonding by means of a pressurization process.