Method for brazing heat treatment of x3crnimo134 steel

Abstract

The application provides a brazing heat treatment method of X3CrNiMo134 steel, and the steps include: preparing heat treatment for X3CrNiMo134 steel wheel covers and X3CrNiMo134 steel wheel discs for processing welded impellers; integrating brazing and quenching for the X3CrNiMo134 steel wheel covers and the X3CrNiMo134 steel wheel discs to obtain X3CrNiMo134 steel welded impellers; ultrasonic detection of brazing welds of the X3CrNiMo134 steel welded impellers; primary tempering treatment of the X3CrNiMo134 steel welded impellers; and secondary tempering treatment of the X3CrNiMo134 steel welded impellers. The brazing heat treatment method of the X3CrNiMo134 steel can not only make the mechanical properties of the material impeller meet the use requirements, but also has high heat treatment efficiency and low cost.

Description

Technical Field

[0001] This invention relates to the field of materials processing technology, and in particular to a brazing heat treatment method for X3CrNiMo134 steel. Background Technology

[0002] As a core component of the compressor rotor, the impeller has a complex structure and requires high precision in its flow channel. Currently, the use of impellers for small-diameter centrifugal compressors with narrow flow channels is becoming increasingly frequent. Due to the limited flow channel, traditional milling cutters cannot enter the machining area, and grooving welding and electrical discharge etching are usually used for machining.

[0003] Electrical spark corrosion requires electrode preparation, which has low processing efficiency, high production cost, and long cycle. Grooving welding is complex to process the bottom of the groove, the welding process is greatly affected by the human operation of the welder, the welding heat input is large, and a stress relief process is required after welding into a wheel. It also has the problem of low welding efficiency.

[0004] Currently, small-diameter, narrow-channel centrifugal compressor impellers can also be manufactured by brazing the impeller cover and disc together. According to ASME Section IX, "Evaluation of Welding and Brazing," before brazing the impeller from the impeller cover and disc, a test sample must be used for brazing to evaluate the brazing quality. After the brazing quality of the joint meets the requirements and is successfully evaluated, the actual production of the impeller brazed from the impeller cover and disc is carried out according to the brazing process, heat treatment process, and process parameters of the test sample.

[0005] Therefore, optimizing the brazing and performance heat treatment processes and their parameters to enable the vacuum brazing of the impeller to be completed efficiently and at low cost while meeting the mechanical properties required by the design is an urgent problem to be solved. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a brazing heat treatment method for X3CrNiMo134 steel. By optimizing the brazing and performance heat treatment process and process parameters of X3CrNiMo134 test steel parts, the optimized process and process parameters are applied to the actual production of brazed impellers for wheel covers and wheel discs. Under the condition that the mechanical properties of the wheel cover and wheel disc materials can meet the requirements of use, the purpose of high-efficiency and low-cost brazing impellers can be achieved.

[0007] To solve the above-mentioned technical problems, the present invention provides a brazing heat treatment method for X3CrNiMo134 steel, comprising the following steps:

[0008] Preparatory heat treatment for the X3CrNiMo134 steel impeller cover and X3CrNiMo134 steel impeller disc of the machined and welded impeller;

[0009] Integrated brazing and quenching treatment: Brazing filler metal is laid at the joint between the X3CrNiMo134 steel wheel cap and the X3CrNiMo134 steel wheel disc, and the wheel is placed in a vacuum furnace at ≤300℃ with a furnace pressure ≥10. -4 The impeller is heated to 700-800℃ at ≤90℃ / h and held for 1-4 hours, then heated to 880-940℃ at ≤90℃ / h and held for 1-4 hours, then heated to 1030-1070℃ at ≤90℃ / h and held for t = 0.9 × effective thickness mm / 30 mm / hour, with a holding time t not less than 2 hours; then furnace cooled to 800-900℃ and held for 1-4 hours, then cooled to ≤200℃ using nitrogen gas with a purity of 99% or higher and a pressure of 1-3 bar; the X3CrNiMo134 steel wheel cover and X3CrNiMo134 steel wheel disc are brazed together to obtain an X3CrNiMo134 steel welded impeller; then the X3CrNiMo134 steel welded impeller is removed from the furnace and air-cooled to room temperature.

[0010] Ultrasonic testing of brazed welds on X3CrNiMo134 steel welded impellers;

[0011] Tempering treatment of X3CrNiMo134 steel welded impeller;

[0012] Secondary tempering treatment for welded impellers made of X3CrNiMo134 steel.

[0013] Furthermore, the solder is a gold-based solder, comprising 80-85% Au and 5-20% Ni by mass percentage, and the solder has a melting point of 900-1000°C.

[0014] Furthermore, the preliminary heat treatment of the X3CrNiMo134 steel wheel cap and X3CrNiMo134 steel wheel disc includes normalizing treatment and tempering treatment.

[0015] Furthermore, the normalizing treatment involves loading the X3CrNiMo134 steel wheel cap and X3CrNiMo134 steel wheel disc into a furnace at ≤500℃, heating them to 810~890℃ at ≤100℃ / h, holding them at that temperature for 1~4h, then heating them to 1030~1070℃ at ≤100℃ / h, holding them at that temperature for a time t of 0.9×effective thickness mm / 30mm / hour, with a holding time of not less than 2 hours, and then removing them from the furnace and air-cooling them to room temperature.

[0016] Furthermore, the tempering treatment involves loading the X3CrNiMo134 steel wheel cover and the X3CrNiMo134 steel wheel disc into a furnace at ≤350℃, heating them to 690~750℃ at ≤70℃ / h, holding them for a time t of 2.5×effective thickness mm / 30mm / hour, with a holding time of not less than 3 hours, and then removing them from the furnace and air-cooling them to room temperature.

[0017] Furthermore, the effective thicknesses mentioned in the normalizing and tempering processes are respectively the maximum inscribed circle diameters of the wheel cover and the wheel disc.

[0018] Furthermore, the first tempering treatment involves loading the X3CrNiMo134 steel welded impeller into a furnace at ≤350℃, heating it to 560~620℃ at ≤70℃ / h, holding it for t for 2.5×effective thickness mm / 30mm hours, and holding it for no less than 3 hours, and then removing it from the furnace and air cooling it to room temperature.

[0019] Furthermore, the secondary tempering treatment involves loading the X3CrNiMo134 steel welded impeller into a furnace at ≤350℃, heating it to 550~600℃ at ≤70℃ / h, holding it for a time t of 2.5×effective thickness mm / 30mm / hour, and holding it for no less than 3 hours, and then removing it from the furnace and air-cooling it to room temperature.

[0020] Furthermore, the effective thickness mentioned in the quenching treatment, primary tempering treatment, and secondary tempering treatment is the maximum inscribed circle diameter of the welded impeller.

[0021] Furthermore, the ultrasonic testing results of the brazed weld should meet the following requirements:

[0022] (1) The maximum value of a single defect shall not exceed 5% of the total brazing area of ​​a single blade, and the total value of the area of ​​unfused defects of each blade shall not exceed 10% of the total brazing area of ​​the blade.

[0023] (2) The total area of ​​unfused defects in each impeller shall not exceed 7% of the total area of ​​impeller bonding.

[0024] This invention provides a brazing heat treatment method for X3CrNiMo134 steel, which completes the vacuum brazing of X3CrNiMo134 steel during the quenching process of performance heat treatment, realizing the integrated and simultaneous vacuum brazing and performance heat treatment of the impeller. Furthermore, because the brazing is completed during quenching, there is no large local heat input as in conventional welding methods. Therefore, the deformation of the brazed workpiece is smaller, the dimensions are stable, and no stress relief process is required, thereby reducing the production cycle, improving production efficiency, and reducing production costs.

[0025] Furthermore, the brazing heat treatment method for X3CrNiMo134 steel provided by this invention, through optimized control of the brazing and quenching process parameters of X3CrNiMo134 steel and subsequent two tempering treatments, not only ensures the brazing quality of the brazed joint after brazing, but also ensures that the mechanical properties of X3CrNiMo134 steel after vacuum brazing can meet the application requirements.

[0026] Meanwhile, the brazing heat treatment method for X3CrNiMo134 steel provided by this invention can be applied not only to X3CrNiMo134 steel impeller components, but also to other components using X3CrNiMo134 steel. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the normalizing process for the wheel cover and wheel disc in the brazing heat treatment method for X3CrNiMo134 steel provided in this embodiment of the invention.

[0028] Figure 2 This diagram illustrates the tempering process of the wheel cover and wheel disc in the brazing heat treatment method for X3CrNiMo134 steel provided in this embodiment of the invention.

[0029] Figure 3 A schematic diagram of the effective thickness of the wheel cover and wheel disc in the brazing heat treatment method for X3CrNiMo134 steel provided in the embodiments of the present invention;

[0030] Figure 4 A schematic diagram of the impeller quenching heat treatment process in the brazing heat treatment method for X3CrNiMo134 steel provided in the embodiments of the present invention;

[0031] Figure 5 A schematic diagram of the effective thickness of the impeller in the brazing heat treatment method for X3CrNiMo134 steel provided in this embodiment of the invention;

[0032] Figure 6 This is a schematic diagram of the primary tempering process of the impeller in the brazing heat treatment method for X3CrNiMo134 steel provided in an embodiment of the present invention.

[0033] Figure 7 This is a schematic diagram of the secondary tempering process of the impeller in the brazing heat treatment method for X3CrNiMo134 steel provided in an embodiment of the present invention. Detailed Implementation

[0034] This invention provides a brazing heat treatment method for X3CrNiMo134 steel, comprising the following steps:

[0035] Step 1) Perform preliminary heat treatment on the X3CrNiMo134 steel impeller cover and X3CrNiMo134 steel impeller disc for machining and welding.

[0036] The preliminary heat treatment of X3CrNiMo134 steel wheel caps and X3CrNiMo134 steel wheel discs includes normalizing and tempering.

[0037] See Figure 1The normalizing treatment involves loading the X3CrNiMo134 steel wheel cap and X3CrNiMo134 steel wheel disc into the furnace at ≤500℃, heating them to 810~890℃ at ≤100℃ / h, holding them at that temperature for 1~4h, then heating them to 1030~1070℃ at ≤100℃ / h, holding them at that temperature for a time t of 0.9×effective thickness mm / 30mm / hour, with a holding time of not less than 2 hours, and then removing them from the furnace and air-cooling them to room temperature.

[0038] See Figure 2 The tempering process involves loading the X3CrNiMo134 steel wheel cover and X3CrNiMo134 steel wheel disc into the furnace at ≤350℃, heating them to 690~750℃ at ≤70℃ / h, holding them for t for 2.5×effective thickness mm / 30mm hours, and holding them for no less than 3 hours, and then removing them from the furnace and air-cooling them to room temperature.

[0039] Normalizing the X3CrNiMo134 steel wheel caps and discs austenitizes the material's microstructure, eliminating Widmanstätten and banded structures that occur during forging and other processes. Further tempering of the X3CrNiMo134 steel wheel caps and discs yields a uniform and stable microstructure, refines the grain size, and lays a solid foundation for subsequent performance heat treatment.

[0040] Therefore, the present invention provides a brazing heat treatment method for X3CrNiMo134 steel, which pre-heat treats the X3CrNiMo134 steel wheel cover and X3CrNiMo134 steel wheel disc, which can refine the grains and homogenize the microstructure, and obtain superior mechanical properties in subsequent performance heat treatment.

[0041] When performing preliminary heat treatment on X3CrNiMo134 steel wheel covers, the effective thickness mentioned in the normalizing and tempering processes refers to the maximum inscribed circle diameter of the wheel cover. Similarly, when performing preliminary heat treatment on X3CrNiMo134 steel wheel discs, the effective thickness mentioned in the normalizing and tempering processes refers to the maximum inscribed circle diameter of the wheel disc. Regarding the maximum inscribed circle diameters of the wheel cover and wheel disc... Figure 3 As shown.

[0042] Step 2) Integrated brazing and quenching process.

[0043] First, brazing filler metal is laid at the joint between the X3CrNiMo134 steel wheel cap and the X3CrNiMo134 steel wheel disc. To ensure the quality of the brazed joint after brazing, the contact surfaces of the two parts must be horizontal and have a high degree of flatness before the brazing filler metal is laid. When checking the gap at the joint, the gap must be ≤0.05mm.

[0044] The solder is a gold-based solder, comprising 80-85% Au and 5-20% Ni by mass percentage, and the solder has a melting point of 900-1000°C.

[0045] In one specific embodiment of the present invention, the solder comprises 82% Au and 18% Ni by mass percentage, and the melting point of the solder is 950°C.

[0046] See Figure 4 Load the contents into a vacuum furnace at ≤300℃, with a furnace pressure ≥10. -4 The impeller is heated to 700-800℃ at ≤90℃ / h and held for 1-4 hours, then heated to 880-940℃ at ≤90℃ / h and held for 1-4 hours, then heated to 1030-1070℃ at ≤90℃ / h and held for t = 0.9 × effective thickness mm / 30 mm / hour, with a holding time t not less than 2 hours; then furnace cooled to 800-900℃ and held for 1-4 hours, then cooled to ≤200℃ using nitrogen gas with a purity of 99% or higher and a pressure of 1-3 bar; the X3CrNiMo134 steel wheel cover and X3CrNiMo134 steel wheel disc are brazed together to obtain an X3CrNiMo134 steel welded impeller; then the X3CrNiMo134 steel welded impeller is removed from the furnace and air-cooled to room temperature.

[0047] Secondly, the effective thickness mentioned in the quenching process refers to the maximum inscribed circle diameter of the welded impeller. Regarding the maximum inscribed circle diameter of the welded impeller, as follows... Figure 5 As shown.

[0048] During the quenching process, a brazing filler metal with a melting point lower than the required quenching temperature of the base metal is used. At a temperature lower than the required quenching temperature of the base metal but higher than the melting point of the filler metal, the molten liquid filler metal wets and fills the gaps in the base metal surface, achieving a connection between parts through mutual diffusion. Under capillary action, the liquid filler metal effectively fills the gaps at the joint of the base metal. Simultaneously, elements between the filler metal and the base metal undergo mutual diffusion, and these diffused elements combine with elements in the original matrix to form compounds. After cooling and solidification, a strong welded joint is ultimately formed through intermolecular bonding forces, and the resulting product also possesses excellent mechanical properties after the quenching process.

[0049] Since this invention uses a gold-based brazing filler metal with a melting point of 900–1000°C, and considering the need for sufficient melting of the filler metal and the requirements for heat treatment of the base material, the quenching temperature is ultimately set to 1030–1070°C. When the temperature is heated above 900–1000°C, the filler metal begins to melt into a liquid state. Subsequently, during holding at 1030–1070°C, the filler metal completely liquefies. After sufficient holding time, under the action of capillary force, the liquid filler metal can fully fill the gap between the brazed joints and form a metallurgical bond with the base material. Then, it is cooled to 800–900°C. After sufficient holding, the filler metal has completely solidified. Through intermolecular bonding forces, the X3CrNiMo134 steel wheel cover and the X3CrNiMo134 steel wheel disc can be effectively connected to obtain the X3CrNiMo134 steel welded impeller. At this point, the brazing process is basically completed. Subsequently, the X3CrNiMo134 steel welded impeller is further cooled and removed from the furnace, and then undergoes subsequent performance heat treatment.

[0050] Because the melting point of the brazing filler metal is lower than the quenching and holding temperature of the base metal, it not only ensures complete melting of the filler metal but also allows the brazing process to be completed directly during the heat treatment of the base metal's quenching properties, achieving integrated brazing and performance processing. Furthermore, since brazing is performed during quenching, there is no large localized heat input as in conventional welding methods. Therefore, the deformation of the brazed workpiece is smaller, its dimensions are stable, and no stress-relief process is required, thus reducing the production cycle and saving production costs.

[0051] Step 3) Ultrasonic testing of the brazed weld seam of the X3CrNiMo134 steel welded impeller.

[0052] The ultrasonic testing of brazed welds is performed using a four-dimensional rotating ultrasonic flaw detector (X, Y, φ, R). This inspection can detect and identify incomplete fusion defects larger than φ2mm.

[0053] The detection conditions for C-scan are:

[0054] Imaging method: Ultrasound C-scan;

[0055] Probe frequency: 5MHz;

[0056] Coupling method: Water immersion method;

[0057] Scanner: X, Y, Z three-axis automatic scanner;

[0058] Reference: The reference is a φ2.0mm flat-bottomed hole.

[0059] The ultrasonic testing results of brazed welds should meet the following requirements:

[0060] (1) The maximum value of a single defect shall not exceed 5% of the total brazing bonding area of ​​a single blade, and the total value of the non-fusion defect area of ​​each blade shall not exceed 10% of the total bonding area of ​​the blade.

[0061] (2) The total area of ​​unfused defects in each impeller shall not exceed 7% of the total area of ​​impeller bonding.

[0062] After the ultrasonic testing of the brazed weld meets the requirements, the X3CrNiMo134 steel welded impeller undergoes subsequent performance heat treatment.

[0063] Step 4) Perform a first tempering treatment on the X3CrNiMo134 steel welded impeller.

[0064] Among them, see Figure 6 The first tempering process involves loading the X3CrNiMo134 steel welded impeller into the furnace at ≤350℃, heating it to 560~620℃ at ≤70℃ / h, holding it for t for 2.5×effective thickness mm / 30mm hours, and holding it for no less than 3 hours, and then removing it from the furnace and air cooling it to room temperature.

[0065] Step 5) Perform secondary tempering treatment on the brazed X3CrNiMo134 steel welded impeller.

[0066] Among them, see Figure 7 The secondary tempering process involves loading the X3CrNiMo134 steel welded impeller into the furnace at ≤350℃, heating it to 550~600℃ at ≤70℃ / h, holding it for t for 2.5×effective thickness mm / 30mm hours, and holding it for no less than 3 hours, and then removing it from the furnace and air cooling it to room temperature.

[0067] The effective thickness mentioned in the first and second tempering processes refers to the maximum inscribed circle diameter of the welded impeller.

[0068] This invention provides a brazing heat treatment method for X3CrNiMo134 steel. After the brazing and quenching are integrated, the X3CrNiMo134 steel welded impeller is subjected to a first tempering and a second tempering treatment. Through further performance heat treatment, its performance is improved to meet the requirements of its use.

[0069] The following examples illustrate a specific method for heat treatment of X3CrNiMo134 steel brazing provided by the present invention.

[0070] Example 1

[0071] Brazing samples 1 and 2 underwent normalizing and tempering pre-heat treatment, followed by an integrated vacuum brazing and performance heat treatment process, which included quenching, primary tempering, and secondary tempering heat treatment.

[0072] Preparatory heat treatment for brazing samples 1 and 2:

[0073] Normalizing treatment: X3CrNiMo134 steel samples 1 and 2 were loaded into the furnace at 300℃, heated to 840℃ at a heating rate of 90℃ / h and held for 1h, then heated to 1040℃ at a heating rate of 90℃ / h and held for 2h, and then removed from the furnace and air-cooled to room temperature.

[0074] Tempering treatment: X3CrNiMo134 steel samples 1 and 2 were loaded into the furnace at 200℃ and heated to 710℃ at a heating rate of 60℃ / h. After holding at this temperature for 3 hours, they were removed from the furnace and air-cooled to room temperature.

[0075] The integrated vacuum brazing and performance heat treatment process for samples 1 and 2 includes:

[0076] Quenching treatment: After the brazing filler metal was applied to the joint of X3CrNiMo134 steel samples 1 and 2, they were placed in a vacuum furnace at 150°C. The pressure inside the vacuum furnace was 10 kcal / kg. -4 Pa, heat to 760℃ at 70℃ / h and hold for 1h, then heat to 900℃ at 70℃ / h and hold for 1h, then heat to 1040℃ at 75℃ / h and hold for 2h, then furnace cool to 860℃ and hold for 1h, then air cool to 180℃ at 2 bar, and then remove from the furnace and air cool to room temperature.

[0077] Ultrasonic testing of brazed welds is performed after brazing and before final performance heat treatment, using a four-dimensional rotating ultrasonic flaw detector (X, Y, φ, R). The inspection should be able to detect and identify incomplete fusion defects larger than φ2mm.

[0078] The detection conditions for C-scan are:

[0079] Imaging method: Ultrasound C-scan;

[0080] Probe frequency: 5MHz;

[0081] Coupling method: Water immersion method;

[0082] Scanner: X, Y, Z three-axis automatic scanner;

[0083] Reference: The reference is a φ2.0mm flat-bottomed hole.

[0084] The results of ultrasound testing should meet the following requirements:

[0085] (1) The maximum value of a single defect shall not exceed 5% of the total brazing joint area of ​​a single blade, and the total value of the non-fusion defect area of ​​each blade shall not exceed 10% of the total joint area of ​​that blade.

[0086] (2) The total area of ​​unfused defects found in each impeller shall not exceed 7% of the total joint area of ​​that impeller.

[0087] First tempering treatment: The X3CrNiMo134 steel sample that has been brazed is put into the furnace at 200℃, heated to 595℃ at 60℃ / h, held at that temperature for 3h, and then taken out of the furnace and air-cooled to room temperature.

[0088] Secondary tempering treatment: The X3CrNiMo134 steel sample that has been brazed is put into the furnace at 200℃, heated to 580℃ at 50℃ / h, held at that temperature for 3h, and then taken out of the furnace and air-cooled to room temperature.

[0089] After the performance heat treatment is completed, the mechanical properties of the brazed weld are tested. The tensile specimens fracture at the base material, and the mechanical properties are shown in the table below:

[0090]

[0091] Example 2

[0092] Brazing samples 3 and 4 underwent normalizing and tempering pre-heat treatment, followed by an integrated vacuum brazing and performance heat treatment process, which included quenching, primary tempering, and secondary tempering heat treatment.

[0093] Preparatory heat treatment for brazing samples 3 and 4:

[0094] Normalizing treatment: X3CrNiMo134 steel samples 3 and 4 were loaded into the furnace at 280℃, heated to 820℃ at a heating rate of 80℃ / h and held for 1h, then heated to 1030℃ at a heating rate of 80℃ / h and held for 2h, and then removed from the furnace and air-cooled to room temperature.

[0095] Tempering treatment: X3CrNiMo134 steel samples 3 and 4 were loaded into the furnace at 180℃ and heated to 730℃ at a heating rate of 50℃ / h. After holding at this temperature for 3 hours, they were removed from the furnace and air-cooled to room temperature.

[0096] The integrated vacuum brazing and performance heat treatment process for samples 3 and 4 includes:

[0097] Quenching treatment: After the brazing filler metal was applied to the joints of X3CrNiMo134 steel samples 3 and 4, they were placed in a vacuum furnace at 180°C. The pressure inside the vacuum furnace was 10 kcal / kg. -4 Pa, heat to 770℃ at 80℃ / h and hold for 1h, then heat to 910℃ at 60℃ / h and hold for 1h, then heat to 1030℃ at 70℃ / h and hold for 2h, then furnace cool to 840℃ and hold for 1h, then air cool to 200℃ at 2 bar, and then remove from the furnace and air cool to room temperature.

[0098] Ultrasonic testing of brazed welds is performed after brazing and before final performance heat treatment, using a four-dimensional rotating ultrasonic flaw detector (X, Y, φ, R). The inspection should be able to detect and identify incomplete fusion defects larger than φ2mm.

[0099] The detection conditions for C-scan are:

[0100] Imaging method: Ultrasound C-scan;

[0101] Probe frequency: 5MHz;

[0102] Coupling method: Water immersion method;

[0103] Scanner: X, Y, Z three-axis automatic scanner;

[0104] Reference: The reference is a φ2.0mm flat-bottomed hole.

[0105] The results of ultrasound testing should meet the following requirements:

[0106] (1) The maximum value of a single defect shall not exceed 5% of the total brazing joint area of ​​a single blade, and the total value of the non-fusion defect area of ​​each blade shall not exceed 10% of the total joint area of ​​that blade.

[0107] (2) The total area of ​​unfused defects found in each impeller shall not exceed 7% of the total joint area of ​​that impeller.

[0108] First tempering treatment: The X3CrNiMo134 steel sample that has been brazed is put into the furnace at 180℃, heated to 605℃ at 50℃ / h, held at that temperature for 3h, and then taken out of the furnace and air-cooled to room temperature.

[0109] Secondary tempering treatment: The X3CrNiMo134 steel sample that has been brazed is put into the furnace at 180℃, heated to 590℃ at 50℃ / h, held at that temperature for 3h, and then taken out of the furnace and air-cooled to room temperature.

[0110] After the performance heat treatment is completed, the mechanical properties of the brazed weld are tested. The tensile specimens fracture at the base material, and the mechanical properties are shown in the table below:

[0111]

[0112] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A brazing heat treatment method for X3CrNiMo134 steel, characterized in that, Includes the following steps: Preparatory heat treatment, including normalizing and tempering, is performed on the X3CrNiMo134 steel impeller cover and X3CrNiMo134 steel impeller disc for machining and welding. Integrated brazing and quenching treatment: Brazing filler metal is laid at the joint between the X3CrNiMo134 steel wheel cap and the X3CrNiMo134 steel wheel disc. The wheel is then placed in a vacuum furnace at ≤300℃, with a furnace pressure ≥10⁻⁴ Pa. The furnace is heated at ≤90℃ / h to 700~800℃ and held for 1~4 hours. Then, it is heated at ≤90℃ / h to 880~940℃ and held for 1~4 hours. Finally, it is heated at ≤90℃ / h to 1030~1070℃ and held for a time t of 0.9 × effective thickness mm / 30 mm, with a holding time t not less than 2 hours. The furnace is then cooled to 800~900℃ and held for 1~4 hours. After h, the X3CrNiMo134 steel wheel cover and X3CrNiMo134 steel wheel disc are brazed together to obtain the X3CrNiMo134 steel welded impeller. Then the X3CrNiMo134 steel welded impeller is taken out of the furnace and air-cooled to room temperature. Ultrasonic testing of brazed welds on X3CrNiMo134 steel welded impellers; The X3CrNiMo134 steel welded impeller undergoes a first tempering treatment. The first tempering treatment involves loading the X3CrNiMo134 steel welded impeller into a furnace at ≤350℃, heating it to 560~620℃ at ≤70℃ / h, holding it for t for 2.5×effective thickness mm / 30mm hours, and holding it for no less than 3 hours. Then, the impeller is removed from the furnace and air-cooled to room temperature. The impeller of X3CrNiMo134 steel welded impeller is subjected to secondary tempering treatment. The secondary tempering treatment is to load the X3CrNiMo134 steel welded impeller into the furnace at ≤350℃, heat it to 550~600℃ at ≤70℃ / h, hold it for t for 2.5×effective thickness mm / 30mm hours, and hold it for no less than 3 hours, and then remove it from the furnace and air cool it to room temperature. The solder is a gold-based solder, comprising 80-85% Au and 5-20% Ni by mass percentage, and has a melting point of 900-1000°C.

2. The brazing heat treatment method for X3CrNiMo134 steel according to claim 1, characterized in that: The normalizing treatment involves loading the X3CrNiMo134 steel wheel cap and X3CrNiMo134 steel wheel disc into a furnace at ≤500℃, heating them to 810~890℃ at ≤100℃ / h, holding them at that temperature for 1~4 h, then heating them to 1030~1070℃ at ≤100℃ / h, holding them at that temperature for a time t of 0.9×effective thickness mm / 30mm / hour, with a holding time of not less than 2 hours, and then removing them from the furnace and air-cooling them to room temperature.

3. The brazing heat treatment method for X3CrNiMo134 steel according to claim 2, characterized in that: The tempering process of the preheating treatment involves loading the X3CrNiMo134 steel wheel cover and the X3CrNiMo134 steel wheel disc into the furnace at ≤350℃, heating them to 690~750℃ at ≤70℃ / h, holding them at t for 2.5×effective thickness mm / 30mm hours, and holding them for no less than 3 hours, and then removing them from the furnace and air cooling them to room temperature.

4. The brazing heat treatment method for X3CrNiMo134 steel according to claim 2 or 3, characterized in that: The effective thicknesses mentioned in the normalizing and tempering processes of the pre-heat treatment are the maximum inscribed circle diameters of the wheel cover and wheel disc, respectively.

5. The brazing heat treatment method for X3CrNiMo134 steel according to claim 1, characterized in that: The effective thickness is the maximum inscribed circle diameter of the welded impeller.

6. The brazing heat treatment method for X3CrNiMo134 steel according to claim 1, characterized in that: The ultrasonic testing results of the brazed weld seam shall meet the following requirements: (1) The maximum value of a single defect shall not exceed 5% of the total brazing bonding area of ​​a single blade, and the total value of the non-fusion defect area of ​​each blade shall not exceed 10% of the total bonding area of ​​the blade; (2) The total area of ​​unfused defects in each impeller shall not exceed 7% of the total area of ​​impeller bonding.

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