CN111349843A - High-strength alloy nodular cast iron roughing roll and production process thereof - Google Patents
High-strength alloy nodular cast iron roughing roll and production process thereof Download PDFInfo
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- CN111349843A CN111349843A CN202010291239.4A CN202010291239A CN111349843A CN 111349843 A CN111349843 A CN 111349843A CN 202010291239 A CN202010291239 A CN 202010291239A CN 111349843 A CN111349843 A CN 111349843A
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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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/22—Moulds for peculiarly-shaped castings
- B22C9/28—Moulds for peculiarly-shaped castings for wheels, rolls, or rollers
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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
- B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
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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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
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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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
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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
- C21D9/38—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for roll bodies
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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
- C22C37/06—Cast-iron alloys containing chromium
- C22C37/08—Cast-iron alloys containing chromium with nickel
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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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Abstract
The invention discloses a high-strength alloy nodular cast iron roughing roll and a production process thereof, wherein the high-strength alloy nodular cast iron roughing roll comprises the following chemical components in percentage by mass: 3.0-3.5 percent of C, 1.2-1.8 percent of Si, 0.7-1.0 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.015 percent of S, 1.2-2.2 percent of Ni, 0.3-0.8 percent of Mo, 0.1-0.5 percent of V, 0.2-1.0 percent of Cr, 0.045-0.075 percent of Mg, 0.01-0.016 percent of Re, and the balance of Fe and inevitable impurities. According to the invention, through reasonable addition of alloy elements such as Cr, Mo and V, the formation amount of carbides of different types in the material is increased, the wear resistance of the material is improved, the proper amount of the carbide is dissolved in a matrix, the strength of the material is improved, and the combined action of Mg and Re reduces the cutting-off action of graphite on the matrix, so that the toughness of the material is further improved.
Description
Technical Field
The invention relates to the field of metallurgy, in particular to a high-strength alloy nodular cast iron roughing roll and a production process thereof.
Background
At present, rolls made of forged steel or partially cast steel are generally used on a section steel cogging frame, a large-bar rough rolling frame and a plate-strip two-roll rough rolling frame at home and abroad due to large rolling force, the rolls have high strength but poor wear resistance, so that frequent roll replacement in the rolling process influences the operation efficiency, and the surface quality of rolled materials is poor due to poor wear resistance. Chinese patent CN106636879A discloses a nodular cast iron roll body and a preparation method thereof, which solves the problem that the large-size nodular cast iron roll body in the prior art is easy to have casting defects such as shrinkage porosity, shrinkage cavity, slag inclusion, sand inclusion, cracks and the like, but has low strength and poor wear resistance and cannot well meet the requirement of rough rolling; chinese patent CN101654734A discloses a method for manufacturing an alloy nodular cast iron roller of a universal rolling mill, which comprises the steps of smelting, molten iron spheroidizing and inoculation, roller casting, cooling, unpacking and pre-opening, wherein the method adopts a heat treatment process after the pre-opening, so that the base structures of the groove bottom and the side surface of the grooved roller are refined through rapid cooling after the roller is subjected to high-temperature austenitizing and homogenizing, thereby meeting the wear resistance of the groove bottom and the side surface of the roller, but the manufacturing process is complex and basically only can meet the requirement that the total manufacturing cost of a rough rolling frame with lower rolling force is higher; chinese patent CN102268588B discloses a nodular cast iron roller of a steel pipe reducing mill or a sizing mill and a preparation method thereof, wherein a nickel-free scheme is adopted, the composition of other alloy content in the nodular cast iron roller is reduced, isothermal quenching is carried out by a two-step method in heat treatment, and better mechanical properties than the conventional heat treatment nodular cast iron roller are obtained, so that the strength and the toughness are greatly increased, but the manufacturing method of the roller only can meet the requirement of low rolling force on a finished product rack and cannot well adapt to a rough rolling rack with high rolling force, and the roller manufactured by the scheme without nickel and low alloy content has low strength, poor wear resistance, low steel passing amount and easy occurrence of roller breakage accidents.
Disclosure of Invention
The invention aims to provide a high-strength alloy nodular cast iron roughing roll with high wear resistance and a production process thereof.
The first technical scheme for realizing the aim of the invention is as follows: a high-strength alloy nodular cast iron roughing roll comprises the following chemical components in percentage by mass: 3.0-3.5 percent of C, 1.2-1.8 percent of Si, 0.7-1.0 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.015 percent of S, 1.2-2.2 percent of Ni, 0.3-0.8 percent of Mo, 0.1-0.5 percent of V, 0.2-1.0 percent of Cr, 0.045-0.075 percent of Mg, 0.01-0.016 percent of Re, and the balance of Fe and inevitable impurities. Because the reasonable addition of alloy elements such as Cr, Mo and V improves the formation of carbides of different types in the material, the carbides have the characteristics of high hardness, high wear resistance and the like, the wear resistance of the material is improved due to the existence of the wear-resistant points, meanwhile, the proper amount of the elements such as Cr, Mo, V, Ni and the like are dissolved in the matrix to improve the strength of the material, and the combined action of Mg and Re promotes the nucleation of graphite to improve the form of the graphite, reduce the cutting action of the graphite on the matrix and further improve the toughness of the material, so that the ideal high-strength alloy nodular cast iron roughing roll is obtained through the reasonable compatibility of the elements.
The second technical scheme of the invention is as follows: a production process of a high-strength alloy nodular cast iron roughing roll is used for producing the high-strength alloy nodular cast iron roughing roll and comprises the following steps:
s1: smelting; melting and mixing the raw materials, and then adjusting the content of each component to prepare molten steel;
s2: spheroidizing; adding a nodulizer into the molten steel to promote the molten steel to be nodulized;
s3: inoculation; adding an inoculant into the spheroidized molten steel to promote the inoculation and the deterioration of the molten steel;
s4: static pouring: when the temperature of the inoculated and deteriorated molten steel is reduced to a certain temperature, the molten steel is poured into a casting mold and is cooled to cast into a roller;
s5: rough machining and heat treatment; normalizing or quenching the roller, and then tempering;
s6: inspecting and fine processing; and performing finish machining on the roller after the heat treatment to obtain the titanium-containing alloy cast steel roller.
In the step S1, scrap steel, ferromolybdenum, ferrochromium and pure nickel in a certain ratio are added into an intermediate frequency furnace for smelting, sampling and analyzing are carried out after melting down, and ferrovanadium is added within 2-5 minutes before tapping, so that the chemical components and weight percentage content of the high-strength alloy nodular cast iron reach the component requirements before tapping: 3.0 to 3.5 percent of C, less than or equal to 0.6 percent of Si, 0.7 to 1.0 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.015 percent of S, 1.2 to 2.2 percent of Ni, 0.3 to 0.8 percent of Mo, 0.1 to 0.5 percent of V, 0.2 to 1.0 percent of Cr, and the balance of Fe and inevitable impurities.
In the S2, a low Si yttrium based heavy-earth nodulizer with the molten iron amount of 1.2-1.8% is added into a foundry ladle, a 75SiFe inoculant with the molten iron amount of 0.1-0.2% is covered on the nodulizing agent, then molten iron is rapidly poured into the foundry ladle for nodulizing treatment, the total Si increment of the nodulized molten iron is below 0.8%, Si is a strong graphitizing element for promoting graphitization and can also inhibit formation of carbides, the lower graphite formation amount is not enough and is not beneficial to formation of the carbides, the Si amount needs to be controlled in a reasonable range for ensuring the comprehensive performance of the material, the residual magnesium amount is controlled within 0.045-0.075%, and Mg can promote the form of the graphite under the condition of low content and high content, and the effect is best in order to ensure the nodulizing quality through a large number of tests.
In the S3, after the treatment is finished, adding a long-acting heavy rare earth inoculant and a silicon-calcium-barium inoculant with the iron content of 0.6-1.0% into the ladle for inoculation treatment; the ratio of the long-acting heavy rare earth inoculant to the silicon-calcium-barium inoculant is 1: 1. experiments show that the inoculation effect is best at the proportion.
In the step S4, after the inoculation of the molten iron is finished, when the temperature of the molten iron is reduced to 1300-1350 ℃, the molten iron is quickly poured into the roller casting mold by adopting a bottom pouring method, the molten iron is good in fluidity and guaranteed in performance structure and is not easy to produce casting defects by adopting the bottom pouring method, the molten iron poured by adopting the bottom pouring method rotates at a high speed in the cavity, impurities and gas in the molten iron are discharged, the metallurgical quality of a roller casting is improved, after the pouring is finished, a heat preservation agent is added to a riser of the roller, and then the roller is naturally cooled to room temperature to be cast into the roller.
And in the S4, 0.1% of calcium silicon inoculant is added along with the flow in the casting process for stream inoculation.
In S5, rough machining is performed on the cast roll; after rough machining, the roller is quenched at 750-800 ℃ and tempered at 550-600 ℃ after passing inspection.
In the step S6, the mechanical and mechanical properties of the roller after heat treatment are tested, wherein the tensile strength is more than or equal to 800Mpa, and the hardness is 45-60 HSD; and after the roller is inspected to be qualified, performing finish machining on the roller to obtain a high-strength alloy nodular cast iron rough roller finished product meeting the requirements.
By adopting the technical scheme, the invention has the following beneficial effects:
(1) the invention improves the formation amount of different types of carbides in the material by reasonably adding alloy elements such as Cr, Mo and V, the carbides have the characteristics of high hardness, high wear resistance and the like, the wear resistance of the material is improved by the existence of the wear-resistant points, meanwhile, the proper amount of Cr, Mo, V, Ni and the like are dissolved in the matrix to improve the strength of the material, the combined action of Mg and Re promotes the nucleation of graphite to improve the form of the graphite, the cutting-off action of the graphite on the matrix is reduced, the toughness of the material is further improved, the structure is compact, the physical property is excellent, the tensile property is excellent, and the manufactured roller has high steel passing amount and is not easy to break and peel off.
(2) The invention adopts the low Si-Y based heavy rare earth nodulizer for nodulizing and the alloy nodular cast iron rough roller which is multiply inoculated by 75SiFe, the long-acting heavy rare earth inoculant, the silicon-calcium barium and the silicon-calcium inoculant, the nodulizing rate of the alloy nodular cast iron rough roller reaches more than 90 percent, the nodular grade is more than two grades, the graphite is spherical, the structure is more compact, the carbide distribution is more dispersed, and the physical and chemical properties of the roller are enhanced.
(3) The total Si increment of molten iron after spheroidizing treatment is below 0.8 percent, Si is a powerful graphitizing element which promotes graphitization and can inhibit formation of carbides, the lower graphite formation amount is insufficient and too high, which is not beneficial to formation of carbides, so that the Si amount of the material is required to be controlled in a reasonable range for ensuring the comprehensive performance of the material, the residual magnesium amount is controlled within 0.045-0.075 percent, and Mg can promote nucleation of graphite under the condition of low content and can deteriorate the form of the graphite under the condition of high content, so that the spheroidizing quality is ensured, and a large number of tests show that the effect is controlled within 0.045-0.075 percent.
(4) After the molten iron inoculation is finished, when the temperature of the molten iron is reduced to 1300-1350 ℃, the molten iron is quickly poured into the roller casting mold by adopting a bottom pouring method, the molten iron is good in fluidity and guaranteed in performance organization at the temperature by adopting the bottom pouring method, casting defects are not easy to generate, and the molten iron is poured into the mold cavity by adopting the bottom pouring method and rotates at a high speed in the mold cavity, so that impurities and gas in the molten iron are discharged, and the metallurgical quality of a roller casting is improved.
(5) According to the invention, 0.1% of calcium silicon inoculant is added into the cast mold along with the flow after inoculation, so that the molten steel is further inoculated in the cast mold, the molten steel is inoculated more completely, and the performance is enhanced.
(6) The invention has the characteristics of higher roll strength, lower stress, better wear resistance, higher steel passing amount, difficult roll breakage, difficult peeling and the like through low-temperature quenching and tempering.
Detailed Description
(example 1)
This example produced a rough mill roll (BD roll) of phi 1350 х 2800mm steel, the chemical composition of which is expressed in mass percent: 3.25 of C, 0.163 of Si, 0.74 of Mn, 0.024 of P, 0.012 of S, 1.8 of Ni, 0.45 of Mo, 0.27 of V, 0.46 of Cr, 0.067 of Mg, 0.012 of Re, and the balance of Fe and inevitable impurities.
The roller of the embodiment is produced by adopting the production process of the high-strength alloy nodular cast iron rough roller, and comprises the following steps:
smelting: adding scrap steel, ferromolybdenum, ferrochromium and pure nickel in a certain ratio into an intermediate frequency furnace for smelting, sampling and analyzing after melting down, adjusting chemical components in the furnace according to sample components in front of the furnace, adding ferrovanadium 2 minutes before tapping, wherein the chemical components and the weight percentage content of the original molten iron before tapping are as follows: 3.25% of C, 0.58% of Si, 0.74% of Mn, 0.024% of P, 0.012% of S, 1.8% of Ni, 0.45% of Mo, 0.27% of V, 0.46% of Cr and the balance of Fe and inevitable impurities, and raising the temperature to 1485 ℃ to prepare tapping.
Spheroidizing and multiple inoculation treatment by an in-ladle flushing method: firstly, adding a low Si yttrium based heavy rare earth nodulizer with the molten iron amount of 1.6 percent into a ladle, covering the nodulizer with 75SiFe with the molten iron amount of 0.12 percent, and then rapidly pouring base iron into the ladle for nodulizing, wherein the residual magnesium content of the nodulized molten iron is 0.067 percent.
After the treatment is finished, adding iron water into the ladle in a proportion of 0.8 percent to 1: 1, inoculating the long-acting heavy rare earth inoculant and the silicon-calcium-barium inoculant, and preparing for pouring after the inoculation is finished.
Static pouring: after finishing inoculation of molten iron, when the temperature of the molten iron is reduced to 1320 ℃, the molten iron is quickly flushed into a roller casting mold by adopting a bottom pouring method, 0.1 percent of silicon-calcium inoculant is added along with the flow in the mold filling process for stream inoculation, and the molten iron after stream inoculation is sampled and analyzed, wherein the molten iron comprises the following chemical components in percentage by weight: 3.25 percent of C, 0.163 percent of Si, 0.74 percent of Mn, 0.024 percent of P, 0.012 percent of S, 1.8 percent of Ni, 0.45 percent of Mo, 0.27 percent of V, 0.46 percent of Cr, 0.067 percent of Mg, 0.012 percent of Re and the balance of Fe and inevitable impurities, adding a heat insulating agent on a roller riser after casting, and then naturally cooling to room temperature.
Rough machining and heat treatment: and (3) roughly processing the roller after the roller is opened, and respectively carrying out quenching at 780 ℃ and tempering heat treatment at 560 ℃ on the roller which is qualified after rough processing.
And (3) checking and finishing: and (3) inspecting the mechanical and mechanical properties of the roller after heat treatment, wherein the tensile strength is more than or equal to 824Mpa, and the hardness is 48HSD, so that the requirements of the early-stage process design are met.
The steel amount used by a machine is increased by 48 percent compared with a forged steel or cast steel roller, the surface quality of the section is better, and a satisfactory use effect is achieved.
(example 2)
Manufacturing a coarse roll with a phi 900 х 1200mm large rod, wherein the chemical components are expressed by mass percent as follows: 3.42 of C, 1.67 of Si, 0.78 of Mn, 0.021 of P, 0.013 of S, 2.0 of Ni, 0.55 of Mo, 0.36 of V, 0.72 of Cr, 0.057 of Mg, 0.013 of Re, and the balance of Fe and unavoidable impurities.
The roller of the embodiment is produced by adopting the production process of the high-strength alloy nodular cast iron rough roller, and comprises the following steps:
smelting: adding scrap steel, ferromolybdenum, ferrochrome and pure nickel in a certain ratio into an intermediate frequency furnace for smelting, sampling and analyzing after melting down, adjusting chemical components in the furnace according to sample components in front of the furnace, adding ferrovanadium 3 minutes before tapping, wherein the chemical components and the weight percentage content of the tapped high-strength alloy nodular cast iron base iron are as follows: 3.42 of C, 0.55 of Si, 0.78 of Mn, 0.021 of P, 0.013 of S, 2.0 of Ni, 0.55 of Mo, 0.36 of V and 0.72 of Cr, and the balance of Fe and unavoidable impurities, and heating to 1492 ℃ to prepare iron.
Spheroidizing and multiple inoculation treatment by an in-ladle flushing method: firstly, adding a low Si-yttrium based heavy rare earth nodulizer with the molten iron amount of 1.52 percent into a ladle, covering the nodulizer with 75SiFe with the molten iron amount of 0.15 percent, and then rapidly pouring base iron into the ladle for nodulizing, wherein the residual magnesium content of the nodulized molten iron is 0.057 percent.
After the treatment is finished, adding iron water into the ladle in a proportion of 0.75 percent to 1: 1, inoculating the long-acting heavy rare earth inoculant and the silicon-calcium-barium inoculant, and preparing for pouring after the inoculation is finished.
Static pouring: after finishing inoculation of molten iron, when the temperature of the molten iron is reduced to 1330 ℃, the molten iron is quickly flushed into a roller casting mold by adopting a bottom injection method, 0.1 percent of silicon-calcium inoculant is added along with the flow in the mold filling process for stream inoculation, and the molten iron after stream inoculation is sampled and analyzed, wherein the molten iron comprises the following chemical components in percentage by weight: 3.42 percent of C, 1.67 percent of Si, 0.78 percent of Mn, 0.021 percent of P, 0.013 percent of S, 2.0 percent of Ni, 0.55 percent of Mo, 0.36 percent of V, 0.72 percent of Cr, 0.057 percent of Mg, 0.013 percent of Re and the balance of Fe and inevitable impurities, adding a heat insulating agent on a roller riser after casting, and naturally cooling to room temperature.
Rough machining and heat treatment: and (3) roughly processing the roller after the roller is opened, and respectively carrying out quenching at 790 ℃ and tempering heat treatment at 580 ℃ on the roller which is inspected to be qualified after rough processing.
And (3) checking and finishing: and (3) inspecting the mechanical and mechanical properties of the roller after the heat treatment is finished, wherein the tensile strength is more than or equal to 837Mpa, the hardness is 55HSD, and the requirements of the early-stage process design are met.
The steel amount used by the machine is increased by 63 percent compared with a forged steel or cast steel roller, the surface quality of the bar is better, and a satisfactory use effect is achieved.
(example 3)
Manufacturing a phi 1250 х 1810mm sheet strip rough roll, wherein the chemical components are expressed by mass percent as follows: 3.41 of C, 0.56 of Si, 0.72 of Mn, 0.021 of P, 0.012 of S, 2.1 of Ni, 0.55 of Mo, 0.45 of V, 0.74 of Cr, 0.072 of Mg, 0.015 of Re, and the balance of Fe and inevitable impurities.
The roller of the embodiment is produced by adopting the production process of the high-strength alloy nodular cast iron rough roller, and comprises the following steps:
smelting: adding scrap steel, ferromolybdenum, ferrochrome and pure nickel in a certain ratio into an intermediate frequency furnace for smelting, sampling and analyzing after melting down, adjusting chemical components in the furnace according to sample components in front of the furnace, adding ferrovanadium 2 minutes before tapping, wherein the chemical components and the weight percentage content of the tapped high-strength alloy nodular cast iron base iron are as follows: 3.41 percent of C, 0.56 percent of Si, 0.72 percent of Mn, 0.021 percent of P, less than or equal to 0.012 percent of S, 2.1 percent of Ni, 0.55 percent of Mo, 0.45 percent of V, 0.74 percent of Cr and the balance of Fe and inevitable impurities, and the temperature is increased to 1495 ℃ to prepare iron.
Spheroidizing and multiple inoculation treatment by an in-ladle flushing method: firstly, adding a low Si-yttrium based heavy rare earth nodulizer with the molten iron amount of 1.65 percent into a ladle, covering the nodulizer with 75SiFe with the molten iron amount of 0.18 percent, then quickly pouring base iron into the ladle for nodulizing, wherein the residual magnesium content of the nodulized molten iron is 0.072 percent,
after the spheroidization is finished, adding the molten iron into the ladle in a proportion of 0.85 percent to 1: 1, inoculating the long-acting heavy rare earth inoculant and the silicon-calcium-barium inoculant, and preparing for pouring after the inoculation is finished.
Static pouring: after finishing inoculation of molten iron, when the temperature of the molten iron is reduced to 1330 ℃, the molten iron is quickly flushed into a roller casting mold by adopting a bottom injection method, 0.1 percent of silicon-calcium inoculant is added along with the flow in the mold filling process for stream inoculation, and the molten iron after stream inoculation is sampled and analyzed, wherein the molten iron comprises the following chemical components in percentage by weight: 3.41 percent of C, 0.56 percent of Si, 0.72 percent of Mn, 0.021 percent of P, 0.012 percent of S, 2.1 percent of Ni, 0.55 percent of Mo, 0.45 percent of V, 0.74 percent of Cr, 0.072 percent of Mg, 0.015 percent of Re and the balance of Fe and inevitable impurities, adding a heat insulating agent on a roll riser after the casting is finished, and then naturally cooling to room temperature.
Rough machining and heat treatment: and (3) roughly processing the roller after the roller is opened, and respectively carrying out 785 ℃ quenching and 585 ℃ tempering heat treatment on the roller which is qualified after rough processing.
And (3) checking and finishing: and (3) inspecting the mechanical and mechanical properties of the roller after the heat treatment is finished, wherein the tensile strength is more than or equal to 845Mpa, the hardness is 57HSD, and the requirements of the early-stage process design are met.
The steel amount used by the machine is increased by 72 percent compared with a forged steel or cast steel roller, the surface quality of the plate is better, and satisfactory use effects are achieved.
(example 4)
Manufacturing a large bar rough roller with the diameter of 900 mm 900 х 1200mm, wherein the chemical components are expressed by mass percent as follows: 3.0 of C, 1.72 of Si, 0.7 of Mn, 0.01 of P, 0.005 of S, 1.2 of Ni, 0.3 of Mo, 0.1 of V, 0.2 of Cr, 0.045 of Mg, 0.014 of Re, and the balance of Fe and unavoidable impurities.
The roller of the embodiment is produced by adopting the production process of the high-strength alloy nodular cast iron rough roller, and comprises the following steps:
smelting: adding scrap steel, ferromolybdenum, ferrochrome and pure nickel in a certain ratio into an intermediate frequency furnace for smelting, sampling and analyzing after melting down, adjusting chemical components in the furnace according to sample components in front of the furnace, adding ferrovanadium 2 minutes before tapping, wherein the chemical components and the weight percentage content of the tapped high-strength alloy nodular cast iron base iron are as follows: 3.0 of C, 0.6 of Si, 0.7 of Mn, 0.01 of P, 0.005 of S, 1.2 of Ni, 0.3 of Mo, 0.1 of V and 0.2 of Cr, and the balance of Fe and inevitable impurities, and heating to 1480 ℃ to prepare iron tapping.
Spheroidizing and multiple inoculation treatment by an in-ladle flushing method: firstly, adding a low Si-yttrium based heavy rare earth nodulizer with the molten iron amount of 1.2 percent into a ladle, covering the nodulizer with 75SiFe with the molten iron amount of 0.15 percent, then quickly pouring base molten iron into the ladle for nodulizing, wherein the residual magnesium content of the molten iron after the nodulizing is 0.045 percent,
after the spheroidization is finished, adding iron water into the ladle in a proportion of 0.6 percent to 1: 1, inoculating the long-acting heavy rare earth inoculant and the silicon-calcium-barium inoculant, and preparing for pouring after the inoculation is finished.
Static pouring: after finishing inoculation of molten iron, when the temperature of the molten iron is reduced to 1300 ℃, the molten iron is quickly flushed into a roller casting mold by adopting a bottom injection method, 0.1 percent of silicon-calcium inoculant is added along with the flow in the mold filling process for stream inoculation, and the molten iron after stream inoculation is sampled and analyzed, wherein the molten iron comprises the following chemical components in percentage by weight: 3.0 percent of C, 1.72 percent of Si, 0.7 percent of Mn, 0.01 percent of P, 0.005 percent of S, 1.2 percent of Ni, 0.3 percent of Mo, 0.1 percent of V, 0.2 percent of Cr, 0.045 percent of Mg, 0.014 percent of Re and the balance of Fe and inevitable impurities, adding a heat insulating agent on a dead head of the roller after the pouring is finished, and then naturally cooling to room temperature.
Rough machining and heat treatment: and (3) roughly processing the roller after the roller is opened, and respectively carrying out quenching at 750 ℃ and tempering heat treatment at 550 ℃ on the roller which is qualified after rough processing.
And (3) checking and finishing: and (3) inspecting the mechanical and mechanical properties of the roller after the heat treatment is finished, wherein the tensile strength is more than or equal to 800Mpa, the hardness is 54HSD, and the requirements of the early-stage process design are met.
The steel amount used by the machine is improved by 45 percent compared with a forged steel or cast steel roller, the surface quality of the plate is better, and satisfactory use effects are achieved.
(example 5)
Manufacturing a phi 1250 х 1810mm sheet strip rough roll, wherein the chemical components are expressed by mass percent as follows: 3.5 of C, 1.8 of Si, 1.0 of Mn, 0.03 of P, 0.015 of S, 2.2 of Ni, 0.8 of Mo, 0.5 of V, 1.0 of Cr, 0.075 of Mg, 0.016 of Re, and the balance of Fe and inevitable impurities.
The roller of the embodiment is produced by adopting the production process of the high-strength alloy nodular cast iron rough roller, and comprises the following steps:
smelting: adding scrap steel, ferromolybdenum, ferrochrome and pure nickel in a certain ratio into an intermediate frequency furnace for smelting, sampling and analyzing after melting down, adjusting chemical components in the furnace according to sample components in front of the furnace, adding ferrovanadium 2 minutes before tapping, wherein the chemical components and the weight percentage content of the tapped high-strength alloy nodular cast iron base iron are as follows: 3.5% of C, 0.59% of Si, 1.0% of Mn, 0.03% of P, 0.015% of S, 2.2% of Ni, 0.8% of Mo, 0.5% of V, 1.0% of Cr and the balance of Fe and unavoidable impurities, and raising the temperature to 1500 ℃ to prepare iron.
Spheroidizing and multiple inoculation treatment by an in-ladle flushing method: firstly, adding a low Si yttrium based heavy rare earth nodulizer with the molten iron amount of 1.8 percent into a ladle, covering the nodulizer with 75SiFe with the molten iron amount of 0.17 percent, then quickly pouring base iron into the ladle for nodulizing, wherein the residual magnesium content of the nodulized molten iron is 0.075 percent,
after the spheroidization is finished, adding 1.0 percent of molten iron into the ladle according to the proportion of 1: 1, inoculating the long-acting heavy rare earth inoculant and the silicon-calcium-barium inoculant, and preparing for pouring after the inoculation is finished.
Static pouring: after finishing inoculation of molten iron, when the temperature of the molten iron is reduced to 1350 ℃, the molten iron is quickly flushed into a roller casting mold by adopting a bottom injection method, 0.1 percent of silicon-calcium inoculant is added along with flow in the mold filling process for stream inoculation, and the molten iron after stream inoculation is sampled and analyzed, wherein the molten iron comprises the following chemical components in percentage by weight: 3.5 of C, 1.8 of Si, 1.0 of Mn, 0.03 of P, 0.015 of S, 2.2 of Ni, 0.8 of Mo, 0.5 of V, 1.0 of Cr, 0.075 of Mg, 0.016 of Re and the balance of Fe and inevitable impurities, and preparing iron when the temperature is increased to 1500 ℃.
And after the pouring is finished, adding a heat insulating agent on a roller riser, and then naturally cooling to room temperature.
Rough machining and heat treatment: and (3) roughly processing the roller after the roller is opened, and respectively carrying out quenching at 800 ℃ and tempering heat treatment at 600 ℃ on the roller which is qualified after rough processing.
And (3) checking and finishing: and (3) inspecting the mechanical and mechanical properties of the roller after the heat treatment is finished, wherein the tensile strength is more than or equal to 850Mpa, the hardness is 59HSD, and the requirements of the early-stage process design are met.
The amount of steel used on the machine is increased by 73 percent compared with a forged steel or cast steel roller, the surface quality of the plate is better, and satisfactory use effects are achieved.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A high-strength alloy nodular cast iron roughing roll is characterized in that: the chemical components are expressed by mass percentage as follows: 3.0-3.5 percent of C, 1.2-1.8 percent of Si, 0.7-1.0 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.015 percent of S, 1.2-2.2 percent of Ni, 0.3-0.8 percent of Mo, 0.1-0.5 percent of V, 0.2-1.0 percent of Cr, 0.045-0.075 percent of Mg, 0.01-0.016 percent of Re, and the balance of Fe and inevitable impurities.
2. A production process of a high-strength alloy nodular cast iron roughing roll is characterized by comprising the following steps:
s1: smelting; melting and mixing the raw materials, and then adjusting the content of each component to prepare molten steel;
s2: spheroidizing; adding a nodulizer into the molten steel to promote the molten steel to be nodulized;
s3: inoculation; adding an inoculant into the spheroidized molten steel to promote the inoculation and the deterioration of the molten steel;
s4: static pouring: when the temperature of the inoculated and deteriorated molten steel is reduced to a certain temperature, the molten steel is poured into a casting mold and is cooled to cast into a roller;
s5: rough machining and heat treatment; normalizing or quenching the roller, and then tempering;
s6: inspecting and fine processing; and performing finish machining on the roller after the heat treatment to obtain the titanium-containing alloy cast steel roller.
3. The process for producing the high-strength alloy nodular cast iron roughing roll according to the claim 2, characterized in that: in the step S1, scrap steel, ferromolybdenum, ferrochromium and pure nickel in a certain ratio are added into an intermediate frequency furnace for smelting, sampling and analyzing are carried out after melting down, and ferrovanadium is added within 2-5 minutes before tapping, so that the chemical components and weight percentage content of the high-strength alloy nodular cast iron reach the component requirements before tapping: 3.0-3.5% of C, less than or equal to 0.6% of Si, 0.7-1.0% of Mn, less than or equal to 0.03% of P, less than or equal to 0.015% of S, 1.2-2.2% of Ni, 0.3-0.8% of Mo, 0.1-0.5% of V, 0.2-1.0% of Cr and the balance of Fe and unavoidable impurities, and heating to 1480-1500 ℃ to prepare tapping.
4. The process for producing the high-strength alloy nodular cast iron roughing roll according to the claim 2, characterized in that: in the S2, a low Si-yttrium based heavy-earth nodulizer with the molten iron amount of 1.2-1.8% is added into a foundry ladle, a 75SiFe inoculant with the molten iron amount of 0.1-0.2% is covered on the low Si-yttrium based heavy-earth nodulizer, then molten iron is rapidly poured into the foundry ladle for nodulizing, the total Si increment of the molten iron after the nodulizing is below 0.8%, and the residual magnesium amount is controlled within 0.045-0.075%.
5. The process for producing the high-strength alloy nodular cast iron roughing roll according to the claim 2, characterized in that: in the step S3, after the treatment is finished, adding a long-acting heavy rare earth inoculant and a silicon-calcium-barium inoculant with the molten iron amount of 0.6-1.0% into a ladle for inoculation treatment; the ratio of the long-acting heavy rare earth inoculant to the silicon-calcium-barium inoculant is 1: 1.
6. the process for producing the high-strength alloy nodular cast iron roughing roll according to the claim 2, characterized in that: before static pouring, sampling and analyzing the molten iron, and ensuring that the chemical components are expressed by mass percent as follows: 3.0-3.5 percent of C, 1.2-1.8 percent of Si, 0.7-1.0 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.015 percent of S, 1.2-2.2 percent of Ni, 0.3-0.8 percent of Mo, 0.1-0.5 percent of V, 0.2-1.0 percent of Cr, 0.045-0.075 percent of Mg, 0.01-0.016 percent of Re, and the balance of Fe and inevitable impurities.
7. The process for producing the high-strength alloy nodular cast iron roughing roll according to the claim 2, characterized in that: and in the step S4, after the inoculation of the molten iron is finished, when the temperature of the molten iron is reduced to 1300-1350 ℃, the molten iron is quickly poured into the roller casting mold by adopting a bottom pouring method, after the pouring is finished, a heat insulating agent is added on a roller riser, and then the mixture is naturally cooled to room temperature to cast a roller.
8. The process for producing the high-strength alloy nodular cast iron roughing roll according to the claim 2, characterized in that: and in the S4, 0.1% of calcium silicon inoculant is added along with the flow in the casting process for stream inoculation.
9. The process for producing the high-strength alloy nodular cast iron roughing roll according to the claim 2, characterized in that: in S5, rough machining is performed on the cast roll; after rough machining, the roller is quenched at 750-800 ℃ and tempered at 550-600 ℃ after passing inspection.
10. The process for producing the high-strength alloy nodular cast iron roughing roll according to the claim 2, characterized in that: in the step S6, the mechanical and mechanical properties of the roller after heat treatment are tested, wherein the tensile strength is more than or equal to 800Mpa, and the hardness is 45-60 HSD; and after the roller is inspected to be qualified, performing finish machining on the roller to obtain a high-strength alloy nodular cast iron rough roller finished product meeting the requirements.
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