CN114990295A - Heat treatment process of high alloy steel - Google Patents
Heat treatment process of high alloy steel Download PDFInfo
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- CN114990295A CN114990295A CN202210427673.XA CN202210427673A CN114990295A CN 114990295 A CN114990295 A CN 114990295A CN 202210427673 A CN202210427673 A CN 202210427673A CN 114990295 A CN114990295 A CN 114990295A
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- alloy steel
- high alloy
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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
- C21D1/26—Methods of annealing
- C21D1/32—Soft annealing, e.g. spheroidising
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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
- C21D6/00—Heat treatment of ferrous alloys
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Heat Treatment Of Articles (AREA)
Abstract
The invention discloses a heat treatment process of high alloy steel, which is characterized by comprising the following steps: cooling the forged piece, and step two: preheating before spheroidizing annealing, preheating the spheroidizing annealing furnace, setting the preheating temperature to be lower than the spheroidizing temperature of 220-260 ℃, and preserving heat for 3-4 hours; step three: spheroidizing annealing, namely heating the high alloy steel to 20-30 ℃ above ac1, preserving heat for a certain time, cooling the high alloy steel with a furnace to 10-20 ℃ below ar1 for isothermal, setting the isothermal time to be 1.5 times of the heat preservation time, and cooling the high alloy steel with the furnace to 500 ℃ after isothermal, and discharging the high alloy steel from the furnace for air cooling. The method has the advantages that a normalizing process is omitted, a preheating process before spheroidizing return is added, the heat treatment time is saved, the heat treatment efficiency is improved, the energy consumption is saved, the product performance requirement can be met, and CN is met: 5.0 to 5.2; CZ: 6.0-6.2/7.0-7.2, and 100% nodularity.
Description
Technical Field
The invention relates to the field of heat treatment processes, in particular to a heat treatment process of high alloy steel.
Background
Because the finish forging temperature of each type of forge piece or each part of the forge piece is inconsistent and the deformation degree is inconsistent, the inside of the forge piece after cooling has the bad phenomena of uneven structure, residual stress, hardening and the like, and heat treatment is needed to ensure the quality of the forge piece. In the prior art, the heat treatment process adopted for the high alloy steel is that after forging of a forge piece, the forge piece is rapidly cooled to a certain temperature, then furnace cooling is carried out (about 8 hours), then temperature rising and normalizing are started, the heating, heat preservation and cooling time is about 12 hours, and then spheroidizing annealing is carried out for about 34 hours, and the total time is about 54 hours. The heat treatment time is longer, the efficiency is lower, and the energy consumption is higher; there is therefore a need for improvements in the heat treatment processes of high alloy steels of the prior art.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide the heat treatment process for the high-alloy hot steel, which has the advantages of short treatment time, high efficiency and low energy consumption.
In order to achieve the aim, the technical scheme of the invention is to provide a heat treatment process of high alloy steel, which comprises the following operation steps;
the method comprises the following steps: cooling the forged piece, namely quickly cooling the forged piece after the forged piece is taken off the machine, directly putting the cooled line into a sand pit, covering the sand pit with heat insulation cotton, and slowly cooling the forged piece until the forged piece is cooled to room temperature, and removing the heat insulation cotton;
step two: preheating before spheroidizing annealing, preheating the spheroidizing annealing furnace, setting the preheating temperature to be lower than the spheroidizing temperature of 220-260 ℃, and preserving heat for 3-4 hours;
step three: spheroidizing annealing, namely heating the high alloy steel to 20-30 ℃ above ac1, preserving heat for a certain time, cooling the high alloy steel with a furnace to 10-20 ℃ below ar1 for isothermal, setting the isothermal time to be 1.5 times of the heat preservation time, and cooling the high alloy steel with the furnace to 500 ℃ after isothermal, and discharging the high alloy steel from the furnace for air cooling.
Preferably: the temperature of the forged piece entering the pit after the rapid cooling in the first step is set to be 610-640 ℃.
Preferably: the preheating temperature in the second step is set to be 230 ℃ lower than the spheroidizing temperature.
Preferably: the heating temperature of the high alloy steel in the third step is set to be 25 ℃ above the ac1 temperature, and the isothermal temperature is set to be 15 ℃ below the ar1 temperature.
Preferably: and in the third step, the heat preservation time is set to be 0.5-1 hour for the forge piece with the thickness of each centimeter.
The invention has the following beneficial effects: placing the forged piece after the rapid cooling into a sand pit, and performing slow cooling instead of furnace cooling to room temperature in a heat-preservation cotton covering mode, and setting the pit entering temperature to 610-640 ℃; the cooling is ensured to be more uniform, the structure performance is more uniform, and the surface of the forging is effectively prevented from cracking; a preheating stage is added before spheroidizing annealing, the preheating temperature is set to be lower than the spheroidizing temperature of 220-; spheroidizing annealing is carried out, temperature rise and normalizing are not needed, so that the time of heat treatment is saved, the heat treatment efficiency is improved, the energy consumption is saved, and the aims of improving or eliminating various tissue defects caused by the high alloy steel in the forging process, refining crystal grains, improving the distribution and the form of a second phase in the high alloy steel, eliminating internal stress, reducing hardness, improving the tissue and facilitating cutting processing can be achieved; the heat treatment process of the invention can also meet the product performance requirements and meet the requirements of CN: 5.0 to 5.2; CZ: 6.0-6.2/7.0-7.2, and 100% nodularity.
Drawings
FIG. 1 is a time distribution diagram in example 1;
Detailed Description
The following description of the embodiments of the present invention will be made with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
Example 1: a heat treatment process of high alloy steel comprises the following operation steps; the method comprises the following steps: cooling the forged piece, namely quickly cooling the forged piece after the forged piece is taken off the machine, directly putting the cooled line into a sand pit, covering the sand pit with heat preservation cotton, slowly cooling the sand pit, setting the pit entry temperature to be 610 ℃, and removing the heat preservation cotton after the forged piece is cooled to room temperature; step two: preheating before spheroidizing annealing, preheating the spheroidizing annealing furnace, setting the preheating temperature to be lower than the spheroidizing temperature of 220 ℃, specifically to be 600 ℃, and carrying out heat preservation for 4 hours, wherein the preheating time is 6 hours; step three: spheroidizing annealing, wherein the thickness of a forged piece is 12cm, the high alloy steel is heated to 20 ℃ above ac1, the temperature is specifically set to 820 ℃, the heating time is 3 hours, the temperature is kept for 6 hours, the high alloy steel is cooled to 10 ℃ below ar1 along with a furnace to perform isothermal treatment, specifically 780 ℃, the cooling time is 2 hours, the isothermal time is set to 10 hours, the high alloy steel is discharged from the furnace and subjected to air cooling along with the furnace cooling to 500 ℃ after isothermal treatment, and the cooling time is 7 hours.
Example 2: a heat treatment process of high alloy steel comprises the following operation steps; the method comprises the following steps: cooling the forged piece, namely quickly cooling the forged piece after the forged piece is taken off the machine, directly putting the cooled piece into a sand pit, covering the cooled piece with heat-insulating cotton, and slowly cooling the cooled piece, wherein the pit entering temperature is set to be 640 ℃; removing the heat preservation cotton after the forging is cooled to the room temperature; step two: preheating before spheroidizing annealing, preheating the spheroidizing annealing furnace, setting the preheating temperature to be lower than the spheroidizing temperature of 260 ℃, and keeping the temperature for 4 hours; step three: spheroidizing annealing, wherein the thickness of the forged piece is 20cm, heating the high alloy steel to 20 ℃ above ac1, preserving heat for 10 hours, cooling with the furnace to 20 ℃ below ar1 for isothermal temperature, setting the isothermal time to 15 hours, cooling with the furnace to 500 ℃ after isothermal temperature, and discharging and air cooling.
Example 3: a heat treatment process of high alloy steel comprises the following operation steps; the method comprises the following steps: cooling the forged piece, namely quickly cooling the forged piece after the forged piece is taken off the machine, directly putting the cooled piece into a sand pit, covering the forged piece with heat-insulating cotton, and slowly cooling the forged piece, wherein the pit-entering temperature is set to be 630 ℃; removing the heat preservation cotton after the forging is cooled to the room temperature; step two: preheating before spheroidizing annealing, preheating the spheroidizing annealing furnace, setting the preheating temperature to be lower than the spheroidizing temperature of 230 ℃, and keeping the temperature for 4 hours; step three: spheroidizing annealing, wherein the thickness of the forged piece is 20cm, heating the high alloy steel to a temperature of 25 ℃ above ac1, preserving heat for 10 hours, cooling with the furnace to a temperature of 20 ℃ below ar1 for isothermal temperature, setting the isothermal time to be 15 hours, cooling with the furnace to 500 ℃ after isothermal temperature, and discharging and air cooling.
The total time of heat treatment in the solution of the above example is about 38 hours, while the heat treatment process of the prior art takes about 54 hours; the cooling mode and the temperature in the embodiment enable the forging to be cooled more uniformly, the structure performance is more uniform, and the surface of the forging is effectively prevented from cracking; the preheating before spheroidization and the temperature setting in the spheroidization can achieve the aims of improving or eliminating various tissue defects caused by the high alloy steel in the forging process, refining grains, improving the distribution and the form of a second phase in the high alloy steel, eliminating internal stress, reducing hardness, improving tissues and facilitating cutting processing; the invention omits the normalizing step, and adds the preheating step before spheroidizing annealing, thereby not only saving the heat treatment time, improving the heat treatment efficiency and saving the energy consumption, but also achieving the product performance requirement and meeting the CN: 5.0 to 5.2; CZ: 6.0-6.2/7.0-7.2, and 100% nodularity.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the technical principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (5)
1. A heat treatment process of high alloy steel is characterized in that: comprises the following steps of;
the method comprises the following steps: cooling the forging, namely quickly cooling the forging after the forging is taken off the machine, directly placing the cooling line into a sand pit, covering the sand pit with heat preservation cotton, slowly cooling the sand pit, setting the pit entry temperature to be 610-640 ℃, and removing the heat preservation cotton after the forging is cooled to the room temperature;
step two: preheating before spheroidizing annealing, preheating the spheroidizing annealing furnace, setting the preheating temperature to be lower than the spheroidizing temperature of 220-260 ℃, and preserving heat for 3-4 hours;
step three: spheroidizing annealing, namely heating the high alloy steel to 20-30 ℃ above ac1, preserving heat for a certain time, cooling the high alloy steel with a furnace to 10-20 ℃ below ar1 for isothermal, setting the isothermal time to be 1.5 times of the heat preservation time, and cooling the high alloy steel with the furnace to 500 ℃ after isothermal, and discharging the high alloy steel from the furnace for air cooling.
2. The heat treatment process for high alloy steel according to claim 1, characterized in that: the temperature of the forged piece entering the pit after the rapid cooling in the first step is set to be 610-640 ℃.
3. The heat treatment process for high alloy steel according to claim 1, characterized in that: the preheating temperature in the second step is set to be 230 ℃ lower than the spheroidizing temperature.
4. The heat treatment process of high alloy steel according to claim 1, characterized in that: the heating temperature of the high alloy steel in the third step is set to be 25 ℃ above the ac1 temperature, and the isothermal temperature is set to be 15 ℃ below the ar1 temperature.
5. The heat treatment process of high alloy steel according to claim 1, characterized in that: and in the third step, the heat preservation time is set to be 0.5-1 hour for the forge piece with the thickness of each centimeter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210427673.XA CN114990295A (en) | 2022-04-22 | 2022-04-22 | Heat treatment process of high alloy steel |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210427673.XA CN114990295A (en) | 2022-04-22 | 2022-04-22 | Heat treatment process of high alloy steel |
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| CN114990295A true CN114990295A (en) | 2022-09-02 |
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| CN202210427673.XA Withdrawn CN114990295A (en) | 2022-04-22 | 2022-04-22 | Heat treatment process of high alloy steel |
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2022
- 2022-04-22 CN CN202210427673.XA patent/CN114990295A/en not_active Withdrawn
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