CN108504988A - A kind of electric pulse assists the processing method of high chromium cold work die steel nitriding - Google Patents
A kind of electric pulse assists the processing method of high chromium cold work die steel nitriding Download PDFInfo
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- CN108504988A CN108504988A CN201810285835.4A CN201810285835A CN108504988A CN 108504988 A CN108504988 A CN 108504988A CN 201810285835 A CN201810285835 A CN 201810285835A CN 108504988 A CN108504988 A CN 108504988A
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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
- C23C8/60—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 solids, e.g. powders, pastes
- C23C8/62—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 solids, e.g. powders, pastes only one element being applied
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/04—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering with simultaneous application of supersonic waves, magnetic or electric fields
Abstract
The invention discloses the processing methods that a kind of electric pulse assists high chromium cold work die steel nitriding.Including：A, high chromium cold work die steel is cut into sample；B, sample in step a is placed in the middle part of nitriding tank, and nitriding medium is filled in the sample surrounding, seals the nitriding tank；C, the nitriding tank is placed in heating furnace, is warming up to 555~565 DEG C, keep the temperature 6.5~7.5h, in insulating process, at interval of 54~56min, apply 4~6min of electric pulse；The frequency of the electric pulse applied is 6~12Hz, and voltage is 300~900V；D, terminate in step c reactions, the sample is taken out from nitriding tank, is cooled down.The beneficial effects of the invention are as follows：Nitrided case depth is high, and transition region is combined, and infiltration layer is not fallen off, and property indices are excellent；Reach energy saving, shortened the purpose of nitriding time, has improved process efficiency.
Description
Technical field
The present invention relates to metal processing sectors, and in particular to a kind of electric pulse assists the processing of high chromium cold work die steel nitriding
Method.
Background technology
In recent years, with domestic manufacturing fast development, die industry has vast potential for future development, while people couple
Higher requirements are also raised for mold materials performance.Cr12MoV is as cold work die steel, since it is with higher hardness
And intensity, suitable making is complex-shaped, operating condition is heavy, bears the various cold-punching molds and tool of heavy load.Simultaneously as
The performance characteristics such as its higher wearability, quenching degree, high thermal stability, high bending strength and Light deformation, it is raw in industry
It is widely used in production, becomes one of domestic and international widely used cold work die steel.Although Cr12MoV cold work die steels
Wearability is good, hardness and strength are high, but its toughness is relatively low, more demanding with heat processing technique to heat treatment process, be easy to cause
The premature failure of mold.
Result of study shows Cr12MoV steel after surface solid Nitrizing Treatment, and hardness and strength are significantly carried
Height, wearability are also promoted.Nitriding is the chemistry for making in certain medium nitrogen-atoms penetrate into workpiece surface at a certain temperature
Heat treatment process.Common nitriding method has solid nitriding, liquid nitriding, gas nitriding, glow discharge nitriding, carbo-nitriding, ultrasound
The nitriding of wave Cold forging, vacuum pulse nitrogen infiltration etc..Nitrizing Treatment can effectively improve the case hardness of workpiece, wearability, resistance to tired
Labor intensity and corrosion resistance, but traditional nitridation process is long there are the period, nitrogenizes the problems such as of high cost, efficiency is low.
A kind of nitrogenizing effect using raising austenitic stainless steel is disclosed in Chinese patent 201310672610.1,
In, disclose the efficiency that electric pulse is capable of service hoisting nitriding.But due to failing to accurately control impulse waveform, cause its right
The utilization ratio of electric pulse is not high, generally requires the pulse voltage of kilovolt.
Therefore.One kind can efficiently use electrical pulse energy and increase the nitridation process of nitrided case depth, become solution
The key of problem.
Invention content
The purpose of the present invention is to provide one kind capable of efficiently using electrical pulse energy, increases the nitriding work of nitrided case depth
The electric pulse of skill assists the processing method of high chromium cold work die steel nitriding.
To achieve the above object, the present invention adopts the following technical scheme that, a kind of high chromium cold work die steel of electric pulse auxiliary oozes
The processing method of nitrogen, including：
A, high chromium cold work die steel is cut into sample；
B, sample in step a is placed in the middle part of nitriding tank, and nitriding medium is filled in the sample surrounding, described in sealing
Nitriding tank；
C, the nitriding tank is placed in heating furnace, is warming up to 555~565 DEG C, 6.5~7.5h is kept the temperature, in insulating process
In, at interval of 54~56min, apply 4~6min of electric pulse；The frequency of the electric pulse applied is 6~12Hz, voltage 300
~1200V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, is cooled down.
Preferably, in stepb, the nitriding medium by charcoal, urea and chromium trioxide according to 6:2.9~3.1:0.9
~1.1 ratio mixes；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
Preferably, in the step c, the nitriding tank is placed in heating furnace, is warming up to 560~565 DEG C.
Preferably, in the step c, the time of heat preservation is 7h.
Preferably, described in insulating process in the step c, at interval of 55min, apply electric pulse 5min.
Preferably, in the step c, the frequency of the electric pulse of application is 12Hz.
Preferably, in the step c, the voltage of the electric pulse of application is 900V.
Preferably, in the step d, the type of cooling is oil cooling.
The beneficial effects of the invention are as follows：1, wave function using the present invention can effectively utilize electrical pulse energy；2、
Nitrided case depth is high, and transition region is combined, and infiltration layer is not fallen off, and property indices are excellent；3, reached energy saving, shortening is oozed
The purpose of nitrogen time improves process efficiency.
Description of the drawings
Fig. 1 is the microstructure picture that sample is prepared by comparative example 1；
Fig. 2 is the microstructure picture that sample is prepared by comparative example 13；
Fig. 3 is the microstructure picture that sample is prepared by comparative example 14；
Fig. 4 is the microstructure picture that sample is prepared by comparative example 2；
Fig. 5 is the microstructure picture that sample is prepared by comparative example 3；
Fig. 6 is the microstructure picture that sample is prepared by comparative example 4；
Fig. 7 is the microstructure picture that sample is prepared by embodiment 1；
Fig. 8 is the sample surface layer XRD diffracting spectrums that sample is prepared by comparative example 14 and embodiment 1；
Fig. 9 is the sample transition zone XRD diffracting spectrums that sample is prepared by embodiment 1 and comparative example 14；
Figure 10 is the scanning electron microscope shape appearance figure of the nitriding workpiece infiltration layer of the sample prepared by embodiment 1；
Figure 11 is the scanning electron microscope shape appearance figure of the nitriding workpiece infiltration layer of the sample prepared by comparative example 14；
Figure 12 is the nitrogen distribution map of sample nitriding layer prepared by embodiment 1；
Figure 13 is the ferro element distribution map of sample nitriding layer prepared by embodiment 1；
Figure 14 is the chromium distribution map of sample nitriding layer prepared by embodiment 1；
Figure 15 is that other conditions are constant, and electrical impulse frequency is the metallographic microstructure figure of the sample of 0Hz；
Figure 16 is that other conditions are constant, and electrical impulse frequency is the metallographic microstructure figure of the sample of 3Hz；
Figure 17 is that other conditions are constant, and electrical impulse frequency is the metallographic microstructure figure of the sample of 6Hz；
Figure 18 is that other conditions are constant, and electrical impulse frequency is the metallographic microstructure figure of the sample of 9Hz；
Figure 19 is that other conditions are constant, and electrical impulse frequency is the metallographic microstructure figure of the sample of 12Hz；
Figure 20 is pulse frequency influences change curve to nitrided case depth；
Figure 21 be through 0Hz, after 3Hz and 9Hz processing sample surface to intrinsic silicon hardness schematic diagram；
Figure 22 is the wear extent schematic diagram of different pulse frequency processing sample；
Figure 23 is that other conditions are constant, and electric pulse voltage is the metallographic microstructure figure of 300V；
Figure 24 is that other conditions are constant, and electric pulse voltage is the metallographic microstructure figure of 600V；
Figure 25 is that other conditions are constant, and electric pulse voltage is the metallographic microstructure figure of 900V；
Figure 26 is that other conditions are constant, the metallographic microstructure figure that electric pulse is 5min per h processing times；
Figure 27 is that other conditions are constant, the metallographic microstructure figure that electric pulse is 10min per h processing times；
Figure 28 is that other conditions are constant, the metallographic microstructure figure that electric pulse is 15min per h processing times；
Figure 29 is to carry out nitriding layer tissue elements content energy spectrum analysis figure to sample prepared by embodiment 1；
Figure 30 is to carry out matrix constituent content energy spectrum analysis figure to sample prepared by embodiment 1.
Specific implementation mode
Invention is described in further detail below in conjunction with the accompanying drawings, to enable those skilled in the art with reference to specification word
It can implement according to this.
The high chromium cold work die steel is Cr12MoV steel.
Embodiment 1
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h, in insulating process, at interval of
55min applies electric pulse 5min；The frequency of the electric pulse applied is 9Hz, voltage 900V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling；
Wherein, there are following functional relations between the amplitude U and time t of the electrical pulse device output：
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
In formula, E is average field intensity, and c is adjusting parameter c=1.06e-0.03t, l is interelectrode distance, and ω is electric discharge
Rate, t be effect time.
Embodiment 2
A, high chromium cold work die steel is processed into the sample of 4mm*4mm*8mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:2.9:1.1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 555 DEG C, keep the temperature 7.5h, in insulating process, at interval of
54min applies electric pulse 6min；The frequency of the electric pulse applied is 6Hz, voltage 900V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
Embodiment 3
A, high chromium cold work die steel is processed into the sample of 6mm*6mm*12mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3.1:0.9 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 565 DEG C, keep the temperature 6.5h, in insulating process, at interval of
56min applies electric pulse 4min；The frequency of the electric pulse applied is 12Hz, voltage 300V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
Embodiment 4
A, high chromium cold work die steel is processed into the sample of 4mm*4mm*12mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 561 DEG C, keep the temperature 6.8h, in insulating process, at interval of
55min applies electric pulse 5min；The frequency of the electric pulse applied is 9Hz, voltage 600V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
Embodiment 5
A, high chromium cold work die steel is processed into the sample of 4mm*4mm*12mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 563 DEG C, keep the temperature 7.2h, in insulating process, at interval of
55min applies electric pulse 5min；The frequency of the electric pulse applied is 9Hz, voltage 600V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
Embodiment 6
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*8mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3.05:0.95 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 564 DEG C, keep the temperature 7.2h, in insulating process, at interval of
55.5min applies electric pulse 4.5min；The frequency of the electric pulse applied is 7Hz, voltage 900V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
Embodiment 7
A, high chromium cold work die steel is processed into the sample of 4mm*4mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:2.95:1.05 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 562 DEG C, keep the temperature 7.3h, in insulating process, at interval of
55min applies electric pulse 5min；The frequency of the electric pulse applied is 8Hz, voltage 800V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
Comparative example 1
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 550 DEG C, keep the temperature 7h；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling.
Comparative example 2
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 5h；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling.
Comparative example 3
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out water cooling.
Comparative example 4
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h；
D, terminate in step c reactions, the sample is taken out from nitriding tank, is carried out air-cooled.
Comparative example 5
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea according to 6:4 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling.
Comparative example 6
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:2:2 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling.
Comparative example 7
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h, in insulating process, at interval of
50min applies electric pulse 10min；The frequency of the electric pulse applied is 12Hz, voltage 900V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
Comparative example 8
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h, in insulating process, at interval of
59min applies electric pulse 1min；The frequency of the electric pulse applied is 12Hz, voltage 900V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling.
Comparative example 9
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h, in insulating process, at interval of
55min applies electric pulse 5min；The frequency of the electric pulse applied is 3Hz, voltage 900V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
Comparative example 10
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h, in insulating process, at interval of
55min applies electric pulse 5min；The frequency of the electric pulse applied is 15Hz, voltage 900V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
Comparative example 11
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h, in insulating process, at interval of
55min applies electric pulse 5min；The frequency of the electric pulse applied is 9Hz, voltage 100V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
Comparative example 12
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h, in insulating process, at interval of
55min applies electric pulse 5min；The frequency of the electric pulse applied is 9Hz, voltage 1000V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l isa→bDistance, ω be electric discharge
Rate, t are the time of effect.
Comparative example 13
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 580 DEG C, keep the temperature 7h；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling.
Comparative example 14
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling.
Comparative example 15
A, high chromium cold work die steel is processed into the sample of 5mm*5mm*10mm；
B, at the middle part that the sample in step a is placed in nitriding tank, and nitriding medium is filled in the sample surrounding, seals institute
State nitriding tank；The nitriding medium is by charcoal, urea and chromium trioxide according to 6:3:1 ratio mixes.
C, the nitriding tank is placed in heating furnace, is warming up to 560 DEG C, keep the temperature 7h, in insulating process, at interval of
55min applies electric pulse 5min；The frequency of the electric pulse applied is 9Hz, voltage 900V；
D, terminate in step c reactions, the sample is taken out from nitriding tank, carries out oil cooling.
Data analysis
The nitrided case depth through embodiment 1-7 and comparative example 1-13 treated sample is tested respectively, and acquired results are shown in Table
One:
One sample nitrided case depth of table
| Project | Nitrided case depth um | Project | Nitrided case depth um |
| Embodiment 1 | 151 | Comparative example 4 | 0 |
| Embodiment 2 | 143 | Comparative example 5 | 35 |
| Embodiment 3 | 140 | Comparative example 6 | 38 |
| Embodiment 4 | 145 | Comparative example 7 | 113 |
| Embodiment 5 | 146 | Comparative example 8 | 89 |
| Embodiment 6 | 136 | Comparative example 9 | 80 |
| Embodiment 7 | 138 | Comparative example 10 | 130 |
| Comparative example 1 | 45 | Comparative example 11 | 56 |
| Comparative example 2 | 40 | Comparative example 12 | 148 |
| Comparative example 3 | 61 | Comparative example 13 | 40 |
| Comparative example 14 | 60 | Comparative example 15 | 91 |
The sample prepared through embodiment 1-7 it can be seen from table one has the nitriding layer of good thickness.
One, the relationship of holding temperature and nitriding
Fig. 1, Fig. 2 and Fig. 3 are the microstructure picture that sample is prepared by comparative example 1, comparative example 13 and comparative example 14 respectively,
Nitrided case depth as can be seen from Table I first increases with temperature to be reduced afterwards.From Fig. 1,
The microstructure picture of Fig. 2 and Fig. 3 can be seen that 560 DEG C of microstructure due to 545 DEG C and 580 DEG C.
According to Fe-C-N ternary state diagrams it is found that the eutectoid temperature of Fe-C-N ternary alloy three-partalloys be 565 DEG C, this temperature with
Under, solubility of the nitrogen in α-Fe gradually increases, the most advantageous to the absorption and diffusion of nitrogen, more than this temperature, can form γ-
Fe, and diffusion coefficient of the nitrogen in γ-Fe, than small in α-Fe, the formation of γ-Fe phases prevents nitrogen inwardly to spread, and makes nitriding
Speed slows down.Therefore, it is the most suitable that Nitrizing Treatment is carried out at 555~565 DEG C.
Two, the relationship of soaking time and nitriding
Fig. 3 and Fig. 4 is that comparative example 14, comparative example 2 prepare the microstructure picture of sample respectively, as can be seen from Table I
Nitrided case depth increases with the increase of soaking time.It can be seen that nitrided case depth heat preservation 7h alloying layer thicknesses are bright from Fig. 3 and Fig. 4
The aobvious alloying layer thickness for being more than heat preservation 5h.
Three, influence of the different types of cooling to nitriding
Fig. 3, Fig. 5 and Fig. 6 are the microstructure pictures that comparative example 14, comparative example 3 and comparative example 4 prepare sample.From figure
With table one known to it is air-cooled, substantially without nitriding layer；Water cooling alloying layer thickness is approximate with oil cooling, and still, but oil cooling is since its is suitable
Cooling velocity, without being deformed caused by being quickly cooled down, form is best.Thus, patent Very good cooling mode of the present invention is oil cooling.
Four, influence of the electric pulse to nitriding whether application
Fig. 3 and Fig. 7 is the microstructure picture that comparative example 14 and embodiment 1 prepare sample.By microstructure picture and table
One as can be seen that the nitrided case depth by Electric Pulse Treatment obviously increases.
Fig. 8 and Fig. 9 is the sample surface layer XRD diffracting spectrums and sample transition zone that comparative example 14 and embodiment 1 prepare sample
XRD diffracting spectrums, by Fig. 8, Fig. 9 and table one it is found that nitriding layer surface is with Fe3Based on N phases, without Fe2N；And transition zone is mainly
Fe4N and α-Fe mixed phases.The nitriding of electric pulse aid in treatment does not influence the object phase of sample surface layer and transition zone.
Figure 10 and Figure 11 is the scanning electron microscope shape appearance figure of the nitriding workpiece infiltration layer of embodiment 1 and comparative example 14 respectively；Thus
It can be seen that the infiltration layer through Electric Pulse Treatment is more uniform than the nitriding layer without Electric Pulse Treatment, fine and close and continuous, infiltration layer and matrix
Between comb teeth-shaped feature weaken, it is smooth-out.
Figure 12, Figure 13 and Figure 14 are nitriding layer nitrogen distribution map, ferro element distribution map and the chromium of embodiment 1 respectively
Distribution map；It can be seen that after Electric Pulse Treatment, the distribution of alloy surface each element is visibly homogeneous, illustrates the work in pulse electromagnetic field
Under, diffusion of the activated nitrogen atom in alloy surface is promoted, uniform nitriding layer is formed.
Five, influence of the pulse frequency to nitriding layer
In the case where other experiment conditions are constant, i.e., nitriding temperature is 560 DEG C, soaking time 7h, and pulse voltage is
900V, pulse processing time are 5min, and adjustment pulse frequency is 0Hz, 3Hz, 6Hz, 9Hz and 12Hz, the examination prepared respectively to it
The metallographic microstructure of sample is observed, and Figure 15 is the metallographic microstructure of the sample of 0Hz, and Figure 16 is the metallographic of the sample of 3Hz
Microscopic structure, Figure 17 are the metallographic microstructure of the sample of 6Hz, and Figure 18 is the metallographic microstructure of the sample of 9Hz, Tu19Wei
The metallographic microstructure of the sample of 12Hz, by Figure 15-19 it can be seen that as can be seen that nitrided case depth elder generation with pulse frequency
Increase and increases, after reduce with the increase of pulse frequency, and through electric pulse auxiliary Nitrizing Treatment sample nitrided case depth it is equal
Higher than the nitrided case depth of conventional solid nitridation process sample.When wherein 3Hz, about from a surface to thickness at nitride layer, white layer in nitration case
It is 80 μm；Nitrided case depth is about 94 μm when 6Hz；Nitrided case depth is about 151 μm when 9Hz；When frequency increases to 12Hz, ooze
Nitrogen layer thickness reaches 130 μm.
Figure 20 is pulse frequency influences change curve to nitrided case depth.By contrast as can be seen that in patent of the present invention
Under experiment condition, with the increase for applying electrical impulse frequency, nitrided case depth is in the trend of reduction after first increasing.In certain frequency
In range, with the increase of electrical impulse frequency, alloying layer thickness increases.The reason is that, Electric Pulse Treatment generates tool in nitriding tank
There is the impulse electric field of some strength.Impulse electric field can promote the activated nitrogen atom after decomposing to accelerate to hit to nitriding specimen surface
It hits.With being continuously increased for frequency, the electric field change number in the unit interval increases, and extends action time, increases activity
The energy of nitrogen-atoms.When pulse frequency is more than critical value, electric field applies to be shortened with the time of revocation, the part on workpiece surface
Activated nitrogen atom fails to interact with the iron atom in mould steel in time, is effectively combined.So increasing pulse
The variation tendency reduced is presented in the nitride thickness of the obtained mould steel of frequency.
Figure 21 be through 0Hz, after 3Hz and 9Hz processing sample surface to intrinsic silicon hardness schematic diagram；As can be seen that
Within the scope of 0-9Hz, with the increase of electrical impulse frequency, microhardness is increased therewith.Think, with pulse frequency
The thickness of the increase of rate, nitriding layer (nitride layer, white layer) increases, the Fe in nitride layer, white layer3N phases have higher hardness, and electric pulse is applied
The disperse degree of nitride can be promoted by adding, and with the increase of electrical impulse frequency, the spread also increases as, so in the experiment
Under conditions of, pulse frequency is high, and the microhardness of workpiece is also higher.
It is measured through experiment, identical in testing machine application load, the wear extent of sample is wanted after Electric Pulse Treatment
It significantly reduces, 67.9% or so when about untreated；Change the pulse frequency in nitriding process, wear extent continues to reduce, about
Not apply the 41.5% of electric pulse nitriding, wearability significantly improves.Such as Figure 22.Figure 22 is that different pulse frequency handles sample
Wear extent schematic diagram.Patent of the present invention determines that the pulse frequency more optimized is 9Hz.
Six, influence of the pulse voltage to nitriding layer
In the case where other experiment conditions are constant, i.e., nitriding temperature is 560 DEG C, soaking time 7h, and pulse frequency is
9Hz, pulse processing time are 5min, and adjustment pulse voltage is 300V, 600V, 900V.Figure 23-25 is respectively the sample that it is prepared
Metallographic microstructure figure, alloying layer thickness when pulse voltage is 300V it can be seen from Figure 23-25 is 87 μm, pulse voltage
Alloying layer thickness for 600V is 113 μm, increases 29.8%, and the alloying layer thickness that pulse voltage is 900V is 151 μm, is increased about
73.6%.
According to analysis within the scope of certain pulse voltage, the more high then nitriding layer of pulse voltage is thicker.It generates this
Phenomenon be due to nitrogen-atoms to when spreading inside sample while needing certain nitriding gradient, using electric pulse nitridation process
When, on the one hand the activated nitrogen atom in the case where being acted on compared with high pulse voltage can obtain more energy, on the other hand due to pulse electricity
The electron transfer effect of field so that diffusion of the nitrogen-atoms in metal infiltration layer is accelerated, and activated nitrogen atom is caused to be combined to be formed with Fe
Fe3N abilities enhance, and then to further diffusion inside sample, obtain thicker nitriding layer.It thereby determines that, in this experimental study
In range, pulse voltage 900V more optimizes.
Seven, influence of the pulse processing time to nitriding layer
In the case where other experiment conditions are constant, i.e., nitriding temperature is 560 DEG C, soaking time 7h, and pulse frequency is
9Hz, pulse voltage 900V, per h, adjustment processing time is 5min, 10min and 15min.Figure 26-28 is respectively the examination that it is prepared
The metallographic microstructure figure of sample.By Figure 26-28 it is found that the thickness of nitriding layer is continuously decreased with the increase of pulse processing time,
This is because pulse processing time it is long keep nitrogenous in infiltration layer and phosphorus content excessively high, nitride occurs and decomposes and denitrogenation phenomenon, it is former
Sub- nitrogen becomes dinitrogen and forms cavity.It thereby determines that, prolonged pulse processing may have specimen surface certain anti-
Effect, patent of the present invention determine that the burst length more optimized is to add 5min per 55min.
Eight, impulse waveform is to the influence to nitriding layer
Have preferably when impulse waveform meets the functional expression of the present invention it can be seen from embodiment 1 and comparative example 15
Pulse utilization rate can obtain thicker carburized layer thickness.
Nine, optimal parameter is verified
The constituent content energy spectrum analysis that nitriding layer tissue and matrix are carried out to sample prepared by embodiment 1, obtains Figure 29-
30 and table two.
The element percentage composition of two diffusion layer organization of table and matrix
By Figure 29-30 and 2 comparative analysis of table it is found that electric pulse assists the nitrogen in sample energy spectrum analysis obtained by Nitrizing Treatment
Element percentage composition is higher than the percentage composition of nitrogen in matrix.By the chemical reaction mechanism of metal it is found that chromium nitrification
Object is more, and chromium content is higher.And the N content of matrix also illustrates that this nitridation process is best.
It summarizes
Patent research of the present invention influence of the Electric Pulse Treatment to cold work die steel surface solid nitriding.By changing nitriding
Technique observes the metallographic structure under different technology conditions, and carries out performance evaluation.Pass through metallographic microscope (OM), scanning electron microscope
(SEM), energy spectrum analysis (EDS), the means of testing such as X-ray diffractometer (XRD) and microhardness testers are obtained as drawn a conclusion：
(1) as pulse voltage 900V, with the increase of pulse frequency, nitride thickness first increases and reduces afterwards.Work as pulse
When frequency is 9Hz, nitrided case depth is 151 μm, 2.5 times when about untreated.
(2) as the increase alloying layer thickness of pulse voltage increases.When pulse voltage is 900V, nitrided case depth is 151 μ
M, 2.5 times when being untreated.
(3) alloying layer thickness is related with the burst length, i.e. the burst length is longer, and nitriding layer is thicker, processing time 5min, interval
When 55min, alloying layer thickness is maximum, is 151 μm, is 2.5 times of traditional handicraft (60 μm).But excessive continuous impulse processing, nitrogen
Change effect but to run counter to desire.After the time increasing to 10min, the thickness of nitration case is on a declining curve.By comparison, ideal electricity
Pulse processing time is processing time 5min, is spaced 55min.
(4) through research, best process parameter for nitriding be pulse voltage 900V, pulse frequency 9Hz, 560 DEG C of holding temperature,
Soaking time 7h, oil cooling.Nitrided case depth is 151 μm under this technique, is 2.5 times of 60 μm of traditional handicraft.Properties are higher,
Reach energy saving, has shortened the purpose of time.
Although the embodiments of the present invention have been disclosed as above, but its is not only in the description and the implementation listed
With it can be fully applied to various fields suitable for the present invention, for those skilled in the art, can be easily
Realize other modification, therefore without departing from the general concept defined in the claims and the equivalent scope, the present invention is simultaneously unlimited
In specific details and legend shown and described herein.
Claims (8)
1. a kind of electric pulse assists the processing method of high chromium cold work die steel nitriding, including：
A, high chromium cold work die steel is cut into sample；
B, the sample is placed in the middle part of nitriding tank, and nitriding medium is filled in the sample surrounding, seals the nitriding tank；
C, the nitriding tank is placed in heating furnace, is warming up to 555~565 DEG C, keep the temperature 6.5~7.5h, in insulating process, often
It is spaced 54~56min, applies 4~6min of electric pulse；The frequency of the electric pulse applied be 6~12Hz, voltage be 300~
900V；
D, the sample is taken out from nitriding tank, is cooled down；
Wherein, there are following functional relations between the amplitude and time t of the electrical pulse device output：
In formula,For average field intensity, c is adjusting parameter c=1.06e-0.03t, l is the distance of a → b, and ω is the speed of electric discharge
Rate, t are the time of effect.
2. electric pulse according to claim 1 assists the processing method of high chromium cold work die steel nitriding, it is characterised in that：
In step b, the nitriding medium is by charcoal, urea and chromium trioxide according to 6:2.9~3.1:0.9~1.1 ratio mixes.
3. electric pulse according to claim 1 assists the processing method of high chromium cold work die steel nitriding, it is characterised in that：
In the step c, the nitriding tank is placed in heating furnace, is warming up to 560~565 DEG C.
4. electric pulse according to claim 1 assists the processing method of high chromium cold work die steel nitriding, it is characterised in that：
In the step c, the time of heat preservation is 7h.
5. electric pulse according to claim 1 assists the processing method of high chromium cold work die steel nitriding, it is characterised in that：
It is described in insulating process in the step c, at interval of 55min, apply electric pulse 5min.
6. electric pulse according to claim 1 assists the processing method of high chromium cold work die steel nitriding, it is characterised in that：
In the step c, the frequency of the electric pulse of application is 12Hz.
7. electric pulse according to claim 1 assists the processing method of high chromium cold work die steel nitriding, it is characterised in that：
In the step c, the voltage of the electric pulse of application is 900V.
8. electric pulse according to claim 1 assists the processing method of high chromium cold work die steel nitriding, it is characterised in that：
In step d, the type of cooling is oil cooling.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4030947A (en) * | 1975-09-10 | 1977-06-21 | Kemper Eugene L | Heating treatment method and system of utilizing same |
| JP2006104549A (en) * | 2004-10-08 | 2006-04-20 | Nippon Steel Corp | High strength bolt having excellent delayed fracture resistance and method for improving its delayed fracture resistance |
| WO2012124899A3 (en) * | 2011-03-16 | 2012-11-08 | Jeon Hae-Dong | Machine parts with excellent corrosion resistance and abrasion resistance, and manufacturing method thereof |
| CN103741092A (en) * | 2013-12-12 | 2014-04-23 | 辽宁工业大学 | Electric pulse-assisted nitriding method of austenitic stainless steel |
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2018
- 2018-04-03 CN CN201810285835.4A patent/CN108504988B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4030947A (en) * | 1975-09-10 | 1977-06-21 | Kemper Eugene L | Heating treatment method and system of utilizing same |
| JP2006104549A (en) * | 2004-10-08 | 2006-04-20 | Nippon Steel Corp | High strength bolt having excellent delayed fracture resistance and method for improving its delayed fracture resistance |
| WO2012124899A3 (en) * | 2011-03-16 | 2012-11-08 | Jeon Hae-Dong | Machine parts with excellent corrosion resistance and abrasion resistance, and manufacturing method thereof |
| CN103741092A (en) * | 2013-12-12 | 2014-04-23 | 辽宁工业大学 | Electric pulse-assisted nitriding method of austenitic stainless steel |
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