CN113802086A - Nitriding method for surface of die - Google Patents
Nitriding method for surface of die Download PDFInfo
- Publication number
- CN113802086A CN113802086A CN202110949467.0A CN202110949467A CN113802086A CN 113802086 A CN113802086 A CN 113802086A CN 202110949467 A CN202110949467 A CN 202110949467A CN 113802086 A CN113802086 A CN 113802086A
- Authority
- CN
- China
- Prior art keywords
- nitriding
- die
- die workpiece
- workpiece
- nitriding furnace
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- 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
- C23C8/24—Nitriding
- C23C8/26—Nitriding 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
- C21D10/00—Modifying the physical properties by methods other than heat treatment or deformation
-
- 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
- C23C8/02—Pretreatment of the material to be coated
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Abstract
The invention discloses a nitriding method for the surface of a die, in particular to the technical field of the die, a high-voltage pulse electric explosion device is used for adhering a modified layer on a die workpiece, a martensite fine-grain modified layer is adhered, the grain refinement of the modified layer and the formation of martensite are beneficial to accelerating the migration of nitrogen atoms from the surface to the inside in the gas nitriding process, the toughness and the thickness of the nitriding layer are improved, meanwhile, the die workpiece is pre-oxidized before nitriding, a uniform active oxide layer is formed on the surface of the die workpiece, active nitrogen can be adsorbed on the surface of the die with higher efficiency, the nitriding speed is accelerated, the nitriding stability is improved, quantitative ammonia gas is uniformly introduced into a nitriding furnace in a vacuum environment, the ammonia decomposition rate in the nitriding furnace is controlled, the nitriding proportion of the die workpiece is effectively controlled, and the aim of nitriding of the die workpiece according to the specified standard is effectively met, thereby improving the quality of the die workpiece.
Description
Technical Field
The invention relates to the technical field of dies, in particular to a method for nitriding a surface of a die.
Background
The nitriding process comprises modes such as gas nitriding, ion nitriding and liquid nitriding, each nitriding mode comprises a plurality of nitriding technologies, the nitriding technologies can meet the requirements of different steel types and different workpieces, the nitriding technologies can form surfaces with excellent performance, the nitriding process and the quenching process of the die steel are well coordinated, meanwhile, the nitriding temperature is low, the nitriding process does not need to be cooled violently after nitriding, the deformation of the die is extremely small, and therefore the surface strengthening of the die is realized by adopting the nitriding technology earlier and is also most widely applied.
The development of the mold industry affects the level of manufacturing industry of a country, the mold forming process replaces the traditional cutting processing process and has the advantages of reducing production cost, improving production quality, saving energy to the maximum extent and the like, along with the increasing application of high-performance metal materials such as high-strength steel, high-temperature alloy and the like, non-metal materials and composite materials, higher requirements are put forward on mold materials, surface modification treatment is carried out on mold steel and is a key for comprehensively improving the mold performance, the surface modification treatment can not only improve the surface performance of a mold, so that the surface of the mold material has the performances of high hardness, corrosion resistance, adhesion resistance and the like, but also can ensure that the core part of the mold keeps enough good obdurability, the service life of the mold can be prolonged, and the cost can be greatly reduced.
At present, the surface of a hot stamping forming die material is nitrided mostly through gas nitriding, however, the gas nitriding process of a hot forming die is established mainly through the experience of workers or the gas nitriding process of other materials used on the hot forming die material has no corresponding specification and standard, so that the thickness of a nitriding bright layer cannot be accurately controlled, the problems of poor wear resistance, insufficient thickness of the bright layer or over-thick thickness of the bright layer occur in the using process of the die, the bright layer is too thick and fragile, and is easy to break, and the purpose of nitriding a die workpiece according to the specified standard cannot be met; meanwhile, only by means of single gas nitriding, the infiltrated layer on the die workpiece is easy to have insufficient thickness, and the mechanical property and the wear resistance of the infiltrated layer cannot be further improved.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a method for nitriding the surface of a die, and the technical problems to be solved by the invention are as follows: therefore, the thickness of the nitriding bright layer cannot be accurately controlled, so that the problems of poor wear resistance, insufficient thickness of the bright layer or excessive thickness of the bright layer occur in the using process of the die, the bright layer is too thick and fragile, and is easy to break, and the aim of nitriding a die workpiece according to the specified standard cannot be met; meanwhile, only the treatment is carried out in a single gas nitriding mode, and the problem that the thickness of a permeating layer on a die workpiece is insufficient and the mechanical property and the wear resistance of the permeating layer cannot be further improved is solved.
In order to achieve the purpose, the invention provides the following technical scheme: a method for nitriding a surface of a mold comprises the following steps:
s1, screening: firstly, selecting a die workpiece, and screening out a die meeting the hardness requirement for finish machining, wherein the hardness of the formed die workpiece is 50-60 HRC.
S2, polishing treatment: and polishing and cleaning the screened die workpiece, wherein the surface roughness of the polished die workpiece is less than or equal to 0.25 mu m, and after the machining is finished, the surface of the grinding tool workpiece is subjected to dust removal, cleaning and drying treatment.
S3, preprocessing:
a. the method comprises the steps of pretreating a die workpiece by adopting a high-voltage pulse electric explosion technology, passing air into a high-voltage pulse explosion cabin, and then introducing propane and oxygen into the high-voltage pulse explosion cabin, wherein the ratio of propane to oxygen is 3: 7.
b. The ignition operation is carried out by starting the high-voltage pulse electric explosion device, the propane, the oxygen and the melted air are mixed and exploded to form explosion flame flow, and the pulse discharge is generated between the die workpiece and the electrode by starting the high-voltage pulse discharge.
S4, processing of the modified layer: and (4) placing the die workpiece obtained in the step (S3) on a three-dimensional processing platform, wherein the distance from a high-voltage pulse explosion hatch to the surface of the die workpiece is 25-30 mm, and moving the three-dimensional processing platform to enable a layer of martensite fine-grain modified layer to be attached to the die workpiece.
And S5, performing fine polishing on the obtained die workpiece, and removing dust and oil stains on the surface of the die by using alcohol or acetone to ensure that the surface of the die workpiece is not damaged.
S6, placing the die workpiece cleaned in the step into a nitriding furnace, sealing the nitriding furnace to enable nitriding to be performed in a vacuum environment, vacuumizing the nitriding furnace to 12mbar, heating the nitriding furnace, keeping the temperature to be continuously increased, uniformly heating the nitriding furnace to 480 ℃ at the temperature increasing efficiency of 15 ℃/min, and preserving the heat for 1.5-2 hours to perform nitriding furnace treatment on the die workpiece.
S7, firstly, introducing ammonia gas into the nitriding furnace, adjusting the ammonia gas decomposition rate, keeping the ammonia gas decomposition rate for 15-18 h, controlling the nitriding heat preservation temperature to be 400-600 ℃, and introducing nitrogen gas to carry out nitriding work.
S8, after the nitriding work is finished, the heating device can be closed, the heat exchange system of the nitriding furnace is opened, the temperature in the nitriding furnace cabin is uniformly reduced, after the nitriding furnace cabin is cooled for a period of time, the temperature in the nitriding furnace cabin is reduced, then the ammonia gas valve is closed, the nitriding furnace is discharged after the ammonia gas valve is cooled to the normal temperature, and the composite nitriding protective layer is attached to the die workpiece.
As a further scheme of the invention: in S3, the flow rates of oxygen and propane are respectively 2L/min and 0.8L/min, and in S3, the voltage of high-voltage pulse discharge is controlled to be 2-5 kV.
As a further scheme of the invention: in the S8, the heating device is a heat exchanger, and in the composite nitriding protective layer, the depth of a diffusion layer is 230-320 μm, and the thickness of a white layer is 3.5-5 μm.
As a further scheme of the invention: and in the step S5, after the die workpiece is subjected to finish polishing, the polishing thickness of the die workpiece is kept at 0.01-0.015 mm.
As a further scheme of the invention: in the S7, continuously introducing ammonia gas into the nitriding furnace at 2500-3000L/h, and adjusting the ammonia gas decomposition rate to 38% -50%.
As a further scheme of the invention: and in the S8, cooling at the cooling efficiency of 8 ℃/min, and closing an ammonia gas valve after the temperature in the nitriding furnace cabin is reduced to 155 ℃.
The invention has the beneficial effects that:
the invention carries out the adhesion of the modified layer on the die workpiece through the high-voltage pulse electric explosion device, adheres to the martensite fine-grained modified layer, leads the surface of the die workpiece to generate phase change and grain refinement under the composite action of explosion flame flow and high-voltage discharge, then carries out gas nitriding on the surface layer of the modified die workpiece, and the grain refinement and the martensite formation of the modified layer are beneficial to accelerating the migration of nitrogen atoms from the surface to the inside in the gas nitriding process, thereby improving the toughness and the thickness of the nitriding layer;
meanwhile, the mould workpiece is pre-oxidized before nitriding, so that a uniform active oxidation layer is formed on the surface of the mould workpiece, active nitrogen can be adsorbed on the surface of the mould with high efficiency, the nitriding speed is accelerated, the nitriding stability is improved, quantitative ammonia gas is uniformly introduced into the nitriding furnace in a vacuum environment, the ammonia decomposition rate in the nitriding furnace is controlled, the nitriding proportion of the mould workpiece is effectively controlled, the depth of a permeable layer in the composite nitriding protective layer is 230 and 320 mu m, and the thickness of a white layer is 3.5-5 mu m, so that the aim of nitriding the mould workpiece according to a specified standard is effectively fulfilled, the quality of the mould workpiece is improved, and the mould workpiece has wide market application prospect.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1:
a method for nitriding a surface of a mold comprises the following steps:
s1, screening: firstly, selecting a die workpiece, and screening out a die meeting the hardness requirement for finish machining, wherein the hardness of the formed die workpiece is 50-60 HRC.
S2, polishing treatment: and polishing and cleaning the screened die workpiece, wherein the surface roughness of the polished die workpiece is less than or equal to 0.25 mu m, and after the machining is finished, the surface of the grinding tool workpiece is subjected to dust removal, cleaning and drying treatment.
S3, preprocessing:
a. the method comprises the steps of pretreating a die workpiece by adopting a high-voltage pulse electric explosion technology, passing air into a high-voltage pulse explosion cabin, and then introducing propane and oxygen into the high-voltage pulse explosion cabin, wherein the ratio of propane to oxygen is 3: 7.
b. The ignition operation is carried out by starting the high-voltage pulse electric explosion device, the propane, the oxygen and the melted air are mixed and exploded to form explosion flame flow, and the pulse discharge is generated between the die workpiece and the electrode by starting the high-voltage pulse discharge.
S4, processing of the modified layer: and (4) placing the die workpiece obtained in the step (S3) on a three-dimensional processing platform, wherein the distance from a high-voltage pulse explosion hatch to the surface of the die workpiece is 25-30 mm, and moving the three-dimensional processing platform to enable a layer of martensite fine-grain modified layer to be attached to the die workpiece.
And S5, performing fine polishing on the obtained die workpiece, and removing dust and oil stains on the surface of the die by using alcohol or acetone to ensure that the surface of the die workpiece is not damaged.
S6, placing the die workpiece cleaned in the step into a nitriding furnace, sealing the nitriding furnace to enable nitriding to be performed in a vacuum environment, vacuumizing the nitriding furnace to 12mbar, heating the nitriding furnace, keeping the temperature to be continuously increased, uniformly heating the nitriding furnace to 480 ℃ at the temperature increasing efficiency of 15 ℃/min, and preserving the heat for 1.5-2 hours to perform nitriding furnace treatment on the die workpiece.
S7, firstly, introducing ammonia gas into the nitriding furnace, adjusting the ammonia gas decomposition rate, keeping the ammonia gas decomposition rate for 15-18 h, controlling the nitriding heat preservation temperature to be 400-600 ℃, and introducing nitrogen gas to carry out nitriding work.
S8, after the nitriding work is finished, the heating device can be closed, the heat exchange system of the nitriding furnace is opened, the temperature in the nitriding furnace cabin is uniformly reduced, after the nitriding furnace cabin is cooled for a period of time, the temperature in the nitriding furnace cabin is reduced, then the ammonia gas valve is closed, the nitriding furnace is discharged after the ammonia gas valve is cooled to the normal temperature, and the composite nitriding protective layer is attached to the die workpiece.
In S3, the flow rates of oxygen and propane are respectively 2L/min and 0.8L/min, in S3, the voltage of high-voltage pulse discharge is controlled to be 2-5 kV, in S8, a heating device is a heat exchanger, in a composite nitriding protective layer, the depth of a permeable layer is 230-320 mu m, the thickness of a white layer is 3.5-5 mu m, in S5, after a die workpiece is subjected to fine polishing processing, the polishing thickness of the die workpiece is kept at 0.01-0.015 mm, in S7, ammonia gas is continuously introduced into a nitriding furnace at 2500-3000L/h, the decomposition rate of the ammonia gas is adjusted to be 38-50%, in S8, cooling is carried out at the cooling efficiency of 8 ℃/min, and after the temperature in a nitriding furnace cabin is reduced to 155 ℃, an ammonia gas valve is closed.
In the composite nitriding protective layer of the die workpiece: the depth of the diffusion layer is 230-320 μm, the thickness of the white layer is 3.5-5 μm, and the hardness can reach 1100-1200 HV.
Example 2:
a method for nitriding a surface of a mold comprises the following steps:
s1, screening: firstly, selecting a die workpiece, and screening out a die meeting the hardness requirement for finish machining, wherein the hardness of the formed die workpiece is 50-60 HRC.
S2, polishing treatment: and polishing and cleaning the screened die workpiece, wherein the surface roughness of the polished die workpiece is less than or equal to 0.25 mu m, and after the machining is finished, the surface of the grinding tool workpiece is subjected to dust removal, cleaning and drying treatment.
S3, preprocessing:
the method comprises the steps of pretreating a die workpiece by adopting a high-voltage pulse electric explosion technology, passing air into a high-voltage pulse explosion cabin, and then introducing propane and oxygen into the high-voltage pulse explosion cabin, wherein the ratio of propane to oxygen is 3: 7.
And S4, placing the die workpiece obtained in the step S3 on a three-dimensional processing platform, wherein the distance from a high-voltage pulse explosion hatch to the surface of the die workpiece is 25-30 mm, and grinding and scraping the outer wall of the die workpiece.
And S5, performing fine polishing on the obtained die workpiece, and removing dust and oil stains on the surface of the die by using alcohol or acetone to ensure that the surface of the die workpiece is not damaged.
S6, placing the die workpiece cleaned in the step into a nitriding furnace, sealing the nitriding furnace to enable nitriding to be performed in a vacuum environment, vacuumizing the nitriding furnace to 12mbar, heating the nitriding furnace, keeping the temperature to be continuously increased, uniformly heating the nitriding furnace to 480 ℃ at the temperature increasing efficiency of 15 ℃/min, and preserving the heat for 1.5-2 hours to perform nitriding furnace treatment on the die workpiece.
S7, firstly, introducing ammonia gas into the nitriding furnace, adjusting the ammonia gas decomposition rate, keeping the ammonia gas decomposition rate for 15-18 h, controlling the nitriding heat preservation temperature to be 400-600 ℃, and introducing nitrogen gas to carry out nitriding work.
S8, after the nitriding work is finished, the heating device can be closed, the heat exchange system of the nitriding furnace is opened, the temperature in the nitriding furnace cabin is uniformly reduced, after the nitriding furnace cabin is cooled for a period of time, the temperature in the nitriding furnace cabin is reduced, then the ammonia gas valve is closed, the nitriding furnace is discharged after the ammonia gas valve is cooled to the normal temperature, and the composite nitriding protective layer is attached to the die workpiece.
In S3, the flow rates of oxygen and propane are respectively 2L/min and 0.8L/min, in S5, after the die workpiece is subjected to fine polishing processing, the polishing thickness of the die workpiece is kept at 0.01-0.015 mm, in S7, ammonia gas is continuously introduced into a nitriding furnace at the rate of 2500-3000L/h, the decomposition rate of the ammonia gas is adjusted to be 38-50%, in S8, cooling is carried out at the cooling efficiency of 8 ℃/min, and after the temperature in a nitriding furnace cabin is reduced to 155 ℃, an ammonia gas valve is closed.
In the composite nitriding protective layer of the die workpiece: the depth of the diffusion layer is 150-200 μm, the thickness of the white layer is 6.5-9.8 μm, and the hardness can reach 750-800 HV.
Example 3:
a method for nitriding a surface of a mold comprises the following steps:
s1, screening: firstly, selecting a die workpiece, and screening out a die meeting the hardness requirement for finish machining, wherein the hardness of the formed die workpiece is 50-60 HRC.
S2, polishing treatment: and polishing and cleaning the screened die workpiece, wherein the surface roughness of the polished die workpiece is less than or equal to 0.25 mu m, and after the machining is finished, the surface of the grinding tool workpiece is subjected to dust removal, cleaning and drying treatment.
S3, preprocessing:
a. the method comprises the steps of pretreating a die workpiece by adopting a high-voltage pulse electric explosion technology, passing air into a high-voltage pulse explosion cabin, and then introducing propane and oxygen into the high-voltage pulse explosion cabin, wherein the ratio of propane to oxygen is 3: 7.
b. The ignition operation is carried out by starting the high-voltage pulse electric explosion device, the propane, the oxygen and the melted air are mixed and exploded to form explosion flame flow, and the pulse discharge is generated between the die workpiece and the electrode by starting the high-voltage pulse discharge.
S4, processing of the modified layer: and (4) placing the die workpiece obtained in the step (S3) on a three-dimensional processing platform, wherein the distance from a high-voltage pulse explosion hatch to the surface of the die workpiece is 25-30 mm, and moving the three-dimensional processing platform to enable a layer of martensite fine-grain modified layer to be attached to the die workpiece.
And S5, performing fine polishing on the obtained die workpiece, and removing dust and oil stains on the surface of the die by using alcohol or acetone to ensure that the surface of the die workpiece is not damaged.
S6, placing the die workpiece cleaned in the step into a nitriding furnace, heating, keeping the temperature continuously rising, heating to 480 ℃, and preserving the heat for 1.5-2 hours to perform nitriding furnace treatment on the die workpiece.
S7, firstly, introducing ammonia gas into the nitriding furnace, keeping the time for 15-18 h, controlling the nitriding heat preservation temperature at 400-600 ℃, and introducing nitrogen gas to carry out nitriding work.
S8, after the nitriding work is finished, the heating device can be closed, the heat exchange system of the nitriding furnace is opened, the temperature in the nitriding furnace cabin is uniformly reduced, after the nitriding furnace cabin is cooled for a period of time, the temperature in the nitriding furnace cabin is reduced, then the ammonia gas valve is closed, the nitriding furnace is discharged after the ammonia gas valve is cooled to the normal temperature, and the composite nitriding protective layer is attached to the die workpiece.
In S3, the flow rates of oxygen and propane are respectively 2L/min and 0.8L/min, in S3, the voltage of high-voltage pulse discharge is controlled to be 2-5 kV, in S8, a heating device is a heat exchanger, in S5, after the die workpiece is subjected to fine polishing processing, the polishing thickness of the die workpiece is kept to be 0.01-0.015 mm, and after the temperature in a nitriding furnace cabin is reduced to 155 ℃, an ammonia gas valve is closed.
In the composite nitriding protective layer of the die workpiece: the depth of the diffusion layer is 200-280 μm, the thickness of the white layer is 8-12 μm, and the hardness can reach 800-850 HV.
In conclusion, the present invention:
the modified layer is attached to the die workpiece through a high-voltage pulse electric explosion device, the martensite fine-grain modified layer is attached, so that the surface of the die workpiece is subjected to phase change and grain refinement under the composite action of explosion flame flow and high-voltage discharge, then gas nitriding is performed on the surface layer of the modified die workpiece, the grain refinement of the modified layer and the formation of martensite are beneficial to accelerating the migration of nitrogen atoms from the surface to the inside in the gas nitriding process, and the toughness and the thickness of the nitriding layer are improved.
Meanwhile, the mould workpiece is pre-oxidized before nitriding, so that a uniform active oxidation layer is formed on the surface of the mould workpiece, active nitrogen can be adsorbed on the surface of the mould with high efficiency, the nitriding speed is accelerated, the nitriding stability is improved, quantitative ammonia gas is uniformly introduced into the nitriding furnace in a vacuum environment, the ammonia decomposition rate in the nitriding furnace is controlled, the nitriding proportion of the mould workpiece is effectively controlled, the depth of a permeable layer in the composite nitriding protective layer is 230 and 320 mu m, and the thickness of a white layer is 3.5-5 mu m, so that the aim of nitriding the mould workpiece according to a specified standard is effectively fulfilled, the quality of the mould workpiece is improved, and the mould workpiece has wide market application prospect.
The points to be finally explained are: although the present invention has been described in detail with reference to the general description and the specific embodiments, on the basis of the present invention, the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (6)
1. A method for nitriding a surface of a mold is characterized by comprising the following steps:
s1, screening: firstly, selecting a die workpiece, screening out a die meeting the hardness requirement, and performing finish machining, wherein the hardness of the formed die workpiece is 50-60 HRC;
s2, polishing treatment: polishing and cleaning the screened die workpiece, wherein the surface roughness of the polished die workpiece is less than or equal to 0.25 mu m, and after the machining is finished, performing dust removal, cleaning and drying treatment on the surface of the grinding tool workpiece;
s3, preprocessing:
a. pretreating a die workpiece by adopting a high-voltage pulse electric explosion technology, passing air into a high-voltage pulse explosion cabin, and then introducing propane and oxygen into the high-voltage pulse explosion cabin, wherein the ratio of the propane to the oxygen is 3: 7;
b. igniting by starting a high-voltage pulse electric explosion device, mixing the propane, the oxygen and the melted air, exploding to form an explosion flame flow, and starting high-voltage pulse discharge to generate pulse discharge between the die workpiece and the electrode;
s4, processing of the modified layer: placing the die workpiece obtained in the step S3 on a three-dimensional processing platform, wherein the distance from a high-voltage pulse explosion hatch to the surface of the die workpiece is 25-30 mm, and moving the three-dimensional processing platform to enable a layer of martensite fine-grain modified layer to be attached to the die workpiece;
s5, performing fine polishing on the obtained die workpiece, and removing dust and oil stains on the surface of the die by using alcohol or acetone to ensure that the surface of the die workpiece is not damaged;
s6, placing the die workpiece cleaned in the step into a nitriding furnace, sealing the nitriding furnace to enable nitriding to be carried out in a vacuum environment, vacuumizing the nitriding furnace to 12mbar, heating the nitriding furnace, keeping the temperature to be continuously increased, uniformly heating the nitriding furnace to 480 ℃ at the temperature increasing efficiency of 15 ℃/min, and preserving the heat for 1.5-2 hours to carry out nitriding furnace treatment on the die workpiece;
s7, firstly, introducing ammonia gas into the nitriding furnace, adjusting the ammonia gas decomposition rate, keeping the ammonia gas decomposition rate for 15-18 h, controlling the nitriding heat preservation temperature to be 400-600 ℃, and introducing nitrogen gas to carry out nitriding work;
s8, after the nitriding work is finished, the heating device can be closed, the heat exchange system of the nitriding furnace is opened, the temperature in the nitriding furnace cabin is uniformly reduced, after the nitriding furnace cabin is cooled for a period of time, the temperature in the nitriding furnace cabin is reduced, then the ammonia gas valve is closed, the nitriding furnace is discharged after the ammonia gas valve is cooled to the normal temperature, and the composite nitriding protective layer is attached to the die workpiece.
2. A method for nitriding a mold surface according to claim 1, characterized by: in S3, the flow rates of oxygen and propane are respectively 2L/min and 0.8L/min, and in S3, the voltage of high-voltage pulse discharge is controlled to be 2-5 kV.
3. A method for nitriding a mold surface according to claim 1, characterized by: in the S8, the heating device is a heat exchanger, and in the composite nitriding protective layer, the depth of a diffusion layer is 230-320 μm, and the thickness of a white layer is 3.5-5 μm.
4. A method for nitriding a mold surface according to claim 1, characterized by: and in the step S5, after the die workpiece is subjected to finish polishing, the polishing thickness of the die workpiece is kept at 0.01-0.015 mm.
5. A method for nitriding a mold surface according to claim 1, characterized by: in the S7, continuously introducing ammonia gas into the nitriding furnace at 2500-3000L/h, and adjusting the ammonia gas decomposition rate to 38% -50%.
6. A method for nitriding a mold surface according to claim 1, characterized by: and in the S8, cooling at the cooling efficiency of 8 ℃/min, and closing an ammonia gas valve after the temperature in the nitriding furnace cabin is reduced to 155 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110949467.0A CN113802086A (en) | 2021-08-18 | 2021-08-18 | Nitriding method for surface of die |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110949467.0A CN113802086A (en) | 2021-08-18 | 2021-08-18 | Nitriding method for surface of die |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113802086A true CN113802086A (en) | 2021-12-17 |
Family
ID=78893752
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110949467.0A Pending CN113802086A (en) | 2021-08-18 | 2021-08-18 | Nitriding method for surface of die |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113802086A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117165898A (en) * | 2023-11-02 | 2023-12-05 | 潍坊丰东热处理有限公司 | Heat treatment method for improving corrosion resistance of medium carbon alloy steel |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20080055039A (en) * | 2006-12-14 | 2008-06-19 | 유겐가이샤 유키코슈하 | A quenched nitride and the method of manufacture thereof |
| CN105177493A (en) * | 2015-09-22 | 2015-12-23 | 华南理工大学 | Electric arc plasma auxiliary low-voltage nitriding method for surface of hot-working die |
| CN108914050A (en) * | 2018-08-22 | 2018-11-30 | 江西省科学院应用物理研究所 | A method of compound nitriding layer is prepared in mold steel surface |
| CN110205580A (en) * | 2019-06-21 | 2019-09-06 | 宁波合力模具科技股份有限公司 | A kind of gas nitriding process of Automobile Plate hot-forming die |
-
2021
- 2021-08-18 CN CN202110949467.0A patent/CN113802086A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20080055039A (en) * | 2006-12-14 | 2008-06-19 | 유겐가이샤 유키코슈하 | A quenched nitride and the method of manufacture thereof |
| CN105177493A (en) * | 2015-09-22 | 2015-12-23 | 华南理工大学 | Electric arc plasma auxiliary low-voltage nitriding method for surface of hot-working die |
| CN108914050A (en) * | 2018-08-22 | 2018-11-30 | 江西省科学院应用物理研究所 | A method of compound nitriding layer is prepared in mold steel surface |
| CN110205580A (en) * | 2019-06-21 | 2019-09-06 | 宁波合力模具科技股份有限公司 | A kind of gas nitriding process of Automobile Plate hot-forming die |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117165898A (en) * | 2023-11-02 | 2023-12-05 | 潍坊丰东热处理有限公司 | Heat treatment method for improving corrosion resistance of medium carbon alloy steel |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106011738A (en) | Surface plating composite coating process for die | |
| CN112404461A (en) | Turning method of titanium target assembly | |
| CN113802086A (en) | Nitriding method for surface of die | |
| CN110863182A (en) | Method for strengthening surface coating of gear cold extrusion die | |
| CN109652757A (en) | A kind of high vacuum squeezes the surface recombination processing method of compression mod | |
| CN112795863A (en) | Titanium alloy surface ion carbonitriding processing apparatus | |
| CN105908120A (en) | Ion nitriding-low pressure oxidation composite treatment method of aluminum alloy die-casting die or die steel | |
| CN110773721B (en) | Anti-oxidation treatment process before heat treatment of steel structure material | |
| JP2000343151A (en) | Punch press die and manufacture thereof | |
| CN112359310A (en) | Method for coating surface of roll shaft | |
| CN112517659A (en) | Processing method of titanium alloy wire for plasma arc/electric arc additive manufacturing | |
| CN106987793B (en) | H13 steel mold nitrogenation treatment technology again | |
| US20060086439A1 (en) | Clean atmosphere heat treat for coated turbine components | |
| CN106637063A (en) | Ion nitriding surface modification method for improving heat fatigue of H13 hot-working die | |
| RU2291227C1 (en) | Construction-steel parts surface hardening method | |
| CN113999953B (en) | Chemical heat treatment method of high-hardness 38CrMoAl nitrided steel | |
| JPH083721A (en) | Surface treatment of piston rod | |
| CN113462858B (en) | Method for performing vacuum stress relief annealing by using ion nitriding furnace | |
| CN114540807A (en) | Method for repairing and PVD surface strengthening of cutting edge of disc shear blade | |
| CN106637064A (en) | Nitridation loosening layer heat treatment method capable of controlling ion nitriding formation effectively | |
| CN112553562A (en) | Method for composite treatment of 30CrMnSi low-carbon alloy steel | |
| CN110592579A (en) | TC4 titanium alloy surface electric spark composite strengthening process | |
| CN111826606A (en) | Aluminum and aluminum alloy surface plasma oxidation method | |
| CN112176298A (en) | High-wear-resistance compound coating and preparation method thereof | |
| CN115584456B (en) | Hardening method for ball surface of titanium and titanium alloy ball valve |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |