JP2787176B2 - Roller for transporting steel material and method of manufacturing roller body trunk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conveying roller such as a table roller, a guide roller, a bridle roller and the like in a conveying line for a high-temperature steel material such as a red hot slab and a method of manufacturing a body member thereof.

[0002]

2. Description of the Related Art FIG.
As shown in the figure, the main body body (sleeve) which is a hollow cylindrical body
Roller shafts 3 and 3 are connected to hub materials 2 and 2
It has a structure assembled via 2,. The main body 1 of the transport roller carries a red-hot slab on its surface and transports the slab at a speed of about 100 m / min or more.
It must be hard to cause seizure with the glowing slab and have excellent abrasion resistance. Further, at a place where the slab is subjected to water cooling, the slab must have both thermal shock resistance and corrosion and wear resistance.

[0003] Japanese Patent Publication No. 2-2941 discloses an improved alloy for forming the body of the above-mentioned transport roller.
C: 1.0-3.0%, Si: 0.3-2.5%, M
n: 0.3 to 2.5%, Cr: 7.5 to 18.0%, N
i: 0.1 to 6.0%, W: 0.3 to 3.0%, Mo,
One or two of V: 1.0 to 5.0%;
An iron-based alloy having a chemical composition in which the amount ratio [Cr (%) / C (%)] of C and C is 2.5 to 18 and having a structure in which carbides are dispersed and precipitated on a martensite matrix is disclosed. .

When the alloy described in the above publication is applied to the body 1 of the main body of the conveying roller, the thickness of the body is divided into an outer layer 1a and an inner layer 1b as shown in FIG. It is reasonable to use a cylindrical body made of steel for use (for example, SS41 material) and form an outer layer 1a made of the above alloy on the outer peripheral surface to form a two-layer laminate. This is because, although the above alloy has excellent seizure resistance and wear resistance, it has poor weldability. Therefore, if the entire body thickness of the main body was made of that alloy, the hub material in the roller assembly work This is because welding can no longer be applied to the joint with the slab 2, and the seizure resistance and abrasion resistance required for improving the durability of the body 1 are not the inner layer 1 b but the contact surface of the slab. Outer layer 1a
This is because the material characteristics are That is, the inner layer 2b facing the hub member 2 is formed of general structural steel to secure weldability, and the outer layer 1a is formed of the above alloy to improve the durability of the roller while securing the weldability. It secures sex and so on.

[0005]

As described above, the method of manufacturing the main body of the transporting roller as a two-layer laminate of the outer layer 1a and the inner layer 1b involves a cylindrical body (hereinafter referred to as an "inner cylindrical body") serving as the inner layer 1b. )) To form the outer layer 1a by overlay welding to form an outer layer 1a. Canning a metal powder to be an outer layer 1a around an inner layer cylindrical body, and then hot isostatic pressing sintering (HI)
P) to form the outer layer 1a made of a sintered alloy, or a method of supplying a molten metal of the outer layer 1a around the inner layer cylindrical body to cool and solidify (for example, a cast-in-place casting method). Can be

However, since the outer layer forming alloy has poor weldability, it is not possible to form a sound outer layer on the surface of the inner layer cylinder using the overlay welding method. The method of applying the HIP treatment using the alloy powder as the outer layer forming raw material is as follows:
The outer layer can be formed as a dense sintered alloy, but the production costs are significantly higher. The body 1 is usually a large member (the body length is, for example, 2000 to 2500).
mm), an extremely large capacity HIP device is required, which is not practical. On the other hand, the method of surrounding the inner layer cylindrical body with the outer layer metal melt and solidifying it does not require special equipment and equipment, and is advantageous in cost. However, the alloy for forming the outer layer has a high melting point (about 1250 ° C or higher)
If the inner layer cylinder made of general structural steel such as SS material is surrounded by the molten metal, the inner layer cylinder is significantly melted and damaged, and a sound two-layer laminate cannot be formed.

Accordingly, the present invention is directed to a novel alloy which has the same seizure resistance and wear resistance as the outer layer alloy, and has a sufficiently lower melting point than general structural steel such as SS material as an inner layer cylinder. An object of the present invention is to provide a conveying roller having a two-layer laminated body having an outer layer formed thereon as a main body, and a method of manufacturing the main body.

[0008]

The steel material transporting roller of the present invention is a two-layer laminate comprising a main body having an inner layer and an outer layer fused to an outer peripheral surface of the inner layer. C:
1.0 to 3.0%, Si: 0.3 to 2.5%, Mn:
0.3 to 2.5%, Cr: 7.5 to 18.0%, Ni:
0.1 to 6.0%, W: 0.3 to 3.0%, one or two of Mo and V: 1.0 to 5.0% (total amount), P:
2.0 to 5.0%, B: 1.0 to 3.0%, the balance being substantially composed of Fe, and the quantitative ratio of Cr to C [Cr (%) / C
(%)] Has a chemical composition of 2.5 to 18 and 6 to 25%
(Weight) has a structure in which carbides are dispersed and mixed, and the amount of the carbides and the amounts of C and Cr are represented by the following formula: [amount of carbide (%) − 0.6 × amount of Cr (%) + 15.2] ]
/ C amount (%) = 11 to 13... [I]

The two-layer laminate, which is the main body member of the transport roller, comprises a hollow cylindrical body (hereinafter referred to as an "inner cylindrical body") as an inner layer and a hollow cylindrical body separately prepared as an encapsulant being concentrically outer. It fits and stands upright, and as a material for forming an outer layer, C: 1.0-3.
0%, Si: 0.3 to 2.5%, Mn: 0.3 to 2.5
%, Cr: 7.5 to 18.0%, Ni: 0.1 to 6.0
%, W: 0.3 to 3.0%, one or more of Mo and V
Species: 1.0-5.0% (total), P: 2.0-5.0
%, B: 1.0 to 3.0%, the balance being substantially composed of Fe, and the ratio of C to Cr [Cr (%) / C (%)] is 2.5%
After filling with an alloy powder having a chemical composition of ~ 18 and degassing and sealing, the alloy powder layer is heated and melted, and the resulting molten metal layer is solidified upward from the bottom by directional cooling to form an outer layer. , And then can be manufactured through a step of removing the capsule material.

[0010]

The steel material transporting roller of the present invention has high seizure resistance and abrasion resistance due to the outer layer of the body portion being formed of an alloy having the above-mentioned chemical composition and metal structure. Further, since the outer layer metal has a chemical composition containing P and B in combination, the melting point is about 1100.
° C or lower and the melting point of general structural steel such as SS material (for example, SS
Melting point of the material 41: about 1500 ° C.). Therefore, an SS material or the like can be used as the inner layer cylinder, and the outer layer molten metal layer can be formed around the inner layer cylinder using the difference in melting point. By a metallurgical bond generated at the phase-liquid phase interface, a two-layer laminate in which the outer layer and the inner layer are firmly bonded and integrated at the layer interface can be formed.

Hereinafter, a method of manufacturing the transport roller and the body of the transport roller according to the present invention will be described in detail. The reasons for limiting the chemical composition and structure of the outer layer metal of the body trunk are as follows. All percentages indicating element content and the like are percentages by weight. C: 1.0 to 3.0% C has a solid solution strengthening action of the matrix, but in the present invention, in particular, carbide, mainly M ₇ C ₃ type carbide [(Cr, Fe) ₇
The formation of C ₃ ] improves wear resistance and seizure resistance. The seizure resistance of the alloy depends on the form and amount of the Cr carbide. The amount of C for obtaining the amount of carbide necessary for enhancing the seizure resistance is determined by the ratio of the amount of Cr to the amount of Cr [Cr (%) / C
(%)] Must be 2.5 to 18. Since the amount of Cr is limited to 7.5 to 18% as described below,
7.5% requires 3.0% C and Cr 18%
Requires 1.0% C. Therefore, the lower limit of the C content is set to 1.0%, and the upper limit is set to 3.0%.

Si: 0.3 to 2.5% Si is a deoxidizing agent and is added in an amount of 0.3 to 2.5% in order to enhance the fluidity of the molten alloy.

Mn: 0.3 to 2.5% Mn is added in an amount of 0.3 to 2.5% as a deoxidizing element.

Cr: 7.5 to 18% Cr is not only indispensable for the formation of the Cr carbide, but also indispensable for increasing the corrosion resistance and making the alloy matrix a martensitic phase having high wear resistance. Element. If the amount is less than 7.5%, corrosion resistance will be insufficient, and if it exceeds 18%, it will be difficult to obtain a martensite structure. Therefore, it is set to 7.5 to 18%.
The seizure resistance of the alloy has a relationship with the amount of carbides mainly composed of M ₇ C ₃ type, and if the amount is less than 6% by weight, the seizure resistance is insufficient. From the viewpoint of seizure resistance, the larger the amount of precipitation, the more advantageous. However, if it exceeds 25% by weight, the toughness is deteriorated. For this reason, the amount of carbide is set to 6 to 25% by weight. In order to further enhance the seizure resistance, the amount of carbide, the amount of C and the amount of C
The value calculated by the formula [I] for the amount of r is 11 to
It is required to be 13, and particularly preferably 12.

Ni: 0.1 to 6.0% Ni enhances toughness and is an element necessary for forming a martensite matrix in a high Cr alloy. The amount is 0.
If less than 1%, the above effect is insufficient. However, when the Ni content exceeds 6.0% with respect to the Cr content of 16 to 18%,
At a temperature of 100 ° C. or higher, martensitic transformation does not occur. Therefore, it is set to 0.1 to 6.0%.

Mo: 1.0-5.0%, V: 1.0-
5.0% Mo and V are both effective elements for improving the hardening ability of the alloy. By setting the Mo amount to 1.0% or more,
A quench hardening ability with a critical diameter of 25 mm or more can be obtained. However, even if it exceeds 5.0%, the effect is not so increased and the economic efficiency is impaired. Therefore, the content is set to 1.0 to 5.0%. V enhances the quench hardening ability by the crystal grain refinement effect. This requires at least 1.0%, but 5.
If it exceeds 0%, the toughness is reduced. Therefore, 1.0-
5.0%. Any one of the above Mo and V can be arbitrarily selected, and when both are used in combination, a higher hardness can be obtained as a combined effect and the wear resistance can be improved. In that case, the content may be a total amount of 1.0 to 5.0%.

W: 0.3-3.0% W is an element effective for improving corrosion and wear resistance. 0.3%
If less than 3.0%, the effect is not sufficient, and if it exceeds 3.0%, toughness is reduced. Therefore, 0.3 to 3.0%
And This W addition effect becomes more remarkable when it is combined with Mo.

P: 2.0-5.0% P is an element usually excluded as a harmful impurity,
In the present invention, this is an essential component of the outer layer forming alloy.
That is, by adding an appropriate amount of P and B described later, the alloy has a low melting point without substantially impairing the seizure resistance and abrasion resistance required for the outer layer. This makes it possible to form the outer layer by utilizing the difference in melting point between the two. The reason why the lower limit of the P content is set to 2.0% is that if it is less than that, the lowering of the melting point of the alloy is not sufficient, while the upper limit of 5.0% is that if a large amount is added beyond that, This is because the reduction in toughness is large, and it is difficult to secure the suitability of the body of the roller as the outer layer forming material.

B: 1.0-3.0% B has the effect of lowering the melting point of the alloy. Further, it is effective in improving the hardenability of the alloy, improving the strength by the action of refining the crystal grains, and improving the toughness. The effect of improving the toughness associated with the crystal grain refining action helps to reduce the embrittlement of the alloy accompanying the addition of P. In order to obtain these effects, addition of at least 1.0% is required, and the effect is increased by increasing the amount of addition. However, if the amount is too large, the toughness of the alloy is rather deteriorated. Therefore, the upper limit is 3.0%.

The outer layer of the body of the roller body made of an alloy having the above-mentioned chemical composition can be formed on the outer peripheral surface of the inner layer cylindrical body by a melting and solidifying process. No special heat treatment is required to make the outer layer have the predetermined metallographic structure. By cooling the solidified outer layer as it is, a martensitic base and a predetermined amount of carbide mainly containing M ₇ C ₃ type are contained in the base. Is formed in a dispersed structure. If necessary, an annealing treatment for removing residual stress is performed, and the annealing treatment is performed at a temperature of about 600 to 700 ° C. for an appropriate time (for example,
0.5 to 5 hours) It is achieved by air-cooling after heating and holding.

Tables 1 and 2 show the chemical composition, structure and seizure resistance and abrasion resistance of the outer layer alloys a to c of the conveying roller of the present invention, the alloy d described in the above publication, and the conventional typical alloy e. The gender is compared and shown. The seizure resistance was measured by rotating a cylindrical test piece (diameter 10 mm) with a rotary bending tester, and fixing a fixed body (material type: SS41, width: 1) on the outer peripheral surface thereof.
0 mm) was evaluated based on the state of occurrence of seizure on the peripheral surface of the test piece in the seizure test (contact pressure of the fixed body: 8.9).
２７27 kgf / mm ² , sliding speed: 180 m / min, friction time: 10 minutes). In the table, "○" means no seizure,
“X” indicates that seizure is remarkable.
The abrasion resistance was evaluated by a wear coefficient K (kg ^-1 ) calculated from the wear amount of the test piece in the wear test under the same conditions as the seizure test. K = amount of wear (mm ³ ) / contact area (cm ² ) × elastic limit (kg) × friction distance (cm)

The alloy for forming an outer layer of the present invention has seizure resistance and abrasion resistance comparable to those of the alloy d, and the difference from the conventional typical alloy e is obvious. It also has good thermal shock resistance and corrosion wear resistance. Moreover, while the melting point of the alloy d is about 1250 ° C., the outer layer alloy of the present invention has about 1100 ° C. or less without impairing seizure resistance and wear resistance as a composite content effect of P and B ( About 1050 ° C
(Before and after).

[0023]

[Table 1]

[0024]

[Table 2]

Next, a description will be given of a manufacturing process of a body trunk which is a two-layer laminate having an outer layer made of the above alloy, with reference to the drawings. In FIG. 1, reference numeral 11 denotes a hollow cylindrical body (inner cylindrical body) serving as an inner layer of the main body, and 12 denotes a hollow cylindrical capsule material having a diameter larger than the inner cylindrical body 11 by a predetermined dimension. As the inner layer cylindrical body 11 and the capsule material 12, for example, a centrifugal force cast product or the like is used. The inner cylindrical body 11 and the encapsulant 12 have a donut-shaped bottom plate 13 at the bottom open end.
Are mounted upright on a horizontal table with their axes aligned with each other, and have a predetermined chemical composition for forming an outer layer in a space defined by the inner layer cylinder 11 and the capsule material 12. Alloy powder M is filled.

Capsule material 12 externally fitted to inner cylinder 11
May be general structural steel such as SS material similar to the inner layer cylindrical body 11 or various heat-resistant steels, but unlike the inner layer cylindrical body 11, the capsule material 12 has the inner space. There is no need for metallurgical bonding with the outer layer metal to be formed. Rather, no bonding is required, which simplifies the processing in the subsequent steps and is advantageous. For this reason, the encapsulant 12 is coated on its inner peripheral surface with a film f having low wettability with the outer layer metal melt, for example, an oxide ceramic (preferably zirconia is mentioned as an example). It is advisable to block the contact. Thereby, after forming the outer layer, the capsule material 12 can be removed from the outer layer surface and reused repeatedly. The ceramic film may be formed by a spraying method or the like, and has a thickness of about 50 to 100 μm.
A degree is enough.

The inner cylindrical body 11 and the encapsulant 12 have a body length longer than the body of the roller body to be manufactured, and the portion A in the height direction is a product forming portion. Product forming department A
The reason why the excess length B is provided on the upper side of the steel sheet and a large amount of the alloy powder is applied thereto is that the outer layer metal is supplied to the product forming portion A during the heating and melting process of the alloy powder packed layer, and the molten metal is formed. This is because the function of a feeder for replenishing the molten metal with respect to the solidification shrinkage in the cooling process of the outer layer metal is performed.

The space between the inner cylinder 11 and the capsule material 12 is filled with the outer layer forming alloy powder, and the top open end face is sealed with a donut-shaped cover plate 14. The metal powder packed layer is vacuum degassed (for example, through the degassing pipe 15 of the cover plate 14).
1 × 10 ^{-2 -1} × 10 ^-4 Torr)
5 is pressed (sealed) by a press, and then the metal powder packed layer is heated and melted. The vacuum degassing of the metal powder packed layer prior to the heat melting is performed by the alloy powder M in the heat melting step.
Oxidation and oxidation of the surface of the inner layer cylinder 11 (oxidation of the alloy powder impairs the material properties of the outer layer formed, and oxidation of the surface of the inner layer cylinder prevents metallurgical bonding of the layer interface with the outer layer formed. To prevent the air bubbles from remaining in the outer layer beforehand, and to ensure the dense uniformity.

In the heating and melting of the alloy powder layer M, heat is supplied to the alloy powder layer by conduction and heat conduction from the outside of the inner cylinder 11 and the capsule material 12 in a heating furnace, and the temperature is higher than the melting point of the alloy powder (preferably, It can be carried out by maintaining the temperature at the melting point + 10 ° C. to 50 ° C. for an appropriate time (for example, 1 to 4 hours). At the interface between the generated molten metal layer and the inner layer cylinder 11, metallurgical bonding between the liquid phase and the solid phase occurs.

After the formation of the molten layer of the outer metal layer, the heat supply is stopped and cooling and solidification are performed. In the coagulation process, in order to prevent shrinkage cavities due to shrinkage, directional coagulation is directed upward from the lower portion. The directional solidification is achieved by giving a sufficient amount of riser to the extra length B above the product forming section A.

After the solidification of the outer layer metal is completed, the encapsulant 12 is removed, and the excess lengths B and C on the upper and lower sides of the product part A are cut and removed. Next, an annealing treatment for removing stress is performed as necessary, and further, the outer peripheral surface of the outer layer metal and the inner peripheral surface of the inner layer cylindrical body are subjected to machining to finish them to predetermined dimensions, thereby forming the outer layer 1a and the inner layer 1b. Is obtained as a two-layer laminate in which the body is firmly bonded at the layer interface. this,
The roller for conveyance shown in FIG. 2 is completed by assembling the separately prepared roller shafts 3 and 3 and performing welding with the hub members 2, 2, 2.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an inner cylinder 11 and an encapsulant 12 are polymerized concentrically and filled with an outer layer forming powder. The inner layer cylinder 11 and the capsule material 12
Each is a cast product of centrifugal force of SS41 material (melting point: about 1400 ° C.), and the capsule material 12 has a sprayed coating of zirconia ceramics (film thickness: 60 to 80 μm) formed on its inner peripheral surface. Inner layer cylinder 11 and capsule material 1 in product forming section A
The radial gap width of No. 2 is 15 mm, and the outer layer forming alloy powder filled therein is a powder (melting point: 1050 ° C.) having the same chemical composition as alloy a in Table 1 above.

After filling the outer layer forming alloy powder, the alloy powder layer was degassed and sealed (1 × 10 ⁻⁴ Torr), and the alloy powder layer was heated and melted in a heating furnace. Heating dissolution temperature: 1100 ° C, retention time: 2.5Hr. After the outer layer molten layer is solidified under directional cooling, the encapsulant 12 is extracted from the outer layer metal surface, and the upper and lower extra lengths B and C of the two-layer laminate are cut and removed, and the inner and outer surfaces are machined. In addition, the roller body was finished to have a predetermined size. Outer layer thickness: 10m
m, inner layer thickness: 20 mm, body length: 2300 mm, outer diameter:
350 mm.

The outer layer and the inner layer of the obtained main body have a substantially uniform layer thickness over the entire length, and a metallurgical bonding state is formed over the entire lamination interface. And cross-sectional macro-etching inspection). In addition, it was observed that the outer layer metal had a structure in which carbides were dispersed and precipitated on a matrix composed of a martensite phase, and the amount of carbides was 13 to 14%.

[0035]

The steel material conveying roller of the present invention has excellent seizure resistance and abrasion resistance on the surface of the body of its body.
Damage and deterioration due to contact of a high-temperature steel material such as a red-hot slab are prevented and suppressed, stable use over a long period of time is possible, and effects such as reduction of roller maintenance and improvement of operation efficiency of a transfer line are obtained. Further, the production of the two-layer laminate, which is the main body of the transport roller of the present invention, does not require any special equipment, and after the inner layer cylindrical body is filled with the outer layer alloy powder and heated and melted, It can be manufactured by a simple process of solidification, has excellent practicality, is advantageous in cost, and is suitable for mass production.

[Brief description of the drawings]

FIG. 1 is a half sectional view for explaining a method of manufacturing a body of a conveying roller body according to the present invention.

FIG. 2 is an axial cross-sectional view showing a transport roller having a main body of a two-layer laminate.

[Explanation of symbols]

1: roller body trunk, 1a: outer layer, 1b: inner layer, 2: hub material, 3: shaft 11: inner layer cylinder, 12: capsule material, 13: bottom plate, 1
4: lid plate, 15: degassing tube, M: alloy powder for forming outer layer

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B21B 39/00 B65G 39/00 F16C 13/00 C22C 38/00, 38/54

Claims (3)

(57) [Claims] 1. A two-layer laminate in which a body portion of a roller includes an inner layer and an outer layer fusion-bonded to an outer peripheral surface thereof, wherein the outer layer has C: 1.0 to 3.0% and Si: 0.3-2.5
%, Mn: 0.3 to 2.5%, Cr: 7.5 to 18.0
%, Ni: 0.1 to 6.0%, W: 0.3 to 3.0%,
One or two types of Mo and V: 1.0 to 5.0% (total amount), P: 2.0 to 5.0%, B: 1.0 to 3.0%,
The balance substantially consists of Fe, and the ratio of Cr and C [Cr
(%) / C (%)] has a chemical composition of 2.5 to 18 and a matrix composed of a martensite phase has a chemical composition of 6 to 2
It has a structure in which carbides occupying 5% (weight) are dispersed and mixed, and the amount of the carbides and the amounts of C and Cr are represented by the following formula [I]: [amount of carbides (%) − 0.6 × Cr amount ( %) + 15.2]
/ C amount (%) = 11 to 13... A steel material conveying roller comprising an iron-based alloy satisfying [I]. 2. A hollow cylindrical capsule material (hereinafter, referred to as an “inner cylinder”) which is to be an inner layer, is concentrically externally fitted with the hollow cylindrical capsule material and is erected, and is inserted into a gap between the inner cylinder and the capsule material. As an outer layer forming material, C: 1.0 to 3.0%, Si: 0.3 to
2.5%, Mn: 0.3 to 2.5%, Cr: 7.5 to 1
8.0%, Ni: 0.1-6.0%, W: 0.3-3.
0%, 1 or 2 types of Mo and V: 1.0 to 5.0%
(Total amount), P: 2.0-5.0%, B: 1.0-3.
0%, the balance substantially consisting of Fe, and an alloy powder having a chemical composition in which the ratio of Cr to C [Cr (%) / C (%)] is 2.5 to 18 was filled and hermetically sealed. In addition, the alloy powder packed layer is heated and melted, and the resulting molten metal layer is
2. The method of claim 1, wherein the encapsulant is removed after the outer layer is formed by solidifying upward from a lower portion by directional cooling, and then the encapsulant is removed. 3. The roller according to claim 2, wherein the encapsulant is formed by forming a ceramic film having low wettability with an outer layer metal melt on an inner surface thereof. The method of manufacturing the body of the body.