WO2006126678A1

WO2006126678A1 - Roll for rolling seamless pipes

Info

Publication number: WO2006126678A1
Application number: PCT/JP2006/310563
Authority: WO
Inventors: Kunio Goto
Original assignee: Sumitomo Metal Industries, Ltd.
Priority date: 2005-05-27
Filing date: 2006-05-26
Publication date: 2006-11-30
Also published as: JP4710904B2; EP1894641A4; BRPI0611407B1; BRPI0611407A2; JPWO2006126678A1; EP1894641B1; EP1894641A1

Abstract

A roll for rolling seamless pipes which has a roll neck and a roll body, wherein the surface layer of the roll body comprises by mass: C: 1.5 to 2.5%, Si: 1.3 to 3.5%, Mn: 0.1 to 2.0%, Ni: 0.5 to 8.0%, Cr: 0.1 to 2.0%, Mo: 0.2 to 5.0%, V: 0.1 to 5.0%, W: 0.1 to 5.0%, Nb: 0.1 to 5.0%, and Co: 0.05 to 2.0% with the balance being Fe and impurities, and further contains 0.5 to 5.0% of graphite by area ratio. The roll has high abrasion resistance and excellent biting properties.

Description

Specification

Seamless pipe rolling roll

Technical field

[0001] The present invention relates to a roll, and more particularly to a seamless pipe rolling roll used for seamless pipe piercing or rolling.

Background art

[0002] A roll used in a rolling process for covering a material into a predetermined shape is required to have wear resistance in order to improve the life of the roll. Moreover, in order to improve the surface quality of the workpiece, the roll is required to have seizure resistance. As a roll having improved wear resistance and seizure resistance, a high speed roll as disclosed in Japanese Patent No. 3219987 has been developed. High-roll is mainly used for plate rolling, which has a very high surface hardness.

[0003] On the other hand, a roll for seamless pipe rolling used in the manufacture of seamless pipes by the Mannesmann method is required to have squeezing properties. For example, when piercing material with a piercer, a pair of piercer rolls 1 comes into contact with material 2 and swallows material 2 as shown in FIG. The swallowed material 2 is perforated in the axial direction by the plug 3 while rotating in the circumferential direction. When piersaroll 1 contacts material 2, the contact area between piersaroll 1 and material 2 is very small. Therefore, it is easy for material 2 to slip into the stagnation. Therefore, seamless pipe rolling rolls such as piercer rolls and erogenator rolls are required to have excellent penetration.

[0004] Conventionally, rolls for seamless pipe rolling have been improved in hardness by reducing the hardness of the roll surface. However, reducing the hardness of the roll surface reduces wear resistance and shortens the life of the roll. In particular, when high alloy steel or stainless steel is pierced and rolled, the amount of wear of the seamless pipe rolling roll increases. Therefore, it is necessary for the roll for seamless pipe rolling to satisfy both the penetration property and the wear resistance.

[0005] Japanese Patent Application Laid-Open No. 10-81937 discloses a seamless pipe rolling forging roll excellent in penetration and wear resistance. The roll disclosed in this document has large spherical carbides in the base. As the roll wear progresses, spherical carbides are exposed on the surface and the mouth Since the surface of the tool is in a certain rough state, it is said that the squeezing property is improved.

[0006] However, it is considered difficult to improve the stagnation property only with the exposed spherical carbide.

Disclosure of the invention

[0007] An object of the present invention is to provide a seamless pipe rolling roll having high wear resistance and excellent squeezing properties.

[0008] The present inventor has considered that if a predetermined amount of graphite is generated at the base of the roll, the penetration property is improved. When a roll that produces graphite is used for the base, the graphite is exposed on the surface as the surface wears. The graphite exposed on the surface easily peels off and falls off the surface. Therefore, moderate unevenness is formed on the roll surface. By forming the irregularities, the roll penetration is improved.

[0009] On the other hand, in order to improve wear resistance, it was considered important to produce a high-hardness composite carbide. This is because even if the base is worn, the wear of the roll can be suppressed by contacting the workpiece with the high-hardness composite carbide exposed on the surface. For this reason, it was considered necessary to add V, W, and Nb to form high-hardness carbides.

[0010] Based on the above technical idea, the following invention has been completed.

[0011] A seamless pipe rolling roll according to the present invention is a seamless pipe rolling roll provided with a roll neck and a roll body, and the surface layer of the roll body is in mass%, C: l. 5 to 2.5%, Si: 1.3 to 3.5%, Mn: 0.1 to 2.0%, Ni: 0.5 to 8.0%, Cr: 0.1 to 2.0% , Mo: 0.2 to 5.0%, V: 0.1 to 5.0%, W: 0.1 to 5.0%, Nb: 0.1 to 5.0%, Co: 0.05 It contains ˜2.0%, the balance is Fe and impurity power, and contains 0.5 to 5.0% graphite by area ratio.

Here, the seamless pipe rolling roll is a roll for piercing or rolling the seamless pipe. The rolls for seamless pipe rolling are, for example, cone-type or barrel-type piercer rolls, Elongage taro nore, mandreno ronoro ole, rede usa ronole and sizaron nore.

[0013] The seamless pipe rolling roll according to the present invention includes graphite having an area ratio of 0.5 to 5.0% in the base. Since the graphite exposed on the surface is easily peeled off, irregularities are formed on the surface and the penetration is improved. The seamless pipe rolling roll according to the present invention further comprises: Includes MC type high-hardness composite carbides such as V carbide, W carbide and Nb carbide. for that reason

The wear resistance can be improved by the high hardness composite carbide.

[0014] Preferably, the surface layer of the roll body has a Shore hardness of 30 to 50.

In this case, the wear resistance can be further improved by setting the Shore hardness (Hs) of the surface layer to 30-50. Even if the Shore hardness of the surface layer is 30 to 50, irregularities are formed on the roll surface by graphite, so that the penetration property can be secured.

Brief Description of Drawings

FIG. 1 is a diagram for explaining perforation of a material by a piercer.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail.

[0018] 1. Role configuration

The seamless pipe rolling roll according to the present embodiment includes a roll neck and a roll body. The seamless pipe rolling roll is a roll used for seamless pipe piercing or rolling. Specifically, cone-type and barrel-type piercer rolls, elongator rolls, mandrel rolls, reducer rolls, and sizer rolls.

[0019] The seamless pipe roll may be an integrated roll manufactured as a roll neck and roll body, or the inner (inner layer) of the roll body and the surface layer (outer layer) are made of different steel types. It may be a composite roll. Preferably, the surface layer has a depth of at least 1% of the radius of the roll body from the roll surface, and more preferably has a depth of at least 5% of the radius of the roll surface force roll body. In the case of a composite roll, the surface layer preferably has a depth of at least 50% of the outer layer thickness from the outer layer surface.

[0020] 2. Chemical composition

At least the surface layer of the roll body of the seamless tube rolling roll has the following chemical composition. Here, the surface layer of the roll body portion is a portion of the roll body portion that is used for drilling or rolling the target material, and has a surface force of the roll body portion having a predetermined depth. is there.

Henceforth,% regarding an element shows the mass%.

[0021] C: l. 5 to 2.5% C crystallizes out as graphite and improves the roll penetration. In addition, C combines with V, W, and Nb, which will be described later, to produce MC-type high-hardness composite carbides, improving the wear resistance of the roll. However, if C is contained excessively, composite carbides are produced excessively, and the roll penetration is reduced. In addition, excessive graphite is produced, which reduces wear resistance and makes the base brittle. Also, excessive inclusion of C decreases the heat cracking resistance. Therefore, the C content is 1.5 to 2.5%.

[0022] The crystallization of graphite in the matrix can be suppressed by carbide forming elements (V, W, Nb, etc.) that preferentially consume C contained in the molten metal. Considering the balance between the amount of graphite produced in the matrix and the amount of high-hardness carbide, the preferable C content is 1.9 to 2.5%.

[0023] Si: l. 3 ~ 3.5%

[0024] Si deoxidizes the molten metal. Si also improves the flow of molten metal. Si is an element necessary for crystallizing or precipitating graphite. However, excessive Si content produces excessive graphite and reduces wear resistance. Furthermore, if Si is contained excessively, mechanical properties such as toughness are lowered. Therefore, the Si content is 1.3 to 3.5%. A preferable Si content is 1.3 to 2.2%.

[0025] As will be described later, it is preferable that a Si content of 0.2 to 1.0% of the Si content is added at the time of pouring U. The other amount of Si is added to the melt before pouring.

[0026] Mn: 0.1-2.0%

Mn deoxidizes the molten metal. Furthermore, Mn combines with S in the steel to produce MnS and suppresses embrittlement of the base. However, if Mn is contained excessively, toughness decreases. Therefore, the Mn content is set to 0.1 to 2.0%.

[0027] Ni: 0.5 to 8.0%

Ni dissolves in the base and improves strength. Ni further promotes crystallization of graphite. However, if Ni is contained excessively, graphite is excessively generated and wear resistance is lowered. Therefore, the Ni content should be 0.5 to 8.0%. A preferable Ni content is 0.9 to 4.0%.

[0028] Cr: 0.1-2.0%

Cr dissolves in the base and improves strength. Cr is further combined with C to have high hardness of MC type

7 3

Precipitates composite carbide to improve wear resistance and toughness. However, if it contains excessive Cr MC type composite carbide is excessively generated, so graphite and MC type composite carbide

7 3

Production is inhibited. The hardness of the MC type composite carbide is equal to the hardness of the MC type composite carbide.

7 3

Therefore, if Cr is excessively contained, the wear resistance may be reduced. Therefore, the Cr content should be 0.1-2.

[0029] Mo: 0.2-5.0%

Mo dissolves in the base to increase the high temperature soft resistance. Mo is further combined with C to form M C

It produces composite carbides such as No. 6 and MC type, and improves wear resistance. However, excessive Mo content

2

If present, the formation of graphite is inhibited. Therefore, the Mo content is set to 0.2 to 5.0%. A preferable Mo content is 0.5 to 4.5%.

[0030] V: 0.1-5.0%

V combines with C to form MC-type high-hardness composite carbide, improving wear resistance. V further refines crystal grains and improves toughness. However, if V is contained excessively, the formation of graphite is inhibited. Therefore, the V content is 0.1 to 5.0%. The preferred V content is 0.2 to 4.0%.

[0031] W: 0.1-5.0%

W combines with C to form a high-hardness composite carbide, improving wear resistance. Furthermore, W dissolves in the base and increases the high temperature softening resistance. However, if w is excessively contained, the formation of graphite is inhibited. In addition, toughness reduces heat cracking resistance, and prejudice tends to occur. Therefore, the W content should be 0.1 to 5.0%.

[0032] Nb: 0.1-5.0%

Nb combines with C to form MC-type high-hardness composite carbide, improving wear resistance. Nb further refines crystal grains to improve toughness and heat cracking resistance. However, excessive Nb content inhibits the formation of graphite. Furthermore, if Nb is excessively contained, toughness and thermal cracking resistance are reduced. Therefore, the Nb content is 0.1 to 5.0%. A preferable Nb content is 0.1 to 4.5%.

[0033] Co: 0.05-2.0%

Co dissolves in the base to increase the base hardness and resistance to high-temperature softening and improve wear resistance. However, if Co is excessively contained, carbide prayers tend to occur and the toughness of the base Decreases. Therefore, the Co content should be 0.05-2.0%.

[0034] The balance may contain impurities such as forces P and S composed of Fe.

[0035] Since P and S deteriorate the mechanical properties, the content of these elements should be low.

. Therefore, the P content is preferably 0.2% or less, and the S content is preferably 0.2% or less.

[0036] It should be noted that impurities other than P and S may be included due to various factors in the manufacturing process.

[0037] 3.Organization

[Amount of graphite]

The surface layer of the roll body of the seamless pipe rolling roll according to the present embodiment contains graphite. The area ratio of graphite contained in the surface layer is 0.5 to 5.0%.

[0038] The area ratio of graphite can be measured by the following method. Select an arbitrary area on the surface of the body of the roll for seamless pipe rolling. Using an optical microscope or scanning electron microscope (SEM), measure the area ratio of graphite in the selected area. For the measurement of the area ratio of graphite, for example, etching is used! /, A metallographic image of the state or image analysis using a photograph is used.

[0039] The graphite exposed on the roll surface is easily peeled off and the roll surface force is lost. Therefore, irregularities are formed on the roll surface. Even if the roll surface is worn, the graphite exposed on the surface layer is peeled off due to wear, and irregularities are always formed on the roll surface. This concave / convex shape improves the squeezing property. In addition, graphite has a lubricating action and prevents the occurrence of seizure on the roll surface.

[0040] If the area ratio of graphite is less than 0.5%, the amount of graphite is small, so that it is difficult to form irregularities on the surface. Therefore, the squeezing property is reduced. On the other hand, if the area ratio of graphite exceeds 5.0%, the roll base becomes brittle and wear resistance decreases.

[0041] The shape of the graphite is not particularly limited! It can be spherical! /, And it can be flaky! /.

[0042] [Hardness]

The Shore hardness of the surface layer of the seamless pipe roll is preferably 30-50 (Hs)! /. This is because if the Shore hardness is too low, the wear resistance is lowered, and if the Shore hardness is too high, the penetration property is lowered. If the Shore hardness is 30-50, high wear resistance can be obtained, and the penetration can be maintained by graphite. In addition, the Shore hardness of the roll for seamless pipe rolling Even if the degree is out of the above range, if it has the above chemical composition and graphite with the above area ratio, the penetration property and the wear resistance are improved as compared with the conventional case.

[0043] The Shore hardness of the surface layer can be measured by the following method. The Shore hardness test CFISZ2240) is conducted in multiple areas on the surface of the roll body for seamless pipe rolling. The average of the measured values obtained in multiple areas is the Shore hardness.

[0044] The chemical composition and structure described above may be at least filled with the surface layer of the roll body, but the entire roll body force may be the above-described chemical composition and structure, or the entire roll may be the above-mentioned. The chemical composition and organization of the!

[0045] 4. Manufacturing method

The seamless pipe rolling roll according to the present embodiment may be manufactured as an integral roll or a composite roll.

[0046] [Method of manufacturing integrated roll]

When the seamless pipe rolling roll according to the present embodiment is manufactured as an integral roll, the seamless pipe rolling roll is manufactured by stationary forging or forging.

[0047] In order to reduce the area ratio of graphite to 0.5 to 5.0%, the following conditions (A) and (

It is preferable to satisfy B).

[0048] (A) At the time of swallowing, the cooling rate up to just above the solidus in the phase diagram is made slower than the normal cooling rate. This is because graphite is produced in the vicinity of the solidus, so that if the cooling rate is slow, the amount of graphite produced can be increased.

[0049] (B) Inoculate at the time of filling. Specifically, an inoculum containing Si (such as silicone) is added at the time of swallowing. Si contained in the inoculum serves as a nucleus for producing graphite. Therefore, a desired amount of graphite can be generated at the time of filling.

[0050] The ability to increase the amount of graphite by adding Si at the time of pouring If excessive Si is added at the time of pouring, coarse graphite is produced, and the mechanical properties of the seamless pipe rolling roll are reduced. To do. Therefore, the amount of Si added at the time of filling is preferably 0.2 to 1.0%. A more preferable Si amount is 0.2 to 0.6%.

[0051] Since Si is added at the time of pouring, the amount of Si added to the molten metal before pouring is set lower than the target component. In short, the Si content at the end of filling is the same as the Si content described in 2. Adjust the amount of Si to be added during melting and pouring.

[0052] In the manufacturing method described above, heat treatment is performed on the roll after staking or forging in order to remove the distortion of the roll and adjust the hardness. Specifically, quenching and tempering are performed. Preferably, after quenching is performed at a quenching temperature of 1000 to 1200 ° C, tempering is performed a plurality of times at a tempering temperature of 450 to 650 ° C. By this heat treatment, the Shore hardness of the surface layer of the seamless tube rolling roll can be made 30-50.

[0053] [Production method of composite roll]

When the seamless pipe rolling roll is manufactured as a composite roll, the outer layer material may have the chemical composition and structure described in 2. and 3. The inner layer material may be a generally used tough material such as ductile pig iron, ordinary pig iron, graphite pig iron, spheroidal graphite pig iron, forged steel, pig steel, and the like.

[0054] The composite roll is a continuous buildup method disclosed in, for example, centrifugal force forging method, Japanese Patent Publication No. 44-4903, etc., and is a continuous buildup method using high-frequency heating, Japanese Patent Laid-Open No. 47-2851. A method of forming an outer layer by hot isostatic pressure using a powder metallurgy method, a build-up method disclosed in JP-A-57-2862, Manufactured by overlaying method using slag melting.

[0055] It is preferable that the above conditions (A) and (B) are satisfied when the outer layer material is inserted. Moreover, the heat treatment after squeezing is performed in the same manner as in the method for producing an integral roll.

Example 1

[0056] Piercer rolls having various chemical compositions and graphite amounts were prepared and investigated for penetration and wear resistance of each piercer roll.

[0057] First, corn-type pierce rolls having the chemical composition shown in Table 1 were produced.

[table 1]

* Is outside the scope of the present invention

[0058] Specifically, molten steel having the chemical composition shown in Table 1 was produced by electric furnace melting. Subsequently, the molten steel was made into a steel ingot by the ingot-making method.

[0059] For roll numbers 1 to 16, an amount of Si of 0.2 to 1.0% by mass was added as an inoculum at the time of swallowing. On the other hand, for roll number 17, no inoculum was added at the time of filling. For roll number 18, a Si content of 1.5% out of a Si content of 2.8% was added at the time of mixing.

[0060] The manufactured steel ingot was forged to form a cone-type piercer roll. The formed roll was quenched and tempered, and the surface layer of the roll was given a Shore hardness (Hs) shown in Table 1. The Shore hardness was measured by the method described in 3. Further, the area ratio (%) of graphite on the surface of the formed roll was measured by the method described in 3. Table 1 shows the measured area ratio (%) of graphite.

[0061] The piercer roll manufactured in this example was an integral roll, and the gorge diameter was 410 mm.

[0062] Each role shown in Table 1 was incorporated into a piercer. The crossing angle of each roll was 0-30 °.

[0063] After incorporating the rolls, each roll number roll was drilled with 10 high alloy (25% Cr-35% Ni) billets with an outer diameter of 70mm and a length of 400mm. The wear resistance and seizure resistance were investigated. The survey results are shown in Table 2.

[¾2]

[0064] [Penetration]

When ten billets were drilled, the penetration was judged visually. The judgment results are shown in the “Smearability” column of Table 2. When all 10 billets were squeezed into a roll without slipping and perforated, it was judged that the squeezing property of the roll was very high (marked “◎” in Table 2). At least one of the 10 billets slipped with the roll, but if all of the billet was swallowed and perforated, it was judged that the roll was highly squeezed (“〇” in Table 2). mark). If at least one of the 10 billets did not squeeze into the roll and it was unable to perforate, it was judged that the squeezing property was low (“X” in Table 2).

[0065] [Abrasion resistance]

Of the rolls of each roll number, the wear amount _m ) of the roll was investigated for the rolls that could perforate all 10 billets. The survey results are shown in the “Abrasion” column of Table 2. The amount of wear was measured by the following method. The surface of the roll body was measured before drilling and after drilling 10 billets with a two-dimensional shape measuring instrument. Based on the measurement data before and after drilling, the maximum wear depth was determined, and the determined maximum wear depth (m) was used as the roll wear amount. “One” in Table 2 indicates that the wear resistance could not be evaluated due to the low penetration.

[0066] [Seizure resistance]

Of the rolls of each roll number, it was judged visually whether or not seizure occurred on the roll after punching of all the ten billets. The judgment results are shown in the “Seizure” column of Table 2. When a part of the drilled billet was not welded to the roll surface after drilling, it was judged that the seizure resistance was high (“◯” in Table 2). On the other hand, when a part of the billet was welded to the roll surface after perforation, it was judged that the seizure resistance was low. The “-” in Table 2 indicates that the seizure resistance was low and the seizure resistance could not be evaluated.

[0067] [Test results]

Referring to Table 1 and Table 2, the rolls of roll numbers 1 to L0 had high chemical penetration and graphite area ratio within the scope of the present invention, so that they all had high squeezing properties. The wear amount was less than 70 m, which was a little more wear resistant. [0068] Furthermore, the rolls with roll numbers 2 to 9 had a surface hardness (Hs) in the range of 30 to 50, so the amount of wear with very high penetration was less than 50 m. .

[0069] The rolls with roll numbers 1 to 10 all had high seizure resistance.

[0070] On the other hand, the rolls of roll numbers 11 to 18 had low chemical penetration or graphite area ratio, and therefore had low penetration and / or wear resistance. Specifically, roll No. 11 had a low penetration rate because the graphite area ratio with a low Si content was less than the lower limit of the present invention. In roll No. 12, the graphite area ratio in which the C and Si contents were low was less than the lower limit of the present invention, so that the squeezing property was low. In roll number 13, the graphite area ratio with a high C content exceeded the upper limit of the present invention. As a result, the wear amount exceeded 70 m, and the wear resistance was low. In roll No. 14, the graphite area ratio with a high Si content exceeded the upper limit of the present invention. Therefore, the wear amount exceeded 70 / z m and the wear resistance was low. Since roll number 15 had a low Ni content, the graphite area ratio was less than the lower limit of the present invention. As a result, the squeezing ability was low. Roll No. 16 had a high Cr, V, W, and Nb content that produced a high-hardness composite carbide, so the graphite area ratio was less than the lower limit of the present invention. For this reason, the squeezing ability was low.

[0071] Although the chemical composition of roll number 17 was within the scope of the present invention, the area ratio of graphite was less than the lower limit of the present invention because the inoculum was not added at the time of swallowing. As a result, the squeezing ability was low.

[0072] The chemical composition of roll number 18 was within the scope of the present invention and was similar to the chemical composition of roll number 9, but the amount of Si added at the time of pouring was as high as 1.5%. Therefore, the graphite area ratio exceeded the upper limit of the present invention. Therefore, the wear amount exceeded 70 / zm and the wear resistance was low.

[0073] Although the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit of the invention.

Industrial applicability

[0074] The roll for seamless pipe rolling according to the present invention is used at the time of seamless pipe piercing and rolling. It is widely available for rolls. In particular, it is suitable for barrel-type and cone-type piercer rolls in which the material is pierced and rolled in the axial direction while rotating in the circumferential direction.

Claims

The scope of the claims

A roll for seamless pipe rolling comprising a roll neck and a roll body,

The surface layer of the Ronole trunk is

Mass ^{_{0/0, C: l.5~2.5%}} , Si: l.3~3.5%, Mn:. 0 1~2.0%, Ni: 0.5~8 .0%, Cr: 0.1~2.0%, Mo : 0.2-5.0%, V: 0.1-5.0%, W: 0.1-5.0%, Nb: 0.1-5.0%, Co: 0.05-2.0%, the balance consists of Fe and impurities, and the area ratio is 0.5- A seamless pipe rolling roll characterized by containing 5.0% graphite. The seamless pipe rolling roll according to claim 1,

A roll for seamless pipe rolling, wherein the surface layer of the roll body has a Shore hardness of 30 to 50.