WO2022083248A1 - Carburized workpiece and preparation method therefor - Google Patents

Carburized workpiece and preparation method therefor Download PDF

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Publication number
WO2022083248A1
WO2022083248A1 PCT/CN2021/112411 CN2021112411W WO2022083248A1 WO 2022083248 A1 WO2022083248 A1 WO 2022083248A1 CN 2021112411 W CN2021112411 W CN 2021112411W WO 2022083248 A1 WO2022083248 A1 WO 2022083248A1
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Prior art keywords
carburized
workpiece
temperature
carbon concentration
quenching
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PCT/CN2021/112411
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French (fr)
Chinese (zh)
Inventor
杨日平
杨俊�
杨湘龙
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长沙黑金刚实业有限公司
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Priority to AU2021366577A priority Critical patent/AU2021366577B2/en
Priority to CA3196428A priority patent/CA3196428A1/en
Publication of WO2022083248A1 publication Critical patent/WO2022083248A1/en

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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
    • C23C8/08—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 only one element being applied
    • C23C8/20—Carburising
    • C23C8/22—Carburising of ferrous surfaces
    • 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
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C21D1/20—Isothermal quenching, e.g. bainitic hardening
    • 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
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/607—Molten salts
    • 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
    • C21D9/22—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for drills; for milling cutters; for machine cutting tools
    • 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
    • C23C8/80—After-treatment

Definitions

  • the invention belongs to the technical field of material and workpiece preparation, in particular to a carburized workpiece and a preparation method thereof.
  • the failure study shows that the crack source of the spline fracture of the carburized drill bit is the hot crack caused by the secondary hardening caused by frictional heat generation between the spline of the drill bit and the spline of the chuck.
  • the higher the concentration of the drill spline carburized layer the higher the retained austenite content in the structure, and the greater the risk of hot cracking caused by secondary hardening.
  • the carburizing concentration control of carburizing drill bits is generally high, and there is often a lot of retained austenite in the carburized layer. Therefore, under the continuously increasing working air pressure, the probability of frictional thermal cracking at the spline of the drill bit is high.
  • the technical problem to be solved by the present invention is to provide a carburized workpiece and a preparation method thereof that can effectively reduce the probability of spline breaking.
  • the invention provides a carburized workpiece, the carburized layer of the carburized workpiece is from the surface to the inside, the carbon concentration first increases and then decreases, and the surface carbon concentration is not less than 0.46%, and the highest carbon concentration is 0.58% to 0.68% %, the carburizing depth that reaches the highest carbon concentration is 15% to 50% of the total depth of the carburized layer.
  • the carburizing depth at which the highest hardness is reached in the carburized layer is no more than 0.5 mm, and the hardness of the carburizing layer decreases in a gradient after the highest hardness is reached.
  • the total depth of the carburized layer is 1.6-2.2 mm; the carburizing depth that reaches the highest carbon concentration is 0.4-1.1 mm.
  • the material of the carburized workpiece is selected from 18CrNi3Mo, 23CrN3iMo or 30CrNi4Mo.
  • the present invention also provides a preparation method of the carburized workpiece, comprising:
  • the time of the strong infiltration stage is 4.5-7h; the time of the diffusion stage is 4-6h.
  • the furnace is cooled to 855° C. or less, and the gas is quenched and cooled to room temperature.
  • the temperature of the quenching treatment in the step S2) is 830°C to 850°C; the protective carbon potential is 0.45% to 0.5%; and the time of the quenching treatment is 3 to 5 hours.
  • the temperature of the high-temperature tempering in the step S3) is 660°C to 700°C; the high-temperature tempering time is 5-7 hours; the high-temperature tempering is performed in an inert atmosphere.
  • the heating temperature of the salt bath quenching in the intermediate temperature salt bath quenching treatment is 790 ° C ⁇ 850 ° C; the heating time of the salt bath quenching is 25 ⁇ 90min; the isothermal salt bath quenching treatment in the isothermal salt bath quenching treatment is isothermal quenching
  • the temperature is 230 °C ⁇ 280 °C; the time of isothermal quenching in nitrate bath is 20 ⁇ 70min; the temperature of low temperature tempering in the step S5) is 180 °C ⁇ 230 °C; the time of low temperature tempering is 4 ⁇ 6h.
  • the invention provides a carburized workpiece, the carburized layer of the carburized workpiece is from the surface to the inside, the carbon concentration first increases and then decreases, and the surface carbon concentration is not less than 0.46%, and the highest carbon concentration is 0.58% to 0.68% %, the carburizing depth that reaches the highest carbon concentration is 15% to 50% of the total depth of the carburized layer.
  • the present invention effectively controls the amount of retained austenite in the outermost layer by controlling the change curve of the carbon concentration of the carburized layer, and at the same time reduces the carbon concentration of the outermost layer, and reduces the amount of residual austenite in the outermost layer.
  • the hardness of the carburized workpiece accelerates the running-in degree of the spline of the carburized workpiece and the spline of the chuck, and reduces the thermal cracking phenomenon of the carburized layer under high-frequency friction, which can effectively reduce the probability of the spline of the carburized workpiece breaking. It greatly prolongs the service life of carburized workpieces, and has a wide range of applications in the field of high-frequency and high-load DTH drills.
  • Fig. 1 is the carburizing concentration and the hardness gradient graph of the HD55A-152 drill bit carburizing layer obtained in the embodiment of the present invention 1;
  • FIG. 2 is a microscopic picture of the metallographic structure of the carburized layer of the HD55A-152 drill bit obtained in Example 1 of the present invention.
  • the invention provides a carburized workpiece, the carburized layer of the carburized workpiece is from the surface to the inside, the carbon concentration first increases and then decreases, and the surface carbon concentration is not less than 0.46%, and the highest carbon concentration is 0.58% to 0.68% %, the carburizing depth that reaches the highest carbon concentration is 15% to 50% of the total depth of the carburized layer.
  • the carburizing workpiece is preferably a carburizing drill bit; the carburizing workpiece is preferably formed of high-strength structural steel; the material of the carburizing workpiece is more preferably 18CrNi3Mo, 23CrN3iMo or 30CrNi4Mo;
  • the diameter of the key shank is preferably 50-180 mm, and the diameter of the big head of the insert is preferably 100-380 mm.
  • the surface of the carburized workpiece is a carburized layer; the carburized layer is from the surface to the inside, and the carbon concentration first increases and then decreases, that is, the carbon concentration distribution curve is parabolic; the surface carbon concentration of the carburized layer is preferably The surface carbon concentration is preferably 0.48% to 0.5%; the surface carbon concentration is preferably the concentration at 0.2 mm of the surface layer; the highest carbon concentration of the carburized layer is preferably 0.60% to 0.68%, more Preferably, it is 0.62% to 0.66%, more preferably 0.62% to 0.65%; the carburized depth of the highest carburized layer in the carburized layer is preferably 20% to 45% of the total depth of the carburized layer, more preferably 25% to 25%.
  • the carburizing depth to reach the highest carbon concentration is preferably 0.4 to 1.1 mm, more preferably 0.4 to 0.8 mm, and then It is preferably 0.4-0.7mm, most preferably 0.5-0.6mm;
  • the total depth of the carburized layer is preferably 1%-1.5% of the diameter of the carburized workpiece, more preferably 1%-1.4%, and more preferably 1% ⁇ 1.3%, more preferably 1.1% ⁇ 1.2%, most preferably 1.1% ⁇ 1.15%; in the present invention, the total depth of the carburized layer is preferably 1.6 ⁇ 2.2mm, more preferably 1.6 ⁇ 2mm, and then It is preferably 1.6 to 1.8 mm, and most preferably 1.7 mm.
  • the carburizing depth that achieves the highest hardness in the carburized layer is preferably no more than 0.5 mm, more preferably 0.25-0.45 mm, still more preferably 0.3-0.4 mm, and most preferably 0.3 mm; After the highest hardness is reached in the carburized layer, the hardness will gradually decrease. In the present invention, the hardness of the carburized layer preferably decreases in a gradient after the highest hardness is reached.
  • the metallographic structure of the carburized layer of the carburized workpiece provided by the present invention has almost no residual austenite in the field of view of a 50-500 magnification microscope.
  • the present invention effectively controls the amount of residual austenite in the outermost layer by controlling the change curve of the carbon concentration of the carburized layer and at the same time reduces the carbon concentration of the outer layer, reduces the hardness of the outermost layer, and accelerates the carburizing workpiece
  • the degree of running-in between the splines and the splines of the clamping sleeve reduces the thermal cracking phenomenon of the carburized layer under high-frequency friction, which can effectively reduce the probability of the spline fracture of the carburized workpiece, and greatly prolong the life of the carburized workpiece. It has a wide range of applications in the field of high-frequency and high-load down-the-hole drill bit rock drilling.
  • the present invention also provides a method for preparing the above carburized workpiece, comprising: S1) carburizing the workpiece; the temperature of the carburizing treatment is 920°C to 930°C; the strong carburizing potential is 1% to 1.15% ; Diffusion carbon potential is 0.78% to 0.85%; S2) quench the workpiece after carburizing treatment; S3) perform high temperature tempering on the workpiece after quenching treatment; S4) perform isothermal salt bath on the workpiece after high temperature tempering Quenching treatment; S5) performing low temperature tempering on the workpiece after isothermal salt bath quenching treatment to obtain a carburized workpiece.
  • the workpiece can be prepared according to a method well known to those skilled in the art, preferably through blanking, die forging and machining to obtain the workpiece;
  • the initial forging temperature in the die forging process is preferably 1180°C to 1250°C ;
  • the final forging temperature is preferably 870 °C ⁇ 890 °C.
  • the temperature of the carburizing treatment is preferably 922°C to 928°C, more preferably 924°C to 926°C, and more preferably 925°C;
  • the strong carburizing potential is preferably 1.05% to 1.15%;
  • the time of the infiltration stage is preferably 4.5-7h, more preferably 5-6h;
  • the carbon diffusion potential is preferably 0.78%-0.83%;
  • the time of the diffusion stage is preferably 4-6h, more preferably 4.5-5h;
  • the carburizing treatment When the carburizing agent is preferably methanol and acetone, the carbon potential in the carburizing process can be controlled by the combination of the two.
  • the carburizing treatment After the carburizing treatment, it is preferable to cool down to 855°C or less with the furnace, and cool to room temperature by gas quenching; the gas quenching uses high-pressure nitrogen as a medium, which can realize rapid cooling.
  • the workpiece after carburizing treatment is subjected to quenching treatment; the temperature of the quenching treatment is preferably 830°C to 850°C; the protective carbon potential is preferably 0.45% to 0.5%; the time of the quenching treatment is preferably 3 to 5h; Cooling with rapid quenching cooling oil.
  • the quenched workpiece is subjected to high temperature tempering; the temperature of the high temperature tempering is preferably 660°C to 700°C; the time of the high temperature tempering is preferably 5 to 7 hours; the high temperature tempering is preferably performed in an inert atmosphere; The inert atmosphere is preferably nitrogen.
  • machining is preferably performed to obtain a carburized workpiece of a specific size, and then an isothermal salt bath quenching treatment is performed; the heating temperature of the salt bath quenching in the isothermal salt bath quenching treatment is preferably 790 °C ⁇ 850 °C.
  • the heating time of salt bath quenching is preferably 25 ⁇ 90min, more preferably 35 ⁇ 60min, more preferably 40 ⁇ 50min, most preferably 40 ⁇ 45min; in isothermal salt bath quenching treatment
  • the temperature of isothermal quenching in nitrate tank is preferably 230 °C ⁇ 280 °C; the isothermal quenching time in nitrate tank is preferably 20 ⁇ 70min, more preferably 30 ⁇ 50min, more preferably 30 ⁇ 45min, most preferably 35 ⁇ 40min.
  • the workpiece after isothermal salt bath quenching treatment is subjected to low-temperature tempering; the temperature of the low-temperature tempering is preferably 180° C. to 230° C.; the time of low-temperature tempering is preferably 4-6 h; A carburized workpiece is obtained.
  • the invention obtains a carburized layer with a parabolic gradient change in carbon concentration and no residual austenite near the surface, reduces the key influencing factor of the drill bit spline friction thermal cracking, and accelerates the drill bit operation During the process, the matching degree of the spline and the drill sleeve can effectively reduce the probability of the spline of the drill bit being broken.
  • the selection of temperature and carbon potential in the carburizing process, the selection of quenching temperature, carbon potential and cooling method, as well as the selection of high return temperature and protective atmosphere are the keys to obtain the parabolic curve change of carbon concentration gradient, which is the key to effectively control carburization
  • the preconditions for the amount of retained austenite near the surface layer; the selection of the salt bath temperature and the isothermal temperature of the nitrate bath in the salt quenching process, as well as the selection of the temperature and cooling method in the low-return process are the key measures to further effectively control the retained austenite.
  • 23CrNi3Mo as the base material of the drill bit, it is made by blanking, die forging, machining, carburizing treatment, quenching treatment, high return, machining, isothermal salt quenching, low temperature tempering, drilling alloy teeth holes and inserting alloy teeth. HD55A-152 drill bit.
  • the initial forging temperature is 1180 °C; the final forging temperature is 870 °C; After cooling with the furnace to 855 °C, the high-pressure nitrogen is used as the medium for gas quenching and cooling to room temperature; the quenching temperature is 850 °C, the quenching treatment time is 3h, the protective carbon potential is 0.45%, and the quenching cooling medium selects rapid quenching cooling oil; the high return temperature is 700 °C, high return time is 5h, using nitrogen protection; salt bath temperature is 830 °C, salt bath time is 40min, nitrate tank temperature is 230 °C, nitrate tank isothermal time 35min; low return temperature is 180 °C, low return temperature The time is 4h, and the oven is air-cooled.
  • the carburized concentration and hardness of the carburized layer of the HD55A-152 drill bit obtained in Example 1 were analyzed, and the carbon concentration and hardness curves were obtained, as shown in FIG. 1 .
  • Example 2 The HD55A-152 drill bit obtained in Example 1 was analyzed with a metallographic microscope, and the metallographic microscopic picture of its carburized layer was obtained, as shown in Figure 2. From Figure 2, it can be seen that the metallographic structure was observed under a metallographic microscope at a magnification of 500 times. Almost no retained austenite exists in the field of vision.
  • the test results of the carburized layer show that the carbon concentration gradient of the carburized layer is parabolic.
  • the hardness of the carburized layer is 1.7mm; the hardness of the carburized layer is 0.3mm, and the hardness of the carburized layer decreases gradually; the metallographic structure has almost no residual austenite under the field of 500 times the metallographic microscope. 50 test bits were tested on the condition that the proportion of broken bits was 20%, and there was no case of breakage.
  • 30CrNi3Mo as the base material of the drill bit, it is made by blanking, die forging, machining, carburizing treatment, quenching treatment, high return, machining, isothermal salt quenching, low temperature tempering, drilling alloy teeth holes and inserting alloy teeth. HD55A-152 drill bit.
  • the initial forging temperature is 1180°C; the final forging temperature is 870°C; the carburizing temperature is 925°C; , cooled with the furnace to 855 °C and then quenched to room temperature with high pressure nitrogen as the medium; the quenching temperature is 830 °C, the quenching treatment time is 3h, the protective carbon potential is 0.50%, and the quenching cooling medium selects rapid quenching cooling oil; the high return temperature is 680°C, high return time is 5h, nitrogen protection is adopted; salt bath temperature is 810°C, salt bath time is 45min, nitrate tank temperature is 260°C, nitrate tank isothermal time is 40min; low return temperature is 230°C, low return temperature The time is 4h, and the oven is air-cooled.
  • the test results of the carburized layer show that the carbon concentration gradient of the carburized layer is parabolic.
  • the hardness of the carburized layer is 1.7mm; the hardness of the carburized layer is 0.4mm, and the hardness of the carburized layer decreases gradually; the metallographic structure has almost no residual austenite under the field of 500 times the metallographic microscope. 50 test bits were tested under the condition that the proportion of broken bits was 20%, and there was no case of breakage.
  • 30CrNi4Mo as the base material of the drill bit, it is made by blanking, die forging, machining, carburizing treatment, quenching treatment, high return, machining, isothermal salt quenching, low temperature tempering, drilling alloy teeth holes and inserting alloy teeth. HD55A-152 drill bit.
  • the initial forging temperature is 1180°C; the final forging temperature is 870°C; the carburizing temperature is 925°C; h, after cooling with the furnace to 855 °C, high-pressure nitrogen is used as the medium to quench and cool to room temperature; the quenching temperature is 830 °C, the quenching treatment time is 3h, the protective carbon potential is 0.48%, and the quenching cooling medium selects rapid quenching cooling oil; high return temperature
  • the temperature of the salt bath is 800°C, the salt bath time is 45min, the temperature of the nitrate tank is 280°C, and the isothermal time of the nitrate tank is 40min; the low temperature is 230°C, the low temperature The return time is 4h, and the oven is air-cooled.
  • the test results of the carburized layer show that the carbon concentration gradient of the carburized layer is parabolic.
  • the hardness of the carburized layer is 1.7mm; the hardness of the carburized layer is 0.35mm, and the hardness of the carburized layer decreases gradually; the metallographic structure has almost no residual austenite under the field of 500 times the metallographic microscope. 50 test bits were tested on the condition that the proportion of broken bits was 20%, and there was no case of breakage.

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Abstract

Provided is a carburized workpiece. From a surface to the inside, the carbon concentration of a carburized layer of the carburized workpiece first increases and then decreases, the surface carbon concentration of the carburized layer is not lower than 0.46%, the highest carbon concentration of the carburized layer is 0.58-0.68%, and a carburization depth reaching the highest carbon concentration is 15-50% of the total depth of the carburized layer. Compared with the prior art, by means of controlling a change curve of the carbon concentration of the carburized layer and also reducing the carbon concentration of an outer surface layer, the amount of retained austenite on the outermost layer is effectively controlled, the hardness of the outermost layer is reduced, the run-in degree of a carburized workpiece spline and a clamping drill sleeve spline is increased, and the thermal cracking phenomenon of the carburized layer under high-frequency friction is reduced, such that the probability of breakage of the carburized workpiece spline can be effectively reduced, the service life of the carburized workpiece can be greatly prolonged, and the carburized workpiece is widely used in the field of rock drilling with high-frequency high-load down-the-hole drill bits.

Description

一种渗碳工件及其制备方法A kind of carburized workpiece and preparation method thereof
本申请要求于2020年10月22日提交中国专利局、申请号为202011138231.0、发明名称为“一种渗碳工件及其制备方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。This application claims the priority of the Chinese patent application filed on October 22, 2020 with the application number 202011138231.0 and the invention titled "A carburized workpiece and its preparation method", the entire contents of which are incorporated herein by reference Applying.
技术领域technical field
本发明属于材料与工件制备技术领域，尤其涉及一种渗碳工件及其制备方法。The invention belongs to the technical field of material and workpiece preparation, in particular to a carburized workpiece and a preparation method thereof.
背景技术Background technique
随着空压机与凿岩设备技术的提升，钻机输出风压越来越高，导致钻头凿岩频率和冲击作用力越来越高，钻头花键断体的几率也越来越大。With the improvement of air compressor and rock drilling equipment technology, the output wind pressure of the drilling rig is getting higher and higher, resulting in higher and higher drilling frequency and impact force of the drill bit, and the probability of the bit spline breaking is also increasing.
经失效研究表明渗碳钻头花键断体的裂纹源为钻头花键与卡钎套花键之间因摩擦生热而产生的二次淬硬而导致的热裂。钻头花键渗碳层浓度越高，组织中残余奥氏体含量越高，二次淬硬导致的热裂风险越大。而潜孔钻头领域渗碳钻头的渗碳浓度控制普遍较高，渗碳层往往又存在较多的残余奥氏体，因此在不断提高的工作风压下，钻头花键处摩擦热裂的几率不断增加，花键断体的几率也不断增加。此外，刚开始时，由于钻头花键与卡钎套花键的接触为线接触，钻头花键表面硬度越高，钻头花键与卡钎套花键之间的磨合越困难，越容易导致局部过载，进而加快热裂纹的产生于扩展。The failure study shows that the crack source of the spline fracture of the carburized drill bit is the hot crack caused by the secondary hardening caused by frictional heat generation between the spline of the drill bit and the spline of the chuck. The higher the concentration of the drill spline carburized layer, the higher the retained austenite content in the structure, and the greater the risk of hot cracking caused by secondary hardening. In the field of down-the-hole drill bits, the carburizing concentration control of carburizing drill bits is generally high, and there is often a lot of retained austenite in the carburized layer. Therefore, under the continuously increasing working air pressure, the probability of frictional thermal cracking at the spline of the drill bit is high. As it continues to increase, the probability of spline breaking is also increasing. In addition, at the beginning, since the contact between the spline of the drill bit and the spline of the drill sleeve is line contact, the higher the surface hardness of the spline of the drill bit, the more difficult the running-in between the spline of the drill bit and the spline of the drill sleeve, and the easier it is to cause local overload, which in turn accelerates the growth of thermal cracks.
发明内容SUMMARY OF THE INVENTION
有鉴于此，本发明要解决的技术问题在于提供一种可有效减少花键断体几率的渗碳工件及其制备方法。In view of this, the technical problem to be solved by the present invention is to provide a carburized workpiece and a preparation method thereof that can effectively reduce the probability of spline breaking.
本发明提供了一种渗碳工件，所述渗碳工件的渗碳层由表面向里，碳浓度先升高后降低，且表面碳浓度不低于0.46％，最高碳浓度为0.58％～0.68％，达到最高碳浓度的渗碳深度为渗碳层总深度的15％～50％。The invention provides a carburized workpiece, the carburized layer of the carburized workpiece is from the surface to the inside, the carbon concentration first increases and then decreases, and the surface carbon concentration is not less than 0.46%, and the highest carbon concentration is 0.58% to 0.68% %, the carburizing depth that reaches the highest carbon concentration is 15% to 50% of the total depth of the carburized layer.
优选的，所述渗碳层中达到最高硬度的渗碳深度不超过0.5mm，且所述渗碳层中达到最高硬度后硬度呈梯度下降。Preferably, the carburizing depth at which the highest hardness is reached in the carburized layer is no more than 0.5 mm, and the hardness of the carburizing layer decreases in a gradient after the highest hardness is reached.
优选的，所述渗碳层的总深度为1.6～2.2mm；达到最高碳浓度的渗碳深度为0.4～1.1mm。Preferably, the total depth of the carburized layer is 1.6-2.2 mm; the carburizing depth that reaches the highest carbon concentration is 0.4-1.1 mm.
优选的，所述渗碳工件的材料选自18CrNi3Mo、23CrN3iMo或30CrNi4Mo。Preferably, the material of the carburized workpiece is selected from 18CrNi3Mo, 23CrN3iMo or 30CrNi4Mo.
本发明还提供了一种渗碳工件的制备方法，包括：The present invention also provides a preparation method of the carburized workpiece, comprising:
S1)将工件进行渗碳处理；所述渗碳处理的温度为920℃～930℃；强渗碳势为1％～1.15％；扩散碳势为0.78％～0.85％；S1) Carburizing the workpiece; the temperature of the carburizing treatment is 920℃～930℃; the strong carburizing potential is 1%～1.15%; the diffusion carbon potential is 0.78%～0.85%;
S2)将渗碳处理后的工件进行淬火处理；S2) quenching the carburized workpiece;
S3)将淬火处理后的工件进行高温回火；S3) carry out high temperature tempering to the workpiece after quenching treatment;
S4)将高温回火后的工件进行等温盐浴淬火处理；S4) the workpiece after high temperature tempering is subjected to isothermal salt bath quenching treatment;
S5)将等温盐浴淬火处理后的工件进行低温回火，得到渗碳工件。S5) low-temperature tempering is performed on the workpiece after isothermal salt bath quenching to obtain a carburized workpiece.
优选的，所述步骤S1)中强渗阶段的时间为4.5～7h；扩散阶段的时间为4～6h。Preferably, in the step S1), the time of the strong infiltration stage is 4.5-7h; the time of the diffusion stage is 4-6h.
优选的，所述步骤S1)中渗碳处理后随炉冷却至小于等于855℃，气淬冷却至室温。Preferably, in the step S1), after the carburizing treatment, the furnace is cooled to 855° C. or less, and the gas is quenched and cooled to room temperature.
优选的，所述步骤S2)中淬火处理的温度为830℃～850℃；保护碳势为0.45％～0.5％；淬火处理的时间为3～5h。Preferably, the temperature of the quenching treatment in the step S2) is 830°C to 850°C; the protective carbon potential is 0.45% to 0.5%; and the time of the quenching treatment is 3 to 5 hours.
优选的，所述步骤S3)中高温回火的温度为660℃～700℃；高温回火的时间为5～7h；所述高温回火在惰性气氛中进行。Preferably, the temperature of the high-temperature tempering in the step S3) is 660°C to 700°C; the high-temperature tempering time is 5-7 hours; the high-temperature tempering is performed in an inert atmosphere.
优选的，所述步骤S4)中等温盐浴淬火处理中盐浴淬火的加热温度为790℃～850℃；盐浴淬火的加热时间为25～90min；等温盐浴淬火处理中硝盐槽等温淬火的温度为230℃～280℃；硝盐槽等温淬火的时间为20～70min；所述步骤S5)中低温回火的温度为180℃～230℃；低温回火的时间为4～6h。Preferably, in the step S4), the heating temperature of the salt bath quenching in the intermediate temperature salt bath quenching treatment is 790 ° C ~ 850 ° C; the heating time of the salt bath quenching is 25 ~ 90min; the isothermal salt bath quenching treatment in the isothermal salt bath quenching treatment is isothermal quenching The temperature is 230 ℃～280 ℃; the time of isothermal quenching in nitrate bath is 20～70min; the temperature of low temperature tempering in the step S5) is 180 ℃～230 ℃; the time of low temperature tempering is 4～6h.
本发明提供了一种渗碳工件，所述渗碳工件的渗碳层由表面向里，碳浓度先升高后降低，且表面碳浓度不低于0.46％，最高碳浓度为0.58％～0.68％，达到最高碳浓度的渗碳深度为渗碳层总深度的15％～50％。与现有技术相比，本发明通过控制渗碳层碳浓度的变化曲线，同时通过降低外表层碳浓度的方式，有效的控制住了最表层残余奥氏体的量，又降低了最表层的硬度，加速了渗碳工件花键与卡钎套花键的磨合程度，减少了渗碳层在高频摩擦下的热裂现象，从而能够有效的减少渗碳工件花键断体的几率，能够大大的延长渗碳工件的使用寿命，在高频高载潜孔钻头凿岩领域具有广泛的应用。The invention provides a carburized workpiece, the carburized layer of the carburized workpiece is from the surface to the inside, the carbon concentration first increases and then decreases, and the surface carbon concentration is not less than 0.46%, and the highest carbon concentration is 0.58% to 0.68% %, the carburizing depth that reaches the highest carbon concentration is 15% to 50% of the total depth of the carburized layer. Compared with the prior art, the present invention effectively controls the amount of retained austenite in the outermost layer by controlling the change curve of the carbon concentration of the carburized layer, and at the same time reduces the carbon concentration of the outermost layer, and reduces the amount of residual austenite in the outermost layer. The hardness of the carburized workpiece accelerates the running-in degree of the spline of the carburized workpiece and the spline of the chuck, and reduces the thermal cracking phenomenon of the carburized layer under high-frequency friction, which can effectively reduce the probability of the spline of the carburized workpiece breaking. It greatly prolongs the service life of carburized workpieces, and has a wide range of applications in the field of high-frequency and high-load DTH drills.
附图说明Description of drawings
图1为本发明实施例1中得到的HD55A-152钻头渗碳层的渗碳浓度及硬 度梯度曲线图；Fig. 1 is the carburizing concentration and the hardness gradient graph of the HD55A-152 drill bit carburizing layer obtained in the embodiment of the present invention 1;
图2为本发明实施例1中得到的HD55A-152钻头渗碳层的金相组织显微镜图。FIG. 2 is a microscopic picture of the metallographic structure of the carburized layer of the HD55A-152 drill bit obtained in Example 1 of the present invention.
具体实施方式Detailed ways
下面将结合本发明实施例，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
本发明提供了一种渗碳工件，所述渗碳工件的渗碳层由表面向里，碳浓度先升高后降低，且表面碳浓度不低于0.46％，最高碳浓度为0.58％～0.68％，达到最高碳浓度的渗碳深度为渗碳层总深度的15％～50％。The invention provides a carburized workpiece, the carburized layer of the carburized workpiece is from the surface to the inside, the carbon concentration first increases and then decreases, and the surface carbon concentration is not less than 0.46%, and the highest carbon concentration is 0.58% to 0.68% %, the carburizing depth that reaches the highest carbon concentration is 15% to 50% of the total depth of the carburized layer.
在本发明中，渗碳工件优选为渗碳钻头；所述渗碳工件优选由高强度结构钢形成；所述渗碳工件的材料更优选为18CrNi3Mo、23CrN3iMo或30CrNi4Mo；所述渗碳钻头的花键柄直径优选为50～180mm，镶齿大头直径优选为100～380mm。In the present invention, the carburizing workpiece is preferably a carburizing drill bit; the carburizing workpiece is preferably formed of high-strength structural steel; the material of the carburizing workpiece is more preferably 18CrNi3Mo, 23CrN3iMo or 30CrNi4Mo; The diameter of the key shank is preferably 50-180 mm, and the diameter of the big head of the insert is preferably 100-380 mm.
所述渗碳工件的表面为渗碳层；所述渗碳层由表面向里，碳浓度先升高后降低，即碳浓度分布曲线呈类抛物线状；所述渗碳层的表面碳浓度优选为0.2mm处浓度；所述表面碳浓度优选为0.48％～0.5％；所述表面碳浓度优选为表层0.2mm处的浓度；所述渗碳层最高碳浓度优选为0.60％～0.68％，更优选为0.62％～0.66％，再优选为0.62％～0.65％；渗碳层中达到最高渗碳层的渗碳深度优选为渗碳层总深度的20％～45％，再优选为25％～40％，再优选为28％～38％，最优选为29.4％～35.2％；在本发明中，达到最高碳浓度的渗碳深度优选为0.4～1.1mm，更优选为0.4～0.8mm，再优选为0.4～0.7mm，最优选为0.5～0.6mm；所述渗碳层的总深度优选为渗碳工件直径的1％～1.5％，更优选为1％～1.4％，再优选为1％～1.3％，再优选为1.1％～1.2％，最优选为1.1％～1.15％；在本发明中，所述渗碳层的总深度优选为1.6～2.2mm，更优选为1.6～2mm，再优选为1.6～1.8mm，最优选为1.7mm。The surface of the carburized workpiece is a carburized layer; the carburized layer is from the surface to the inside, and the carbon concentration first increases and then decreases, that is, the carbon concentration distribution curve is parabolic; the surface carbon concentration of the carburized layer is preferably The surface carbon concentration is preferably 0.48% to 0.5%; the surface carbon concentration is preferably the concentration at 0.2 mm of the surface layer; the highest carbon concentration of the carburized layer is preferably 0.60% to 0.68%, more Preferably, it is 0.62% to 0.66%, more preferably 0.62% to 0.65%; the carburized depth of the highest carburized layer in the carburized layer is preferably 20% to 45% of the total depth of the carburized layer, more preferably 25% to 25%. 40%, more preferably 28% to 38%, most preferably 29.4% to 35.2%; in the present invention, the carburizing depth to reach the highest carbon concentration is preferably 0.4 to 1.1 mm, more preferably 0.4 to 0.8 mm, and then It is preferably 0.4-0.7mm, most preferably 0.5-0.6mm; the total depth of the carburized layer is preferably 1%-1.5% of the diameter of the carburized workpiece, more preferably 1%-1.4%, and more preferably 1% ～1.3%, more preferably 1.1%～1.2%, most preferably 1.1%～1.15%; in the present invention, the total depth of the carburized layer is preferably 1.6～2.2mm, more preferably 1.6～2mm, and then It is preferably 1.6 to 1.8 mm, and most preferably 1.7 mm.
按照本发明，所述渗碳层中达到最高硬度的渗碳深度优选为不超过0.5mm，更优选为0.25～0.45mm，再优选为0.3～0.4mm，最优选为0.3mm；在 渗碳层中达到最高硬度后，硬度会逐渐变小，在本发明中渗碳层中达到最高硬度后硬度优选呈梯度下降。According to the present invention, the carburizing depth that achieves the highest hardness in the carburized layer is preferably no more than 0.5 mm, more preferably 0.25-0.45 mm, still more preferably 0.3-0.4 mm, and most preferably 0.3 mm; After the highest hardness is reached in the carburized layer, the hardness will gradually decrease. In the present invention, the hardness of the carburized layer preferably decreases in a gradient after the highest hardness is reached.
本发明提供的渗碳工件的渗碳层的金相组织在50～500倍显微镜视野下几乎无残余奥氏体存在。The metallographic structure of the carburized layer of the carburized workpiece provided by the present invention has almost no residual austenite in the field of view of a 50-500 magnification microscope.
本发明通过控制渗碳层碳浓度的变化曲线，同时通过降低外表层碳浓度的方式，有效的控制住了最表层残余奥氏体的量，又降低了最表层的硬度，加速了渗碳工件花键与卡钎套花键的磨合程度，减少了渗碳层在高频摩擦下的热裂现象，从能够有效的减少渗碳工件花键断体的几率，能够大大的延长渗碳工件的使用寿命，在高频高载潜孔钻头凿岩领域具有广泛的应用。The present invention effectively controls the amount of residual austenite in the outermost layer by controlling the change curve of the carbon concentration of the carburized layer and at the same time reduces the carbon concentration of the outer layer, reduces the hardness of the outermost layer, and accelerates the carburizing workpiece The degree of running-in between the splines and the splines of the clamping sleeve reduces the thermal cracking phenomenon of the carburized layer under high-frequency friction, which can effectively reduce the probability of the spline fracture of the carburized workpiece, and greatly prolong the life of the carburized workpiece. It has a wide range of applications in the field of high-frequency and high-load down-the-hole drill bit rock drilling.
本发明还提供了一种上述渗碳工件的制备方法，包括：S1)将工件进行渗碳处理；所述渗碳处理的温度为920℃～930℃；强渗碳势为1％～1.15％；扩散碳势为0.78％～0.85％；S2)将渗碳处理后的工件进行淬火处理；S3)将淬火处理后的工件进行高温回火；S4)将高温回火后的工件进行等温盐浴淬火处理；S5)将等温盐浴淬火处理后的工件进行低温回火，得到渗碳工件。The present invention also provides a method for preparing the above carburized workpiece, comprising: S1) carburizing the workpiece; the temperature of the carburizing treatment is 920°C to 930°C; the strong carburizing potential is 1% to 1.15% ; Diffusion carbon potential is 0.78% to 0.85%; S2) quench the workpiece after carburizing treatment; S3) perform high temperature tempering on the workpiece after quenching treatment; S4) perform isothermal salt bath on the workpiece after high temperature tempering Quenching treatment; S5) performing low temperature tempering on the workpiece after isothermal salt bath quenching treatment to obtain a carburized workpiece.
其中，本发明对所有原料的来源并没有特殊的限制，为市售即可。Wherein, in the present invention, there is no special restriction on the sources of all raw materials, and they can be commercially available.
在本发明中，所述工件按照本领域技术人员熟知的方法制备即可，优选经下料、模锻与机加工，得到工件；所述模锻过程中始锻温度优选为1180℃～1250℃；终锻温度优选为870℃～890℃。In the present invention, the workpiece can be prepared according to a method well known to those skilled in the art, preferably through blanking, die forging and machining to obtain the workpiece; the initial forging temperature in the die forging process is preferably 1180°C to 1250°C ; The final forging temperature is preferably 870 ℃ ~ 890 ℃.
将工件进行渗碳处理；所述渗碳处理的温度优选为922℃～928℃，更优选为924℃～926℃，再优选为925℃；强渗碳势优选为1.05％～1.15％；强渗阶段的时间优选为4.5～7h，更优选为5～6h；扩散碳势优选为0.78％～0.83％；扩散阶段的时间优选为4～6h，更优选为4.5～5h；所述渗碳处理时的渗碳剂优选为甲醇与丙酮，通过两种的组合可控制渗碳过程中的碳势。Carburizing the workpiece; the temperature of the carburizing treatment is preferably 922°C to 928°C, more preferably 924°C to 926°C, and more preferably 925°C; the strong carburizing potential is preferably 1.05% to 1.15%; The time of the infiltration stage is preferably 4.5-7h, more preferably 5-6h; the carbon diffusion potential is preferably 0.78%-0.83%; the time of the diffusion stage is preferably 4-6h, more preferably 4.5-5h; the carburizing treatment When the carburizing agent is preferably methanol and acetone, the carbon potential in the carburizing process can be controlled by the combination of the two.
渗碳处理后优选随炉冷却至小于等于855℃，气淬冷却至室温；所述气淬以高压氮气为介质，可实现快速冷却。After the carburizing treatment, it is preferable to cool down to 855°C or less with the furnace, and cool to room temperature by gas quenching; the gas quenching uses high-pressure nitrogen as a medium, which can realize rapid cooling.
将渗碳处理后的工件进行淬火处理；所述淬火处理的温度优选为830℃～850℃；保护碳势优选为0.45％～0.5％；淬火处理的时间优选为3～5h；淬火处理后优选采用快速淬火冷却油进行冷却。The workpiece after carburizing treatment is subjected to quenching treatment; the temperature of the quenching treatment is preferably 830°C to 850°C; the protective carbon potential is preferably 0.45% to 0.5%; the time of the quenching treatment is preferably 3 to 5h; Cooling with rapid quenching cooling oil.
将淬火处理后的工件进行高温回火；所述高温回火的温度优选为 660℃～700℃；高温回火的时间优选为5～7h；所述高温回火优选在惰性气氛中进行；所述惰性气氛优选为氮气。The quenched workpiece is subjected to high temperature tempering; the temperature of the high temperature tempering is preferably 660°C to 700°C; the time of the high temperature tempering is preferably 5 to 7 hours; the high temperature tempering is preferably performed in an inert atmosphere; The inert atmosphere is preferably nitrogen.
高温回火处理后，优选进行机加工，以得到特定的尺寸的渗碳工件，然后在进行等温盐浴淬火处理；所述等温盐浴淬火处理中盐浴淬火的加热温度优选为790℃～850℃，更优选为800℃～830℃；盐浴淬火的加热时间优选为25～90min，更优选为35～60min，再优选为40～50min，最优选为40～45min；等温盐浴淬火处理中硝盐槽等温淬火的温度优选为230℃～280℃；，硝盐槽等温淬火时间优选为20～70min，更优选为30～50min，再优选为30～45min，最优选为35～40min。After the high-temperature tempering treatment, machining is preferably performed to obtain a carburized workpiece of a specific size, and then an isothermal salt bath quenching treatment is performed; the heating temperature of the salt bath quenching in the isothermal salt bath quenching treatment is preferably 790 ℃～850 ℃. ℃, more preferably 800℃～830℃; the heating time of salt bath quenching is preferably 25～90min, more preferably 35～60min, more preferably 40～50min, most preferably 40～45min; in isothermal salt bath quenching treatment The temperature of isothermal quenching in nitrate tank is preferably 230 ℃～280 ℃; the isothermal quenching time in nitrate tank is preferably 20～70min, more preferably 30～50min, more preferably 30～45min, most preferably 35～40min.
将等温盐浴淬火处理后的工件进行低温回火；所述低温回火的温度优选为180℃～230℃；低温回火的时间优选为4～6h；低温回火后，优选出炉风冷，得到渗碳工件。The workpiece after isothermal salt bath quenching treatment is subjected to low-temperature tempering; the temperature of the low-temperature tempering is preferably 180° C. to 230° C.; the time of low-temperature tempering is preferably 4-6 h; A carburized workpiece is obtained.
本发明通过精控热处理过程的关键工艺参数，获得具有碳浓度呈类抛物线梯度变化，近表面无残余奥氏体的渗碳层，减少了钻头花键摩擦热裂的关键影响因子，加速钻头作业过程中花键和卡钎套的匹配度，从而有效的减少钻头花键断体的几率。By precisely controlling the key process parameters of the heat treatment process, the invention obtains a carburized layer with a parabolic gradient change in carbon concentration and no residual austenite near the surface, reduces the key influencing factor of the drill bit spline friction thermal cracking, and accelerates the drill bit operation During the process, the matching degree of the spline and the drill sleeve can effectively reduce the probability of the spline of the drill bit being broken.
其中，渗碳处理过程中的温度和碳势选择，淬火温度、碳势和冷却方式选择，以及高回温度和保护气氛选择是获取碳浓度梯度呈类抛物线曲线变化的关键，是有效控制渗碳层近表层残余奥氏体量的前提条件；盐淬过程盐浴温度和硝盐槽等温温度的选择，以及低回过程温度和冷却方式的选择是进一步有效控制残余奥氏体的关键措施。Among them, the selection of temperature and carbon potential in the carburizing process, the selection of quenching temperature, carbon potential and cooling method, as well as the selection of high return temperature and protective atmosphere are the keys to obtain the parabolic curve change of carbon concentration gradient, which is the key to effectively control carburization The preconditions for the amount of retained austenite near the surface layer; the selection of the salt bath temperature and the isothermal temperature of the nitrate bath in the salt quenching process, as well as the selection of the temperature and cooling method in the low-return process are the key measures to further effectively control the retained austenite.
为了进一步说明本发明，以下结合实施例对本发明提供的一种渗碳工件及其制备方法进行详细描述。In order to further illustrate the present invention, a carburized workpiece provided by the present invention and a preparation method thereof are described in detail below with reference to the embodiments.
以下实施例中所用的试剂均为市售。The reagents used in the following examples are all commercially available.
实施例1Example 1
采用23CrNi3Mo作为钻头基体材料，经下料、模锻、机加工、渗碳处理、淬火处理、高回、机加工、等温盐淬、低温回火，钻合金齿孔和镶合金齿等步骤制成HD55A-152钻头。其中始锻温度为1180℃；终锻温度为870℃；渗碳温度为925℃，强渗碳势为1.05％，强渗阶段时间为6h，扩散碳势为0.78％， 扩散阶段时间为5h，随炉冷却855℃后以高压氮气为介质气淬冷却到室温；淬火处理温度为850℃，淬火处理时间为3h，保护碳势为0.45％，淬火冷却介质选择快速淬火冷却油；高回温度为700℃，高回时间为5h，采用氮气保护；盐浴温度为830℃，盐浴时间为40min，硝盐槽温度为230℃，硝盐槽等温时间35min；低回温度为180℃，低回时间为4h，出炉风冷。Using 23CrNi3Mo as the base material of the drill bit, it is made by blanking, die forging, machining, carburizing treatment, quenching treatment, high return, machining, isothermal salt quenching, low temperature tempering, drilling alloy teeth holes and inserting alloy teeth. HD55A-152 drill bit. The initial forging temperature is 1180 °C; the final forging temperature is 870 °C; After cooling with the furnace to 855 ℃, the high-pressure nitrogen is used as the medium for gas quenching and cooling to room temperature; the quenching temperature is 850 ℃, the quenching treatment time is 3h, the protective carbon potential is 0.45%, and the quenching cooling medium selects rapid quenching cooling oil; the high return temperature is 700 ℃, high return time is 5h, using nitrogen protection; salt bath temperature is 830 ℃, salt bath time is 40min, nitrate tank temperature is 230 ℃, nitrate tank isothermal time 35min; low return temperature is 180 ℃, low return temperature The time is 4h, and the oven is air-cooled.
对实施例1中得到的HD55A-152钻头渗碳层的渗碳浓度及硬度进行分析，得到其碳浓度及硬度曲线图，如图1所示。The carburized concentration and hardness of the carburized layer of the HD55A-152 drill bit obtained in Example 1 were analyzed, and the carbon concentration and hardness curves were obtained, as shown in FIG. 1 .
利用金相显微镜对实施例1中得到的HD55A-152钻头进行分析，得到其渗碳层的金相组织显微镜图，如图2所示，由图2可知，金相组织在500倍金相显微镜视野下几乎无残余奥氏体存在。The HD55A-152 drill bit obtained in Example 1 was analyzed with a metallographic microscope, and the metallographic microscopic picture of its carburized layer was obtained, as shown in Figure 2. From Figure 2, it can be seen that the metallographic structure was observed under a metallographic microscope at a magnification of 500 times. Almost no retained austenite exists in the field of vision.
渗碳层检测结果表明：渗碳层碳浓度梯度呈类抛物线状，表层0.2mm处浓度为0.48％，最高碳浓度为0.62％，达到最高浓度的渗碳深度为0.6mm，渗碳层总深度为1.7mm；渗碳层硬度低头为0.3mm，渗碳层硬度低头后呈梯度下降；金相组织在500倍金相显微镜视野下几乎无残余奥氏体存在。50个试验钻头在钻头断体比例在20％的工况上试验，无一断体案例发生。The test results of the carburized layer show that the carbon concentration gradient of the carburized layer is parabolic. The hardness of the carburized layer is 1.7mm; the hardness of the carburized layer is 0.3mm, and the hardness of the carburized layer decreases gradually; the metallographic structure has almost no residual austenite under the field of 500 times the metallographic microscope. 50 test bits were tested on the condition that the proportion of broken bits was 20%, and there was no case of breakage.
实施例2Example 2
采用30CrNi3Mo作为钻头基体材料，经下料、模锻、机加工、渗碳处理、淬火处理、高回、机加工、等温盐淬、低温回火，钻合金齿孔和镶合金齿等步骤制成HD55A-152钻头。其中始锻温度为1180℃；终锻温度为870℃；渗碳温度为925℃，强渗碳势为1.15％，强渗阶段时间为5h，扩散碳势为0.80％，扩散阶段时间为4.5h，随炉冷却855℃后以高压氮气为介质气淬冷却到室温；淬火温度为830℃，淬火处理时间为3h，保护碳势为0.50％，淬火冷却介质选择快速淬火冷却油；高回温度为680℃，高回时间为5h，采用氮气保护；盐浴温度为810℃，盐浴时间为45min，硝盐槽温度为260℃，硝盐槽等温时间40min；低回温度为230℃，低回时间为4h，出炉风冷。Using 30CrNi3Mo as the base material of the drill bit, it is made by blanking, die forging, machining, carburizing treatment, quenching treatment, high return, machining, isothermal salt quenching, low temperature tempering, drilling alloy teeth holes and inserting alloy teeth. HD55A-152 drill bit. The initial forging temperature is 1180℃; the final forging temperature is 870℃; the carburizing temperature is 925℃; , cooled with the furnace to 855 ℃ and then quenched to room temperature with high pressure nitrogen as the medium; the quenching temperature is 830 ℃, the quenching treatment time is 3h, the protective carbon potential is 0.50%, and the quenching cooling medium selects rapid quenching cooling oil; the high return temperature is 680℃, high return time is 5h, nitrogen protection is adopted; salt bath temperature is 810℃, salt bath time is 45min, nitrate tank temperature is 260℃, nitrate tank isothermal time is 40min; low return temperature is 230℃, low return temperature The time is 4h, and the oven is air-cooled.
渗碳层检测结果表明：渗碳层碳浓度梯度呈类抛物线状，表层0.2mm处浓度为0.50％，最高碳浓度为0.65％，达到最高浓度的渗碳深度为0.5mm，渗碳层总深度为1.7mm；渗碳层硬度低头为0.4mm，渗碳层硬度低头后呈梯度下降；金相组织在500倍金相显微镜视野下几乎无残余奥氏体存在。50个试 验钻头在钻头断体比例在20％的工况上试验，无一断体案例发生。The test results of the carburized layer show that the carbon concentration gradient of the carburized layer is parabolic. The hardness of the carburized layer is 1.7mm; the hardness of the carburized layer is 0.4mm, and the hardness of the carburized layer decreases gradually; the metallographic structure has almost no residual austenite under the field of 500 times the metallographic microscope. 50 test bits were tested under the condition that the proportion of broken bits was 20%, and there was no case of breakage.
实施例3Example 3
采用30CrNi4Mo作为钻头基体材料，经下料、模锻、机加工、渗碳处理、淬火处理、高回、机加工、等温盐淬、低温回火，钻合金齿孔和镶合金齿等步骤制成HD55A-152钻头。其中始锻温度为1180℃；终锻温度为870℃；渗碳温度为925℃，强渗碳势为1.05％，强渗阶段时间为5.5h，扩散碳势为0.83％，扩散阶段时间为4.5h，随炉冷却855℃后以高压氮气为介质气淬冷却到室温；淬火温度为830℃，淬火处理时间为3h，保护碳势为0.48％，淬火冷却介质选择快速淬火冷却油；高回温度为670℃，高回时间为5h，采用氮气保护；盐浴温度为800℃，盐浴时间为45min，硝盐槽温度为280℃，硝盐槽等温时间40min；低回温度为230℃，低回时间为4h，出炉风冷。Using 30CrNi4Mo as the base material of the drill bit, it is made by blanking, die forging, machining, carburizing treatment, quenching treatment, high return, machining, isothermal salt quenching, low temperature tempering, drilling alloy teeth holes and inserting alloy teeth. HD55A-152 drill bit. The initial forging temperature is 1180℃; the final forging temperature is 870℃; the carburizing temperature is 925℃; h, after cooling with the furnace to 855 °C, high-pressure nitrogen is used as the medium to quench and cool to room temperature; the quenching temperature is 830 °C, the quenching treatment time is 3h, the protective carbon potential is 0.48%, and the quenching cooling medium selects rapid quenching cooling oil; high return temperature The temperature of the salt bath is 800℃, the salt bath time is 45min, the temperature of the nitrate tank is 280℃, and the isothermal time of the nitrate tank is 40min; the low temperature is 230℃, the low temperature The return time is 4h, and the oven is air-cooled.
渗碳层检测结果表明：渗碳层碳浓度梯度呈类抛物线状，表层0.2mm处浓度为0.50％，最高碳浓度为0.65％，达到最高浓度的渗碳深度为0.5mm，渗碳层总深度为1.7mm；渗碳层硬度低头为0.35mm，渗碳层硬度低头后呈梯度下降；金相组织在500倍金相显微镜视野下几乎无残余奥氏体存在。50个试验钻头在钻头断体比例在20％的工况上试验，无一断体案例发生。The test results of the carburized layer show that the carbon concentration gradient of the carburized layer is parabolic. The hardness of the carburized layer is 1.7mm; the hardness of the carburized layer is 0.35mm, and the hardness of the carburized layer decreases gradually; the metallographic structure has almost no residual austenite under the field of 500 times the metallographic microscope. 50 test bits were tested on the condition that the proportion of broken bits was 20%, and there was no case of breakage.

Claims (10)

  1. 一种渗碳工件，其特征在于，所述渗碳工件的渗碳层由表面向里，碳浓度先升高后降低，且表面碳浓度不低于0.46％，最高碳浓度为0.58％～0.68％，达到最高碳浓度的渗碳深度为渗碳层总深度的15％～50％。A carburized workpiece is characterized in that, the carburized layer of the carburized workpiece is from the surface to the inside, the carbon concentration first increases and then decreases, and the surface carbon concentration is not less than 0.46%, and the highest carbon concentration is 0.58% to 0.68% %, the carburizing depth that reaches the highest carbon concentration is 15% to 50% of the total depth of the carburized layer.
  2. 根据权利要求1所述的渗碳工件，其特征在于，所述渗碳层中达到最高硬度的渗碳深度不超过0.5mm，且所述渗碳层中达到最高硬度后硬度呈梯度下降。The carburized workpiece according to claim 1, characterized in that the carburizing depth at which the highest hardness is reached in the carburized layer is no more than 0.5 mm, and the hardness in the carburized layer decreases gradually after reaching the highest hardness.
  3. 根据权利要求1所述的渗碳工件，其特征在于，所述渗碳层的总深度为1.6～2.2mm；达到最高碳浓度的渗碳深度为0.4～1.1mm。The carburized workpiece according to claim 1, characterized in that, the total depth of the carburized layer is 1.6-2.2 mm; the carburizing depth that reaches the highest carbon concentration is 0.4-1.1 mm.
  4. 根据权利要求1所述的渗碳工件，其特征在于，所述渗碳工件的材料选自18CrNi3Mo、23CrN3iMo或30CrNi4Mo。The carburized workpiece according to claim 1, wherein the material of the carburized workpiece is selected from 18CrNi3Mo, 23CrN3iMo or 30CrNi4Mo.
  5. 一种渗碳工件的制备方法，其特征在于，包括：A method for preparing a carburized workpiece, comprising:
    S1)将工件进行渗碳处理；所述渗碳处理的温度为920℃～930℃；强渗碳势为1％～1.15％；扩散碳势为0.78％～0.85％；S1) Carburizing the workpiece; the temperature of the carburizing treatment is 920℃～930℃; the strong carburizing potential is 1%～1.15%; the diffusion carbon potential is 0.78%～0.85%;
    S2)将渗碳处理后的工件进行淬火处理；S2) quenching the carburized workpiece;
    S3)将淬火处理后的工件进行高温回火；S3) carry out high temperature tempering to the workpiece after quenching treatment;
    S4)将高温回火后的工件进行等温盐浴淬火处理；S4) the workpiece after high temperature tempering is subjected to isothermal salt bath quenching treatment;
    S5)将等温盐浴淬火处理后的工件进行低温回火，得到渗碳工件。S5) low-temperature tempering is performed on the workpiece after isothermal salt bath quenching to obtain a carburized workpiece.
  6. 根据权利要求5所述的制备方法，其特征在于，所述步骤S1)中强渗阶段的时间为4.5～7h；扩散阶段的时间为4～6h。The preparation method according to claim 5, characterized in that, in the step S1), the time of the strong infiltration stage is 4.5-7h; the time of the diffusion stage is 4-6h.
  7. 根据权利要求5所述的制备方法，其特征在于，所述步骤S1)中渗碳处理后随炉冷却至小于等于855℃，气淬冷却至室温。The preparation method according to claim 5, characterized in that, in the step S1), after the carburizing treatment, the furnace is cooled to less than or equal to 855°C, and the gas is quenched and cooled to room temperature.
  8. 根据权利要求5所述的制备方法，其特征在于，所述步骤S2)中淬火处理的温度为830℃～850℃；保护碳势为0.45％～0.5％；淬火处理的时间为3～5h。The preparation method according to claim 5, wherein the temperature of the quenching treatment in the step S2) is 830°C to 850°C; the protective carbon potential is 0.45% to 0.5%; and the time of the quenching treatment is 3 to 5 hours.
  9. 根据权利要求5所述的制备方法，其特征在于，所述步骤S3)中高温回火的温度为660℃～700℃；高温回火的时间为5～7h；所述高温回火在惰性气氛中进行。The preparation method according to claim 5, wherein the temperature of the high-temperature tempering in the step S3) is 660°C to 700°C; the high-temperature tempering time is 5-7h; the high-temperature tempering is performed in an inert atmosphere in progress.
  10. 根据权利要求5所述的制备方法，其特征在于，所述步骤S4)中等温盐浴淬火处理中盐浴淬火的加热温度为790℃～850℃；盐浴淬火的加热时间为25～90min；等温盐浴淬火处理中硝盐槽等温淬火的温度为230℃～280℃；硝盐槽等温淬火的时间为20～70min；所述步骤S5)中低温回火的温度为180℃～230℃；低温回火的时间为4～6h。The preparation method according to claim 5, characterized in that, the heating temperature of the salt bath quenching in the intermediate temperature salt bath quenching treatment in the step S4) is 790 ℃～850 ℃; the heating time of the salt bath quenching is 25～90min; In the isothermal salt bath quenching treatment, the temperature of isothermal quenching in the nitrate bath is 230°C～280°C; the time for isothermal quenching in the nitrate bath is 20～70min; the temperature of the low temperature tempering in the step S5) is 180°C～230°C; The time of low temperature tempering is 4-6h.
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