CN110541141A - method for processing carburized straight ejector rod product - Google Patents
method for processing carburized straight ejector rod product Download PDFInfo
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- CN110541141A CN110541141A CN201910788081.9A CN201910788081A CN110541141A CN 110541141 A CN110541141 A CN 110541141A CN 201910788081 A CN201910788081 A CN 201910788081A CN 110541141 A CN110541141 A CN 110541141A
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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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
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- 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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- 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
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- 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
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- 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
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- 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
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/34—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases more than one element being applied in more than one step
Abstract
The invention relates to a method for processing a carburized straight ejector rod product, which comprises the steps of firstly carrying out surface carburization treatment on alloy steel raw materials, secondly carrying out heat treatment on carburized alloy steel, and finally carrying out carburized alloy steel ejector rod processing to obtain the straight ejector rod with high toughness, high hardness, uniformity and low fraction defective. The method is simple and easy to popularize, effectively reduces the cost, and solves the problems of high hardness of the nitriding layer, shallow nitriding layer, uneven nitriding hardness and bending distortion of the product in the prior art.
Description
Technical Field
The invention mainly relates to a brand new production process of a straight ejector rod product, and mainly relates to a processing method capable of improving the surface toughness and hardness of product raw materials, in particular alloy tool steel, and further improving the wear resistance and fatigue resistance of the straight ejector rod product.
background
The traditional mould straight ejector rod on the existing market mainly has two forms: the die straight ejector rod made of the alloy tool steel is made of common alloy tool steel without any treatment on the surface, has larger defects in the aspects of surface hardness, wear resistance, fatigue strength, seizure resistance and the like, is difficult to meet the use requirement of the die, has poor atmosphere and superheated steam corrosion resistance and tempering softening resistance, has higher notch sensitivity, and belongs to a lower-grade product in the die straight ejector rod.
the other is to add a nitriding process on the basis of the product, and carry out nitriding treatment on the surface of a common alloy tool steel raw material, so that the process really solves the problems of poor surface hardness, wear resistance, fatigue strength and seizure resistance, improves the atmospheric and superheated steam corrosion resistance and tempering softening resistance, and reduces the notch sensitivity. However, the core hardness is low, and the infiltration layer is shallow, so that the wear-resistant and fatigue-resistant requirements of bearing light and medium loads can be generally met, and the heat resistance and corrosion resistance of the infiltration layer can not achieve the use effect of the hot working die; the nitriding hardness of the surface is uneven and is not well controlled after nitriding, which indicates that the nitride is not well dissolved and diffused into the product; and the deformation and bending phenomena of steel are easily generated in the nitriding process, so that the product reject ratio is improved.
Therefore, there is a need in the art for a new process to produce a new mold straight ejector pin to solve the problems of uneven nitrided hardness and bending distortion of the product due to the shallow nitrided layer with high hardness.
Disclosure of Invention
In order to make up for the defects of the prior art, the invention provides a production process method of a straight ejector rod with high toughness, high hardness, uniformity and low reject ratio.
The invention adopts the following technical scheme:
S1, firstly, carrying out a surface carburization treatment process on an alloy steel raw material, wherein the alloy tool steel raw material comprises 0.35-0.45% of carbon element, 0.8-1.2% of silicon element, 0.3-0.5% of manganese element, less than or equal to 0.03% of phosphorus element, less than or equal to 0.02% of sulfur element, 5.0-5.5% of chromium element, 1.3-1.6% of molybdenum element, 1.0-1.25% of vanadium element and the balance of iron element;
s2, carrying out heat treatment on the carburized alloy steel;
S3, processing of carburized alloy steel ejector rod
S3.1 nitriding: cleaning the surface of the carburized alloy steel, and charging the washed straight carburized alloy steel within two hours, wherein the height of the alloy steel cannot exceed that of an exhaust pipe; heating up, heating up to 420 +/-10 ℃ after heating up for 1.5h, introducing ammonia gas, controlling the flow of ammonia gas to be 2-3 MPa/h, continuing heating up, introducing 0.5-1h, heating up to 530 +/-10 ℃, increasing the pressure of ammonia gas to 3-4 MPa/h, entering a heat preservation state, preserving heat for 2-2.5h, reducing the pressure of ammonia gas to 1.5 MPa/h, preserving heat for 3-4h, closing the ammonia gas, cooling to below 300 ℃, and discharging;
S3.2, after the straight strip carburized alloy steel is cut into short rods with corresponding specifications, the processes of fine grinding, upsetting, head forming and polishing are sequentially carried out.
Further, the step S1 includes the following specific steps:
s1.1, raising the temperature of a furnace to 800 +/-10 ℃, placing a disc-shaped alloy tool steel raw material to be treated into a carburizing periodic furnace, closing a furnace cover, raising the temperature to 930 +/-10 ℃, dropping kerosene into the furnace at a speed of 160 drops per minute in the process of raising the temperature, and exhausting gas for 60-80 minutes generally;
s1.2, judging a strong permeation time point, increasing the dropping amount of kerosene during strong permeation, putting a test bar during strong permeation according to 180-200 drops per minute, wherein the carburizing speed is 0.15-0.2 mm/h, and when the depth of an upper permeation layer of the test bar reaches one half, the next diffusion period can be carried out after the strong permeation is finished;
s1.3, keeping the temperature unchanged in a diffusion period, reducing the kerosene drop amount, and controlling the diffusion time to be 60-90 minutes according to 100 drops per minute;
s1.4, starting cooling after the diffusion period is ended, cooling to 810 +/-10 ℃, preserving heat for 10-20 minutes at the temperature, reducing the kerosene drop amount in the cooling period, cutting off a heater according to 60 drops per minute after the heat preservation is ended, vertically cooling a workpiece in oil with the temperature of 50-70 ℃, and lifting the material after the cooling time is generally 10-20 minutes;
And S1.5, tempering the cooled material at low temperature within half an hour, taking the material out of the furnace for air cooling at the temperature of 160-190 ℃ for about 2 hours, and obtaining the alloy steel raw material subjected to surface carburization.
further, the step S2 includes the following specific steps:
S2.1, placing the carburized alloy steel to be treated on a clamping stretching mechanism on heat treatment equipment, sending the carburized alloy steel to a quenching area for quenching, quenching and heating the steel to 1100 ℃ through output current, and then preserving heat until quenching is finished;
s2.2, the clamping straightening mechanism continues to move forward, in the process, the carburized alloy steel is cooled to 30-50 ℃, after the carburized alloy steel reaches a tempering area, a tempering electrode is heated to start working, the tempering temperature reaches 650-670 ℃, heat preservation is carried out for 30-50S, and after the tempering is finished, the carburized alloy steel continues to move forward and is cooled;
S2.3, the clamping stretching mechanism comes to a secondary tempering area, the carburized alloy steel is cooled to 30-50 ℃ and then is subjected to secondary tempering, the tempering temperature reaches 650-670 ℃, heat preservation is carried out for 30-50S, after the secondary tempering, the whole heat treatment process is finished, the carburized alloy steel is naturally cooled, and the carburized alloy steel is fed to a feeding area; and the hardness of the finally heat-treated carburized alloy steel core can reach 52HRC, the surface hardness can reach 62HRC, and the clamping stretching mechanism returns to the initial feeding area for the next round of heat treatment production.
Has the advantages that: the method provided by the invention solves the problems of shallow nitriding layer, uneven nitriding hardness and bending distortion of the product although the existing nitriding layer has high hardness. The method is simple and easy to popularize, and effectively reduces the cost.
Detailed Description
The invention is described in more detail below with reference to specific examples, without limiting the scope of the invention. The apparatus used for heat treatment of carburized alloy steel in this example was the quenching and tempering heat treatment apparatus described in CN2017107691589 patent application.
example 1
The first stage is as follows: surface carburizing treatment process for alloy steel raw material
s1, firstly, carrying out a surface carburization treatment process on the basis of raw materials of alloy tool steel (SKD61 Japanese mark number, national standard mark number 4Cr5MoSiV1, American mark number H13 and German mark number 1.2344. most of the raw materials comprise iron elements, and also comprise other special metal and nonmetal elements, wherein the iron elements comprise 0.35-0.45 of carbon element, 0.8-1.2 of silicon element, 0.3-0.5 of manganese element, less than or equal to 0.03 of phosphorus element, less than or equal to 0.02 of sulfur element, 5.0-5.5 of chromium element, 1.3-1.6 of molybdenum element and 1.0-1.25 of vanadium element, and the elements are the specified standard content of the material);
S1.1, raising the temperature of the furnace to 800 +/-10 ℃, turning off a power supply, opening a furnace cover, placing the disc-shaped alloy tool steel raw material to be treated into a carburizing periodic furnace, and closing the furnace cover to raise the temperature to 930 +/-10 ℃. In the temperature rise process, the fan and the kerosene valve are opened, 160 drops of the kerosene are dropped into the furnace every minute, exhaust is carried out, and simultaneously, the sample hole and the exhaust pipe are opened and the exhaust flame is ignited. The exhaust time is generally 60-80 minutes, wherein the exhaust time is about 30 minutes after the temperature is ensured to reach the carburizing temperature.
the flame shape is required to be noticed at any time in the carburizing process, and the strong carburizing time point is judged by observing the flame color, and the judgment method comprises the following steps: if the flame is golden yellow, the flame is unable to extinguish and is in a normal state; once intermittently extinguished, the moisture content was proved to be high; the flame is free of black flame and sparks, the flame is 100-150 mm long, and the flame is in a normal state; if the flame appears sparks, the carbon black in the furnace is excessive; the flame is too long, and the outer edge of the tip is bright white, which indicates that the supply of the carburizing agent is too much; the short flame, light blue outer edge and transparency indicate insufficient supply of carburizing agent or furnace leakage.
The purpose of the exhaust is to drive off the air in the furnace and to restore the air in the furnace to a carbon atmosphere specified in the process. The purpose of heat preservation is to make the temperature of the workpiece in the furnace uniform. The heat preservation time is generally 40 min-1 h. The carburizing temperature is generally 900-940 ℃, the carburizing time is determined according to the required carburized layer depth and is related to factors such as the carburizing temperature, the carbon potential of the furnace atmosphere and the like. The higher the carburizing temperature and the higher the atmospheric carbon potential concentration, the deeper the carburized layer in a certain time. When the carburizing agent is drop-injection type carburizing, the carburizing agent can be selected according to the conditions of a production plant. Ordinary kerosene is used as carburizing agent, and more carbon black is contained in the furnace. Aviation kerosene is selected, carbon black is not easy to generate, methanol is used as carrier gas, kerosene is used as enriching gas, and carbon black in the furnace is less. Methanol is used as carrier gas, acetone or acetic ether is used as enriching gas, and the carbon black in the furnace is less, so that the carbon potential of the atmosphere can be controlled. The dosage of the carburizing agent is adjusted according to factors such as the loading capacity of the workpiece, the surface area and the like.
s1.2, when the flame is in the color of egg yolk, strong permeation is started, and the dropping amount of kerosene needs to be increased according to 180-200 drops per minute. And (3) placing a test rod (the test rod is a material with low carbon content and has the size of phi 8 multiplied by 100mm) during strong infiltration, closing the test sample hole, and keeping the furnace pressure at 6-10 grids, namely taking the high value of the deep furnace pressure of the infiltration layer. The carburizing speed is generally calculated according to 0.15-0.2 mm/h, if the depth of a to-be-carburized layer is 0.8-1.2 mm, the strong permeation time is 6 hours, a test bar is taken out half an hour before the strong permeation setting time is finished, the depth of the to-be-carburized layer is observed (the depth of the to-be-carburized layer of the test bar is generally half of that of a workpiece), the next stage diffusion period can be started after the strong permeation process is finished after the depth is reached, otherwise, the strong permeation time is increased;
and S1.3, the temperature is kept unchanged in the diffusion period, the kerosene drop amount is reduced, the diffusion time is generally 60-90 minutes according to 100 drops per minute, and the effect is to homogenize the carbon solubility of the surface layer of the material.
and (4) starting cooling after the S1.4 diffusion period is finished, turning off the heater at the moment, cooling to about 810 +/-10 ℃, keeping the temperature for 10-20 minutes, and reducing the kerosene drop amount in the cooling period according to 60 drops per minute. And (3) disconnecting the heater when the heat preservation is finished, closing the fan, opening the furnace cover, lifting the tool by using a travelling crane, vertically entering oil with the temperature of 50-70 ℃ for cooling, slightly shaking the tool up and down, left and right during cooling, generally cooling for about 10-20 minutes, and paying attention to the temperature of the oil discharged from the material when the tool is lifted.
S1.5, in order to prevent the material from cracking, the cooled material is tempered at a low temperature within half an hour, the temperature is generally 160-190 ℃, the temperature is determined according to the hardness requirement, and the material is taken out of the furnace and cooled after the heat preservation time is about 2 hours.
and a second stage: heat treatment processing of carburized alloy steel:
S2, setting corresponding quenching and tempering technological parameters of heat treatment induction line equipment according to the high alloy steel processing specification; setting the frequency conversion parameter of the equipment to be 30, and setting the power supply voltage 380V, the direct current voltage 240V, the direct current 220A and the power parameter 3.2KW of the quenching intermediate frequency device; setting the direct current voltage of 350V, the direct current of 90A and the power of 3.9KW of a quenching high-frequency device; the direct current voltage of the tempering intermediate frequency device is 75V, the intermediate frequency voltage is 50V, the direct current is 20A, and the power is 1.5 KW.
S2.1, placing a carburized alloy steel disc raw material (a straight strip material which is cut into 1 meter from the disc raw material) to be processed on a rotating material rack, driving the raw material to rotate by a motor below the material rack, straightening the raw material by a clamping and straightening mechanism of a water-flowing type induction line device, sequentially entering induction coils (or electrodes) of quenching medium frequency and quenching high frequency to carry out quenching heat treatment after straightening, connecting automatic electrode connecting mechanisms in a quenching area to two ends of the clamping and straightening mechanism, starting quenching processing, quenching and heating the steel material to 1100 ℃ by induction current, just leaving the induction coils (or electrodes), carrying out air cooling while advancing forwards, and straightening the material by a straightening and straightening device during quenching.
S2.2, the clamping straightening mechanism continues to move forward, the carburized alloy steel is cooled to 30-50 ℃ until the quenching agent liquid tank starts to be further cooled, and then the carburized alloy steel is discharged out of the quenching agent liquid tank and enters a tempering area. After entering a tempering area, tempering treatment is carried out in a tempering medium-frequency induction coil (or an electrode), tempering heating current can be the same as that before, heat preservation is carried out after the tempering temperature reaches 650-670 ℃, the heat preservation time is 30-50s, the material is continuously stretched forward and naturally cooled after the tempering is finished, the material is further stretched and straightened through a straightening and straightening device in the process, and finally the material is fed to a feeding area by an automatic induction cutting saw according to a fixed size; the hardness of the core part of the carburized alloy steel after final heat treatment can reach 52HRC, and the surface hardness can reach 62 HRC.
And a third stage: processing of carburized alloy steel ejector rod product
(1) nitriding: cleaning the surface of the straight carburized alloy steel, wiping the surface clean by cotton cloth, then washing by gasoline, and finally wiping the workpiece clean by the cotton cloth; the tool and the fixture are kept clean without oil dirt and rust, and the iron wire is required to remove the tin coating on the surface; the washed straight carburized alloy steel is charged in two hours, and the height of the alloy steel cannot exceed that of an exhaust pipe; after loading, the temperature starts to rise, the furnace cover is sealed and the temperature rises to 420 ℃ after 1.5h, the fan is opened to introduce ammonia gas, and the temperature continues to rise. When the temperature of the furnace rises to about 450 ℃, controlling the temperature rising speed not to be too high so as to avoid causing overtemperature at the initial stage of heat preservation, controlling the flow of ammonia gas at 2 MPa/h, keeping the air inlet pressure at 20-40mm oil column, raising the temperature of the furnace to 530 ℃ after 0.5h, increasing the flow of ammonia gas to 3 MPa/h, entering the heat preservation stage, and stopping temperature rising. The temperature and the ammonia decomposition rate are kept correct and stable to prevent the product from being oxidized; and after heat preservation is carried out for 2h, reducing the flow of ammonia gas to 1.5 MPa/h, continuing heat preservation for 3h, then closing the ammonia gas, starting an air blower to cool, and after 1h, cooling to below 300 ℃ and discharging. At the initial stage of heat preservation, when the measured decomposition rate is within 35-70%, the gas inlet and gas outlet pressures are recorded, and the pressure is kept unchanged in the whole process. Measuring the ammonia decomposition rate once every half hour or one hour; in addition, whether the furnace temperature control system and the fan operate normally and whether the air inlet and exhaust pressure are stable or not are observed frequently.
(2) Fine grinding: the method comprises the following steps of cutting straight carburized alloy steel into short rods with corresponding specifications, transferring the short rods to a feeding frame of a centerless grinder, feeding the short rods one by an automatic feeding mechanism, adjusting the distance between guide wheels and grinding wheels of the centerless grinder according to production specifications through the centerless grinder to carry out short rod polishing production, and discharging polished products from a discharging frame.
(3) The heads of upsetting: and setting the corresponding heat treatment parameters of the upsetting machine according to the production specifications, and replacing the base film with the corresponding specifications. The polished carburized alloy steel short rod is fed one by a upsetting feeding machine and enters a rotating tire mold, one end of the short rod is heated by an induction coil at the front end of the tire mold, a pressing head is then carried out after heating, blanking is carried out, annealing treatment is carried out on the upsetting part after cooling.
(4) Head molding: and adjusting the position of a processing cutter of the numerically controlled lathe and related feed and cutting parameters according to the production specification, and processing the head of the slightly raised product to ensure that the head size is in a processing standard range.
(5) polishing: and adjusting the position of a grinding wheel of the polishing machine tool and related polishing parameters according to the production specification, carrying out final rod polishing treatment on the product with the processed head, removing the annealing traces which are not removed, and ensuring that the size of the rod is within the processing standard range.
The performance of the carburized ejector pin product prepared by the method described in example 1 of the present invention was compared with that of a conventional ejector pin product, and the specific data are shown in table 1.
TABLE 1 comparison of Properties
| surface hardness | Core hardness | Tensile strength | |
| common ejector rod product | 51-53HRC | 45-50HRC | 1580MPa |
| carburized ejector rod product | 60-65HRC | 50-55HRC | 1880MPa |
The data in table 1 show that the main essential differences between the carburized ejector rod product of the present invention and the common ejector rod product are as follows: the edge of the common ejector rod product only has a nitriding layer with the thickness of about 0.06mm, but the carburized ejector rod product of the invention also has a carburized layer with the thickness of about 0.1mm besides the nitriding layer, and a part of overlapped area is in a carbonitriding mutual solution state, which is a new straight ejector rod product which does not appear in the market.
The above description is only for the purpose of creating a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can substitute or change the technical solution and the inventive concept of the present invention within the technical scope of the present invention.
Claims (4)
1. The processing method of the carburized straight ejector rod product is characterized by comprising the following steps of:
S1, firstly, carrying out a surface carburization treatment process on an alloy steel raw material, wherein the alloy tool steel raw material comprises 0.35-0.45% of carbon element, 0.8-1.2% of silicon element, 0.3-0.5% of manganese element, less than or equal to 0.03% of phosphorus element, less than or equal to 0.02% of sulfur element, 5.0-5.5% of chromium element, 1.3-1.6% of molybdenum element, 1.0-1.25% of vanadium element and the balance of iron element;
s2, carrying out heat treatment on the carburized alloy steel;
S3, processing of carburized alloy steel ejector rod
S3.1 nitriding: cleaning the surface of carburized alloy steel, then charging, sealing a furnace cover, heating to 420 +/-10 ℃, introducing ammonia gas, controlling the flow of the ammonia gas to be 2-3 MPa/h, continuously heating, introducing for 0.5-1h, heating to 530 +/-10 ℃, increasing the pressure of the ammonia gas to 3-4 MPa/h, entering a heat preservation state, preserving heat for 2-2.5h, reducing the pressure of the ammonia gas to 1.5 MPa/h, preserving heat for 3-4h, closing the ammonia gas, cooling to below 300 ℃, and discharging;
S3.2, after the straight strip carburized alloy steel is cut into short rods with corresponding specifications, the processes of fine grinding, upsetting, head forming and polishing are sequentially carried out.
2. The processing method according to claim 1, wherein the step S1 includes the following steps:
s1.1, raising the temperature of a furnace to 800 +/-10 ℃, placing a disc-shaped alloy tool steel raw material to be treated into a carburizing periodic furnace, closing a furnace cover, raising the temperature to 930 +/-10 ℃, dropping kerosene into the furnace at a speed of 160 drops per minute in the process of raising the temperature, and exhausting gas for 60-80 minutes generally;
S1.2, judging a strong permeation time point, increasing the dropping amount of kerosene during strong permeation, putting a test bar during strong permeation according to 180-200 drops per minute, wherein the carburizing speed is 0.15-0.2 mm/h, and when the depth of an upper permeation layer of the test bar reaches one half, the next diffusion period can be carried out after the strong permeation is finished;
S1.3, keeping the temperature unchanged in a diffusion period, reducing the kerosene drop amount, and controlling the diffusion time to be 60-90 minutes according to 100 drops per minute;
S1.4, starting cooling after the diffusion period is ended, cooling to 810 +/-10 ℃, preserving heat for 10-20 minutes at the temperature, reducing the kerosene drop amount in the cooling period, cutting off a heater according to 60 drops per minute after the heat preservation is ended, vertically cooling a workpiece in oil with the temperature of 50-70 ℃, and lifting the material after the cooling time is generally 10-20 minutes;
and S1.5, tempering the cooled material at low temperature within half an hour, taking the material out of the furnace for air cooling at the temperature of 160-190 ℃ for about 2 hours, and obtaining the alloy steel raw material subjected to surface carburization.
3. The processing method according to claim 1, wherein the step S2 includes the following steps:
S2.1, placing the carburized alloy steel to be treated on a clamping stretching mechanism on heat treatment equipment, sending the carburized alloy steel to a quenching area for quenching, quenching and heating the steel to 1100 ℃ through output current, and then preserving heat until quenching is finished;
S2.2, the clamping straightening mechanism continues to move forward, in the process, the carburized alloy steel is cooled to 30-50 ℃, after the carburized alloy steel reaches a tempering area, a tempering electrode is heated to start working, the tempering temperature reaches 650-670 ℃, heat preservation is carried out for 30-50S, and after the tempering is finished, the carburized alloy steel continues to move forward and is cooled;
S2.3, the clamping stretching mechanism comes to a secondary tempering area, the carburized alloy steel is cooled to 30-50 ℃ and then is subjected to secondary tempering, the tempering temperature reaches 650-670 ℃, heat preservation is carried out for 30-50S, after the secondary tempering, the whole heat treatment process is finished, the carburized alloy steel is naturally cooled, and the carburized alloy steel is fed to a feeding area; the clamping stretching mechanism returns to the original feeding area for the next round of heat treatment production.
4. A carburized straight shank product produced by the process of claim 1.
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| US20190024226A1 (en) * | 2016-01-22 | 2019-01-24 | GM Global Technology Operations LLC | Method of manufacturing a pin for a mold for a die casting process |
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| CN117144288A (en) * | 2023-10-24 | 2023-12-01 | 中国科学院力学研究所 | Chemical heat treatment process for surface modified layer steel |
| CN117144288B (en) * | 2023-10-24 | 2024-01-30 | 中国科学院力学研究所 | Chemical heat treatment process for surface modified layer steel |
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