CN107739790A - Heat treatment method and vacuum high-pressure the air cooling stove of extrusion die - Google Patents
Heat treatment method and vacuum high-pressure the air cooling stove of extrusion die Download PDFInfo
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- CN107739790A CN107739790A CN201711057465.0A CN201711057465A CN107739790A CN 107739790 A CN107739790 A CN 107739790A CN 201711057465 A CN201711057465 A CN 201711057465A CN 107739790 A CN107739790 A CN 107739790A
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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
- C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
- C21D1/613—Gases; Liquefied or solidified normally gaseous material
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
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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
- C21D1/62—Quenching devices
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0062—Heat-treating apparatus with a cooling or quenching zone
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
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- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Extrusion Of Metal (AREA)
Abstract
The present invention relates to a kind of heat treatment method of extrusion die and vacuum high-pressure air cooling stove.The heat treatment method comprises the following steps：The extrusion die being slightly molded is placed in vacuum high-pressure air cooling stove；By the way of heat stepwise, extrusion die is heated to austenitizing temperature and the insulation of its used material；Under the first air pressure, ventilated machine is cooled down using the first rotating speed to extrusion die；Under the second air pressure, ventilated machine is cooled down using the second rotating speed to extrusion die, until the temperature of the center portion of extrusion die is down to 530 DEG C 570 DEG C；Under the 3rd air pressure, ventilated machine carries out sub-sectional cooling to extrusion die, until the surface temperature of extrusion die is down to 50 70 DEG C；Extrusion die after grade quench is subjected to double tempering.Heat treatment method and vacuum high-pressure the air cooling stove of above-mentioned extrusion die, enable to the surface of extrusion die and the uniform texture of center portion, and then cause the carbide dispersion degree height separated out, improve the service life of extrusion die.
Description
Technical field
The present invention relates to die treatment technical field, a kind of heat treatment method more particularly to extrusion die and it is used for
The vacuum high-pressure air cooling stove of the heat treatment method of extrusion die.
Background technology
Aluminum alloy extrusion section bar mould is manufactured using 4Cr5MoSi V1 (U.S. trade mark H13) die steels, aluminium section bar from
The center die hole portion position extrusion of mould, mold center position is the position of most stress most critical, high to its mechanical property requirements.
Traditional die ＆ mold treatment quenching is using vacuum high-pressure air cooling continuous coo1ing, die surface and center portion when quenching cools down
The temperature difference it is big, the institutional framework difference of surface and center portion is big after cooling, after double tempering, carbonization that die surface separates out
The thing spread is high, and the carbide dispersion degree that mould center portion separates out is low, so that the tensile strength and impact flexibility of mould center portion
Mechanical property it is low, because the structural homogenity of mould center portion is bad, the spread of carbide is not high, in follow-up surface chemistry
Easily there is pulse, herring-bone form, heap, netted nitride in mould center portion in heat treatment nitridation, and then causes the mold use longevity
Life reduces.
The content of the invention
Based on this, it is necessary to cause tissue of the mould from surface to center portion for the Technology for Heating Processing of traditional extrusion die
The problem of uneven, there is provided heat treatment method and vacuum high-pressure the air cooling stove of a kind of extrusion die.
A kind of heat treatment method of extrusion die, comprises the following steps：
(1) shove charge
The extrusion die being slightly molded is placed in vacuum high-pressure air cooling stove；
(4) quench
By the way of heat stepwise, the extrusion die is heated to the austenitizing temperature of its used material simultaneously
Insulation；
Under the first air pressure, ventilated machine is cooled down using the first rotating speed to the extrusion die, until the extruding
The surface temperature of mould is between 500 DEG C -520 DEG C, and the temperature of the center portion of the extrusion die is between 630 DEG C -650 DEG C；
Under the second air pressure, the ventilated machine is cooled down using the second rotating speed to the extrusion die, until described
The temperature of the center portion of extrusion die is down to 530 DEG C -570 DEG C；
Under the 3rd air pressure, the ventilated machine carries out sub-sectional cooling to the extrusion die, until the extrusion die
Surface temperature be down to 50-70 DEG C；
(5) it is tempered
The extrusion die after grade quench is subjected to double tempering.
Extrusion die is heated to it and used by the heat treatment method of above-mentioned extrusion die, the mode for first passing through heat stepwise
Material austenitizing temperature and insulation, then carry out quenching classification cooling, under the first air pressure, ventilated machine use first turn
Speed cools down to extrusion die, until the surface temperature of extrusion die is between 500 DEG C -520 DEG C, and the center portion of extrusion die
Temperature between 630 DEG C -650 DEG C, while monitor the surface of extrusion die and the temperature of center portion so that the surface of extrusion die
Less with the temperature difference of center portion, then, under the second air pressure, ventilated machine is carried out cold using the second rotating speed to extrusion die
But, until the temperature of the center portion of extrusion die is down to 530 DEG C -570 DEG C, between the surface and the center portion that further reduce extrusion die
Temperature difference, now, then under the 3rd air pressure, ventilated machine to extrusion die carry out sub-sectional cooling, until extrusion die table
Face temperature is down to preset value, and the surface of extrusion die and center portion cool simultaneously, by under different air pressure and rotating speed to extrusion die
Tool carry out quenching classification cooling, then by after grade quench extrusion die carry out double tempering so that the surface of extrusion die and
The uniform texture of center portion, and then cause the carbide dispersion degree height separated out, improve the service life of extrusion die.
In one of the embodiments, the heat stepwise in the quenching Step comprises the following steps：
The surface of the extrusion die is heated to 650 DEG C and is incubated 180-240 minutes；
Continue to heat the extrusion die, until the temperature on the surface of the extrusion die reaches 850 DEG C and protected
Warm 180-240 minutes；
Continue to heat up, until the temperature on the surface of the extrusion die reaches 1030 DEG C, and be incubated 180-240 minutes.
In one of the embodiments, first air pressure is 0.5MPa-0.7MPa；First rotating speed is 1440 turns every
Minute；The time cooled down to the extrusion die is 10-12 minutes.
In one of the embodiments, described under the second air pressure, second air pressure is 0.1MPa-0.3MPa；It is described
Second rotating speed is 100-200 rpms；The time cooled down to the extrusion die is 25-35 minutes.
In one of the embodiments, the sub-sectional cooling in the quenching Step comprises the following steps：
Nitrogen is passed through into vacuum high-pressure air cooling stove so that the 3rd air pressure is 0.5MPa-0.7MPa；
The ventilated machine cools down 13-15 minutes using 1440 rpms of rotating speed to the extrusion die；
The rotating speed for adjusting the ventilated machine is 500-600 rpms, until the surface temperature of the extrusion die drops
To 50-70 DEG C.
In one of the embodiments, by frequency-variable controller, the rotating speed of the ventilated machine and the vacuum are adjusted
Air pressure in high pressure gas black furnace.
In one of the embodiments, the step of tempering includes：At 500-600 DEG C to grade quench after described in
Extrusion die carries out double tempering, and is incubated 3.5-4.5 hours.
In one of the embodiments, it is further comprising the steps of after the tempering step：Described in after double tempering
Extrusion die carries out nitrogen treatment.
A kind of vacuum high-pressure air cooling stove of heat treatment method for above-mentioned extrusion die, including body of heater, temperature-measuring part, heat
Exchanger and ventilated machine, the body of heater have heating chamber, and the heating chamber is used to accommodate nitrogen；The temperature-measuring part
It is arranged in the heating chamber, the temperature-measuring part is used for the temperature for measuring the center portion of the extrusion die；The air-cooled electricity
Machine is used for the flowing for accelerating the nitrogen；The heat exchanger is arranged in the body of heater, and the heat exchanger is used for heat
Discharge the body of heater.
In one of the embodiments, the temperature-measuring part is thermocouple.
Above-mentioned vacuum high-pressure air cooling stove, the temperature of the center portion of extrusion die is monitored in real time by temperature-measuring part, so as to extrude
Mould, can be with the temperature between the surface of Real Time Observation extrusion die and center portion when vacuum high-pressure is gas-cooled and quench cooling in stove
Degree is poor, beneficial to the heat treatment of extrusion die, improves thermal treatment quality.
Brief description of the drawings
Fig. 1 is the schematic flow sheet of the heat treatment method of the extrusion die of an embodiment；
Fig. 2 is the metallograph using the extrusion die after the heat treatment method of embodiment 1；
Fig. 3 is the metallograph using the extrusion die after the heat treatment method of comparative example.
Embodiment
As described by background technology, die ＆ mold treatment quenching uses vacuum high-pressure air cooling continuous coo1ing, when quenching cools down
The temperature difference of die surface and center portion is big, and the institutional framework difference of surface and center portion is big after cooling, after double tempering, mould
The carbide dispersion degree that surface separates out is high, and the carbide dispersion degree that mould center portion separates out is low, so that the tension of mould center portion
The mechanical property of intensity and impact flexibility is low, and because the structural homogenity of mould center portion is bad, the spread of carbide is not high,
Easily there is pulse, herring-bone form, heap, netted nitride in mould center portion in follow-up Surface thermo-chemical treatment nitridation, and then leads
Cause mold use service life reduction.
In addition, mould, in extruded aluminium section, mould center portion bears very big shearing and friction stree, due to mould center portion
Nitration case in underproof pulse, herring-bone form, heap, netted nitride be present, these nitride and nitration case matrix
Adhesion is weaker, is at the germinating of formation of crack.In the presence of stress, mould center portion easy fracture peels off, and die life is not
Long, production cost is big.And mould cooling velocity in quenching is too fast, thermal stress and the superimposed change for causing mould of structural stress
Shape amount is big, and in follow-up finishing, the loss of lathe and cutter is big, processing technology time length, the manufacture low production efficiency of mould.
After further research, in one of the embodiments, there is provided a kind of heat treatment method of extrusion die, including
Following steps：(1) shove charge, the extrusion die being slightly molded is placed in vacuum high-pressure air cooling stove；(2) quench, added using segmentation
The mode of heat, extrusion die is heated to austenitizing temperature and the insulation of its used material；It is air-cooled under the first air pressure
Motor is cooled down using the first rotating speed to extrusion die, until extrusion die surface temperature between 500 DEG C -520 DEG C, and
The temperature of the center portion of extrusion die is between 630 DEG C -650 DEG C；Under the second air pressure, ventilated machine is using the second rotating speed to extruding
Mould is cooled down, until the temperature of the center portion of extrusion die is down to 530 DEG C -570 DEG C；Under the 3rd air pressure, ventilated machine pair
Extrusion die carries out sub-sectional cooling, until the surface temperature of extrusion die is down to 50-70 DEG C；(3) tempering is by after grade quench
Extrusion die carries out double tempering.
Further, a kind of vacuum high-pressure air cooling stove is also provided based on above-mentioned heat treatment method.
It is understandable to enable the above objects, features and advantages of the present invention to become apparent, below in conjunction with the accompanying drawings to the present invention
Specific embodiment be described in detail
Fig. 1, the heat treatment method of the extrusion die of an embodiment are refer to, the extrusion die can be used for extruded aluminium section,
Comprise the following steps：
S1：The extrusion die being slightly molded is placed in vacuum high-pressure air cooling stove.
Specifically, need to carry out Precision Machining again after being heat-treated for extrusion die made from roughing, to improve
Precision and hardness of extrusion die etc..The extrusion die being slightly molded, which frames up, to be placed in the high air cooling stove of vacuum.The vacuum high-pressure gas
Temperature-measuring part is installed, temperature-measuring part is used for the temperature for measuring the center portion of extrusion die in black furnace.In one embodiment, thermometric portion
Part is thermocouple.
S2：By the way of heat stepwise, extrusion die is heated to the austenitizing temperature of its used material simultaneously
Insulation.
In the present embodiment, material is 4Cr5MoSi V1 (U.S. trade mark H13) die steel used by extrusion die,
Its austenitizing temperature is 1030 DEG C.Specifically, in one embodiment, the process of heat stepwise is as follows：By the table of extrusion die
Face is heated to 650 DEG C and is incubated 180-240 minutes；Continue to heat extrusion die, until the temperature on the surface of extrusion die
Degree reaches 850 DEG C and is incubated 180-240 minutes；Continue to heat up, until the temperature on the surface of extrusion die reaches 1030 DEG C, and protect
Warm 180-240 minutes, now, the temperature on the surface of extrusion die are consistent with the temperature of the center portion of extrusion die, and austenite is uniform
Change finishes.
S3：Under the first air pressure, ventilated machine is cooled down using the first rotating speed to extrusion die.Until extrusion die
Surface temperature is between 500 DEG C -520 DEG C, and the temperature of the center portion of extrusion die is between 630 DEG C -650 DEG C.
First air pressure can be 0.5MPa-0.7MPa, and the first rotating speed can be 1440 rpms.Carried out in step S2
After heat stepwise, stop heating, cooled down.Specifically, it is passed through nitrogen into vacuum high-pressure air cooling stove so that the first air pressure is
0.5MPa-0.7MPa.Then, soft start ventilated machine, ventilated machine are entered using 1440 rpms of rotating speed to extrusion die
Row cooling, the time of cooling is 10-12 minutes.Nitrogen in vacuum high-pressure air cooling stove is under the drive of ventilated machine, in vacuum
Flowed in high pressure gas black furnace, so as to take the heat of extrusion die in vacuum high-pressure stove to heat exchanger, following in heat exchanger
Ring cooling water constantly moves the heat of extrusion die and brought into cooling pond, so as to be cooled to extrusion die, until squeezing
The surface temperature of compression mould is between 500 DEG C -520 DEG C, and the temperature of the center portion of extrusion die is between 630 DEG C -650 DEG C.By
Higher in the rotating speed of ventilated machine, the pressure of nitrogen is bigger, cooling hasten it is also faster, so as under the step, to extrusion die
Quickly cooled down so that the overcooling austenite of extrusion die has tided over secondary carbide precipitation line and perlitic transformation area.
It should be noted that understanding as described above, the temperature of the center portion of extrusion die is measured by thermocouple, so as to
To monitor the temperature of the center portion of extrusion die in real time.In addition, in one of the embodiments, ventilated machine uses soft start side
Formula, the rotating speed of ventilated machine can be adjusted in real time.The rotating speed of ventilated machine can be adjusted by frequency converter.Need
It is bright, air pressure (be nitrogen pressure) in vacuum high-pressure air cooling stove can also frequency converter be adjusted, frequency converter can lead to
Cross and control the electromagnetic inflation valve being electrically connected with it and electromagnetic release valve to adjust the air pressure in vacuum high-pressure air cooling stove.
S4：Under the second air pressure, ventilated machine is cooled down using the second rotating speed to extrusion die, until extrusion die
The temperature of center portion is down to 530 DEG C -570 DEG C.
Specifically, the air pressure in vacuum high-pressure air cooling stove is reduced so that the second air pressure in vacuum high-pressure air cooling stove is (also
It is nitrogen pressure) it is 0.1-0.3MPa.Meanwhile the rotating speed of ventilated machine is adjusted to 100-200 rpms, so as to continue to squeezing
Compression mould is cooled down, and cool time is 25-35 minutes.Now, nitrogen pressure is relatively low, and the rotating speed of ventilated machine is smaller, from
And make it that the heat of the center portion of extrusion die is transmitted to the surface of extrusion die, supplement the damage of the temperature on the surface of extrusion die
Lose so that between the surface temperature of extrusion die maintains 500 DEG C -520 DEG C, meanwhile, the temperature of the center portion of extrusion die drops to
530℃-570℃。
Cooled down by step S3 and step S4 classification so that the overall temperature of extrusion die has been cooled to 500 DEG C to 600
DEG C temperature range, the surface of extrusion die and the temperature difference of center portion be less, so as to the surface for extrusion die and center portion
Structural transformation has been prepared condition simultaneously, ensure that the uniformity organized after transformation.Should it is possible to further reduce heat
Power, reduce the deformation of extrusion die.
S5：Under the 3rd air pressure, ventilated machine carries out sub-sectional cooling to extrusion die, until the surface temperature of extrusion die
It is down to 50-70 DEG C.
Specifically, it is passed through nitrogen into vacuum high-pressure air cooling stove so that the 3rd air pressure (namely nitrogen pressure) is
0.5MPa-0.7MPa.Meanwhile by frequency converter adjust ventilated machine rotating speed be 1440 rpms, ventilated machine is in this turn
Speed cools down 13-15 minutes to extrusion die.By improving nitrogen pressure and rotation speed of fan, extrusion die is quickly cooled down,
So that extrusion die tides over bainite transformation area, the temperature of the center portion of extrusion die is down to the geneva of 4Cr5MoSi V1 mould steel
Body transition point (330 DEG C).
When the temperature of the center portion of extrusion die is down to martensite point (330 DEG C) of 4Cr5MoSi V1 mould steel, lead to
The rotating speed of frequency converter adjustment ventilated machine is crossed, it is 500-600 rpms to make its rotating speed, reduction cooling velocity, Slow cooling, directly
Temperature to the surface of extrusion die is down to 50-70 DEG C.During being somebody's turn to do, the surface of extrusion die is almost transformed into simultaneously with center portion
Martensite adds retained austenite and undissolved carbide.
S6：Extrusion die after grade quench is subjected to double tempering.
Specifically, double tempering is carried out to the extrusion die after grade quench at 500-600 DEG C, and is incubated 3.5-4.5
Hour.Tempering can be carried out in well formula tempering furnace.The knot of tissue of extrusion die after double tempering, its surface and center portion
Structure is uniform, and the carbide dispersion degree of precipitation is high, and the Surface thermo-chemical treatment nitridation for the center portion of follow-up extrusion die provides
Preferable institutional framework.
S7：Extrusion die after double tempering is subjected to nitrogen treatment.
Specifically, the extrusion die after double tempering is placed in gas nitriding furnace and carries out nitrogen treatment, to nitriding furnace
Interior logical ammonia, the resolution ratio of ammonia is controlled between 35%-40%, kept for 10 hours at 520 DEG C, then be warming up to 540 DEG C, control
The resolution ratio of ammonia processed is incubated 3 hours between 55%-60% so that the surface of extrusion die carries out nitrogen treatment.Extrusion die
Nitride small and dispersed in the nitration case of the center portion of tool is uniform, does not occur pulse, herring-bone form, heap, netted nitride, such as
Shown in Fig. 2.The uniform nitride of these small and disperseds hinders dislocation motion, increases the wearability fatigability of mould center portion, and then
Improve the service life of extrusion die.
Extrusion die is heated to it and used by the heat treatment method of above-mentioned extrusion die, the mode for first passing through heat stepwise
Material austenitizing temperature and insulation, then carry out quenching classification cooling, under the first air pressure, ventilated machine use first turn
Speed cools down to extrusion die, until the surface temperature of extrusion die is between 500 DEG C -520 DEG C, and the center portion of extrusion die
Temperature between 630 DEG C -650 DEG C, while monitor the surface of extrusion die and the temperature of center portion so that the surface of extrusion die
Less with the temperature difference of center portion, then, under the second air pressure, ventilated machine is carried out cold using the second rotating speed to extrusion die
But, until the temperature of the center portion of extrusion die is down to 530 DEG C -570 DEG C, between the surface and the center portion that further reduce extrusion die
Temperature difference, now, then under the 3rd air pressure, ventilated machine to extrusion die carry out sub-sectional cooling, until extrusion die table
Face temperature is down to preset value, and the surface of extrusion die and center portion cool simultaneously, then the extrusion die after grade quench is carried out into two
Secondary tempering so that the surface of extrusion die and the uniform texture of center portion, and then cause the carbide dispersion degree height separated out, squeeze
Nitride small and dispersed after the work band nitridation of the center portion of compression mould, is not in pulse, herring-bone form, heap, network nitride,
Reduce extrusion die to work band germinating of formation of crack in the presence of stress, improve the service life of extrusion die, extruding
The yield of aluminium alloy extrusions is high 0.5 times.In addition, reduce the quenching distortion amount of extrusion die, so as to reduce follow-up finishing
The difficulty of work, improve the production efficiency of extrusion die.
Embodiment 1
(1) extrusion die being slightly molded is framed up and be placed in vacuum high-pressure air cooling stove；
(2) extrusion die is heated to 650 DEG C and is incubated 180 minutes；Continue to heat extrusion die, until extruding
The temperature of mould reaches 850 DEG C and is incubated 180 minutes；Continue to heat up, until the temperature of extrusion die reaches 1030 DEG C, stop adding
Heat, and it is incubated 240 minutes；
(3) it is passed through nitrogen into vacuum high-pressure air cooling stove so that nitrogen pressure 0.6MPa；Soft start ventilated machine, wind
Cool electric machine is cooled down using 1440 rpms of rotating speed to extrusion die, and the time of cooling is 12 minutes；
(4) air pressure in vacuum high-pressure air cooling stove is reduced so that the nitrogen pressure in vacuum high-pressure air cooling stove is 0.2MPa；
Meanwhile the rotating speed of ventilated machine is adjusted to 150 rpms, and so as to continue that extrusion die is cooled down, cool time 30
Minute, the temperature of the center portion of extrusion die drops to 550 DEG C；
(5) it is passed through nitrogen into vacuum high-pressure air cooling stove so that nitrogen pressure 0.6MPa, meanwhile, adjusted by frequency converter
The rotating speed of rectification campaign cool electric machine is 1440 rpms, and ventilated machine cools down 15 minutes in the rotating speed to extrusion die；Pass through frequency conversion
Device adjusts the rotating speed of ventilated machine, and it is 600 rpms to make its rotating speed, the temperature on the surface of Slow cooling extrusion die, until
The temperature on the surface of extrusion die is down to 60 DEG C；
(6) double tempering is carried out to the extrusion die after grade quench at 570 DEG C, and is incubated 4 hours；
(7) extrusion die after double tempering is placed in nitriding furnace and carries out nitrogen treatment, nitridation conditions are：Nitriding furnace
Interior temperature is 520 DEG C, ammonia decomposition 35%, and nitridation time is 10 hours；540 degree are warming up to again, the resolution ratio of ammonia
For 60%, nitrogenize 3 hours.
Fig. 2 is the metallograph of the extrusion die after thermally treated method is heat-treated under 500 multiplication factors.Such as Fig. 2
Extrusion die that is shown, being heat-treated by the heat treatment method of embodiment 1, the nitrogen in the nitration case of the center portion of extrusion die
Compound small and dispersed is uniform, does not occur pulse, herring-bone form, heap, netted nitride.
Comparative example
The extrusion die being slightly molded is framed up and is placed in vacuum high-pressure air cooling stove；Extrusion die is heated to 650 DEG C simultaneously
Insulation 180 minutes；Continue to heat extrusion die, until the temperature of extrusion die reaches 850 DEG C and is incubated 180 minutes；
Continue to heat up, until the temperature of extrusion die reaches 1030 DEG C, stop heating, and be incubated 240 minutes；To vacuum high-pressure air cooling stove
Inside it is passed through nitrogen so that nitrogen pressure 0.6MPa；Soft start ventilated machine, ventilated machine use 1440 rpms of rotating speed
After continuous coo1ing being carried out to extrusion die；Double tempering is carried out to extrusion die at 570 DEG C, and is incubated 4 hours；By double tempering
Extrusion die afterwards, which is placed in nitriding furnace, carries out nitrogen treatment, and nitrogen treatment process is：Lead to ammonia into nitriding furnace, control ammonia
The resolution ratio of gas is 35%, is kept for 10 hours at 520 DEG C；540 DEG C are warming up to again, controls the resolution ratio position 60% of ammonia, are protected
Temperature 3 hours.
In comparative example, by the nitrogen in the high rotating speed forced circulation furnace of ventilated machine, pass through the heat exchanger in stove
The heat of extrusion die is taken away, the surface cooling velocity of extrusion die is very fast, and its center portion cooling velocity is slow, and quenching has cooled down
Bi Hou, the institutional framework on the surface of extrusion die add undissolved carbide and retained austenite, the center portion of extrusion die for martensite
Institutional framework be upper bainite, lower bainite, martensite, undissolved carbide and the line and staff control of retained austenite structure.Through
After crossing double tempering, the core structure structure of extrusion die is uneven, and the carbide dispersion degree of precipitation is not high so that extrusion die
Center portion there is pulse, fish-bone, heap, netted nitride after follow-up Surface thermo-chemical treatment nitridation, such as Fig. 3 institutes
Show.
For the extrusion die in extruded aluminium section, the center portion of extrusion die bears very big shearing and friction stree, due to
Underproof pulse, herring-bone form, heap, netted nitride, these nitride in the nitration case of the center portion of extrusion die be present
It is weaker with the adhesion of nitration case matrix, turn at the germinating of formation of crack, in the presence of stress, the center portion of extrusion die is easily broken
Split peeling.
Service life is tested
One 6 meters long of mould steel material manufacture is squeezed with model and the rectangular elliptical tube aluminium alloys of a diameter of 160cm of 40 sets of specification
Section bar mold is pressed, wherein 20 sets use vacuum heat quenching technical, 20 sets use vacuum heat stepped quenching process in addition.
When upper machine extruding rice weighs 0.5 kilogram of rectangular elliptical tube aluminium section bar, extruded using the extrusion die of vacuum heat quenching technical
After 10 tons of rectangular elliptical tube aluminium section bars, there is fracture peeling phenomenon, the rectangular elliptical tube aluminium profiles squeezed out in the center portion of extrusion die
There is concavo-convex line in material surface, and aluminium section bar quality is unqualified, and extrusion die failure is scrapped.And use vacuum heat grade quench work
After the mould of skill extrudes 15 tons of rectangular elliptical tube aluminium section bars, mould center portion just occurs being broken peeling phenomenon, and service life improves
0.5 times.
The vacuum high-pressure air cooling stove of the heat treatment method for above-mentioned extrusion die of one embodiment, including body of heater, thermometric
Part, heat exchanger and ventilated machine.Body of heater has heating chamber, and heating chamber is used to accommodate nitrogen, that is to say, that by nitrogen
Gas is passed through in the heating chamber to change the nitrogen pressure in heating chamber.
Temperature-measuring part is arranged in heating chamber, and temperature-measuring part is used for the temperature for measuring the center portion of the extrusion die.
In one embodiment, temperature-measuring part is thermocouple.Ventilated machine is used for the flowing for accelerating the nitrogen.The rotating speed of ventilated machine can be with
Adjustment.Heat exchanger is arranged in the body of heater, and heat exchanger is used to heat discharging body of heater.Heat exchanger can be full copper heat
Exchanger.
In one of the embodiments, in addition to frequency converter, frequency converter electrically connect with ventilated machine, are adjusted by frequency converter
The rotating speed of rectification campaign cool electric machine.
In one of the embodiments, in addition to gas storage part, vent valve and charge valve.The gas storage part is used to store
Nitrogen, and the gas storage part is connected with body of heater.Vent valve and charge valve are provided between gas storage part and body of heater.Put by control
The opening and closing of air valve and charge valve controls the air pressure in body of heater.Vent valve can electrically connect with frequency converter, and charge valve can also
Electrically connected with frequency converter, so as to control the opening and closing of vent valve and charge valve by frequency converter, and then adjust the air pressure in body of heater,
So as to control the quenching cooling velocity of extrusion die.It should be noted that vent valve can be electromagnetic release valve, charge valve
It can be electromagnetic inflation valve.
In one of the embodiments, in addition to cooling pond, the cooling pond are connected with heat exchanger by pipeline.When
Nitrogen is passed through in heating chamber, and after starting ventilated machine, opens heat exchanger tube of the pump switch of cooling pond into stove
Road leads to recirculated cooling water, and under the drive of the blade of ventilated machine, stove inner high voltage nitrogen is between extrusion die and heat exchanger
Circulation, the heat of extrusion die take heat exchanger to by nitrogen, and the recirculated cooling water in heat exchanger is constantly extrusion die
Heat take out of the vacuum high-pressure air cooling stove.
Above-mentioned vacuum high-pressure air cooling stove, the temperature of the center portion of extrusion die is monitored in real time by temperature-measuring part, so as to extrude
Mould can be with the temperature between the surface of Real Time Observation extrusion die and center portion when vacuum high-pressure is gas-cooled in stove and carries out quenching cooling
Degree is poor, beneficial to the heat treatment of extrusion die.The air pressure in rotating speed and stove by adjusting blower fan, reach quenching classification cooling, carry
High thermal treatment quality.
Each technical characteristic of embodiment described above can be combined arbitrarily, to make description succinct, not to above-mentioned reality
Apply all possible combination of each technical characteristic in example to be all described, as long as however, the combination of these technical characteristics is not deposited
In contradiction, the scope that this specification is recorded all is considered to be.
Embodiment described above only expresses the several embodiments of the present invention, and its description is more specific and detailed, but simultaneously
Can not therefore it be construed as limiting the scope of the patent.It should be pointed out that come for one of ordinary skill in the art
Say, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to the protection of the present invention
Scope.Therefore, the protection domain of patent of the present invention should be determined by the appended claims.
Claims (10)
1. a kind of heat treatment method of extrusion die, it is characterised in that comprise the following steps：
(1) shove charge
The extrusion die being slightly molded is placed in vacuum high-pressure air cooling stove；
(2) quench
By the way of heat stepwise, the extrusion die is heated to austenitizing temperature and the guarantor of its used material
Temperature；
Under the first air pressure, ventilated machine is cooled down using the first rotating speed to the extrusion die, until the extrusion die
Surface temperature between 500 DEG C -520 DEG C, and the temperature of the center portion of the extrusion die is between 630 DEG C -650 DEG C；
Under the second air pressure, the ventilated machine is cooled down using the second rotating speed to the extrusion die, until the extruding
The temperature of the center portion of mould is down to 530 DEG C -570 DEG C；
Under the 3rd air pressure, the ventilated machine carries out sub-sectional cooling to the extrusion die, until the table of the extrusion die
Face temperature is down to 50-70 DEG C；
(3) it is tempered
The extrusion die after grade quench is subjected to double tempering.
2. the heat treatment method of extrusion die according to claim 1, it is characterised in that the segmentation in the quenching Step
Heating comprises the following steps：
The surface of the extrusion die is heated to 650 DEG C and is incubated 180-240 minutes；
Continue to heat the extrusion die, until the temperature on the surface of the extrusion die reaches 850 DEG C and is incubated
180-240 minutes；
Continue to heat up, until the temperature on the surface of the extrusion die reaches 1030 DEG C, and be incubated 180-240 minutes.
3. the heat treatment method of extrusion die according to claim 1, it is characterised in that first air pressure is
0.5MPa-0.7MPa；First rotating speed is 1440 rpms；The time cooled down to the extrusion die is 10-12
Minute.
4. the heat treatment method of extrusion die according to claim 1, it is characterised in that second air pressure is
0.1MPa-0.3MPa；Second rotating speed is 100-200 rpms；The time cooled down to the extrusion die is 25-
35 minutes.
5. the heat treatment method of extrusion die according to claim 1, it is characterised in that according to claim 4
The heat treatment method of extrusion die, it is characterised in that the sub-sectional cooling in the quenching Step comprises the following steps：
Nitrogen is passed through into vacuum high-pressure air cooling stove so that the 3rd air pressure is 0.5MPa-0.7MPa；The air-cooled electricity
Machine cools down 13-15 minutes using 1440 rpms of rotating speed to the extrusion die；
The rotating speed for adjusting the ventilated machine is 500-600 rpms, until the temperature on the surface of the extrusion die is down to
50-70℃。
6. the heat treatment method of the extrusion die according to any one of claim 1-5, it is characterised in that pass through frequency conversion control
Device processed, adjust the air pressure in the rotating speed and vacuum high-pressure air cooling stove of the ventilated machine.
7. the heat treatment method of extrusion die according to claim 1, it is characterised in that include the step of the tempering：
Double tempering is carried out to the extrusion die after grade quench at 500-600 DEG C, and is incubated 3.5-4.5 hours.
8. the heat treatment method of extrusion die according to claim 1, it is characterised in that after the tempering step, also
Comprise the following steps：The extrusion die after double tempering is subjected to nitrogen treatment.
9. a kind of vacuum high-pressure air cooling stove for being used for the heat treatment method of extrusion die as any one of claim 1-8,
It is characterised in that it includes body of heater, temperature-measuring part, heat exchanger and ventilated machine, the body of heater has heating chamber, described to add
Hot chamber is used to accommodate nitrogen；The temperature-measuring part is arranged in the heating chamber, and the temperature-measuring part is described for measuring
The temperature of the center portion of extrusion die；The ventilated machine is used for the flowing for accelerating the nitrogen；The heat exchanger is arranged on institute
State in body of heater, the heat exchanger is used to heat discharging the body of heater.
The stove 10. vacuum high-pressure according to claim 9 is gas-cooled, it is characterised in that the temperature-measuring part is thermocouple.
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| CN112501396A (en) * | 2020-11-30 | 2021-03-16 | 北京航空航天大学 | Isothermal quenching heat treatment process method for third-generation bearing steel |
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