CN116237523A - Method for producing composite gear steel casting blank - Google Patents

Method for producing composite gear steel casting blank Download PDF

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Publication number
CN116237523A
CN116237523A CN202310268084.6A CN202310268084A CN116237523A CN 116237523 A CN116237523 A CN 116237523A CN 202310268084 A CN202310268084 A CN 202310268084A CN 116237523 A CN116237523 A CN 116237523A
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casting blank
casting
blank
steel
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刘洪银
刘成宝
王利
李浩秋
路峰
王毅
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Shandong Iron and Steel Co Ltd
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Shandong Iron and Steel Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
    • B22F7/08—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools with one or more parts not made from powder
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D19/00—Casting in, on, or around objects which form part of the product
    • B22D19/16—Casting in, on, or around objects which form part of the product for making compound objects cast of two or more different metals, e.g. for making rolls for rolling mills
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/02—Compacting only
    • B22F3/03—Press-moulding apparatus therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Powder Metallurgy (AREA)

Abstract

The invention provides a method for producing a composite gear steel casting blank, which comprises the following steps of: s1, online production of a casting blank shell by using a powder metallurgy technology; s2, injecting molten steel in the tundish into a casting blank shell through a submerged nozzle by the continuous casting machine for casting, and cooling to form a casting blank; wherein the components of the powder adopt a CrNiMo gear steel component system with high carbon content, and the mass percentage of the components is as follows: 1.00 to 1.10 percent of C, 0.05 to 0.15 percent of Si, 0.5 to 0.6 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.015 percent of S, 1.5 to 1.8 percent of Cr, 1.7 to 1.8 percent of Ni, 0.3 to 0.4 percent of Mo, 0.4 to 0.6 percent of lubricant and the balance of Fe and unavoidable impurities. The invention can produce the composite gear steel casting blank with different materials in the casting blank shell and the casting blank on line, and the produced casting blank can meet the requirements of wear resistance and hardness at the gear tooth part position, and simultaneously ensure the toughness and the processability of the whole gear, and has the advantages of short flow, high production efficiency and low cost.

Description

Method for producing composite gear steel casting blank
Technical Field
The invention relates to the technical field of metallurgy, in particular to a method for producing a composite gear steel casting blank.
Background
The gear manufacturing process generally comprises the steps of blank forging, normalizing, rough turning, UT flaw detection, pre-heating vertical turning, scribing, drilling, gear hobbing, chamfering, carburizing and quenching, shot blasting strengthening, post-heating finish turning, numerical control vertical grinding, gear grinding, MT flaw detection, burn detection, spline cutting, cleaning and installation, wherein the functions of the carburizing and quenching and shot blasting strengthening procedures are to improve the wear resistance and hardness at the tooth position. However, since the whole gear steel is made of the same steel, even if the process for improving the wear resistance and the hardness of the tooth position is adopted, the phenomenon of insufficient hardness of the tooth part still exists, the phenomenon of tooth breakage in the application process of the gear steel occurs, carburization is used as a high-energy-consumption process, and the process cost is high and the energy consumption is high.
The composite materials in the metallurgical field generally comprise a double-layer composite material and a three-time composite material, wherein the double-layer composite material refers to materials with different materials on the upper surface and the lower surface, the three-layer composite material refers to materials with different materials on the upper surface, the lower surface and the inside, and the materials with different materials can play different functions. The high alloy content of the upper and lower surfaces can improve the wear resistance and hardness of the tooth position, and the low alloy content of the inner thickness can improve the toughness and the processability of the whole gear.
The Chinese patent publication No. CN100377814C discloses a high-efficiency forming method of a coating material, which comprises the following steps: the cladding metal is insulated by a cladding metal temperature-controlling crucible, flows through a cladding metal insulation cavity, is injected into a casting mould formed by a cladding metal crystallizer and a core metal liquid pouring pipe to be solidified into a cladding metal pipe, and then the core metal liquid is poured into the metal pipe, and the core metal is solidified in the solidified cladding metal pipe and forms a composite cast ingot with the cladding metal pipe. However, the method needs two containers (a tundish or a ladle) for containing different molten metal, the equipment is complex, and the difficulty of manufacturing the coated metal pipe by a horizontal continuous casting method is very high in view of the existing continuous casting technology, and the technology does not describe how the core molten metal pouring pipe cools the coated metal, and does not describe how to realize the stripping problem between the solidified coated metal pipe and the coated metal crystallizer and the core molten metal pouring pipe.
The Chinese patent publication No. CN109128691B discloses a preparation process of a composite casting blank for a high-carbon high-alloy steel plate, which comprises the following steps: preparing a raw material blank; raw material blank processing, namely processing high-carbon and high-alloy steel raw material blanks, wherein the processing method comprises two processing methods of groove processing and thinning processing; preheating a edging welding or surfacing welding cladding transition layer to prepare a combined blank; cutting, milling and cleaning the welded combined blank to obtain a blank to be compounded; vacuum processing and welding the blank to be compounded to obtain a compound blank; and heating the composite blank. The method disclosed by the invention needs to polish the steel plates to be welded to remove the iron scales, and then the steel plates with different materials are welded into a whole by utilizing a vacuum welding method. The method needs to carry out surface processing and vacuum welding of the steel plate, and has low production efficiency and high cost.
From the above, the technologies disclosed in the prior art about composite casting blanks mainly comprise two types: firstly, casting a steel shell, and then casting molten steel of another material into the steel shell to form a composite casting blank, wherein the method requires two containers for containing different molten metals, the equipment is complex, and the existing continuous casting technology horizontally casts a defect-free steel shell with great difficulty; the other is to weld two metal materials with smooth surfaces together by using a vacuum welding method to form a composite casting blank, but the defects of low production efficiency and high cost exist because the surface of the steel plate is polished and the iron oxide scale is removed.
In view of the above, there is currently a lack of a method for producing a composite gear steel billet with operability in the metallurgical field.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides a method for producing a composite gear steel casting blank, which comprises the steps of firstly utilizing a powder metallurgy technology to press a casting blank shell on line, then injecting molten steel into the casting blank shell through a submerged nozzle, and under the high temperature effect of the molten steel, carrying out sintering reaction on the casting blank shell to improve the strength of the casting blank shell, and carrying out hot rolling on a follow-up casting blank to form a round bar gear steel blank, so that the compactness of the casting blank is further improved in the rolling process.
The technical scheme adopted by the invention is as follows:
a method for producing a composite gear steel casting blank comprises the steps of casting a casting blank shell made of powder by pressing and molten steel to form the composite gear steel casting blank.
The method specifically comprises the following steps:
s1, online production of a casting blank shell by using a powder metallurgy technology: pressing the powder into a casting blank shell by adopting a die;
s2, injecting molten steel into the casting blank shell through the immersion nozzle: a tundish filled with molten steel is arranged above the submerged nozzle, and the continuous casting machine injects the molten steel in the tundish into a casting blank shell through the submerged nozzle for casting, and the casting blank is formed after cooling.
Preferably, the components of the powder in the S1 adopt a CrNiMo gear steel component system with high carbon content, which is marked as a first metal, and the components in percentage by mass are as follows: 1.00 to 1.10 percent of C, 0.05 to 0.15 percent of Si, 0.5 to 0.6 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.015 percent of S, 1.5 to 1.8 percent of Cr, 1.7 to 1.8 percent of Ni, 0.3 to 0.4 percent of Mo, 0.4 to 0.6 percent of lubricant and the balance of Fe and unavoidable impurities.
Preferably, the particle size of the powder in S1 is: the granularity of the powder with 600 meshes is less than or equal to 100 meshes.
The lubricant in the step S1 is a lubricant special for the powder metallurgy gear.
Preferably, in the step S1, the blank shape size of the blank shell is 100-300 mm, the rectangular blank with the cross section shape being a rectangular pipe is arranged in the die, and the gap in the die is in a labyrinth-like zigzag trend from top to bottom so as to improve the powder compression molding force and the strength after compression molding.
Preferably, the powder is pressed along the labyrinth-like meandering of the slit: the powder moves downwards, then horizontally, then upwards, then horizontally, then downwards, then horizontally, then upwards, then horizontally and then downwards in the die to form a final rectangular blank shell, and the repeated tortuous movement can increase the resistance of the powder movement and improve the density and strength of the blank shell after compression molding.
Preferably, the powder is uniformly poured into a mould for pressing the composite gear steel casting blank shell, a pressing machine presses the powder into the casting blank shell in a sinusoidal motion mode, the pressing frequency is 150-200 times/min, the pressing amplitude is 2-4 mm, the thickness of the pressed casting blank shell is 5-45 mm, and the density is 6.8-7.2 g/cm 3 。
Preferably, the molten steel in the step S2 adopts a 20CrMnTi component system, which is marked as a second metal, and comprises the following components in percentage by mass: 0.17 to 0.24 percent of C, 0.17 to 0.30 percent of Si, 0.8 to 1.0 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.015 percent of S, 0.04 to 0.06 percent of Ti, and the balance of Fe and unavoidable impurities.
After molten steel is injected into the casting blank shell, the temperature difference between the casting blank shell and the molten steel after compression molding reaches more than 1500 ℃, and the temperature of the molten steel and the solidus temperature only have the temperature difference of about 100 ℃, so that the molten steel can quickly solidify a second metal layer on the inner surface of the casting blank shell, and the casting blank shell and the second metal layer play a role in resisting the hydrostatic pressure of the molten steel together.
Preferably, in the step S2, the pulling speed of the casting blank is controlled to be 1-2 m/min through a flow control device, and the flow control device is a stopper rod or a water gap sliding block.
And (2) adding crystallizer casting powder at the top of molten steel in the casting blank shell in the step (S2) to play roles in preventing secondary oxidation and heat preservation of the molten steel.
Wherein, the periphery of the casting blank shell in the step S2 is supported by small-roller-diameter supporting rollers, the roller diameter of the supporting rollers is 40-180 mm, and the roller spacing is 60-250 mm.
Preferably, the diameter of the supporting roller from the molten steel liquid surface at the top of the casting blank shell to the position 4m is 40-50 mm, the distance between rollers is 50-70 mm, the diameter of the supporting roller from the position 4m to the position 12m is 70-80 mm, the distance between rollers is 90-110 mm, the diameter of the supporting roller from the position 12m to the position downward is 120-140 mm, and the distance between rollers is 150-250 mm.
The cooling water can be sprayed between the two rollers to control the outer surface temperature of the casting blank shell, the outer surface temperature of the casting blank shell is controlled below 1080 ℃ before the casting blank is straightened, and when the outer surface temperature of the casting blank shell is lower than 1040 ℃, the cooling water is not sprayed to the outer surface of the casting blank shell, and the higher temperature is favorable for the rapid sintering reaction of the casting blank shell pressed and formed by powder metallurgy.
And after the interior of the casting blank is completely solidified, the arc-shaped casting blank continuous casting machine cuts the casting blank to a fixed length.
The casting blank is heated in a heating furnace after being cut to length, and a casting blank shell pressed and formed by powder metallurgy is further subjected to sintering reaction in the heating furnace, and then is subjected to rough rolling and finish rolling to form a round bar gear steel blank.
Preferably, the heating time of the casting blank in a heating furnace is 2-3 h, and the soaking section temperature of the heating furnace is 1230-1270 ℃.
Preferably, the initial rolling temperature in the rolling process is 1170-1230 ℃, the final rolling temperature is 900-950 ℃, and the compression ratio of the casting blank in the rolling process is more than or equal to 5, so as to be beneficial to improving the compactness of the casting blank shell pressed and formed by powder metallurgy.
The invention has the beneficial effects that:
1) The invention can produce the composite gear steel casting blank with different materials inside the casting blank shell and the casting blank on line, only one container for containing molten steel is needed to be arranged, the composite gear steel casting blank can be produced without subsequent physical processing and vacuum welding, and the casting blank shell pressed and formed by powder metallurgy is self-sintered by utilizing the heat of the molten steel, so that the sintering cost is saved, and the invention has the advantages of short flow, high production efficiency and low cost;
2) The casting blank produced by the method is hot rolled to form a composite gear steel blank, the alloy content of the surface layer is high, the alloy content at the inner thickness is low, the surface of the material has high hardness and high wear resistance, the core part has higher toughness and strength, the high energy consumption processes such as carburization, nitridation and the like in the conventional gear production are reduced, the requirements of wear resistance and hardness at the tooth position are met, and the toughness and the processability of the whole gear are ensured.
Drawings
FIG. 1 is a schematic view of the vertical flow direction of powder in the process of pressing a composite gear steel casting blank shell provided by the invention;
FIG. 2 is a schematic cross-sectional view at A-A of FIG. 1;
FIG. 3 is a schematic vertical cross-sectional view of a mold for pressing a composite gear steel blank shell provided by the invention;
in the figure, 1. Powder; 2. pressing the vertical section of the upper part of the die of the composite gear steel casting blank shell; 3. pressing the vertical section of the lower part of the die of the composite gear steel casting blank shell; 4. the outermost periphery of the die is provided with a gap with a rectangular cross section; 5. the innermost part of the mould is provided with a slit with a rectangular cross section.
Detailed Description
The following description is made in connection with specific embodiments:
example 1:
1. on-line production of casting blank shell by powder metallurgy technology
The component 1 of the powder adopts a CrNiMo gear steel component system with high carbon content, which is marked as a first metal and comprises the following components in percentage by mass: 1.03% of C, 0.07% of Si, 0.54% of Mn, 0.007% of P, 0.003% of S, 1.74% of Ni, 1.53% of Cr, 0.32% of Mo, 0.5% of lubricant and the balance of Fe and unavoidable impurities.
The granularity of the powder 1 is 200 meshes, and the lubricant is a lubricant special for a powder metallurgy gear.
The blank shape size of the blank shell is 180mm x 220mm rectangular blank, the powder 1 is pressed into the blank shell by adopting a die, a gap with a rectangular pipe in cross section is arranged in the die, and the gap in the die is in labyrinth-shaped zigzag trend from top to bottom. As shown in fig. 1 and 2, the powder 1 is pressed along the labyrinth-like meandering of the slit as follows: firstly, moving downwards, then horizontally, then upwards, then horizontally, then downwards, the powder 1 is pressed from the outermost periphery 4 into the innermost part 5 gradually; the sectional view of the die for pressing the composite gear steel casting blank shell is shown in fig. 3, the composite gear steel casting blank shell is formed by combining an upper die part and a lower die part, and a gap formed by combining is the movement track of the powder 1 in the die.
The powder 1 is put into a die for pressing a composite gear steel casting blank shell at a constant speed, a pressing machine presses the powder downwards in a sinusoidal motion mode, the powder moves along a gap to form the casting blank shell, the pressing frequency is 170 times/min, the pressing amplitude is 3mm, the thickness of the casting blank shell after the pressing forming is 10mm, and the density of the casting blank shell is 6.9g/cm 3 。
2. Casting blank is formed by injecting molten steel into a casting blank shell through a submerged nozzle
A tundish filled with molten steel is arranged above the submerged nozzle, the continuous casting machine injects the molten steel in the tundish into a casting blank shell through the submerged nozzle, the casting blank pulling speed is controlled to be 1.5m/min through a stopper rod, and crystallizer covering slag is added to the top of the molten steel in the blank shell, so that the effects of preventing secondary oxidation and heat preservation of the molten steel are achieved.
The molten steel adopts a 20CrMnTi component system, which is marked as second metal, and comprises the following components in percentage by mass: 0.19% of C, 0.22% of Si, 0.93% of Mn, 0.008% of P, 0.005% of S, 0.052% of Ti, and the balance of Fe and unavoidable impurities.
The periphery of the casting blank shell is supported by small-rod-diameter supporting rollers, the rod diameter of the supporting rollers is 40mm from the molten steel liquid level at the top of the casting blank shell to the position of 4m, the roller spacing is 60mm, the rod diameter of the supporting rollers from the position of 4m to the position of 12m is 80mm, the roller spacing is 110mm, the rod diameter of the supporting rollers from the position of 12m to the position of downward is 120mm, and the roller spacing is 150mm.
And spraying cooling water between the two rollers to control the outer surface temperature of the casting blank shell, wherein the outer surface temperature of the casting blank shell is controlled below 1080 ℃ before the casting blank is straightened, and when the outer surface temperature of the casting blank shell is lower than 1040 ℃, the cooling water is not sprayed to the outer surface of the casting blank shell.
In the embodiment, water spray cooling is not needed to be performed to the outer surface of the casting blank shell from the liquid level of molten steel of the crystallizer to the position of 1.8m, because heat exchange occurs between the molten steel and the casting blank shell within the distance, the molten steel gradually heats the outer surface of the casting blank shell to 1040 ℃, a second metal layer is quickly solidified on the inner surface of the casting blank shell, the thickness of the blank shell at the position of the liquid level of molten steel at the top of the casting blank shell to the position of 1.8m is 32mm, and the casting blank shell with the thickness completely has the capability of resisting the hydrostatic pressure of molten steel; spraying cooling water between the two rollers from 1.8m to control the outer surface temperature of the casting blank shell, controlling the outer surface temperature of the casting blank shell to be 1040-1080 ℃ before the casting blank is straightened, and measuring and calculating to obtain the total specific water quantity of the cooled casting blank of 0.12m 3 Water/t steel.
The casting blank continuous casting machine is an arc continuous casting machine, the arc radius is 10m, the position of complete solidification in the casting blank is the position of the liquid level of molten steel at the top of the casting blank shell downwards to 15m, and the cutting equipment cuts the casting blank to length after the casting blank moves to the position of the cutting equipment.
3. Hot rolling the casting blank into round bar gear steel blank
Heating the casting blank after the fixed-length cutting in a heating furnace for 2.5 hours, wherein the temperature of a soaking section of the heating furnace is 1250 ℃, a casting blank shell formed by compression molding of powder metallurgy further undergoes sintering reaction in the heating furnace, and then rough rolling and finish rolling are carried out to obtain a round bar gear steel blank, wherein the initial rolling temperature in the rolling process is 1180 ℃, the finish rolling temperature is 910 ℃, and the compression ratio of the casting blank is 8.
Through detection, the gear steel blank is a first metal layer within a depth range of 1mm from the surface of the gear steel blank, a second metal layer is below a depth of 2mm from the surface of the gear steel blank, a transition composition layer is within a depth range of 1mm to 2mm from the surface of the gear steel blank, and the mass percentage contents of all the components are shown in the following table 1:
TABLE 1 detection of Gear steel blank composition (%)
Figure BDA0004133772300000061
As can be seen from the table 1, the surface and the inside of the composite gear steel blank produced by the method have obvious component differences, and C, cr and the like on the surface can improve the hardenability and the hardenability, and the element content is higher, so that the surface does not need to be carburised by a carburizing process, the hardness and the wear resistance on the surface of the finished gear are improved, and the service life of the gear is prolonged. The hardness of the gear tooth part produced by using the composite gear steel blank after quenching is detected to be 85HRC, and the hardness of the core part is detected to be 35HRC; the hardness of the gear tooth part produced by carburizing and quenching the normal non-composite gear steel blank is 59HRC, and the technology provided by the invention improves the hardness of the gear tooth part by about 50 percent without reducing the toughness of the gear core part.
In addition, the composite gear steel blank produced by the method has the advantages that the first metal layer with high precious alloy (Mo and Ni) content is only a second metal layer with low alloy content and no precious alloy at other positions within the depth range of 1mm from the surface of the gear steel blank, the toughness of the gear core part is ensured, and meanwhile, the total addition amount of the precious alloy is small.
Example 2:
the powder 1 component in the embodiment adopts a CrNiMo gear steel component system with high carbon content, which is marked as a first metal and comprises the following components in percentage by mass: 1.09% of C, 0.14% of Si, 0.58% of Mn, 0.015% of P, 0.015% of S, 1.75% of Ni, 1.8% of Cr, 0.4% of Mo, 0.6% of lubricant and the balance of Fe and unavoidable impurities; the granularity of the powder 1 is 600 meshes, and the lubricant is a lubricant special for a powder metallurgy gear.
The molten steel adopts a 20CrMnTi component system, which is marked as second metal, and comprises the following components in percentage by mass: 0.23% of C, 0.29% of Si, 0.95% of Mn, 0.014% of P, 0.014% of S, 0.058% of Ti, and the balance of Fe and unavoidable impurities.
A composite gear steel blank was produced by the same method as in example 1, and the composite gear steel blank was inspected to have a first metal layer within a depth of 1mm from the surface of the gear steel blank, a second metal layer within a depth of 2mm from the surface of the gear steel blank, and a transition composition layer within a depth of 1mm to 2mm from the surface of the gear steel blank, wherein the mass percentages of the respective compositions are shown in Table 2 below:
TABLE 2 detection of Gear steel blank composition (%)
Figure BDA0004133772300000071
As can be seen from table 2 above, the surface and the interior of the composite gear steel blank produced by the method have obvious component differences, and the hardness of the gear tooth part produced by using the composite gear steel blank after quenching is 89HRC and the hardness of the core part is 37HRC.
Example 3:
the powder 1 component in the embodiment adopts a CrNiMo gear steel component system with high carbon content, which is marked as a first metal and comprises the following components in percentage by mass: 1.05% of C, 0.1% of Si, 0.55% of Mn, 0.009% of P, 0.002% of S, 1.75% of Ni, 1.65% of Cr, 0.35% of Mo, 0.5% of lubricant and the balance of Fe and unavoidable impurities; the granularity of the powder 1 is 400 meshes, and the lubricant is special for the powder metallurgy gear.
The molten steel adopts a 20CrMnTi component system, which is marked as second metal, and comprises the following components in percentage by mass: 0.2% of C, 0.25% of Si, 0.9% of Mn, 0.007% of P, 0.004% of S, 0.052% of Ti, and the balance of Fe and unavoidable impurities.
A composite gear steel blank was produced by the same method as in example 1, and the composite gear steel blank was inspected to have a first metal layer within a depth of 1mm from the surface of the gear steel blank, a second metal layer within a depth of 2mm from the surface of the gear steel blank, and a transition composition layer within a depth of 1mm to 2mm from the surface of the gear steel blank, wherein the mass percentages of the respective compositions are shown in Table 2 below:
TABLE 3 detection of Gear steel blank composition (%)
Figure BDA0004133772300000072
Figure BDA0004133772300000081
As can be seen from Table 3 above, the composite gear steel blank produced by the method has obvious composition differences on the surface and inside, and the hardness of the gear tooth part produced by quenching the composite gear steel blank is 87HRC and the hardness of the core part is 36HRC.
Comparative example 1:
the powder 1 in the comparative example adopts a CrNiMo gear steel component system with low carbon content, which is marked as a first metal and comprises the following components in percentage by mass: 0.18% of C, 0.10% of Si, 0.56% of Mn, 0.008% of P, 0.002% of S, 1.75% of Ni, 1.54% of Cr, 0.33% of Mo, 0.45% of lubricant and the balance of Fe and unavoidable impurities.
The composition system of molten steel (second metal) and the method for producing a composite cast slab were the same as in example 1.
Through detection, a first metal layer is arranged in a depth range of 1mm from the surface of the gear steel blank, a second metal layer is arranged below a depth of 2mm from the surface of the gear steel blank, a transition composition layer is arranged in a depth range of 1mm to 2mm from the surface of the gear steel blank, and the mass percentage of each composition is shown in the following table 4:
TABLE 4 comparative example 1 Gear steel blank composition detection (%)
Figure BDA0004133772300000082
The hardness at the gear teeth produced after quenching using the composite gear steel blank was found to be 43HRC, which is lower than the hardness at the gear teeth produced in example 1, indicating that a high carbon content powder is beneficial for increasing the hardness at the quenched gear teeth.
Comparative example 2:
the comparative example does not adopt the composite gear steel casting method described in the embodiment 1, but adopts the traditional method to produce casting blanks, the produced casting blanks are not composite casting blanks, the components of the surfaces and the core parts of the casting blanks are the same, wherein the components of the casting blanks adopt a high-carbon-content CrNiMo gear steel component system, and the specific components are as follows in percentage by mass: 1.03% of C, 0.07% of Si, 0.54% of Mn, 0.007% of P, 0.003% of S, 1.74% of Ni, 1.53% of Cr, 0.32% of Mo, and the balance of Fe and unavoidable impurities;
firstly, condensing molten steel through a crystallizer to generate a casting blank shell, spraying water on the surface of the casting blank to cool the casting blank secondarily after the casting blank is discharged out of the crystallizer, so that the interior of the casting blank is completely solidified, and the solidified casting blank is hot-rolled into a gear steel blank.
Through detection, the hardness of the gear tooth part produced by using the gear steel blank after quenching is 86HRC, the hardness of the gear core part is 82HRC, the hardness of the core part is high, the toughness of the corresponding core part is poor, the gear is easy to break integrally under the impact of alternate load in the use process, and the service life of the gear in the use process is low. In comparative example 2, the technical method provided in example 1 of the present invention was not adopted to produce a composite cast blank, resulting in the same composition of the gear tooth portion and the core portion, but the toughness of the whole gear was sacrificed although the hardness at the tooth portion was improved, resulting in a shortened life of the gear in use.
Comparative example 3:
the casting blank is produced by adopting the traditional method same as that of the comparative example 2, and in order to ensure the toughness of the whole gear, the components of the casting blank adopt a 20CrMnTi component system, and the mass percentage is as follows: 0.19% of C, 0.24% of Si, 0.95% of Mn, 0.007% of P, 0.004% of S, 0.052% of Ti, and the balance of Fe and unavoidable impurities.
The hardness of the gear tooth part produced by using the gear steel blank after carburization and quenching is 59HRC, and the hardness of the core part is 36HRC; the carbon content at the 0.8mm thickness of the tooth portion after carburization was 0.52%, which was about 0.51% lower than that at the 1mm thickness of the gear in example 1. Compared with the embodiment 1, the gear carburizing process flow is increased, the energy consumption is high, the process flow is long, and the hardness of the gear tooth part is still lower than that of the embodiment 1, because the whole gear steel blank of the embodiment adopts a low carbon component system, and the carbon content of the gear tooth part at the thickness of about 0.8mm can only be increased by about 0.3-0.5% by the carburizing process, so that the hardness of the gear tooth part is still lower, and the phenomenon of broken teeth is easy to occur.
In summary, the invention provides a method for producing a composite gear steel casting blank, and simultaneously provides a high-carbon-content CrNiMo gear steel component system for preparing a composite gear steel casting blank shell, which can produce composite gear steel casting blanks with different materials inside the casting blank shell and the casting blank on line, and the produced casting blanks can meet the requirements of wear resistance and hardness at gear tooth positions without subsequent physical processing and vacuum welding, and simultaneously ensure the toughness and the processability of the whole gear.

Claims (10)

1. A method for producing a composite gear steel casting blank is characterized in that a casting blank shell made by powder pressing and molten steel are cast to form the composite gear steel casting blank.
2. The method for producing the composite gear steel casting blank according to claim 1, comprising the following steps:
s1, online production of a casting blank shell by using a powder metallurgy technology: pressing the powder into a casting blank shell by adopting a die;
s2, injecting molten steel into the casting blank shell through the immersion nozzle: a container containing molten steel is arranged above the immersed nozzle, and the continuous casting machine injects the molten steel in the tundish into a casting blank shell through the immersed nozzle for casting, and the casting blank is formed after cooling.
3. The method for producing the composite gear steel casting blank according to claim 2, wherein the components of the powder in the S1 adopt a CrNiMo gear steel component system with high carbon content, and the components are as follows by mass percent: 1.00 to 1.10 percent of C, 0.05 to 0.15 percent of Si, 0.5 to 0.6 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.015 percent of S, 1.5 to 1.8 percent of Cr, 1.7 to 1.8 percent of Ni, 0.3 to 0.4 percent of Mo, 0.4 to 0.6 percent of lubricant and the balance of Fe and unavoidable impurities; preferably, the particle size of the powder is: the granularity of the powder with 600 meshes is less than or equal to 100 meshes.
4. The method for producing a composite gear steel casting blank according to claim 2, wherein the blank shell in S1 has a rectangular blank with a blank size of 100-300 mm x 100-300 mm, and the die has a slit with a rectangular tube in cross-section; preferably, the gaps in the die are in labyrinth-like zigzag trend from top to bottom: the powder moves down the slit, then horizontally, then upwardly, then horizontally, then downwardly in the die to form the final rectangular green blank.
5. The method for producing a composite gear steel casting according to claim 2, wherein the powder in S1 is uniformly fed into a die for pressing the composite gear steel casting, the pressing machine presses the powder into the casting in a sinusoidal motion, the pressing frequency is 150 to 200 times/min, the pressing amplitude is 2 to 4mm, the thickness of the pressed casting is 5 to 45mm, and the density is 6.8 to 7.2g/cm 3 。
6. The method for producing the composite gear steel casting blank according to claim 2, wherein the molten steel in the S2 adopts a 20CrMnTi component system, and comprises the following components in percentage by mass: 0.17 to 0.24 percent of C, 0.17 to 0.30 percent of Si, 0.8 to 1.0 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.015 percent of S, 0.04 to 0.06 percent of Ti, and the balance of Fe and unavoidable impurities.
7. The method for producing a composite gear steel casting blank according to claim 2, wherein the crystallizer casting powder is added to the top of molten steel in the shell of the casting blank in S2; the periphery of the casting blank shell is supported by small-roller-diameter supporting rollers, the roller diameter of the supporting rollers is 40-180 mm, and the roller spacing is 60-250 mm; preferably, the diameter of the supporting roller from the molten steel liquid surface at the top of the casting blank shell to the position 4m is 40-50 mm, the distance between rollers is 50-70 mm, the diameter of the supporting roller from the position 4m to the position 12m is 70-80 mm, the distance between rollers is 90-110 mm, the diameter of the supporting roller from the position 12m to the position downward is 120-140 mm, and the distance between rollers is 150-250 mm.
8. The method of producing a composite gear steel billet according to claim 1 wherein the billet is hot rolled into a composite gear steel blank; wherein the heating time of the casting blank in a heating furnace is 2-3 h, and the temperature of a soaking section of the heating furnace is 1230-1270 ℃; preferably, the initial rolling temperature in the hot rolling process is 1170-1230 ℃, the final rolling temperature is 900-950 ℃, and the casting blank compression ratio is more than or equal to 5.
9. A high-carbon-content CrNiMo gear steel component system is characterized by comprising the following components in percentage by mass: 1.00 to 1.10 percent of C, 0.05 to 0.15 percent of Si, 0.5 to 0.6 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.015 percent of S, 1.5 to 1.8 percent of Cr, 1.7 to 1.8 percent of Ni, 0.3 to 0.4 percent of Mo, 0.4 to 0.6 percent of lubricant and the balance of Fe and unavoidable impurities.
10. Use of the CrNiMo gear steel composition system of claim 9 for the production of a steel billet shell for composite gear steel.
CN202310268084.6A 2023-03-15 2023-03-15 Method for producing composite gear steel casting blank Pending CN116237523A (en)

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CN116237523A true CN116237523A (en) 2023-06-09

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