JPS59127911A - Rolling roll having tough neck part - Google Patents

Abstract

PURPOSE:To assure tensile strength of 50-60kg/mm.<2> in the core part and neck part of a cylindrical shaft in a composite high Cr roll having a slender neck shape by interposing an intermediate layer of a specific material between a cylindrical shell part and the core part of the cylindrical shaft. CONSTITUTION:The cylindrical shell part (a) of a roll having a slender neck shape wherein the ratios lN/lB, lB/DN of a neck length and cylindrical length or neck diameter are respectively 0.8-1.2, 3.8-13.0 consists of high-Cr steel contg., by wt%, 2.0-3.2 Cr, 0.5-1.5 Si, 0.5-1.5 Mn, <=0.08 P, <=0.06 S, 0.5-2.0 Ni, 10- 25 Cr, 0.5-3.0 Mo, <=1.0 V and <=1.0 Nb. The core part (c) of a cylindrical shaft and neck part (d) consist of a ductile cast iron contg. 2.8-3.8 C, 1.8-3.0 Si, 0.3-1.0 Mn, <=0.1 P, <=0.02 S, <=2.0 Ni, <=1.5 Cr, <=1.0 Mo and 0.02-0.1 Mg. An intermediate layer (b) consisting of a steel contg. 1.0-2.5 C, 0.5-1.5 Si, 0.5-1.5 Mn, <=0.1 P, <=0.1 S, <=1.5 Ni, 3.0-10 Cr, <=1.0 Mo and <=0.1 Ti is interposed between the parts (a) and (c) and the above-mentioned three parts are united by welding to one body.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the provision of a composite roll suitable for a rolling roll having an elongated neck shape, a special shape requiring particular toughness at the neck end, and usage characteristics. Concerning an improved version of chrome roll.

Because the required properties of the body and neck of rolling rolls are different, composite rolls are often used in which the body outer shell, body shaft core, and neck are made of different materials. In recent years, new types of hot strip mills for rolling steel plates have emerged to control the shape of steel plates. In other words, these methods include a method of shifting (moving) the work roll in the axial direction, a method of forcibly bending the work roll, or a method of making two work rolls cross with respect to the axis of the pick-up roll. Method etc.

Therefore, work rolls used in these rolling methods tend to have smaller body diameters.

Due to the type of rolling mill, the neck length must be longer than that of conventional rolls, and the diameter of the neck must also be smaller. In addition, in this type of roll, greater stress is generated in the neck portion than in the past, and particularly toughness is required.

The conventional general shape roll is shown in Figure 1, and the special shape roll used for the above new rolling method is shown in Figure 2 in comparison, and the specific differences in shape and dimensions are summarized as follows. .

/! HeH/IBDN 1rI)ti DBly
:*') Rilong (+iv), I! B: Torso length (W
m), DN: Neck diameter (cap, C: body diameter (IK-
) As mentioned above, the rolls used for this new rolling method usually have a neck length to body length ratio eH/b of 0.8 to 1.2 or a neck length to neck diameter ratio l! H/'[)H is 3,8~
It is characterized by an elongated neck shape in the range of 13.0 mm.

By the way, the use characteristics of the body and the neck as a whole are also different for such specially shaped rolling rolls, and as shown in Fig. 3, the body (1) in contact with the rolled material has wear resistance. , roughness resistance, crack resistance, etc. are required.

On the other hand, the required characteristics of the neck part differ further in the axial direction, with the bearing part (2) near the body part ft) requiring wear resistance and toughness against friction with the bearing, and the other part requiring wear resistance and toughness against friction with the bearing part (1). The neck end (3) remote from the neck is elongated in shape and requires particular toughness because it must withstand large stresses.

As shown in Figures 2 and 3, in the specially shaped roll with a trench, there is a part of the neck end (3) that is smaller in diameter than the neck diameter DH, and depending on the rolling method, for example, the work side [At Wl, large thrust stress is generated, and the drive side (
In D), a large torsional stress is generated, so this part requires particularly strong toughness.

In this way, the present invention has a neck length to body length ratio 1xi/ln of 0.8 to 1.2 or a neck length to neck diameter ratio IH/'D.
It has an elongated neck shape with H of 5.8 to 13.0,
This product provides a composite roll that is compatible with special rolling rolls that generate large stress at the neck end.The outer shell of the roll is made of high chromium material, and the shaft core and neck are made of ductile cast iron. To provide an improved high chromium roll which is made of aluminum and which has an intermediate layer of a specific material interposed between the trunk outer shell part and the trunk shaft core part to ensure the toughness of the trunk shaft core part and the neck part. It is something.

Conventionally, adamite material and high chromium material are generally used for work rolls for hot strip mill finishing front stands. However, in rolling methods that aim to improve the quality of sheet materials and save energy, the contact stress applied to the roll body is 150 to 2, compared to the conventional contact stress of 90 to 130.
The compressive yield stress of adamite material is low (50 to 90 KyyW), which causes dents and plastic flow on the surface of the spacer cylinder, causing a problem of significantly deteriorating the roughness resistance. ing.

On the other hand, from the perspective of compressive yield stress, high chromium material is 130
It has a compressive yield stress of ~16o K9A+J, and therefore, from the rolling conditions of high surface pressure, it can be said that the high chromium roll is a heavy roll material to prevent dents and plastic flow.

Next, from the viewpoint of the toughness of the roll itself, adamite material generally has a tensile strength of 50 to aoK9AJ, which is satisfactory for the toughness required for the neck end. On the other hand, in the case of high chromium rolls, in order to make the core material strong, it is necessary to use ductile cast iron as the core material, so-called composite rolls. However, even if the shaft core material is made stronger, the outer shell of this type of roll is made of a high-chromium material, so chromium diffuses from the outer shell into the ductile cast iron material that forms the shaft core and neck. As a result, extreme embrittlement is inevitable, and in order to ensure toughness, it is necessary to reduce and prevent chromium contamination as much as possible.

The present invention improves the high chromium roll from this point of view and provides one that meets the usage characteristics of the special rolling roll having the above-mentioned elongated neck shape.

That is, in the composite roll according to the present invention, as shown in FIG.
In order to prevent Cr from being diffused and mixed into the core part fQl, an intermediate layer (bl) having an appropriate thickness is interposed.

Here, the high chromium cast iron material forming the shell outer shell (al) is
C2,0-3,2, SiO,5-15, Mn 0.5
~1.5, PO, 08 or less, SO, 06 or less, Ni
O, 5-2,0, Cr1O~25, MoQ, 5~3.
0, ■ 1.0 or less, Nb 1.0 or less in each weight % T, and the remainder substantially consists of Fe. In addition, the ductile cast iron material forming the trunk shaft core part ←) and neck part (al (dl) is C2.8~3.8, Si 1.8~3.0
, Mn O, 3 to 1.0, PO, 1 or less, SO, 02
Below, Ni 2.0 or less, Or 1.5 or less, Mo 1
．． 0 or less, containing Mg 0.02 to 0.1 in each weight%,
The remainder essentially consists of Fe.

Regarding the material forming the intermediate layer (bl), C1.0 to 2.5, MBf, etc. are used for the purpose of preventing Cr from being mixed into the shaft core material and ensuring the toughness of the intermediate layer itself.
f5$-127911(3) SiO,5-1,5, Mn 0.5-1.5, po
, 1 or less, SO, 1 or less, Ni 1.5 or less, Cr
3.0-10, Mo1. It is specified that it contains Q or less, TiO, 1 or less in each weight%, and the remainder consists essentially of re.

By interposing the intermediate layer as described above and integrating the three parts of the body shell, the intermediate layer, and the shaft core by welding, the body shell exhibits the necessary characteristics as a roll-use layer. On the other hand, the trunk core and neck have a tensile strength of 50 to 50, which is suitable for use with special rolls with elongated neck shapes.
Toughness of 6oKy/na is ensured.

The reason for limiting the range of components of the outer shell, intermediate layer and core material is as follows.

Outer shell> C should be determined by the desired amount of carbide while keeping a balance with Or within the range that stabilizes the (Fe-Cr)7C3 type carbide, but if it is less than 2.0%, the amount of carbide will decrease. If the content exceeds 3.2%, the amount of carbides becomes too large, resulting in significant deterioration of mechanical strength, especially toughness. Therefore, C is defined as 2.0 to 3.2%.

Sl is necessary for deoxidizing the molten metal, and if it is less than 0.5%, it has no effect, while if it is contained in more than 1.5%, it causes deterioration of PA properties and also causes Arc metamorphosis. Lower hardness becomes difficult to obtain. Therefore, the S1 content is 0.1~
The range is 1.5%.

Mn is required to have a content of at least 0.5% as an aid to deoxidizing Si, and if it is less than 0.5%, there is no deoxidizing effect. However, if the content exceeds 1.5, mechanical properties, particularly toughness, will deteriorate significantly.

Therefore, the Mn content is also set in the range of 0.5 to 1.5%.

Particularly in the roll material, P is an element that is preferably as small as possible, and from the viewpoint of making the material brittle, it should be kept at 0.08% or less.

Like P, S makes the roll material brittle, so the smaller the amount, the heavier it is, and its content should be 0.06% or less.

N1 is included to improve hardenability and actively adjust hardness, and if it is less than 0.5%, it has no effect;
．． If the content exceeds 0%, residual aus Nhl.

Tenite increases and hardness becomes difficult to increase. Therefore, N
1 content is in the range of 0.5 to 2.0%.

Cr is used to improve toughness and wear resistance, but if its content is less than 10%, many M3C type carbides will be produced, making it impossible to obtain toughness and fine uniformity of carbides.
Moreover, if the content exceeds 25%, the amount of M2SO4 type carbides increases. This carbide has lower hardness than the M7C3 type carbide and cannot provide sufficient wear resistance. In the present invention, as the range in which M and C3 type carbides occur, the Cr content is defined in a range of 10 to 25%, in balance with the above defined range of C content.

Mo increases the quenching and tempering resistance and at the same time enters into the carbide and is effective in increasing the hardness of the carbide and promoting the tempering softening resistance.If the content is less than 0.5%, this effect is small; However, if the content exceeds 3.0%, residual austenite will stabilize in the matrix, which will actually cause a decrease in hardness. Therefore, the MO content is set in the range of 0.5 to 3.0%.

The outer shell material contains each of the above components in weight percent, and basically the remainder is substantially composed of Fe, but other components other than the above-mentioned tooth 11, which are added as supplements and are particularly effective, include: The following Nb and V can be mentioned.

Nb is effective in refining the casting structure, and the inclusion of Nb promotes precipitation hardening and improves wear resistance.
This effect exists when the Nb content is less than 1.0%, and 1.0%
If this value is exceeded, this effect will become saturated and the cost will increase.

Therefore, the Nb content is set to 1.0% or less.

V is contained for the same purpose as Nb, and in particular, the V content may be less than 1.0%, and if it is contained in excess of 1.0%, V carbide increases, resulting in poor toughness and deterioration. . Therefore,
The content of V is 1.0% or less.

Middle layer> Next, the middle layer will be explained. This intermediate layer is interposed between the first outer shell and the second inner shell, and Cr is mixed and diffused from the outer shell made of high chromium material to the inner shell (shaft core), and the inner shell material has a high chromium content. The purpose of this is to prevent deterioration of toughness due to Orization. The range of each component of the intermediate layer material and the reason for its limitation will be explained as follows.

First, the C content is in the range of 1.0 to 2.5% when it is partially mixed with the outer shell, that is, when it is a product.

When casting the molten metal in the middle layer, if it is cast on the inner surface of the outer shell, a part of the inner surface will be melted and the C content of the middle layer material will fluctuate (increase), and the amount of melt in the outer shell will be completely uniform in the middle layer. When mixed, the C content increases, so care must be taken. The reason for limiting the above components is that when C is 1.0% or less, the casting temperature of the intermediate layer becomes high, the outer shell becomes easy to melt, the amount of Cr mixed into the intermediate layer further increases, and the inner shell of Cr ( This is because the reason for the existence of the intermediate layer is lost in order to prevent diffusion to the axial core part), and if the carbon content exceeds 2.5%, the amount of carbides increases, and the toughness of the intermediate layer itself deteriorates. This is because the purpose of existence will be lost.

Sl has a deoxidizing effect on the molten metal and is necessary in an amount of 0.5% or more, but if it exceeds 1.5%, it becomes brittle and deteriorates the mechanical properties of the intermediate layer, so it should be added in an amount of 0.5 to 1. The range shall be 5%.

Mn also has the same effect as Sl, and Mn81
0.5% or more is necessary to eliminate the negative effects of S as 13, but if it exceeds 1.5%, the effect is saturated and also,
Since it causes deterioration in mechanical properties, the content is set in the range of 0.5 to 1.5%.

P increases the fluidity of the molten metal, but in roll materials it reduces the toughness of the material, so it is kept at 0.1% or less.

Like P, S also makes the roll material brittle, so it should be kept at 0.1% or less without causing any actual damage.

Although N1 is contained in an amount of 0.1% or more due to contamination from the outer shell material even if it is not added separately, Ni0 content up to 15% does not pose a problem. However, if it exceeds 1.5%, the hardenability will improve, but this will make the matrix too hard, which is undesirable from the standpoint of toughness, and will also increase residual stress, so it is regulated to 1.5% or less. There is a need.

Regarding Cr, the Cr content of the product component is 3.0~
It is said to be 10%. That is, about 3.0% of the content is inevitably due to diffusion from the high chromium outer shell material. However, if the Cr content exceeds 10%, the material deterioration of the intermediate layer 14 itself becomes significant. In addition, in this case, it is necessary to regulate the Cr content of the intermediate layer molten metal to a certain value or less.

MO has the same effect as N1, but if it is contained in an amount of 1.0% or more, the intermediate layer becomes too hard, so it is limited to 10% or less as a range that does not cause any actual damage.

The intermediate layer material contains the above-mentioned components in respective weight percents, and basically the remainder is substantially composed of Fe, but Ti can be added as a deoxidizing agent among other components other than the above-mentioned components. That is, since the material of the intermediate layer is relatively easily oxidized, by adding less than 10.1% of T and deoxidizing it, a more sound intermediate layer can be obtained.

Next, the shaft core material of the roll according to the present invention will be explained. This shaft core material is made of so-called spheroidal graphite cast iron, and the range of each component and the reason for the limitation will be explained as follows. As for the core material, during casting, a part of the inner surface of the previous intermediate layer is washed and welded, so it is necessary to take into consideration the amount of washing when determining the molten metal composition at NQ15 when casting the inner shell.

In the case of spheroidal graphite cast iron, C melts into the matrix and becomes graphite. (In some cases, a portion becomes eutectic cementite.) When the C content is less than 2.8%, melting and casting temperatures become high, resulting in increased costs. On the other hand, if it exceeds 3.8%, the toughness will deteriorate.

Therefore, C is defined as 2.8 to 3.8%.

Have difficulty. However, if the content exceeds 3.0%, Sl dissolved into the ferrite tends to deteriorate the toughness of the material. Therefore, the S1 content is in the range of 1.8 to 3.0. It is generally known that inoculating 81 immediately before casting in order to promote graphitization brings about good results, and in the present invention, this technology is applied to the production of 81, and inoculation immediately before casting CaSi etc. can be added.

Mn combines with S and acts as MnS to remove the negative effects of S, but if it is less than 0.3%, this effect cannot be obtained, while if it exceeds 1.0%, the toughness of the material will deteriorate significantly. , its content is in the range of 0.3 to 1.0%.

P increases the fluidity of the molten metal, but since it makes the material brittle, it is preferably as low as possible, and is set at 0.1% or less.

Like P, S makes the material brittle, so the lower the content, the better, and should be 0.02% or less.

N1 is effective in slowing down the transformation of the material and making it tougher, but 2.0
% or less is necessary and sufficient.

Since the outer shell of Cr is a high chromium material, it is unavoidable that some amount of Cr will be mixed into the inner shell as the outer and inner shells are welded together, and care must be taken to dispose of this, especially when determining the composition of the inner shell molten metal. . This varies depending on the outer shell components, inner shell components, and casting conditions, but it is appropriate that the Or content of the inner shell as a product is 1.5% or less. In other words, Cr is effective in making the material tougher, but if it exceeds 1.5%, it becomes difficult for graphite to crystallize, which actually deteriorates the toughness.

Like N1, MO is an important element in ensuring toughness, but if it exceeds 1.0%, it becomes hard and becomes brittle, so the MO content should be 10% or less.

Mg is necessary for spheroidizing graphite, and must be contained in an amount of 0.02% or more in order to prevent defective spheroidization during solidification and to make the core material a strong ductile cast iron material. But 0
．． If it exceeds 1%, problems arise due to the chilling effect of Mg and the appearance of dross, which is not preferable.

Next, examples of the composite roll according to the present invention will be described.

Body diameter 50φ, body length 1800/, neck length 2100
I! , when the neck end diameter is 250φ, iH/eB=1.
17, eN/l! Each roll with D = 8.4 was cast by centrifugal casting. The chemical composition of each part and the tensile strength and elongation of the neck part are summarized in the table below.

The core of each roll was inoculated with Q3 at 81 minutes during casting in order to ensure the toughness of the neck, and the amount of the component shows the value after inoculation. Regarding the thickness, it is based on test pieces taken at each 250φ position.

Hermitage 18 1 l') l l>I I ritsugu
3°.

++R++ Bath 1 1 Plan 0
nohe tube.

(Company) I I LOt
Ill 110 0
0+ 1 Swamp + +F+ +
$ + clear 1 8 Lu 8 宕 ＞l l I”I + 書 11 TomohōQ Zhong 1 ″ ″ 1 ″ 1 eye 1 ′ Tochi.

To Nikuchi 8 Kuchi Shinme 8388 ≠ Fortune CJ 宕 8 Ka 5 yen Exit '6
'l J+4. , υ 0 to υ ■ size
To He OA χ True CA 8th 315
Eyes Sa5 eyes Haneko eyes 88 baths 8 譬tun 山 8 き 言 Tomamiya 3 ゝ ゝ 1clcl
d ” Iris 53 eyes 8 eyes 3 eyes feathers 88- minutes 6
To the book of horse folklore 3. 3. Horsemanship Fan/Fang 1. Agony Moss
Shin Hi Hi 3 Araki Itsuki II! A dirt II
! A. 1C. Nozomi Touge, Sugi.

For reference, the compressive yield stress value of the outer shell of the trunk was also shown as follows. In other words, although the measured value varies somewhat depending on the heat treatment conditions, ■15B vertical-1■145
K9/fl and ■165 hit, both of which exceeded the standard target compressive yield stress value 1 rs o Ky/+J.

As described above, in the improved high chromium roll of the present invention, the compressive yield stress of 120 to 160 K9/d, which is necessary to withstand high surface pressure, can be secured in the outer shell part of the body, and
The shaft core material, particularly the neck portion, can satisfy the toughness required for the neck end, and can be adapted to the use of the specially shaped rolling roll described above. That is, especially at the neck end, the tensile strength is 50 to 6o Kp/J, and the elongation is 0.
5 to 1.0 can be satisfied.

In addition, in the case of conventional high chromium rolls in which the outer shell part and the shaft core material are directly welded, it is difficult to prevent the diffusion and mixing of Or, and the above-mentioned toughness cannot be ensured. This is because if we deliberately reduce the amount of Cr welded in order to suppress the amount of Cr mixed in and diffused, 'pI 127911
(6) This is because the defective rate increases due to poorly welded skin.

The high chromium material used for the outer shell of the body usually has a Young's modulus of 21.
000 Qz&J, and the ductile cast iron of the blade shaft core material is about 16000 to 1'70006/-, but when the two are directly welded, stress tends to concentrate at the welded part, so this shield, an intermediate layer, was used. It is also advantageous in terms of accident resistance.

Specific examples of specially shaped rolls with elongated neck portions to which the present invention is directed include work rolls for 6Hi mills, work rolls for cross rolling, and the like, in addition to the work rolls for hot strip mills listed above.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of the shape of a conventional rolling roll, and FIG. 2 is a side view showing an example of the shape of a rolling roll to which the present invention is applied. FIG. 3 is a partially enlarged side view of a rolling roll to which the present invention is applied, and FIG. 4 is a half-sectional side view showing an example of the structure of the rolling roll according to the present invention. (al... trunk outer shell part, (bl... middle layer, [ol/
...Body axis, @) 21 Figure 7 Figure 2 Figure 3 Procedural amendment (voluntary) 1 Indication of the case 1988 Patent Application No. 48!4 No. 2 Invention
The name of the strong rolling roll 3 at the neck part, relationship with the person making the amendment case. Clock applicant Idllttsu I11# (Otori 05) Kubota Tekkorinshiki Company 4, agent Tatami 577 [lv/DN] is corrected. . 59-

Claims (1)

[Claims] 1. The ratio IH/IB of neck length to torso length is 0.8 to 1.2.
, or the ratio of neck length to neck diameter lH/'DH is 3.8~
In a roll that has a long and narrow neck shape of 13.0 and requires particular toughness at the neck end, the outer shell of the body is made of C2, 0 to 3.2, SiO, 5 to 1.5.
, Mn 0.5-1.5, P O, 08 or less, so,
oa or less, Ni O, 5-2,0, Cr1Q-25, M
o 0.5-3.0, V 1.0 or less, Nb 1.0 or less in each weight%, and the balance is made of Fe. , C2,8~3.8,S
i L, S ~3.0, Mn O, 3 ~ 1.0, P O
, 1 or less, SO, 02 or less, Ni 2.0 or less, Cr
1.5 or less, Mo, 1. Q or less, MgO102~0.
C1,0 to C1,0 to C2 between the shell outer shell and the barrel shaft core.
．． 5, SiO, 5-1.5, Mn 0.5-1.5,
PO11 or less, 2 SO,1 or less, Ni 1.5 or less, Cr3. O~YuQ
, Mo1. Q and below, an intermediate layer containing 0.1% by weight or less of Ti and the remainder substantially Fe is interposed, and these three are welded and integrated, and the trunk axis and neck part are provided with tensile strength. A rolling roll having a strong neck portion, which is characterized by ensuring a diameter of 50 to ao KgAJ.