Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C37/00—Cast-iron alloys
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
  • B32B15/011—Layered products comprising a layer of metal all layers being exclusively metallic all layers being formed of iron alloys or steels
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49544—Roller making
  • Y10T29/4956—Fabricating and shaping roller work contacting surface element
  • Y10T29/49563—Fabricating and shaping roller work contacting surface element with coating or casting about a core
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12951—Fe-base component
  • Y10T428/12958—Next to Fe-base component
  • Y10T428/12965—Both containing 0.01-1.7% carbon [i.e., steel]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12951—Fe-base component
  • Y10T428/12972—Containing 0.01-1.7% carbon [i.e., steel]
  • Y10T428/12979—Containing more than 10% nonferrous elements [e.g., high alloy, stainless]

Definitions

• the present invention relates to a composite roll for rolling constituted by forming an outer layer material around a solid phase core material and a method for producing the same.
• Conventional hot-rolling rolls include high-alloy chromium with moderate wear and crack resistance of C 2 to 3.2%, Cr 12 to 18%, and Ni and Mo each of 2% or less.
• wear resistance in which each of C, Mo, W, and Co alloy elements is contained in C 2.4 to 3.5% and V 6.1 to 14%. ⁇ A steel roll material was tried, and the wear resistance was improved.
• the wear-resistant material disclosed in Japanese Patent Application Laid-Open No. 58-87249 has been confirmed to have better wear resistance than the conventional high chrome chromium iron and high alloy Glenn-iron. However, improvement in crack resistance is required.
• the rolling roll roll includes rough surface resistance and roll surface roughness.
• the smaller the surface roughness of the roll subjected to rolling the more beautiful the surface of the product rolled by this roll can be made, so that the surface roughness of the roll is reduced and the rough surface resistance is improved. It is strongly desired to do so.
• An object of the present invention is to provide a composite roll for hot rolling which is excellent in wear resistance, crack resistance, and particularly, surface roughness resistance in view of the above-mentioned circumstances.
• Another object of the present invention is to provide a composite forming method in which the roll is formed by cladding an outer layer material around a core material.
• the present inventors have conducted various studies to achieve the above-mentioned object, and in order to improve the above-mentioned properties of the above-described composite roll, steel having a specific component and a crystal structure is necessary.
• the present inventors have found that it is important to specify the cooling conditions (induction heating conditions as necessary) of the molten metal in the method of forming the composite roll, and have completed the present invention.
• the gist of the present invention is that the outer layer portion of the composite roll is composed of, by weight%, C: 1.5 to 2.4%, V: 3 to 6%, and at least one kind of Cr Mo or W. Contains 10 to 20% of elements, and if necessary, contains one or two elements of 0.05 to 0.20% or Ti: 0.02 to 0.10% as inoculant, with the remaining Fe and inevitable A steel consisting of impurities, wherein the structure of the outer layer has a grain size of 30 to 150; and a metal structure surrounded by a eutectic carbide crystallized at the grain boundary or the crystal structure of the crystal.
• the primary structure further includes a metal structure in which primary carbides are dispersed and crystallized.
• another gist of the present invention is that a molten metal composed of the above-mentioned component (1) is poured between a refractory frame and a core material to perform induction heating, and then the molten metal is formed by a water-cooled mold provided at a lower end of the refractory frame.
• the outer layer is formed by cooling and solidifying at an average solidification speed of 4 to 50% to form an outer layer portion, and then the integrated outer peripheral portion and core material are sequentially pulled out to produce a composite roll.
• the composite roll produced according to the present invention has its outer layer structure in which hard M 6 C carbides (particularly (Cr, o, W) 6 C carbides) are crystallized on a base structure (austenite structure) of fine crystal grains.
• VC carbides have a very fine structure and a base structure hardened by heat treatment (quenching and tempering) of the roll, so that it has a higher resistance than conventional hot rolling rolls. Rough skin It is possible to provide a roll having extremely excellent wear resistance and abrasion resistance.
• FIG. 1 is a diagram showing the relationship between the crystal grain size and the surface roughness after using a roll.
• FIG. 2 shows the relationship between the average solidification rate and the crystal grain size.
• FIG. 3 is a diagram showing a change in an organization during the roll manufacturing process of the present invention.
• FIG. 4 is a microstructure photograph showing the roll structure of the present invention and an explanatory diagram thereof.
• FIG. 5 is a diagram showing the relationship between the frequency of the heating coil and the state of foreign matter entrapment.
• FIG. 6 is a partially sectional perspective view showing an outline of an apparatus for carrying out the manufacturing method of the present invention.
• FIG. 7 is a schematic cross-sectional view schematically showing a main part of the apparatus shown in FIG.
• the reason for limiting the content of C as a component of the outer layer of the roll to the above range of 1.5 to 2.4% is as follows. That is, if C is less than the lower limit, hard carbides are less crystallized, wear resistance is significantly deteriorated, and improvement cannot be expected. On the other hand, if it exceeds the upper limit, the number of brittle carbides increases, and the crack resistance is impaired, and at the same time, the toughness is reduced, so that the wear resistance is also reduced, and the object of the present invention cannot be achieved. In general, it is considered that increasing the C content increases the amount of hard carbides and improves wear resistance. However, since the present invention has a large amount of alloying elements, the form and amount of the carbide change. Thus, the present invention has found 1.5 to 2.4% as an optimum range of C for achieving both the rough surface resistance and the wear resistance.
• V in the present invention The content of V in balance with C to crystallize extremely hard MC carbides (VC in the present invention) compared with conventional aggressive Ntai bets (FeC) system or chromium carbide (Cr 7 C 3) carbides Selected.
• VC carbides are particularly important because they are directly crystallized as primary carbides from the molten metal and are the most important factor for controlling the structure.
• the alloying elements Cr, Mo, and W all combine mainly with C to form eutectic carbides, but in the present invention, are very hard M 6 C-based alloys. Therefore, it plays the role of providing both wear resistance and toughness.
• the content of at least one element must be limited to 10-22%.
• the lower limit is 10% or less, the amount of hard carbide is small and the wear resistance is insufficient.
• the range must be within this range.
• Cr and Mo are partly distributed to the matrix and increase the hardenability, and have the effect of precipitation hardening, especially at high temperatures.
• a £, oxide-forming elements such as Ti is forms such as oxides for example A 1 2 0 3, Ti 2 0 3 raw
• the oxide VC carbides crystallize around this core. Therefore, it is an important element for dispersion crystallization of VC carbide.
• One or two of the above elements must be added in the range of A £: 0.05 to 0.20% and ⁇ ⁇ : 0.02 to 0.10%. There is.
• Si and Mn are useful elements in the melting technology, for deoxidation of molten metal, etc. Is not a problem.
• impurities such as P and S may be occupied as long as they are about 0.03% or less which are contained in ordinary cypress, and these do not imply the effects of the present invention.
• No Ni is preferred to be 1% or less, because it impairs the rough surface resistance of this type of roll.
• Co is the high temperature of the base in the metal structure. Addition of 0.1 to 10%, preferably 5 to 10%, for improving the strength and high-temperature hardness can further improve the rough surface resistance and wear resistance of the roll.
• the surface of the roll becomes as high as 600 to 800, so that the matrix structure is tempered and softened. Therefore, in ferrous rolls such as high-chromium iron, high-alloy glen, and iron, which are commonly used, the base structure is preferentially worn against carbides that are stable even at high temperatures, and the roll surface has irregularities. It causes rough skin. In order to prevent such roughening, it is important to make the matrix fine and to disperse a large amount of hard carbides at the crystal grain boundaries of the matrix and also in the crystal grains.
• the grain size of the roll structure must be in the range of 30 to 150.
• the vertical axis of the figure represents the surface roughness Ra (sir), and the horizontal axis represents the crystal grain size (sir).
• the surface roughness intended by the present invention is the force within the range indicated by the symbol in the figure.
• the figure shows that the grain size required to obtain this surface roughness is 30 to 150 I have.
• the grain boundaries of the present invention is not hard M 6 C carbides as eutectic, also added to this in order to obtain a more dense structure, a very hard MC carbides in the primary crystal in the crystal grains of the matrix structure It crystallized out.
• FIG. 3 shows the progress of the cooling and solidification of the molten metal.
• the molten metal (L) (process 1) having the components of the present invention is cooled and primary MC (VC) carbide is dispersed and crystallized from the molten metal.
• the carbide is an oxide formed during the melt (such as A1 2 0 3) as the core, easily and reliably crystallized (step 2).
• the crystal grain size is set to 30 to 150, but this crystal grain size is the crystal grain size at the time of solidification.
• the composite roll of the present invention is manufactured by the apparatus shown in FIGS. 6 and 7. Built.
• a rod-shaped core material 1 made of alloy ⁇ such as SCM440 is installed so as to be able to move up and down, and is placed on a platform 3 having an opening through which the core material 1 is inserted from above.
• a preheating coil 4, a refractory frame 5, an induction heating coil 6, and a water-cooling mold 7 are arranged coaxially around the core 1 in this order.
• the core 1 is supported by a means (not shown) so as to move downward at a constant speed with a low speed.
• the core 1 is heated by the preheating coil 4 and the molten metal 9 made of high-speed steel or the like stored in the ladle 8 is preheated through the nozzle 8 a to the outer periphery of the core 1.
• the molten metal 9 in the refractory frame 5 is heated by the heating coil 6 provided around the refractory frame 5.
• the lower end of the refractory frame 5 is in contact with the water-cooled mold 7, and the molten metal introduced between the water-cooled mold ⁇ and the core 1 is solidified sequentially to form the outer layer 2.
• the most important things are heating of the molten metal by the induction heating coil 6 and cooling by the water-cooling mold. That is, the above-mentioned heating is an important matter for welding the outer peripheral surface of the core material 1 to the outer layer part 2, and the above-mentioned cooling is an important matter for obtaining a structure having a crystal grain size of 30 to 150. It is.
• the size of the structure due to solidification is determined by the solidification rate. Therefore, the solidification rate must be increased in order to reduce the crystal grain size and refine the structure.
• centrifugal structure which is the most common conventional manufacturing method, removes the mold. Due to the heat, there was a limit of its own, and the size of the roll was not affected by the size of the roll.
• the solidification rate can be increased because the water cooling can be actively performed through the water-cooling mold (mold).
• the average surface solidification rate ie, the drawing speed, is 4 to 50 in order to obtain a crystal grain size of 30 to: L50 m corresponding to the mouth surface roughness Ra 0.3 to: 1.5. This is possible by using lots.
• FIG. 2 shows the relationship between the crystal grain size (; m (vertical axis) and the average coagulation velocity ( ⁇ / min) (horizontal axis) in Example 2; a grain size of 30 to 150 m was obtained. Indicates that a coagulation rate of 4 to 50 nimZ is required.
• Fig. 4 shows that the main components of the molten metal are as follows: C: 2.13%, Cr: 5.13%, Mo: 6.48%, V: 5.31%. W: 4.12%, A%: 0.10%, and
• This figure shows the microscopic metallographic structure of the outer layer of a roll made by cycling at a solidification rate of 20 rpm.
• eutectic carbides surround crystal grains having a particle size of 80; ⁇ , and primary carbides are scattered in the matrix.
• the welding between the outer layer and the core material may be impaired as a side effect.
• heat is applied to the outer layer molten metal using an induction heating coil. Must be supplied and completely welded.
• induction heating supplies heat and stirs the molten metal to heat it.
• the stirring power also increases, and foreign matter such as oxide film material and slag on the surface of the molten metal may remain at the solidification interface, resulting in foreign matter remaining in the outer layer after solidification, which may significantly impair the quality.
• it is necessary to increase the frequency in order to suppress the stirring force As shown in Fig. 5, by setting the frequency to 5 KHz or more, it is possible to prevent the defect caused by this foreign matter entrapment. It became possible.
• the composite roll continuously formed as described above is subjected to ordinary quenching treatment, and the austenite crystallized during solidification becomes a hard martensite, and is further tempered to a tempered martensite.
• the composite roll of the present invention has a hard and dense structure, and thus is extremely excellent as a roll for hot rolling.
• Table 1 shows a comparison list of specific production qualities and use results in actual mill rolling with Examples 1 to 3 of the present invention and Comparative Examples 1 to 5, and shows the crystal grain size of Examples 1, 2, and 3 of the present invention.
• Table 2 shows the production conditions, production quality, and use quality along with Comparative Examples 1 to 5.
• Example material 0.40 0.26 0.79 0.014 0.008 0.12 1.05 0.18
• the composite roll of the present invention exhibited excellent properties in both production quality and use quality.
• the chemical component of the present invention exhibited extremely excellent performance, which is at least five times that of the conventional one, and the surface roughness after use was small, and the skin roughness was improved.
• the present invention By applying the present invention to a hot-rolling roll, it is possible to supply a high-quality roll having good wear resistance and no occurrence of cracks or the like due to insufficient toughness. With regard to the roughness, extremely good results have been confirmed as compared with conventional rolls, and thus the roll of the present invention has great industrial value.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)

Priority Applications (4)

Applications Claiming Priority (6)

Publications (1)

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Cited By (5)

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• 1991
  • 1991-06-13 US US07/989,241 patent/US5419973A/en not_active Expired - Fee Related
  • 1991-06-13 WO PCT/JP1991/000798 patent/WO1991019824A1/ja not_active Ceased
  • 1991-06-13 AU AU79912/91A patent/AU650271B2/en not_active Ceased
  • 1991-06-13 DE DE69127623T patent/DE69127623T2/de not_active Expired - Fee Related
  • 1991-06-13 EP EP91911197A patent/EP0533929B1/en not_active Expired - Lifetime
  • 1991-06-13 KR KR1019920703212A patent/KR950006649B1/ko not_active Expired - Fee Related

Patent Citations (3)

Non-Patent Citations (1)

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