CN108368560B - High-nitrogen stainless steel and heat treatment process thereof - Google Patents
High-nitrogen stainless steel and heat treatment process thereof Download PDFInfo
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- CN108368560B CN108368560B CN201680072346.XA CN201680072346A CN108368560B CN 108368560 B CN108368560 B CN 108368560B CN 201680072346 A CN201680072346 A CN 201680072346A CN 108368560 B CN108368560 B CN 108368560B
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- 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
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Abstract
A heat treatment process of high-nitrogen stainless steel comprises the following steps: placing a high-nitrogen stainless steel sample to be treated in continuous heat treatment equipment, and enabling the sample to sequentially pass through the following different temperature regions of the equipment: a temperature raising preheating zone: under the atmosphere of nitrogen and hydrogen, heating from room temperature to 700-950 ℃ at a first heating rate, and then preserving heat for 5-15 min; a high-temperature heat preservation area: under the atmosphere of nitrogen and hydrogen, continuously heating to 1000-1250 ℃ at a second heating rate, and then preserving heat for 10-40 min; cooling the temperature zone: cooling to 200-300 ℃ by adopting cooling gas; a cooling area: and cooling the stainless steel to room temperature in an air atmosphere to obtain the high-nitrogen stainless steel product.
Description
Technical Field
The embodiment of the invention relates to the technical field of high-nitrogen stainless steel preparation, in particular to high-nitrogen stainless steel and a heat treatment process thereof.
Background
The high-nitrogen stainless steel is stainless steel with high affinity with human body (nickel element is not contained in the high-nitrogen stainless steel, nickel allergy is not caused), and the nitrogen content is 0.75-0.9%. The stainless steel has high strength and non-magnetic properties, and is suitable for use in the appearance of structural parts of consumer goods, such as watchcases, jewelry, etc. Especially, the powder sintered high-nitrogen stainless steel can be formed into a component with a complex shape, and has wide application prospect.
The conventional process for powder sintering high nitrogen stainless steel comprises two steps of sintering and heat treatment: firstly, filling alloy powder without nitrogen (N) element into a mold, providing nitrogen atmosphere during sintering, and infiltrating the N element into the powder and sintering and molding; during subsequent heat treatment, the N element is uniformly dissolved in tetrahedral gaps of iron (Fe) through high-temperature treatment, and finally, the steel is rapidly cooled, so that the N element is dissolved in the lattice gaps of the Fe in a solid mode, and the mechanical property of the stainless steel is effectively improved.
The existing heat treatment process of the high-nitrogen stainless steel comprises the following steps: heating to 1175-1250 ℃ in nitrogen atmosphere, keeping the temperature for 10min, then performing water quenching and cooling, wherein the cooling speed is required to be more than 150 ℃/min when the temperature is reduced from 1000 ℃ to 650 ℃ in the water quenching and cooling process. The existing heat treatment process needs heat treatment equipment which has the characteristics of high temperature, atmosphere filling and rapid cooling, and the equipment is expensive. And the existing heat treatment process has long time, and one furnace is about 7 hours. This results in high cost and low efficiency (500 standard parts/hour) for producing high nitrogen stainless steel.
Disclosure of Invention
The embodiment of the invention provides a high-nitrogen stainless steel heat treatment process and high-nitrogen stainless steel, which are low in cost and high in efficiency.
In a first aspect, an embodiment of the present invention provides a heat treatment process for a high-nitrogen stainless steel, including:
placing a high-nitrogen stainless steel sample to be treated in continuous heat treatment equipment, and enabling the high-nitrogen stainless steel sample to sequentially pass through a heating preheating zone, a high-temperature heat preservation zone, a cooling zone and a cooling zone of the continuous heat treatment equipment; in the continuous heat treatment equipment, the high-nitrogen stainless steel sample is subjected to the following heat treatment:
in the temperature-rising preheating zone, under the atmosphere of nitrogen and hydrogen, the temperature is raised from room temperature to 700-950 ℃ at a first temperature-rising rate, and then the temperature is kept for 5-15 min;
in the high-temperature heat preservation area, under the atmosphere of nitrogen and hydrogen, the temperature is continuously raised to 1000-1250 ℃ at a second temperature raising rate, and then the temperature is preserved for 10-40 min;
cooling to 200-300 ℃ in the cooling zone by adopting cooling gas;
and in the cooling zone, cooling to room temperature by using an air atmosphere to obtain the heat-treated high-nitrogen stainless steel.
Wherein the continuous heat treatment equipment is a mesh belt furnace.
In the temperature-raising preheating zone, the first temperature-raising rate is 60-90 deg.C/min, 70-80 deg.C/min, or 65-75 deg.C/min. Optionally, the temperature is increased from room temperature to 800-900 ℃ or 750-850 ℃ at a first temperature increasing rate, and optionally, the heat preservation time is 8-12 min.
In the stage of heating and preheating, the internal structure of the stainless steel sample can be effectively protected by controlling a proper heating rate, and the crystal grains are controlled not to grow; and atoms can be effectively activated by controlling reasonable heat preservation temperature and heat preservation time, and the solid solution effect of N atoms is improved.
In the high-temperature heat preservation area, the second temperature rise rate is 15-25 ℃/min, 20-24 ℃/min, or 18-22 ℃/min. A suitable second ramp rate ensures that the grain size does not grow while further activating atoms. Optionally, the temperature is increased from the room temperature to 1100-1200 ℃ or 1000-1150 ℃ at a first temperature increasing rate, and optionally, the heat preservation time is 20min-30min or 10min-15 min.
In the temperature-raising preheating zone and the high-temperature heat-preserving zone, the volume ratio of the nitrogen to the hydrogen is 2:1-5:1 or 3:1-4: 1.
In the cooling zone, the cooling gas is ammonia gas or nitrogen gas, and the cooling speed is 70-130 ℃/min or 100-130 ℃/min.
The high-nitrogen stainless steel sample to be processed is conveyed into the continuous heat treatment equipment by using a conveying device and sequentially passes through a heating preheating area, a high-temperature heat preservation area, a cooling area and a cooling area of the continuous heat treatment equipment. And the high-nitrogen stainless steel sample to be treated moves and is transmitted at the speed of 2-20cm/min and sequentially passes through a heating preheating zone, a high-temperature heat preservation zone, a cooling zone and a cooling zone of the continuous heat treatment equipment.
The length dimension of each different temperature region of the continuous heat treatment device in the sample conveying direction is 1-2 m.
The high-nitrogen stainless steel sample to be treated is arranged on the conveying device in a single layer.
The heat treatment process of the high-nitrogen stainless steel provided by the first aspect of the invention is completed by adopting simple continuous heat treatment equipment, has low cost, high efficiency and good solid solution effect, and is beneficial to realizing the mass production application of the high-nitrogen stainless steel.
In a second aspect, the embodiment of the invention provides the high-nitrogen stainless steel prepared by the process, and the high-nitrogen stainless steel product has high solid solubility, high hardness, high strength and excellent mechanical properties.
Drawings
FIG. 1 is a schematic view showing the structure of a continuous heat treatment apparatus according to an embodiment of the present invention;
FIG. 2 is a metallographic structure diagram of a high nitrogen stainless steel according to example 1 of the present invention before heat treatment;
FIG. 3 is a metallographic structure diagram of a high nitrogen stainless steel after heat treatment in example 1 of the present invention.
Detailed Description
The embodiment of the invention provides a high-nitrogen stainless steel heat treatment process which is completed by simple continuous heat treatment equipment and has low cost and high efficiency.
Specifically, the embodiment of the invention provides a heat treatment process of a high-nitrogen stainless steel, which comprises the following steps:
placing a high-nitrogen stainless steel sample to be treated in continuous heat treatment equipment, wherein the high-nitrogen stainless steel sample sequentially passes through a heating preheating zone, a high-temperature heat preservation zone, a cooling zone and a cooling zone of the continuous heat treatment equipment; in the continuous heat treatment equipment, the high-nitrogen stainless steel sample is subjected to the following heat treatment:
in the temperature-rising preheating zone, under the atmosphere of nitrogen and hydrogen, the temperature is raised from room temperature to 700-950 ℃ at a first temperature-rising rate, and then the temperature is kept for 5-15 min;
in the high-temperature heat preservation area, under the atmosphere of nitrogen and hydrogen, the temperature is continuously raised to 1000-1250 ℃ at a second temperature raising rate, and then the temperature is preserved for 10-40 min;
cooling to 200-300 ℃ in the cooling zone by adopting cooling gas;
and in the cooling zone, cooling to room temperature by using an air atmosphere to obtain the heat-treated high-nitrogen stainless steel.
Fig. 1 is a schematic structural view of a continuous heat treatment apparatus used in an embodiment of the present invention. The continuous heat treatment equipment comprises 4 continuously arranged boxes, wherein the 4 boxes are respectively corresponding to different temperature areas: a temperature-raising preheating zone 101, a high-temperature heat-preserving zone 102, a temperature-lowering zone 103 and a cooling zone 104. Wherein the temperature-raising preheating zone 101, the high-temperature holding zone 102 and the temperature-lowering zone 103 have different temperature points in the sample conveyance direction. In the heat treatment process, a high-nitrogen stainless steel sample to be treated sequentially passes through a heating and preheating zone 101, a high-temperature heat preservation zone 102, a cooling zone 103 and a cooling zone 104 of the equipment. The heat treatment process of the embodiment of the invention is completed by adopting the simple continuous heat treatment equipment, so that the equipment cost is greatly reduced. In the whole heat treatment process, the high-nitrogen stainless steel sample continuously passes through 4 different temperature areas of a heating preheating area 101, a high-temperature heat preservation area 102, a cooling area 103 and a cooling area 104 of the equipment in sequence. Therefore, compared with the existing heat treatment process, the process does not need to be subjected to the long temperature rising and reducing processes from room temperature to high temperature (1175-1250 ℃) in one furnace body, and then from the high temperature to the room temperature, so that the process time is greatly shortened. Moreover, the heat treatment process of the embodiment can also be used for continuous production, the production efficiency can reach 3000 standard parts per hour, which is 6 times of the production efficiency of the existing heat treatment process, and the production efficiency of the high-nitrogen stainless steel is effectively improved.
In the embodiment of the present invention, the continuous heat treatment apparatus may be, but is not limited to, a mesh belt furnace, as long as the continuous heat treatment of different temperature zones can be realized. Compared with the vacuum atmosphere furnace used in the existing high-nitrogen stainless steel heat treatment process, the mesh belt furnace has low equipment cost (10-30 ten thousand RMB) which is only 1/7-1/10 of the price of the vacuum atmosphere furnace, thereby effectively reducing the mass production threshold of the high-nitrogen stainless steel.
In an embodiment of the present invention, the stainless steel sample to be processed is sent into the continuous heat treatment apparatus by using a conveyor, and sequentially passes through different temperature regions of the continuous heat treatment apparatus. Wherein, the conveying device can be a conveying mesh belt or a flat plate.
In the temperature-raising preheating zone 101, the temperature is raised from room temperature to 700 ℃ to 950 ℃ at a first temperature-raising rate (for example, 700 ℃, 770 ℃, 830 ℃, 900 ℃, 950 ℃), and then the temperature is maintained for 5min to 15min (for example, 5min, 7min, 11min, 15 min). The atoms can be effectively activated by heat preservation in the heating preheating zone, and the solid solution effect of the N atoms is improved. In the embodiment of the invention, both the temperature rise efficiency and the internal stress of the stainless steel sample are taken into consideration, and the first temperature rise rate can be set to be 60 ℃/min-90 ℃/min (for example, 60 ℃/min, 65 ℃/min, 70 ℃/min, 75 ℃/min, 80 ℃/min, 90 ℃/min).
In the embodiment of the present invention, in the high temperature holding section 102, the temperature is further raised from 700 ℃ to 950 ℃ to 1000 ℃ to 1250 ℃ (for example, 1000 ℃, 1050 ℃, 1090 ℃, 1120 ℃, 1150 ℃, 1180 ℃, 1200 ℃, 1250 ℃) at a second temperature raising rate, and then held for 10min to 40min (for example, 10min, 15min, 25min, 35min, 40 min). A suitable second ramp rate ensures that the grain size does not grow while further activating atoms. In the embodiment of the present invention, the second temperature increase rate may be 15 ℃/min to 25 ℃/min (for example, 15 ℃/min, 18 ℃/min, 20 ℃/min, 24 ℃/min, 25 ℃/min).
Specifically, the control process of the temperature rise may be, for example: the inside of the temperature-raising preheating zone 101 has different temperature points which gradually rise along the sample conveying direction, for example, to the position A in FIG. 1, the temperature reaches up to 720 ℃, if the outside room temperature is 20 ℃, that is, the sample temperature is 20 ℃, and the temperature-raising rate is assumed to be 70 ℃/min, then the stainless steel sample passes through 10min from the conveying device to the position A with the temperature of 720 ℃ on the conveying device, then the stainless steel sample is conveyed away from the temperature-raising preheating zone 101 by the conveying device at the temperature of 720 ℃ for 5min to 15min from the position A and enters the high-temperature heat preservation zone 102, that is, the temperature of the zone section from the position A to the sample outlet of the temperature-raising preheating zone 101 along the sample conveying direction is 720 ℃. Similarly, the inside of the high temperature holding section 102 has different temperature points which gradually rise along the sample conveying direction, for example, to the position B in FIG. 1, the temperature reaches the maximum of 1020 ℃, and assuming that the temperature rising rate is 15 ℃/min, the stainless steel sample enters the high temperature holding section 102 at 720 ℃, passes through 20min to the position B, is conveyed away from the high temperature holding section 102 by the conveying device at 1020 ℃ for 10min to 40min, and enters the cooling section 103, namely, the temperature of the section from the position B to the sample outlet of the high temperature holding section 102 along the sample conveying direction is 1020 ℃.
In the embodiment of the present invention, the temperature-raising preheating zone 101 and the high-temperature heat-preserving zone 102 both use nitrogen and hydrogen atmospheres. The hydrogen has reducibility, and can remove impurity atoms on the surface layer of the high-nitrogen stainless steel sample, reduce surface brittleness and effectively improve the performance of the surface layer. The nitrogen can prevent nitrogen atoms on the surface of the high-nitrogen stainless steel from volatilizing, so that the reduction of the surface hardness of the high-nitrogen stainless steel caused by the volatilization of the nitrogen atoms is avoided.
In an embodiment of the present invention, the volume ratio of nitrogen to hydrogen is 2:1 to 5:1 (for example, 2:1, 3:1, 4:1, 5: 1). The suitable nitrogen-hydrogen volume ratio can effectively prevent the surface nitrogen atoms from volatilizing, avoid the surface from forming brittle phases and improve the surface performance of the high-nitrogen stainless steel.
In the embodiment of the invention, the cooling gas in the cooling zone 103 may be ammonia gas or nitrogen gas, and the cooling rate may be 70 ℃/min to 130 ℃/min (for example, 70 ℃/min, 90 ℃/min, 110 ℃/min, 120 ℃/min, 130 ℃/min).
Specifically, the control process of the temperature reduction may be, for example: the inside of the cooling zone 103 has different temperature points gradually decreasing along the sample conveying direction, and assuming that the temperature at the sample inlet is 1020 ℃, the temperature at the sample outlet is 220 ℃, and the cooling rate is 100 ℃/min, the stainless steel sample enters the cooling zone 103 at 1020 ℃ to be cooled to 220 ℃ after 8min, and then is carried away from the cooling zone 103 by the conveying device to enter the cooling zone 104.
In the embodiment of the present invention, the length dimension of each of the different temperature regions of the continuous heat treatment apparatus in the sample transport direction is generally 1m to 2m (e.g., 1m, 1.2m, 1.5m, 1.8m, 2 m). Specifically, the continuous heat treatment equipment comprises four box bodies which respectively correspond to a heating preheating area, a high-temperature heat preservation area, a cooling area and a cooling area, and the length of each box body in the sample conveying direction is 1-2 m.
In the embodiment of the invention, the specific heating rate and the heat preservation time are determined by the transmission rate of the mesh belt and the length of the box body of each temperature area of the equipment. Therefore, in actual operation, the conveying speed of the conveyor can be set appropriately according to the length of the housing in each temperature region, and the desired temperature rise rate, holding time, or cooling rate. In the embodiment of the invention, optionally, the conveying device moves and transmits at the speed of 2cm/min-20 cm/min. Namely, the high-nitrogen stainless steel sample to be processed is transferred at the speed of 2-20cm/min (such as 2cm/min, 5cm/min, 10cm/min, 15cm/min and 20cm/min) in a moving way and sequentially passes through a temperature-raising preheating zone, a high-temperature heat-preserving zone, a temperature-lowering zone and a cooling zone of continuous heat treatment equipment.
In an embodiment of the invention, the stainless steel sample to be treated is laid on the conveyor in a single layer. The laminated arrangement of the samples can affect the temperature uniformity of the product and the heat treatment effect.
In the embodiment of the invention, the high-nitrogen stainless steel sample to be treated is sintered high-nitrogen stainless steel; the nitrogen distribution in the sintered high-nitrogen stainless steel is not uniform, and the nitrogen distribution can be uniform through heat treatment, so that the performance of the stainless steel is improved.
The heat treatment process of the high-nitrogen stainless steel provided by the embodiment of the invention is completed by adopting simple continuous heat treatment equipment, has low cost, high efficiency and good solid solution effect, and is beneficial to realizing the mass production application of the high-nitrogen stainless steel.
Correspondingly, the embodiment of the invention also provides the high-nitrogen stainless steel prepared by the process, and the high-nitrogen stainless steel product has high solid solubility, high hardness, high strength and excellent mechanical property.
The following examples are intended to illustrate the invention in more detail. The embodiments of the present invention are not limited to the following specific embodiments.
Example 1
A heat treatment process of high-nitrogen stainless steel comprises the following steps:
conveying the high-nitrogen stainless steel sample to be treated into a mesh belt furnace by using a conveying mesh belt, and conveying the sample by using the conveying mesh belt to move at a speed of 5cm/min so that the sample sequentially passes through the following different temperature regions of the equipment:
a temperature raising preheating zone: heating to 770 ℃ from room temperature at a rate of 70 ℃/min under the atmosphere of nitrogen and hydrogen with the volume ratio of 3:1, and then preserving heat for 15 min;
a high-temperature heat preservation area: under the atmosphere of nitrogen and hydrogen with the volume ratio of 3:1, continuously heating to 1200 ℃ at the speed of 20 ℃/min, and then preserving heat for 20 min;
cooling the temperature zone: cooling to 200 ℃ by adopting ammonia gas, wherein the cooling rate is 90 ℃/min;
a cooling area: and cooling the stainless steel to room temperature in an air atmosphere to obtain the high-nitrogen stainless steel product.
Example 2
A heat treatment process of high-nitrogen stainless steel comprises the following steps:
conveying the high-nitrogen stainless steel sample to be treated into a mesh belt furnace by using a conveying mesh belt, and conveying the sample by using the conveying mesh belt to move at the speed of 10cm/min so that the sample sequentially passes through the following different temperature regions of the equipment:
a temperature raising preheating zone: under the atmosphere of nitrogen and hydrogen with the volume ratio of 4:1, raising the temperature from room temperature to 850 ℃ at the speed of 90 ℃/min, and then preserving the temperature for 10 min;
a high-temperature heat preservation area: under the atmosphere of nitrogen and hydrogen with the volume ratio of 4:1, continuously heating to 1000 ℃ at the speed of 15 ℃/min, and then preserving heat for 40 min;
cooling the temperature zone: cooling to 300 ℃ by adopting ammonia gas, wherein the cooling rate is 130 ℃/min;
a cooling area: and cooling the stainless steel to room temperature in an air atmosphere to obtain the high-nitrogen stainless steel product.
Example 3
A heat treatment process of high-nitrogen stainless steel comprises the following steps:
conveying the high-nitrogen stainless steel sample to be treated into a mesh belt furnace by using a conveying mesh belt, and conveying the sample by using the conveying mesh belt to move at a speed of 15cm/min so that the sample sequentially passes through the following different temperature regions of the equipment:
a temperature raising preheating zone: under the atmosphere of nitrogen and hydrogen with the volume ratio of 5:1, raising the temperature from room temperature to 900 ℃ at the speed of 80 ℃/min, and then preserving the temperature for 5 min;
a high-temperature heat preservation area: under the atmosphere of nitrogen and hydrogen with the volume ratio of 5:1, continuously heating to 1250 ℃ at the speed of 25 ℃/min, and then preserving heat for 10 min;
cooling the temperature zone: cooling to 200 ℃ by adopting ammonia gas, wherein the cooling rate is 100 ℃/min;
a cooling area: and cooling the stainless steel to room temperature in an air atmosphere to obtain the high-nitrogen stainless steel product.
Example 4
A heat treatment process of high-nitrogen stainless steel comprises the following steps:
conveying the high-nitrogen stainless steel sample to be treated into a mesh belt furnace by using a conveying mesh belt, and conveying the sample by using the conveying mesh belt to move at the speed of 10cm/min so that the sample sequentially passes through the following different temperature regions of the equipment:
a temperature raising preheating zone: under the atmosphere of nitrogen and hydrogen with the volume ratio of 2:1, raising the temperature from room temperature to 700 ℃ at the speed of 60 ℃/min, and then preserving the temperature for 15 min;
a high-temperature heat preservation area: under the atmosphere of nitrogen and hydrogen with the volume ratio of 2:1, continuously heating to 1100 ℃ at the speed of 20 ℃/min, and then preserving heat for 30 min;
cooling the temperature zone: cooling to 200 ℃ by adopting ammonia gas, wherein the cooling rate is 110 ℃/min;
a cooling area: and cooling the stainless steel to room temperature in an air atmosphere to obtain the high-nitrogen stainless steel product.
Effects of the embodiment
In order to strongly support the beneficial effects brought by the technical scheme of the embodiment of the invention, the following performance test results are provided:
FIGS. 2 and 3 are metallographic structures of a high nitrogen stainless steel of example 1 of the present invention before and after heat treatment, respectively, and it can be seen from these views that example 1 of the present invention was appliedCr in the matrix after heat treatment2N is greatly reduced, which indicates that nitrogen atoms are successfully dissolved in the crystal lattice of Fe in a solid solution manner, and the solid solution effect is achieved. Also, the high nitrogen stainless steel products of examples 2 to 4 of the present invention also obtained good solid solution effect.
Table 1 shows the comparison of the properties of the high nitrogen stainless steel obtained by the heat treatment process of example 1 of the present invention and the existing heat treatment process.
The existing heat treatment process comprises the following steps: heating to 1175-1250 ℃ in a vacuum atmosphere furnace in nitrogen atmosphere, preserving heat for 10min, then quenching with water, cooling to room temperature, and keeping the cooling speed more than 150 ℃/min when cooling to 650 ℃ at 1000 ℃.
TABLE 1 comparison of the Properties (typical values) of the high-Nitrogen stainless steels obtained by the two heat treatment processes
As can be seen from Table 1, the mechanical properties of the stainless steel treated by the two processes are basically consistent, and the high-nitrogen stainless steel products obtained in examples 2-4 have mechanical properties equivalent to those of the existing heat treatment processes through detection, which shows that the mechanical properties identical to those of the existing processes can be obtained by adopting the low-cost heat treatment process of the invention, the low-cost heat treatment process of the invention can replace the existing processes, overcome the problem that the high-nitrogen stainless steel material is difficult to realize low-cost mass production, and has wide commercial application prospect.
It should be noted that, according to the disclosure and the explanation of the above description, the person skilled in the art can make variations and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some equivalent modifications and variations of the present invention should be covered by the protection scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (18)
1. A heat treatment process of high-nitrogen stainless steel is characterized by comprising the following steps:
placing a high-nitrogen stainless steel sample to be treated in continuous heat treatment equipment, and enabling the high-nitrogen stainless steel sample to sequentially pass through a heating preheating zone, a high-temperature heat preservation zone, a cooling zone and a cooling zone of the continuous heat treatment equipment; in the continuous heat treatment equipment, the high-nitrogen stainless steel sample is subjected to the following heat treatment:
in the temperature-rising preheating zone, under the atmosphere of nitrogen and hydrogen with the volume ratio of 2:1-5:1, the temperature is raised from room temperature to 700-950 ℃ at a first temperature-rising rate, and then the temperature is kept for 5-15 min;
in the high-temperature heat preservation area, under the atmosphere of nitrogen and hydrogen with the volume ratio of 2:1-5:1, the temperature is continuously raised to 1000-1250 ℃ at a second temperature raising rate, and then the temperature is preserved for 10-40 min;
cooling to 200-300 ℃ in the cooling zone by adopting cooling gas;
and in the cooling zone, cooling to room temperature by using an air atmosphere to obtain the heat-treated high-nitrogen stainless steel.
2. The heat treatment process for a high nitrogen stainless steel according to claim 1, wherein said continuous heat treatment apparatus is a mesh belt furnace.
3. The heat treatment process for a high-nitrogen stainless steel according to claim 1 or 2, wherein the first temperature increase rate is 60 ℃/min to 90 ℃/min.
4. The heat treatment process for a high-nitrogen stainless steel according to claim 3, wherein the first temperature increase rate is 70 ℃/min to 80 ℃/min.
5. The heat treatment process for a high-nitrogen stainless steel according to claim 1 or 2, wherein the second temperature increase rate is 15 ℃/min to 25 ℃/min.
6. The heat treatment process for a high-nitrogen stainless steel according to claim 5, wherein the second temperature increase rate is 20 ℃/min to 24 ℃/min.
7. The heat treatment process for a high-nitrogen stainless steel according to claim 1, wherein in the temperature-increasing preheating zone, the temperature is increased from room temperature to 800 ℃ to 900 ℃ at the first temperature-increasing rate.
8. The process for heat treating a high-nitrogen stainless steel according to claim 1, wherein the temperature is further raised to 1100 ℃ to 1200 ℃ at the second temperature raising rate in the high-temperature soak zone.
9. The heat treatment process for a high-nitrogen stainless steel according to claim 1, wherein the holding time in the temperature-increasing preheating zone is 8min to 12 min.
10. The heat treatment process for a high-nitrogen stainless steel according to claim 1, wherein the holding time in the high-temperature holding zone is 20min to 30 min.
11. The heat treatment process for a high-nitrogen stainless steel according to claim 1, wherein the volume ratio of the nitrogen gas to the hydrogen gas is 3:1 to 4: 1.
12. The heat treatment process for a high-nitrogen stainless steel according to claim 1, wherein the cooling gas in the cooling zone is ammonia gas or nitrogen gas.
13. The heat treatment process for a high-nitrogen stainless steel according to claim 1, wherein the cooling rate of the cooling zone is 70 ℃/min to 130 ℃/min.
14. The heat treatment process for a high-nitrogen stainless steel according to claim 1 or 2, wherein the sample of the high-nitrogen stainless steel to be treated is fed into the continuous heat treatment apparatus by a conveyor and passes through the temperature-raising and preheating zone, the high-temperature holding zone, the temperature-lowering zone and the cooling zone of the continuous heat treatment apparatus in this order.
15. The heat treatment process of the high-nitrogen stainless steel according to claim 1, wherein the sample of the high-nitrogen stainless steel to be treated is transported at a speed of 2cm/min to 20cm/min, sequentially passing through the temperature-raising and preheating zone, the high-temperature holding zone, the temperature-lowering zone and the cooling zone of the continuous heat treatment apparatus.
16. The heat treatment process for a high-nitrogen stainless steel according to claim 1, wherein each of the different temperature regions of the continuous heat treatment apparatus has a length dimension of 1m to 2m in the sample conveyance direction.
17. The process for heat-treating a high-nitrogen stainless steel according to claim 14, wherein the sample of high-nitrogen stainless steel to be treated is laid on the conveyor in a single layer.
18. A high nitrogen stainless steel produced by the process of any one of claims 1 to 17.
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| JP3588826B2 (en) * | 1994-09-20 | 2004-11-17 | 住友金属工業株式会社 | Heat treatment method for high nitrogen containing stainless steel |
| CN1186471C (en) * | 2002-09-03 | 2005-01-26 | 中国科学院金属研究所 | Ultrapurification high nitrogen austenitic stainless steel and its preparation method |
| JP4379804B2 (en) * | 2004-08-13 | 2009-12-09 | 大同特殊鋼株式会社 | High nitrogen austenitic stainless steel |
| CN102787277A (en) * | 2011-05-18 | 2012-11-21 | 中国科学院金属研究所 | Medical nickel-free high-nitrogen austenite antimicrobial stainless steel, its preparation and its application |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103088283A (en) * | 2013-01-06 | 2013-05-08 | 燕山大学 | Sectional type pressurizing solid solution nitriding accelerating method of austenitic stainless steel |
| CN105624376A (en) * | 2015-06-24 | 2016-06-01 | 长春实越节能材料有限公司 | Toughening-strengthening heat treatment method of high nitrogen austenitic stainless steel |
Non-Patent Citations (1)
| Title |
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| "超级奥氏体不锈钢654SMO组织性能研究";浦恩祥;《中国优秀硕士学位论文全文数据库（电子期刊）·工程科技Ⅰ辑》;20141130;正文第18、39和40页 * |
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| WO2018032406A1 (en) | 2018-02-22 |
| CN108368560A (en) | 2018-08-03 |
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