CN110819888A - High nickel bainite centrifugal composite roll collar and manufacturing method thereof - Google Patents
High nickel bainite centrifugal composite roll collar and manufacturing method thereof Download PDFInfo
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- CN110819888A CN110819888A CN201911119485.5A CN201911119485A CN110819888A CN 110819888 A CN110819888 A CN 110819888A CN 201911119485 A CN201911119485 A CN 201911119485A CN 110819888 A CN110819888 A CN 110819888A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/10—Cast-iron alloys containing aluminium or silicon
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D13/00—Centrifugal casting; Casting by using centrifugal force
- B22D13/04—Centrifugal casting; Casting by using centrifugal force of shallow solid or hollow bodies, e.g. wheels or rings, in moulds rotating around their axis of symmetry
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/10—Making spheroidal graphite cast-iron
- C21C1/105—Nodularising additive agents
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D5/00—Heat treatments of cast-iron
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/40—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rings; for bearing races
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/08—Making cast-iron alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/04—Cast-iron alloys containing spheroidal graphite
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/06—Cast-iron alloys containing chromium
- C22C37/08—Cast-iron alloys containing chromium with nickel
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
Abstract
The invention belongs to the technical field of composite roll collars, and particularly relates to a high-nickel bainite centrifugal composite roll collar and a manufacturing method thereof. The outer layer of the roll collar is high-nickel bainite alloy ductile iron, the transition layer of the roll collar is an inner and outer metal mixed melting layer, the inner layer of the roll collar is inoculation gray iron 250, and the high-nickel bainite alloy ductile iron comprises the following chemical components in percentage by mass: 3.0-3.6% of C, 1.0-2.0% of Si, 0.4-1.2% of Mn, less than or equal to 0.03% of S, less than or equal to 0.03% of P, 0.5-1.5% of Cr, 3.0-4.5% of Ni, 0.3-1.0% of Mo, 0.3-0.5% of Nb and the balance of Fe. The high-nickel bainite centrifugal composite roll collar has the advantages of high hardness, good wear resistance and good impact resistance, and the comprehensive performance index meets the working requirement of a high-fineness building material double-roll machine.
Description
Technical Field
The invention belongs to the technical field of composite roll collars, and particularly relates to a high-nickel bainite centrifugal composite roll collar and a manufacturing method thereof.
Background
At present, in the field of domestic roller crushing, because the crushing mode has the advantages of energy conservation, environmental protection and the like, the crushing mode is gradually adopted by a plurality of industries, but the technical equipment level has a large gap compared with the developed countries, and particularly the manufacturing process level of the wear-resistant material can not meet the development requirements of the industries. Most of the devices adopt roll collars such as surface overlaying welding, chilled cast iron, medium manganese ductile iron and the like, and can not meet the treatment requirements of high wear resistance and ultrafine materials in the industry. The roll collar of the roll crusher can continuously receive the impact and grinding action of materials in work, and grooves appear to influence the crushing effect of the materials. In many cases, some wear-resistant roll collars are not worn, so that early breakage occurs, the roll collars are required to be replaced by halt and overhaul, and the normal operation of equipment is seriously influenced. With the development requirement of large-scale equipment, technical research and development and capital investment of the oversized double-roll mill roll collar with the diameter of 1200-1400mm are promoted by industry experts for many times. The high-nickel bainite centrifugal composite high-alloy roll collar is researched and produced under the background of the development of the industry, and the roll collar of the roll machine produced by the technology reduces the discharge of industrial wastewater, waste gas and the like in the production process compared with the traditional process, and meets the national environmental protection requirement. And the centrifugal composite casting method is adopted, so that the performance of the roll collar is improved, and a large amount of rare metals are saved, so that the high-nickel bainite composite roll collar has high cost performance and extremely high industrial popularization value.
The high nickel bainite composite roll collar can be predicted to bring huge economic benefits for more enterprises after being popularized and used in related domestic industries along with the improvement of product quality, variety and yield, and meanwhile, from the utilization angle of industrial waste, huge environmental protection and social benefits are certainly brought.
The existing process for casting the large-sized roll collar comprises the following steps:
sand casting: the defects of thick structure, sand holes, air holes, slag inclusion, shrinkage porosity and the like are difficult to avoid, and the service performance and the safety and the reliability are seriously influenced. Only single metal casting can be adopted, the alloy waste is large, and the inner hole is difficult to process.
Static metal mold shape and sand mold inner core casting: the defects are that the structure is uneven, the defects of air holes, slag inclusion, shrinkage porosity and the like are difficult to avoid, the white hardness and the thickness of an external working layer are difficult to control, and the service performance and the safety and the reliability are seriously influenced. Only single metal casting can be adopted, and the waste of alloy is large.
Vertical centrifugal casting: the large roll collar is generally cast by vertical centrifugation, and has the defects that the equipment investment is large, an inner hole is easily influenced by gravity to form a parabola shape, so that the thickness difference of two end walls of the roll collar is large, and simultaneously, the metal at two ends is mixed and dissolved greatly due to vertical pouring, so that the performance is influenced.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: overcomes the defects of the prior art and provides a high nickel bainite centrifugal composite roll collar. The composite roll collar has the advantages of high hardness, good wear resistance and good impact resistance, and the comprehensive performance index meets the working requirement of a high-fineness building material double-roll machine; the invention also provides a manufacturing method thereof.
The high-nickel bainite centrifugal composite roll collar provided by the invention has the advantages that the outer layer of the roll collar is high-nickel bainite alloy ductile iron, the transition layer of the roll collar is an inner metal and outer metal mixed melting layer, the inner layer of the roll collar is inoculation gray iron 250, and the high-nickel bainite alloy ductile iron comprises the following chemical components in percentage by mass: 3.0-3.6% of C, 1.0-2.0% of Si, 0.4-1.2% of Mn, less than or equal to 0.03% of S, less than or equal to 0.03% of P, 0.5-1.5% of Cr, 3.0-4.5% of Ni, 0.3-1.0% of Mo, 0.3-0.5% of Nb and the balance of Fe.
Wherein:
the thickness of the inner and outer metal mixed melting layers is 2-3 mm.
The inoculation gray iron 250 comprises the following chemical components in percentage by mass: 3.2-3.5% of C, 1.8-2.3% of Si, 0.6-1.2% of Mn, less than or equal to 0.06% of S, less than or equal to 0.06% of P, and the balance of Fe.
The inoculation gray iron 250 is characterized in that a compound inoculant of 75SiFe and SiCaBa is adopted for inoculation when molten iron of the gray iron 250 is discharged, and the addition amount of the compound inoculant is 0.6-0.8 percent of the weight of the molten iron.
The inner and outer metal mixed melting layers are composite metal oxide slag phases, the composite metal oxide slag phases are O-type and NB-type composite protective slag, high-temperature molten iron is added into the protective slag to react with high-melting-point iron oxide and chromium oxide on the surface of the molten iron to form a new low-melting-point silicate and borate composite slag phase, and the fluidity of the oxide slag is increased.
The O form is a mixture of silicon dioxide, silicate and borate; NB type is anhydrous boric acid.
The invention relates to a manufacturing method of a high nickel bainite centrifugal composite roll collar, which comprises the following steps:
(1) respectively smelting high-nickel bainite alloy ductile iron and inoculated gray iron 250;
(2) when molten iron of the high-nickel bainite alloy ductile iron is discharged from a furnace, composite spheroidization modification treatment is carried out;
(3) preparing a composite roll collar blank by adopting a centrifugal machine;
(4) heat preservation and slow cooling heat treatment;
(5) and (5) post-treatment.
Wherein:
the smelting in the step (1) is carried out in a medium-frequency induction furnace, the smelting temperature of the outer layer of the high-nickel alloy is 1450-1500 ℃, and the smelting temperature of the inner layer of the inoculated gray iron 250 is 1450-1500 ℃.
And (3) when the molten iron in the step (2) is discharged, adding nickel-magnesium alloy, rare earth silicon and silicon-calcium-barium alloy into the ladle for composite spheroidization modification treatment so as to refine matrix grains, change the shapes of casting carbide and graphite and improve the wear resistance and toughness.
The adding amount of the nickel-magnesium alloy is 1.5 to 1.8 percent of the weight of the molten iron, the adding amount of the rare earth silicon is 0.2 to 0.3 percent of the weight of the molten iron, and the adding amount of the silicon, calcium and barium is 0.4 to 0.6 percent of the weight of the molten iron.
And (4) carrying out the preparation in the step (3) on a horizontal type roller centrifuge.
The preparation in the step (3) comprises the following steps:
A. coating a high-temperature resistant coating on the inner wall of the mold of the centrifuge in advance, controlling the temperature to be 130-;
B. pouring the molten iron of the high-nickel bainite alloy ductile iron subjected to composite spheroidization modification into a centrifugal machine mould to form an outer layer of a roll collar, and measuring the slag temperature on the inner surface of the molten iron by adopting a far infrared thermometer;
C. adding O-type and NB-type composite covering slag into the inner surface of the outer layer of the roll collar to form a roll collar transition layer;
D. when the temperature is reduced to 950-980 ℃, pouring inoculated gray iron 250 molten iron;
E. and (4) testing the molten iron slag temperature on the inner wall, stopping the machine to demold after the temperature is lower than 800 ℃, and taking out the composite roll collar blank.
Wherein:
the pouring temperature in the step (3) B is 1340-1380 ℃, and the molten iron inner surface slag temperature is 950-980 ℃.
The adding amount of the composite mold flux in the step (3) C is 5-7Kg/m2。
And (4) in the step (3) C, the pouring temperature is the temperature of the inner surface of the outer layer metal cooled to the liquid-solid two-phase region.
And (3) C, adding O-type and NB-type composite protective slag for anti-oxidation protection to form a composite metal oxide slag phase, so that the melting point of a new slag phase of high-melting-point alloy oxide slag such as Cr, Fe and the like is reduced, the fluidity of the composite oxide slag is increased, and the composite oxide slag floats to the inner surface of the inner-layer metal by virtue of the specific gravity difference of centrifugal force to realize a good metallurgical composite interface.
And (4) the pouring temperature in the step (3) D is 1320-1350 ℃.
And (4) transferring the blank casting in the step (4) to a heat treatment furnace, pre-heating the furnace temperature to 300-400 ℃, and slowly cooling the roll collar to be below 100 ℃ along with the furnace at a speed of less than 8-10 ℃/h so as to reduce casting stress and facilitate subsequent machining.
The post-treatment in the step (5) comprises the working procedures of rough machining, tempering, static machining and inspection.
The rough machining is to perform rough machining on the roller ring after stress relief tempering, and the heat treatment deformation amount and the finish machining amount are reserved.
And in the tempering step, the temperature of the cast after rough machining is raised to 400-450 ℃, heat preservation is carried out for 8-16 hours according to the thickness of the roll collar, and the cast is slowly cooled to be below 100 ℃ along with the furnace and taken out of the furnace.
And the finish machining is to machine the tempered roll collar into a finished product according to requirements.
And the inspection is that the finished casting is printed with a steel grade and leaves the factory after passing hardness and flaw detection inspection.
The invention relates to a high nickel bainite centrifugal composite roll collar, which is applied to the brick and tile building material industry for grinding various materials.
The chemical composition design principle of the molten iron on the inner layer and the outer layer of the high-nickel bainite centrifugal composite roll collar is as follows:
the chemical composition of the high nickel bainite alloy ductile iron is as follows: 3.0-3.6% of C, 1.0-2.0% of Si, 0.4-1.2% of Mn, less than or equal to 0.03% of S, less than or equal to 0.03% of P, 0.5-1.5% of Cr, 3.0-4.5% of Ni, 0.3-1.0% of Mo, 0.3-0.5% of Nb and the balance of Fe.
The matrix structure after heat treatment is as follows: bainite + a small amount of martensite + carbide + residual austenite + graphite.
Carbon is an important element in the wear-resistant alloy cast iron, and a certain amount of carbide and spherical graphite are obtained in a solidification structure due to the cooling speed and the action of spheroidizing inoculation in the metal solidification process. The carbon is comprehensively considered and is properly controlled to be 3.0-3.6 percent.
Silicon is a strong graphitizing element, silicon in the components is used for inoculating and increasing silicon in molten iron and spheroidization, carbides and graphite with different content proportions can be obtained by controlling the content of the silicon, and the content of the selected Si is 1.0-2.0% according to different requirements on wear resistance and crushing impact toughness.
Manganese is a carbide promoting element, and 0.4-1.2% of Mn is selected according to the application condition of the roll collar.
Phosphorus is a harmful element which is easy to form a brittle phase and increases segregation, P is controlled to be less than or equal to 0.05 generally by bainite ductile iron, and the strength and the toughness of a bainite structure can be effectively ensured by the condition that P is less than or equal to 0.03 in consideration of the solidification condition of the large-sized roll collar.
Sulfur is a reverse graphitization element, and S is controlled to be less than or equal to 0.03 through spheroidization desulfurization, so that the form of spherical graphite in the structure is ensured.
Nickel is an important element for obtaining a bainite structure, so that a C curve transformed by a solidification structure is shifted to the right, the formation of pearlite can be effectively inhibited, and the cast bainite structure with high content is obtained at the cooling speed of the centrifugal metal mold. The nickel and the molybdenum are matched, so that the strength and the toughness of the roll collar structure can be greatly improved, and meanwhile, in order to reduce the segregation influence of the large thick-wall roll collar under the centrifugal action, the invention adopts the nickel with higher content, and the Ni in the spheroidized finished product is 3.0-4.5.
Molybdenum is the most key element for obtaining a bainite ductile iron structure, and is matched with nickel for use, so that a C curve is obviously shifted to the right, and the fact that a matrix structure with bainite as a main part is obtained in the continuous cooling process of metal is ensured.
Chromium is a carbide forming element, significantly increasing the hardness and wear resistance of the material. The roll collar is applied to crushing building material raw materials, the working pressure of the roll collar is much smaller than that of metallurgical steel rolling, and the roll collar mainly takes grinding of hard materials, so that the chromium content is selected to be higher, and the Cr content is controlled to be 0.5-1.5%.
Niobium mainly acts to refine grains and forms carbides relatively weakly. The large roll collar is thick as a whole, the solidification speed is relatively slow, the heat strength of the material in the initial solidification stage is increased and the hot cracking tendency is reduced in order to promote the refinement of a solidification structure, and the addition amount of niobium is generally more than 0.3, so that 0.3-0.5% of Nb is selected.
The inner layer material of the roll collar mainly plays a role in bearing assembly stress and slowing down vibration in use, so that casting stress is reduced, and centrifugal composite slag phase floating is facilitated, the roll collar adopts HT250 material C3.2-3.5%, Si 1.8-2.3%, Mn 0.6-1.2%, S is less than or equal to 0.06%, and P is less than or equal to 0.06.
The diameter of the large-scale composite roll collar manufactured by the process is 1200-1400mm, and the single weight is 5-7 tons, so that the large-scale composite roll collar is mainly applied to a high-speed double-roll fine crusher in the building material brick and tile industry, is used for crushing industrial waste materials such as hollow brick raw materials coal gangue, shale, slag and the like, and is also applied to a four-roll crusher in the metallurgical industry, and is used for crushing raw materials such as coal, coke and the like.
The difficulty of adopting a horizontal centrifugal casting process for the large-sized composite roll collar is that the radial line shrinkage of the large-sized roll collar is large, a large gap is formed between the solidified outer layer metal and the inner wall of a metal mold, inner layer molten iron is poured under the condition of high-speed rotation and continuous solidification shrinkage, large pressure is formed on the outer layer, and meanwhile, the inner layer molten iron needs to transfer heat to the outer layer, so that the solidified outer layer metal is heated again, the heat intensity is reduced, the risk of roll collar hot cracking is aggravated, and the process control difficulty is high. The invention adopts reasonable pouring rotating speed and precoated sand suitable for large-scale centrifugal casting, effectively prevents sand washing phenomenon during large-scale roll collar pouring, ensures cooling uniformity of outer layer molten iron, and solves the problem of centrifugal hot cracking from multiple angles.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the manufacturing method of the high-nickel bainite centrifugal composite roll collar, O-type and NB-type composite protective slag is added during casting to perform anti-oxidation protection, the metallurgical bonding strength of the inner layer and the outer layer is high, and the heat treatment residual stress is small.
(2) The high-nickel bainite centrifugal composite roll collar has the advantages that when the high-nickel bainite centrifugal composite roll collar is used, the inner layer and the outer layer are not easy to separate and fall off, the outer layer alloy has high wear resistance and good impact toughness, the phenomena of grooves, edge breakage, block falling and the like are not easy to occur, the inner layer inoculation HT250 has good shock absorption, the vibration during working is reduced, only the outer layer working layer contains noble alloys such as Cr, Mo, Ni, Nb and the like, and the comprehensive manufacturing cost is reduced.
(3) The high-nickel bainite centrifugal composite roll collar disclosed by the invention has the advantages that the outer layer of the roll collar is made of a high-nickel bainite material, and the inner working layer is made of an inoculated gray iron material. The centrifugal force is utilized, the steel plate is cast into a whole by metallurgical bonding, the transition layer of the inner metal layer and the outer metal layer is well controlled, the metallurgical bonding strength is high, and the inner working layer has no defects of slag inclusion and the like.
(4) The high-nickel bainite centrifugal composite roll collar has the advantages of high hardness, good wear resistance and good impact resistance, and the comprehensive performance index meets the working requirement of a high-fineness building material double-roll machine.
Drawings
FIG. 1 is a schematic structural diagram of a high nickel bainite centrifugal composite roll collar;
FIG. 2 is a flow chart of a process for preparing the high nickel bainite centrifugal composite roll collar.
In the figure: 1. an outer layer of high nickel bainite alloy; 2. a metallurgical composite interface; 3 inner layer inoculation HT 250.
Detailed Description
The present invention is further described below with reference to examples.
Example 1
In the high nickel bainite centrifugal composite roll collar described in this embodiment 1, the outer layer of the roll collar is high nickel bainite alloy ductile iron, the transition layer of the roll collar is an inner and outer metal mixed melting layer, the inner layer of the roll collar is inoculation gray iron 250, and a composite roll collar with phi 1400mm × 1200mm is manufactured through trial, and the high nickel bainite alloy ductile iron has a chemical composition, in terms of mass percent, as follows: 3.29 percent of C, 1.724 percent of Si, 0.61 percent of Mn, 0.025 percent of S, 0.026 percent of P, 0.067 percent of Cr, 3.82 percent of Ni, 0.76 percent of Mo, 0.43 percent of Nb and the balance of Fe.
Wherein:
the thickness of the inner and outer metal mixed melting layers is 2.5 mm.
The inoculation gray iron 250 comprises the following chemical components in percentage by mass: 3.45% of C, 2.26% of Si, 0.92% of Mn, 0.046 of S, 0.042 of P and the balance of Fe.
The inoculation gray iron 250 is characterized in that a compound inoculant of 75SiFe and SiCaBa is adopted for inoculation treatment when molten iron of the gray iron 250 is discharged, and the addition amount of the compound inoculant is 0.75 percent of the weight of the molten iron.
The inner and outer metal mixed melting layers are composite metal oxide slag phases, the composite metal oxide slag phases are O-type and NB-type composite protective slag, high-temperature molten iron is added into the protective slag to react with high-melting-point iron oxide and chromium oxide on the surface of the molten iron to form a new low-melting-point silicate and borate composite slag phase, and the fluidity of the oxide slag is increased.
The O form is a mixture of silicon dioxide, silicate and borate; NB type is anhydrous boric acid.
The invention relates to a manufacturing method of a high nickel bainite centrifugal composite roll collar, which comprises the following steps:
(1) respectively smelting high-nickel bainite alloy ductile iron and inoculated gray iron 250;
(2) when molten iron of the high-nickel bainite alloy ductile iron is discharged from a furnace, composite spheroidization modification treatment is carried out;
(3) preparing a composite roll collar blank by adopting a centrifugal machine;
(4) heat preservation and slow cooling heat treatment;
(5) and (5) post-treatment.
Wherein:
the smelting in the step (1) is carried out in a medium-frequency induction furnace, the smelting temperature of the outer layer of the high-nickel alloy is 1480 ℃, and the smelting temperature of the inner layer of the inoculated gray iron 250 is 1458 ℃.
And (3) when the molten iron in the step (2) is discharged, adding nickel-magnesium alloy, rare earth silicon and silicon-calcium-barium alloy into the ladle for composite spheroidization modification treatment so as to refine matrix grains, change the shapes of casting carbide and graphite and improve the wear resistance and toughness.
The adding amount of the nickel-magnesium alloy is 1.6 percent of the weight of the molten iron, the adding amount of the rare earth silicon is 0.25 percent of the weight of the molten iron, and the adding amount of the silicon, calcium and barium is 0.5 percent of the weight of the molten iron.
And (4) carrying out the preparation in the step (3) on a horizontal type roller centrifuge.
The preparation in the step (3) comprises the following steps:
A. coating a high-temperature resistant coating on the inner wall of a mold of the centrifugal machine in advance, controlling the temperature to be 145 ℃, and rotating the centrifugal machine at a rotating speed of 340r/min when the molten alloy iron meets the pouring requirement;
B. pouring the molten iron of the high-nickel bainite alloy ductile iron subjected to composite spheroidization modification into a centrifugal machine mould to form an outer layer of a roll collar, and measuring the slag temperature on the inner surface of the molten iron by adopting a far infrared thermometer;
C. adding O-type and NB-type composite covering slag into the inner surface of the outer layer of the roll collar to form a roll collar transition layer;
D. when the temperature is reduced to 965 ℃, inoculating gray iron 250 molten iron is poured;
E. and (4) testing the molten iron slag temperature on the inner wall, stopping the machine to demould when the temperature is 750 ℃, and taking out the composite roll collar blank.
Wherein:
and (4) in the step (3) B, the pouring temperature is 1360 ℃, and the molten slag temperature on the inner surface of the molten iron is 965 ℃.
The adding amount of the composite mold flux in the step (3) C is 6Kg/m2。
And (4) in the step (3) C, the pouring temperature is the temperature of the inner surface of the outer layer metal cooled to the liquid-solid two-phase region.
The casting temperature in the step (3) D is 1338 ℃.
And (4) transferring the blank casting in the step (4) to a heat treatment furnace, wherein the furnace temperature is raised to 380 ℃ in advance, and the roll collar is slowly cooled to be below 100 ℃ along with the furnace at the speed of less than 8-10 ℃/min so as to reduce casting stress and facilitate subsequent machining.
The post-treatment in the step (5) comprises the working procedures of rough machining, tempering, static machining and inspection.
The rough machining is to perform rough machining on the roller ring after stress relief tempering, and the heat treatment deformation amount and the finish machining amount are reserved.
And in the tempering step, the temperature of the cast after rough machining is raised to 430 ℃, heat preservation is carried out for 12 hours according to the thickness of the roll collar, and the cast is slowly cooled to be below 100 ℃ along with the furnace and taken out of the furnace.
And the finish machining is to machine the tempered roll collar into a finished product according to requirements.
And the inspection is that the finished casting is printed with a steel grade and leaves the factory after passing hardness and flaw detection inspection.
The large-sized high-nickel bainite centrifugal composite roll collar with the diameter of 1400mm x 1200mm produced by the technical process of the embodiment 1 is 6.8 tons per unit weight, has the average hardness of a working layer of HRC57, and is applied to the fine crushing of high-shale-content materials of an automatic production line of building material bricks and hollow bricks. The product of the model is the largest product manufactured by adopting a centrifugal bimetal composite process for the first time in the tile industry. In the field use process, the working clearance of the pair roller can be kept for a long time, and the material treatment granularity is stable. Meanwhile, when the impact of large abnormal materials is applied in production, the phenomena of cracking, edge breakage and block falling do not occur, and the equipment is stable in operation.
Example 2
In the high nickel bainite centrifugal composite roll collar described in this embodiment 2, the outer layer of the roll collar is high nickel bainite alloy ductile iron, the transition layer of the roll collar is an inner and outer metal mixed melting layer, the inner layer of the roll collar is inoculation gray iron 250, and the trial-produced phi 1200mm x 1020mm composite roll collar has the following chemical compositions by mass percent: 3.16%, Si 1.32%, Mn 0.64%, S0.025, P0.028, Cr 0.77%, Ni 3.68, Mo 0.72%, Nb 0.46%, and the balance Fe.
Wherein:
the thickness of the inner and outer metal mixed melting layers is 2.5 mm.
The inoculation gray iron 250 comprises the following chemical components in percentage by mass: 3.36 percent of C, 2.16 percent of Si, 0.93 percent of Mn, 0.046 percent of S, 0.052 percent of P, and the balance of Fe.
The inoculation gray iron 250 is characterized in that a compound inoculant of 75SiFe and SiCaBa is adopted for inoculation treatment when molten iron of the gray iron 250 is discharged, and the addition amount of the compound inoculant is 0.75 percent of the weight of the molten iron.
The inner and outer metal mixed melting layers are composite metal oxide slag phases, the composite metal oxide slag phases are O-type and NB-type composite protective slag, high-temperature molten iron is added into the protective slag to react with high-melting-point iron oxide and chromium oxide on the surface of the molten iron to form a new low-melting-point silicate and borate composite slag phase, and the fluidity of the oxide slag is increased.
The O form is a mixture of silicon dioxide, silicate and borate; NB type is anhydrous boric acid.
The invention relates to a manufacturing method of a high nickel bainite centrifugal composite roll collar, which comprises the following steps:
(1) respectively smelting high-nickel bainite alloy ductile iron and inoculated gray iron 250;
(2) when molten iron of the high-nickel bainite alloy ductile iron is discharged from a furnace, composite spheroidization modification treatment is carried out;
(3) preparing a composite roll collar blank by adopting a centrifugal machine;
(4) heat preservation and slow cooling heat treatment;
(5) and (5) post-treatment.
Wherein:
the smelting in the step (1) is carried out in a medium-frequency induction furnace, the smelting temperature of the outer layer of the high-nickel alloy is 1482 ℃, and the smelting temperature of the inner layer of the inoculation HT250 is 1465 ℃.
And (3) when the molten iron in the step (2) is discharged, adding nickel-magnesium alloy, rare earth silicon and silicon-calcium-barium alloy into the ladle for composite spheroidization modification treatment so as to refine matrix grains, change the shapes of casting carbide and graphite and improve the wear resistance and toughness.
The adding amount of the nickel-magnesium alloy is 1.6 percent of the weight of the molten iron, the adding amount of the rare earth silicon is 0.25 percent of the weight of the molten iron, and the adding amount of the silicon, calcium and barium is 0.5 percent of the weight of the molten iron.
And (4) carrying out the preparation in the step (3) on a horizontal type roller centrifuge.
The preparation in the step (3) comprises the following steps:
A. coating a high-temperature resistant coating on the inner wall of a mold of the centrifugal machine in advance, controlling the temperature to be 158 ℃, and rotating the centrifugal machine at a rotating speed of 340r/min when the molten alloy iron meets the pouring requirement;
B. pouring the molten iron of the high-nickel bainite alloy ductile iron subjected to composite spheroidization modification into a centrifugal machine mould to form an outer layer of a roll collar, and measuring the slag temperature on the inner surface of the molten iron by adopting a far infrared thermometer;
C. adding O-type and NB-type composite covering slag into the inner surface of the outer layer of the roll collar to form a roll collar transition layer;
D. when the temperature is reduced to 972 ℃, inoculating gray iron 250 molten iron is poured;
E. and (4) testing the molten iron slag temperature on the inner wall, stopping the machine to demould when the temperature is 750 ℃, and taking out the composite roll collar blank.
Wherein:
and (4) in the step (3) B, the pouring temperature is 1370 ℃, and the molten iron inner surface slag temperature is 972 ℃.
The adding amount of the composite mold flux in the step (3) C is 6Kg/m2。
And (4) in the step (3) C, the pouring temperature is the temperature of the inner surface of the outer layer metal cooled to the liquid-solid two-phase region.
The casting temperature in the step (3) D is 1326 ℃.
And (4) transferring the blank casting in the step (4) to a heat treatment furnace, wherein the furnace temperature is raised to 380 ℃ in advance, and the roll collar is slowly cooled to be below 100 ℃ along with the furnace at the speed of less than 8-10 ℃/min so as to reduce casting stress and facilitate subsequent machining.
The post-treatment in the step (5) comprises the working procedures of rough machining, tempering, static machining and inspection.
The rough machining is to perform rough machining on the roller ring after stress relief tempering, and the heat treatment deformation amount and the finish machining amount are reserved.
And in the tempering step, the temperature of the cast after rough machining is raised to 430 ℃, heat preservation is carried out for 12 hours according to the thickness of the roll collar, and the cast is slowly cooled to be below 100 ℃ along with the furnace and taken out of the furnace.
And the finish machining is to machine the tempered roll collar into a finished product according to requirements.
And the inspection is that the finished casting is printed with a steel grade and leaves the factory after passing hardness and flaw detection inspection.
Example 3
In the high nickel bainite centrifugal composite roll collar described in this embodiment 3, the outer layer of the roll collar is high nickel bainite alloy ductile iron, the transition layer of the roll collar is an inner and outer metal mixed melting layer, the inner layer of the roll collar is inoculation gray iron 250, and the tried phi 1200mm × 1000mm composite roll collar has the following chemical compositions by mass percent: : 3.14% of C, 1.52% of Si, 0.89% of Mn, 0.023% of S, 0.028% of P, 1.06% of Cr, 3.65% of Ni, 0.74% of Mo, 0.32% of Nb and the balance of Fe.
Wherein:
the thickness of the inner and outer metal mixed melting layers is 2.5 mm.
The inoculation gray iron 250 comprises the following chemical components in percentage by mass: 3.42 percent of C, 2.08 percent of Si, 0.91 percent of Mn, 0.053 percent of S, 0.054 percent of P and the balance of Fe.
The inoculation of the gray iron 250 is carried out by adopting a compound inoculant of 75SiFe and SiCaBa to inoculate when the molten iron of the gray iron 250 is discharged, and the adding amount of the compound inoculant is 0.75 percent of the weight of the molten iron.
The inner and outer metal mixed melting layers are composite metal oxide slag phases, the composite metal oxide slag phases are O-type and NB-type composite protective slag, high-temperature molten iron is added into the protective slag to react with high-melting-point iron oxide and chromium oxide on the surface of the molten iron to form a new low-melting-point silicate and borate composite slag phase, and the fluidity of the oxide slag is increased.
The O form is a mixture of silicon dioxide, silicate and borate; NB type is anhydrous boric acid.
The invention relates to a manufacturing method of a high nickel bainite centrifugal composite roll collar, which comprises the following steps:
(1) respectively smelting high-nickel bainite alloy ductile iron and inoculated gray iron 250;
(2) when molten iron of the high-nickel bainite alloy ductile iron is discharged from a furnace, composite spheroidization modification treatment is carried out;
(3) preparing a composite roll collar blank by adopting a centrifugal machine;
(4) heat preservation and slow cooling heat treatment;
(5) and (5) post-treatment.
Wherein:
the smelting in the step (1) is carried out in a medium-frequency induction furnace, the smelting temperature of the outer layer of the high-nickel alloy is 1480 ℃, and the smelting temperature of the inner layer of the inoculation HT250 is 1460 ℃.
And (3) when the molten iron in the step (2) is discharged, adding nickel-magnesium alloy, rare earth silicon and silicon-calcium-barium alloy into the ladle for composite spheroidization modification treatment so as to refine matrix grains, change the shapes of casting carbide and graphite and improve the wear resistance and toughness.
The adding amount of the nickel-magnesium alloy is 1.6 percent of the weight of the molten iron, the adding amount of the rare earth silicon is 0.25 percent of the weight of the molten iron, and the adding amount of the silicon, calcium and barium is 0.5 percent of the weight of the molten iron.
And (4) carrying out the preparation in the step (3) on a horizontal type roller centrifuge.
The preparation in the step (3) comprises the following steps:
A. coating a high-temperature resistant coating on the inner wall of a mold of the centrifugal machine in advance, controlling the temperature to be 138 ℃, and rotating the centrifugal machine at a rotating speed of 360r/min when the molten alloy iron meets the pouring requirement;
B. pouring the molten iron of the high-nickel bainite alloy ductile iron subjected to composite spheroidization modification into a centrifugal machine mould to form an outer layer of a roll collar, and measuring the slag temperature on the inner surface of the molten iron by adopting a far infrared thermometer;
C. adding O-type and NB-type composite covering slag into the inner surface of the outer layer of the roll collar to form a roll collar transition layer;
D. when the temperature is reduced to 968 ℃, inoculating gray iron 250 molten iron is poured;
E. and (4) testing the molten iron slag temperature on the inner wall, stopping the machine to demould when the temperature is 750 ℃, and taking out the composite roll collar blank.
Wherein:
and (4) in the step (3) B, the pouring temperature is 1365 ℃, and the molten iron inner surface slag temperature is 978 ℃.
The adding amount of the composite mold flux in the step (3) C is 6Kg/m2。
And (4) in the step (3) C, the pouring temperature is the temperature of the inner surface of the outer layer metal cooled to the liquid-solid two-phase region.
The casting temperature in the step (3) D is 1326 ℃.
And (4) transferring the blank casting in the step (4) to a heat treatment furnace, wherein the furnace temperature is raised to 380 ℃ in advance, and the roll collar is slowly cooled to be below 100 ℃ along with the furnace at the speed of less than 8-10 ℃/min so as to reduce casting stress and facilitate subsequent machining.
The post-treatment in the step (5) comprises the working procedures of rough machining, tempering, static machining and inspection.
The rough machining is to perform rough machining on the roller ring after stress relief tempering, and the heat treatment deformation and the fine addition are reserved.
And in the tempering step, the temperature of the cast after rough machining is raised to 430 ℃, heat preservation is carried out for 10 hours according to the thickness of the roll collar, and the cast is slowly cooled to be below 100 ℃ along with the furnace and taken out of the furnace.
And the finish machining is to machine the tempered roll collar into a finished product according to requirements.
And the inspection is that the finished casting is printed with a steel grade and leaves the factory after passing hardness and flaw detection inspection.
Performance tests were performed on the high nickel bainite centrifugal composite collars prepared in examples 1-3, and the results are shown in Table 1.
Table 1 examples 1-3 performance test results
Claims (10)
1. A high nickel bainite centrifugal composite roll collar is characterized in that: the outer layer of the roll collar is high-nickel bainite alloy ductile iron, the transition layer of the roll collar is an inner and outer metal mixed melting layer, the inner layer of the roll collar is inoculation gray iron 250, and the high-nickel bainite alloy ductile iron comprises the following chemical components in percentage by mass: 3.0-3.6% of C, 1.0-2.0% of Si, 0.4-1.2% of Mn, less than or equal to 0.03% of S, less than or equal to 0.03% of P, 0.5-1.5% of Cr, 3.0-4.5% of Ni, 0.3-1.0% of Mo, 0.3-0.5% of Nb and the balance of Fe.
2. The high nickel bainite centrifugal composite roll collar of claim 1, wherein: the thickness of the inner and outer metal mixed melting layers is 2-3 mm.
3. The high nickel bainite centrifugal composite roll collar of claim 1, wherein: the inoculation gray iron 250 comprises the following chemical components in percentage by mass: 3.2-3.5% of C, 1.8-2.3% of Si, 0.6-1.2% of Mn, less than or equal to 0.06% of S, less than or equal to 0.06% of P, and the balance of Fe.
4. The high nickel bainite centrifugal composite roll collar of claim 1, wherein: the inoculation gray iron 250 is characterized in that a compound inoculant of 75SiFe and SiCaBa is adopted for inoculation when molten iron of the gray iron 250 is discharged, and the addition amount of the compound inoculant is 0.6-0.8 percent of the weight of the molten iron.
5. The high nickel bainite centrifugal composite roll collar of claim 1, wherein: the inner and outer metal mixed melting layers are composite metal oxide slag phases, the composite metal oxide slag phases are O-type and NB-type composite protective slag, and the O-type is a mixture of silicon dioxide, silicate and borate; NB type is anhydrous boric acid.
6. A method of manufacturing the high nickel bainite centrifugal composite roll collar of claim 1, wherein: the method comprises the following steps:
(1) respectively smelting high-nickel bainite alloy ductile iron and inoculated gray iron 250;
(2) when molten iron of the high-nickel bainite alloy ductile iron is discharged from a furnace, composite spheroidization modification treatment is carried out;
(3) preparing a composite roll collar blank by adopting a centrifugal machine;
(4) heat preservation and slow cooling heat treatment;
(5) and (5) post-treatment.
7. The method of manufacturing an upper nickel bainite centrifugal composite roll collar according to claim 6, wherein: the smelting in the step (1) is carried out in a medium-frequency induction furnace, the smelting temperature of the outer layer of the high-nickel alloy is 1450-1500 ℃, and the smelting temperature of the inner layer of the inoculation HT250 is 1450-1500 ℃.
8. The method of manufacturing an upper nickel bainite centrifugal composite roll collar according to claim 6, wherein: when the molten iron in the step (2) is discharged, adding a nickel-magnesium alloy, rare earth silicon and a silicon-calcium-barium alloy into the ladle for composite spheroidization modification, wherein the adding amount of the nickel-magnesium alloy is 1.5-1.8% of the weight of the molten iron, the adding amount of the rare earth silicon is 0.2-0.3% of the weight of the molten iron, and the adding amount of the silicon-calcium-barium is 0.4-0.6% of the weight of the molten iron.
9. The method of manufacturing an upper nickel bainite centrifugal composite roll collar according to claim 6, wherein: the preparation in the step (3) comprises the following steps:
A. coating a high-temperature resistant coating on the inner wall of the mold of the centrifuge in advance, controlling the temperature to be 130-;
B. pouring the molten iron of the high-nickel bainite alloy ductile iron subjected to composite spheroidization modification into a centrifugal machine mould to form an outer layer of a roll collar, and measuring the slag temperature on the inner surface of the molten iron;
C. adding O-type and NB-type composite covering slag into the inner surface of the outer layer of the roll collar to form a roll collar transition layer;
D. when the temperature is reduced to 950-980 ℃, pouring inoculated gray iron 250 molten iron;
E. and (4) testing the molten iron slag temperature on the inner wall, stopping the machine to demold after the temperature is lower than 800 ℃, and taking out the composite roll collar blank.
10. The method of manufacturing an upper nickel bainite centrifugal composite roll collar according to claim 9, wherein: in the step (3) B, the pouring temperature is 1340-1380 ℃, and the molten iron inner surface slag temperature is 950-980 ℃; the addition amount of the composite casting powder in the step C is 5-7Kg/m2(ii) a And D, the pouring temperature is 1320-1350 ℃.
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