Vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material and application of vacuum sub-temperature gas quenching heat treatment process

Abstract

The invention discloses a vacuum sub-temperature gas quenching heat treatment process of an X12Cr13 material, which comprises the following steps: isothermal annealing treatment: carrying out heat preservation for an effective thickness of mm / (33-40) mm for hours at a temperature of 930-990 DEG C, then carrying out heat preservation for an effective thickness of mm / (33-40) mm for hours when a furnace is cooled to 740-780 DEG C, and finally carrying out furnace cooling, discharging and air cooling; vacuum sub-temperature gas quenching treatment is conducted, specifically, vacuumizing is conducted till the vacuum degree is smaller than or equal to 1.33 * 10 <-3 > Pa, the temperature is increased to 900-950 DEG C, heat preservation is conducted, the heat preservation time is effective thickness mm / (33-40) mm h, then nitrogen is injected into the furnace for cooling, and finally the steel is taken out of the furnace for air cooling; and tempering treatment is conducted, specifically, vacuumizing is conducted till the vacuum degree is smaller than or equal to 1.33 * 10 <-3 > Pa, the temperature is increased to 680-730 DEG C, heat preservation is conducted, the heat preservation time is effective thickness mm / (18-20) mm hours, then nitrogen is injected into the furnace for cooling, and finally the steel is taken out of the furnace for air cooling. The heat treatment process is used for heat treatment of the compressor impeller X12Cr13 material, the hardenability and the mechanical property of the impeller are guaranteed, and the heat treatment deformation of the impeller is reduced.

Description

Technical Field

[0001] The invention belongs to the field of heat treatment technology, and specifically relates to a vacuum sub-temperature gas quenching heat treatment process and application of X12Cr13 material. Background Art

[0002] X12Cr13 material is a martensitic stainless steel with good hardenability and corrosion resistance. It is widely used in turbine machinery impellers, partitions and other important parts that bear large impact loads. Since the impeller is a high-speed rotating part with complex blade shape, conventional oil quenching is prone to deformation, which seriously affects product quality and unit efficiency.

[0003] In order to strictly control the impeller heat treatment deformation and improve the comprehensive mechanical properties of X12Cr13 material, it is very important to develop a heat treatment process for X12Cr13 material. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a vacuum sub-temperature gas quenching heat treatment process for X12Cr13 material, and to use it for the heat treatment of the impeller of the compressor X12Cr13 material, to strictly control the impeller heat treatment deformation and improve the comprehensive mechanical properties, thereby improving the working efficiency and operation stability of the turbine unit.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A first aspect of the present invention provides a vacuum sub-temperature gas quenching heat treatment process for X12Cr13 material, comprising:

[0007] Isothermal annealing treatment, wherein the isothermal annealing treatment is carried out at a temperature of 930-990°C for an effective thickness of mm / (33-40) mm hours, then furnace-cooled to 740-780°C for an effective thickness of mm / (33-40) mm hours, and finally furnace-cooled and air-cooled after being taken out of the furnace;

[0008] Vacuum sub-temperature gas quenching treatment, wherein the vacuum sub-temperature gas quenching treatment is to evacuate to a vacuum degree of ≤1.33×10 -3 Pa, heat up to 900-950℃ and keep warm for effective thickness mm / (33-40)mm hour, then flush nitrogen into the furnace for cooling, and finally take it out of the furnace for air cooling;

[0009] Tempering treatment, wherein the tempering treatment is to evacuate to a vacuum degree of ≤1.33×10 -3 Pa, heat up to 680-730℃ and keep warm for effective thickness mm / (18-20)mm hours, then flush nitrogen into the furnace for cooling, and finally take it out of the furnace for air cooling.

[0010] Furthermore, the isothermal annealing treatment has a heating rate of 70 to 100° C. / h.

[0011] Furthermore, in the isothermal annealing treatment, the product is finally cooled in the furnace and then air-cooled, and the furnace cooling is controlled to 200-300° C. before being air-cooled.

[0012] Furthermore, the vacuum sub-temperature gas quenching treatment has a heating rate of 0.5 to 1.5°C / min.

[0013] Furthermore, in the vacuum sub-temperature gas quenching treatment, nitrogen gas is injected into the furnace for cooling, and the nitrogen pressure is controlled to be 4-6 bar.

[0014] Furthermore, the vacuum sub-temperature gas quenching treatment requires that nitrogen gas be injected into the furnace to cool the product to no higher than 50° C. before the product is taken out of the furnace and air-cooled.

[0015] Furthermore, the tempering treatment has a heating rate of 0.5 to 1.5°C / min.

[0016] Furthermore, during the tempering treatment, nitrogen gas is injected into the furnace for cooling, and the nitrogen pressure is controlled to be 1.5-2.5 bar.

[0017] Furthermore, the tempering treatment requires that nitrogen is injected into the furnace to cool the steel to a temperature not higher than 50° C., and then the steel is air-cooled after being taken out of the furnace.

[0018] The second aspect of the present invention provides an application of the vacuum sub-temperature gas quenching heat treatment process of the above-mentioned X12Cr13 material for heat treatment of the impeller of the compressor X12Cr13 material.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] The vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material provided by the present invention reduces the heat treatment deformation of X12Cr13 material under the premise of ensuring the hardenability and mechanical properties of X12Cr13 material, and meets the drawing accuracy and subsequent mechanical processing requirements. The vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material provided by the present invention can be used not only for high-speed rotating body parts such as turbine machine impellers made of X12Cr13 material, but also for heat treatment of other parts made of X12Cr13 material. DETAILED DESCRIPTION

[0021] In order to better understand the above-mentioned technical scheme, the technical scheme of the embodiment of the present application is described in detail through specific embodiments below. It should be understood that the embodiment of the present application and the specific features in the embodiment are detailed descriptions of the technical scheme of the embodiment of the present application, rather than limitations on the technical scheme of the present application. In the absence of conflict, the embodiment of the present application and the technical features in the embodiment can be combined with each other.

[0022] A first aspect of an embodiment of the present invention provides a vacuum sub-temperature gas quenching heat treatment process for X12Cr13 material, comprising:

[0023] Isothermal annealing treatment, wherein the isothermal annealing treatment is carried out at a temperature of 930-990°C for an effective thickness of mm / (33-40) mm hours, then furnace-cooled to 740-780°C for an effective thickness of mm / (33-40) mm hours, and finally furnace-cooled and air-cooled after being taken out of the furnace;

[0024] Vacuum sub-temperature gas quenching treatment, wherein the vacuum sub-temperature gas quenching treatment is to evacuate to a vacuum degree of ≤1.33×10 -3 Pa, heat up to 900-950℃ and keep warm for effective thickness mm / (33-40)mm hour, then flush nitrogen into the furnace for cooling, and finally take it out of the furnace for air cooling;

[0025] Tempering treatment, wherein the tempering treatment is to evacuate to a vacuum degree of ≤1.33×10 -3 Pa, heat up to 680-730℃ and keep warm for effective thickness mm / (18-20)mm hours, then flush nitrogen into the furnace for cooling, and finally take it out of the furnace for air cooling.

[0026] The vacuum sub-temperature gas quenching heat treatment process of the X12Cr13 material provided in the embodiment of the present invention reduces the heat treatment deformation of the X12Cr13 material while ensuring the hardenability and mechanical properties of the X12Cr13 material, thereby meeting the drawing accuracy and subsequent mechanical processing requirements.

[0027] Specifically, the chemical composition and weight percentage of X12Cr13 material are: C: 0.08-0.15%; Si: ≤1.0%; Mn: ≤1.0%; Cr: 11.5-13.5%; Ni: ≤0.60%%; S: ≤0.03%; P: ≤0.03%; the rest is Fe. The isothermal annealing process is heated in an electric furnace, but is not limited to an electric furnace; the vacuum sub-temperature gas quenching and tempering processes are heated in a vacuum furnace. For the isothermal annealing, vacuum sub-temperature gas quenching and tempering of X12Cr13 material, the X12Cr13 material reaches the corresponding insulation temperature by gradually increasing the temperature.

[0028] In some embodiments, the isothermal annealing treatment has a heating rate of 70 to 100° C. / h.

[0029] Specifically, controlling the heating rate to 70-100°C / h helps reduce the tendency of deformation and cracking during the heating process of the material, promotes sufficient organizational transformation, and maintains good mechanical properties.

[0030] In some embodiments, the isothermal annealing treatment is finally carried out by air cooling after furnace cooling, and the furnace cooling is controlled to 200-300° C. before air cooling.

[0031] Specifically, controlling the furnace cooling to 200-300° C. and then air cooling out of the furnace can obtain a nearly balanced structure, reduce hardness, facilitate processing, and eliminate internal stress.

[0032] In some embodiments, the vacuum sub-temperature gas quenching treatment has a heating rate of 0.5 to 1.5° C. / min.

[0033] Specifically, controlling the heating rate to 0.5-1.5°C / min helps reduce the tendency of deformation and cracking during the heating process of the material, promotes sufficient organizational transformation, and maintains good mechanical properties.

[0034] In some embodiments, during the vacuum sub-temperature gas quenching treatment, nitrogen gas is injected into the furnace for cooling, and the nitrogen pressure is controlled to be 4-6 bar.

[0035] Specifically, controlling the nitrogen pressure to 4-6 bar can ensure the gas quenching cooling effect while effectively controlling the production cost.

[0036] In some embodiments, the vacuum sub-temperature gas quenching treatment requires flushing nitrogen into the furnace to cool it to no higher than 50° C., and then air cooling it out of the furnace.

[0037] Specifically, the cooling by nitrogen injection to no higher than 50°C is controlled and then air-cooled after being taken out of the furnace, so as to ensure the stability and completeness of the microstructure transformation of the X12Cr13 material during tempering treatment, thereby maintaining good mechanical properties.

[0038] In some embodiments, the annealing treatment has a heating rate of 0.5 to 1.5° C. / min.

[0039] Specifically, controlling the heating rate to 0.5-1.5°C / min can help reduce the tendency of deformation and cracking during the heating process of the material, promote sufficient organizational transformation, and maintain good mechanical properties.

[0040] In some embodiments, during the tempering treatment, nitrogen is injected into the furnace for cooling, and the nitrogen pressure is controlled to be 1.5-2.5 bar.

[0041] In some embodiments, the tempering treatment requires that nitrogen gas is injected into the furnace to cool the temperature to no higher than 50° C., and then the furnace is taken out of the furnace and air-cooled.

[0042] Specifically, the cooling by nitrogen injection to no higher than 50°C is controlled and then air-cooled after being taken out of the furnace, so as to ensure the stability and completeness of the microstructure transformation of the X12Cr13 material during tempering treatment, thereby maintaining good mechanical properties.

[0043] A second aspect of an embodiment of the present invention provides an application of the vacuum sub-temperature gas quenching heat treatment process of the above-mentioned X12Cr13 material for heat treatment of an impeller of a compressor made of X12Cr13 material.

[0044] It can be understood that the vacuum sub-temperature gas quenching heat treatment process of the X12Cr13 material provided in the embodiment of the present invention can not only be used for high-speed rotating parts such as turbine machinery impellers made of X12Cr13 material, but is also suitable for the heat treatment of other parts made of X12Cr13 material.

[0045] Example 1 A vacuum sub-temperature gas quenching heat treatment process for X12Cr13 material

[0046] The chemical composition of the X12Cr13 material used in Example 1 is as follows: C: 0.11%; Si: 0.83%; Mn: 0.87%; Cr: 12.6%; Ni: 0.45%; S: 0.006%; P: 0.008%; the rest is Fe. A vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material, the effective thickness of the impeller is 40mm, comprising the following steps:

[0047] (1) Isothermal annealing: The isothermal annealing temperature is 930°C, the heating rate is 80°C / h, the holding time is 1h (calculated based on the holding time of 40÷(33-40) hours), then the furnace is cooled to 750°C for holding, the holding time is 1 hour, then the furnace is cooled to 220°C and air-cooled;

[0048] (2) Vacuum sub-temperature gas quenching treatment: First, evacuate the vacuum state to make the vacuum degree ≤1.33×10 -3 Pa, then heat up to 930℃ at a rate of 1℃ / min and keep warm for 1 hour, then flush nitrogen into the furnace to cool to 50℃ and air cool out of the furnace, the gas pressure of nitrogen cooling is 5bar;

[0049] (3) Tempering treatment: First, evacuate the furnace to a vacuum degree of ≤1.33×10-3Pa, then heat the furnace to 700℃ at a rate of 1℃ / min and keep the temperature for 2 hours. Then, nitrogen is injected into the furnace to cool the furnace to 50℃ and air-cool it. The gas pressure of nitrogen cooling is 2.5bar.

[0050] The mechanical properties and deformation results of the X12Cr13 material of Example 1 after vacuum sub-temperature gas quenching are shown in Table 1.

[0051] Example 2 A vacuum sub-temperature gas quenching heat treatment process for X12Cr13 material

[0052] The chemical composition of the X12Cr13 material used in Example 2 is as follows: C: 0.13%; Si: 0.85%; Mn: 0.77%; Cr: 13.0%; Ni: 0.48%; S: 0.006%; P: 0.008%; the rest is Fe. The process for vacuum sub-temperature gas quenching of the X12Cr13 material impeller of Example 2, the effective thickness of the impeller is 40 mm, comprises the following steps:

[0053] (1) Isothermal annealing: The isothermal annealing temperature is 950°C, the heating rate is 100°C / h, the holding time is 1.2 hours, and then the furnace is cooled to 780°C for holding, the holding time is 1.2 hours, and then the furnace is cooled to 220°C and air-cooled;

[0054] (2) Vacuum sub-temperature gas quenching treatment: First, evacuate the vacuum state to make the vacuum degree ≤1.33×10 -3 Pa, then heat up to 950℃ at a rate of 1℃ / min and keep warm for 1.2 hours, then flush nitrogen into the furnace to cool it to 50℃ out of the furnace and air-cool it, the gas pressure of nitrogen cooling is 5bar;

[0055] (3) Tempering treatment: First, evacuate the vacuum state to make the vacuum degree ≤1.33×10 -3 Pa, then heat up to 730℃ at a rate of 1℃ / min, keep warm for 2.2 hours, then flush nitrogen into the furnace to cool it to 50℃ out of the furnace and air cool it, the gas pressure of nitrogen cooling is 1.5bar;

[0056] The mechanical properties and deformation results of the X12Cr13 material of Example 2 after vacuum sub-temperature gas quenching are shown in Table 1.

[0057] Example 3 A vacuum sub-temperature gas quenching heat treatment process for X12Cr13 material

[0058] The chemical composition of the X12Cr13 material used in Example 3 is as follows: C: 0.13%; Si: 0.85%; Mn: 0.77%; Cr: 13.0%; Ni: 0.48%; S: 0.006%; P: 0.008%; the rest is Fe. The process method of vacuum sub-temperature gas quenching of the X12Cr13 material impeller of Example 3, the effective thickness of the impeller is 40mm, comprises the following steps:

[0059] (1) Isothermal annealing: The isothermal annealing temperature is 980°C, the heating rate is 100°C / h, the holding time is 1.1 hours, and then the furnace is cooled to 760°C for holding, the holding time is 1.1 hours, and then the furnace is cooled to 220°C and air-cooled;

[0060] (2) Vacuum sub-temperature gas quenching treatment: First, evacuate the vacuum state to make the vacuum degree ≤1.33×10 -3Pa, then heat up to 920℃ at a rate of 1℃ / min, keep warm for 1.1 hours, then flush nitrogen into the furnace to cool it to 50℃ out of the furnace and air cool it, the gas pressure of nitrogen cooling is 5bar;

[0061] (3) Tempering treatment: First, evacuate the vacuum state to make the vacuum degree ≤1.33×10 -3 Pa, then heat up to 680℃ at a rate of 1℃ / min, keep warm for 2.1 hours, then flush nitrogen into the furnace to cool it to 50℃ out of the furnace and air cool it, the gas pressure of nitrogen cooling is 1.5bar;

[0062] The mechanical properties and deformation results of the X12Cr13 material of Example 3 after vacuum sub-temperature gas quenching are shown in Table 1.

[0063] Comparative Example 1 Conventional heat treatment process of a X12Cr13 material

[0064] The chemical composition of the X12Cr13 material used in Comparative Example 1 is as follows: C: 0.11%; Si: 0.83%; Mn: 0.87%; Cr: 12.6%; Ni: 0.45%; S: 0.006%; P: 0.008%; the rest is Fe. The conventional heat treatment process of the X12Cr13 material in Comparative Example 1, with an effective thickness of 40 mm, includes the following steps:

[0065] (1) Normalizing treatment: The normalizing temperature is 850°C, the heating rate is 80°C / h, the holding time is 1 hour, and then air cooling;

[0066] (2) Quenching treatment: the quenching temperature is 1000°C, the heating rate is 80°C / h, the holding time is 1 hour, and then oil cooling;

[0067] (3) Tempering treatment: The tempering treatment temperature is 700°C, the heating rate is 60°C / h, the holding time is 2 hours, and then air cooling; the mechanical properties and deformation results of the X12Cr13 material of comparative example 1 after conventional heat treatment process are shown in Table 1.

[0068] Comparative Example 2 Conventional heat treatment process of a X12Cr13 material

[0069] The chemical composition of the X12Cr13 material used in Comparative Example 2 is as follows: C: 0.13%; Si: 0.85%; Mn: 0.77%; Cr: 13.0%; Ni: 0.48%; S: 0.006%; P: 0.008%; the rest is Fe. The conventional heat treatment process of the X12Cr13 material in Comparative Example 2, with an effective impeller thickness of 40 mm, includes the following steps:

[0070] (1) Normalizing treatment: The normalizing temperature is 880°C, the heating rate is 70°C / h, the holding time is 1.2 hours, and then air cooling;

[0071] (2) Quenching treatment: the quenching temperature is 1020°C, the heating rate is 70°C / h, the holding time is 1.2 hours, and then oil cooling;

[0072] (3) Tempering treatment: The tempering treatment temperature is 730°C, the heating rate is 50°C / h, the holding time is 2.2 hours, and then air cooling; the mechanical properties and deformation results of the X12Cr13 material of comparative example 2 after conventional heat treatment process are shown in Table 1.

[0073] Table 1 Mechanical properties and deformation of X12Cr13 materials after heat treatment process in the examples and comparative examples

[0074]

[0075] Results and Discussion

[0076] It can be seen from the values ​​in Table 1 above that, compared with the conventional heat treatment processes of Comparative Examples 1 and 2, the X12Cr13 material impeller can obtain good comprehensive mechanical properties after vacuum sub-temperature gas quenching. The vacuum sub-temperature gas quenching heating temperature is in the ferrite + austenite two-stage region. Ferrite can also hinder the initiation and expansion of cracks through its own plastic deformation, thereby improving toughness. The impact toughness value of the embodiment is greater than that of the comparative example.

[0077] In addition, since the X12Cr13 material of the embodiment adopts vacuum sub-temperature gas quenching, the heating temperature is lower than the quenching temperature of the comparative example, and the workpiece has a small tendency to deform due to thermal stress during quenching heating. The uniform cooling rate of vacuum sub-temperature gas quenching makes the impeller less deformed during heat treatment, meeting the requirements of the drawings and subsequent mechanical processing.

[0078] It is easy for a person skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed. The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application. The above are only preferred implementations of the present application. It should be pointed out that for a person skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present application, and these improvements and modifications should also be regarded as the protection scope of the present application.

Claims

1. A vacuum sub-temperature gas quenching heat treatment process for X12Cr13 material, characterized in that: include: Isothermal annealing treatment, wherein the isothermal annealing treatment is carried out at a temperature of 930-990°C for an effective thickness of mm / (33-40) mm hours, then furnace-cooled to 740-780°C for an effective thickness of mm / (33-40) mm hours, and finally furnace-cooled and air-cooled after being taken out of the furnace; Vacuum sub-temperature gas quenching treatment, wherein the vacuum sub-temperature gas quenching treatment is to evacuate to a vacuum degree of ≤1.33×10 -3 Pa, heat up to 900-950℃ and keep warm for effective thickness mm / (33-40)mm hour, then flush nitrogen into the furnace for cooling, and finally take it out of the furnace for air cooling; Tempering treatment, wherein the tempering treatment is to evacuate to a vacuum degree of ≤1.33×10 -3 Pa, heat up to 680-730℃ and keep warm for effective thickness mm / (18-20)mm hours, then flush nitrogen into the furnace for cooling, and finally take it out of the furnace for air cooling.

2. The vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material according to claim 1 is characterized in that: The isothermal annealing treatment has a heating rate of 70 to 100° C. / h.

3. The vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material according to claim 1 is characterized in that: The isothermal annealing treatment is finally carried out by furnace cooling and then air cooling, and the furnace cooling is controlled to 200-300° C. and then air cooling is carried out.

4. The vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material according to claim 1 is characterized in that: The vacuum sub-temperature gas quenching treatment has a heating rate of 0.5-1.5°C / min.

5. The vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material according to claim 1 is characterized in that: In the vacuum sub-temperature gas quenching treatment, nitrogen gas is injected into the furnace for cooling, and the nitrogen pressure is controlled to be 4-6 bar.

6. The vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material according to claim 1 is characterized in that: The vacuum sub-temperature gas quenching treatment requires that nitrogen gas be injected into the furnace to cool the furnace to no higher than 50° C., and then the furnace is taken out of the furnace for air cooling.

7. The vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material according to claim 1 is characterized in that: The tempering treatment has a heating rate of 0.5 to 1.5°C / min.

8. The vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material according to claim 1 is characterized in that: During the tempering treatment, nitrogen gas is injected into the furnace for cooling, and the nitrogen pressure is controlled to be 1.5-2.5 bar.

9. The vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material according to claim 1, characterized in that: The tempering treatment requires that nitrogen is injected into the furnace to cool the furnace to no higher than 50°C, and then the furnace is taken out for air cooling.

10. Application of the vacuum sub-temperature gas quenching heat treatment process of X12Cr13 material according to any one of claims 1 to 9, characterized in that: Used for heat treatment of compressor impeller made of X12Cr13 material.

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