Diffusion bonding method of throat section profiled surface multi-metal whole

Abstract

The application discloses a diffusion connection method of a throat section special-shaped surface multi-metal whole, which comprises an outer shell, a base assembled at the bottom end of the outer shell, a flow passage throat pipe, a expansion sleeve and a tapered expansion core arranged in the outer shell in sequence from the center of the circle to the inside, and a throat support connected between the outer shell and the flow passage throat pipe. The diffusion connection method is specifically performed according to the following steps: step 1, pretreating each component and reinforcing by cold welding to obtain an A structure; step 2, assembling the workpiece; step 3, placing the workpiece into a diffusion connection furnace and pretreating; step 4, performing diffusion connection; step 5, controlling, sampling, processing and finally obtaining the diffusion connected throat section special-shaped surface multi-metal whole. The application has high strength of the workpiece connected by diffusion, certain improvement in the sealing performance and the geometric precision of the flow passage size, and certain practicability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of diffusion bonding of dissimilar materials, and provides a diffusion bonding method for a throat section special-shaped surface multi-metal whole. BACKGROUND

[0002] With the comparison and display of the technical achievements in the diffusion bonding industry for more than ten years, there are two methods for the throat section special-shaped surface multi-metal connection at present, most of which are brazing connection, and the diffusion bonding method for the multi-metal whole is rare, and there are many problems in the connection.

[0003] The brazing connection of the throat section special-shaped surface multi-metal whole has the following disadvantages: the brazing filler metal is easy to form slag and overflow during the connection process, resulting in poor sealing of the connection part; the brazing filler metal is easy to form overflow during the connection process, resulting in changes in the cross-sectional size of the flow passage, an increase in the flow resistance, and a decrease in the heat exchange efficiency; no matter what brazing filler metal is used, the brazing connection temperature cannot reach the minimum liquidus temperature of the multi-metal welding base material, and the strength and sealing performance of the brazing part under high temperature and high pressure cannot meet the use requirements in the super-high temperature and high pressure working environment.

[0004] The diffusion bonding method for the throat section special-shaped surface multi-metal whole has the following disadvantages: the throat section shell and the throat support are made of the same material, and the flow passage throat pipe is made of another material. The throat section needs to be connected by the flow passage throat pipe and the throat support, the flow passage throat pipe and the shell, and the throat support and the shell, and the three parts are connected. Since the liquidus lines of the above connection base materials are different, the hot working parameters can only be designed according to the minimum liquidus line of the base material during the connection process, so that the connection strength of the high liquidus line metal is insufficient, the strength of the connection surface between the throat support and the shell is not enough under the alternating load working environment, the connection surface is loose, and the service life is sharply reduced; the isostatic pressing connection method: the flow passage throat pipe is constructed as two back-to-back horn shapes with a thin middle part extending to two end faces. For the connection of the special-shaped surface of such a flow passage throat pipe, the isostatic pressing connection is usually used, and the stress on the entire special-shaped surface is uniform, which will cause the collapse of the bottom part of the flow passage slot and result in changes in the geometric size of the flow passage cross section; the two-section head-to-head expansion core assembly connection method: the upper and lower expansion cores are extruded to the throat part during the high-temperature connection process, the pressure of the throat part is lost, the connection strength is insufficient, and the end face of the flow passage throat pipe and the end face of the shell are dislocated and torn due to the lateral force acting on the connection surface. SUMMARY

[0005] The application aims to provide a diffusion bonding method for a throat section special-shaped surface multi-metal whole, and solve the problems that the existing throat section brazing connection and the diffusion bonding technology for the throat section special-shaped surface multi-metal whole need to be further optimized.

[0006] The technical scheme adopted by the application is as follows,

[0007] The diffusion bonding method of the throat section special-shaped surface multi-metal whole includes an outer shell, a base assembled at the bottom end of the outer shell, a flow passage throat pipe, a expansion sleeve and a tapered expansion core arranged in the outer shell along the center in sequence; and a throat support connected between the outer shell and the flow passage throat pipe;

[0008] The diffusion bonding method is specifically performed according to the following steps:

[0009] Step 1: the connecting surfaces of the outer shell, the throat support and the flow passage throat pipe are all subjected to first pretreatment, the surfaces of the expansion sleeve, the tapered expansion core and the base are subjected to second pretreatment; the throat support is fixedly assembled on the outer side of the flow passage throat pipe; then copper foil is laid on the outer side, and cold welding is used for reinforcement to obtain an A structure;

[0010] Step 2: the A structure is assembled in the inner hole of the outer shell; the expansion sleeve is assembled in the inner hole of the flow passage throat pipe; the tapered expansion core is assembled in the inner hole of the expansion sleeve and is pre-pressed; the base is placed at the bottom of the outer shell and is subjected to spot welding positioning; the tapered expansion core is pre-pressed by a press machine, the tapered expansion core is extended from the expansion sleeve by 48-50 mm at the top of the outer shell, and the real-time pressure value is recorded to obtain an assembled workpiece;

[0011] Step 3: a vacuum furnace is inspected, graphite heating plates are laid in the bottom of the vacuum furnace, the workpiece is placed in the middle of the vacuum furnace, and graphite heating blocks are placed on the top of the workpiece;

[0012] Step 4: a hydraulic device is operated to close the furnace cover of the vacuum furnace, and is pressurized to the original pre-pressing value, the vacuum degree in the furnace body is controlled to be 2*10 -3 pa-3*10 -3 pa, the temperature in the furnace is controlled to be 280-1043 DEG C, the pressure is 2-20T, the holding time is 5-260 min, and diffusion bonding is performed;

[0013] Step 5: the workpiece is cooled to below 200 DEG C with the furnace, the pressure is maintained for 5T during the cooling process, the workpiece is hoisted out of the furnace, the base is removed, the workpiece is inverted, the expansion sleeve and the tapered expansion core are demolded, and finally a throat section special-shaped surface multi-metal whole is obtained.

[0014] The present application is characterized in that,

[0015] In step 1, the first pretreatment is to remove the oxide film and impurities, and the second pretreatment is to perform surface oxidation treatment and coating of a release agent.

[0016] In step 1, the throat support is assembled on the outer side of the flow passage throat pipe through positioning pins and positioning holes.

[0017] In step 1, the cold welding reinforcement is specifically: spot welding reinforcement is adopted.

[0018] In step 2, the pre-pressing value of the press machine is controlled to be 24-28T;

[0019] The expansion sleeve is composed of fourteen petal-shaped parts.

[0020] In step 3, the vacuum furnace is controlled by the following parameters: limit vacuum degree 6.67*10 -3 Pa; pressure range 5T-100T, pressure control accuracy level 0.01MPa; temperature control range 25-2200℃, furnace temperature uniformity ±3℃; rated heating power 380V, 500KW; maximum displacement stroke of pressure head 150mm.

[0021] In step 1, the copper foil is TCr1-0.15.

[0022] The beneficial effects of the diffusion connection method of the throat section special-shaped surface multi-metal whole are: the connection strength of each connection part is as high as 80%-90% of the base material strength, the sealing performance is excellent, and the service life is long;

[0023] The flow passage cross section has high geometric size precision, and the flow passage inner cavity is clean and pollution-free, thereby guaranteeing the heat exchange efficiency required by the original design;

[0024] The one-time whole diffusion connection greatly reduces the process content, shortens the manufacturing period, and reduces the manufacturing cost;

[0025] The method has the advantages of preventing axial tearing and dislocation of the inner shell and the outer shell and tearing during the welding process. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a whole structure schematic diagram of the diffusion connection method of the throat section special-shaped surface multi-metal whole;

[0027] Figure 2 is a sectional view schematic diagram of the diffusion connection method of the throat section special-shaped surface multi-metal whole;

[0028] Figure 3 is a structure schematic diagram of the outer shell in the diffusion connection method of the throat section special-shaped surface multi-metal whole;

[0029] Figure 4 is a structure schematic diagram of the throat support in the diffusion connection method of the throat section special-shaped surface multi-metal whole;

[0030] Figure 5 is a structure schematic diagram of the flow passage throat pipe in the diffusion connection method of the throat section special-shaped surface multi-metal whole;

[0031] Figure 6 is a tooling structure schematic diagram of the multi-petal expansion sleeve in the diffusion connection method of the throat section special-shaped surface multi-metal whole;

[0032] Figure 7 is a tooling structure schematic diagram of the tapered expansion core in the diffusion connection method of the throat section special-shaped surface multi-metal whole;

[0033] Figure 8 Figure is the schematic diagram of the tool structure of the base in the diffusion bonding method of the throat section profiled surface multi-metal whole.

[0034] In the figure, 1. shell, 2. throat support, 3. flow passage throat pipe, 4. expansion sleeve, 5. tapered expansion core, 6. base, 7. positioning hole, 8. positioning pin. DETAILED DESCRIPTION

[0035] The diffusion bonding method of the throat section profiled surface multi-metal whole will be further described in detail below in combination with the drawings and specific embodiments.

[0036] The diffusion bonding method of the throat section profiled surface multi-metal whole,

[0037] The processing steps are as follows:

[0038] As Figure 2 shown, the shell 1 is a 06Cr19Ni10 forging, and the thickness (strength) is processed to meet the requirements of diffusion bonding, and the wall thickness is controlled to be 60-70 mm and a later processing allowance is reserved.

[0039] The throat support 2 is a 06Cr19Ni10 forging, which is rough machined and annealed (to eliminate internal stress) and then finely machined, and the outer circle, copper foil (TCr1-0.15) and the inner circle of the shell 1 are matched, wherein the copper foil is closely laid on the outer circle of the throat support 2 and is cold-welded to be reinforced, so that the throat support 2 with the attached copper foil is ensured to be installed into the inner hole of the shell 1, and the gap of the inner hole of the shell 1 is 0.1-0.15 mm.

[0040] The flow passage throat pipe 3 is a TCr1-0.15 forging, and the thickness (strength) is processed to meet the requirements of diffusion bonding, and the wall thickness is controlled to be 18-20 mm and a later processing allowance is reserved, and the width and depth of the flow passage groove are pre-reserved by 0.1-0.2 mm according to the heat processing compression amount.

[0041] The expansion sleeve 4 is made of high-temperature alloy 2520 stainless steel material, which is rough machined and annealed (to eliminate internal stress) and then finely machined, and the size head of one side is machined by 0.03-0.05 mm smaller than the inner hole line type of the flow passage throat pipe 3 to match and butt joint two parts, and the inner hole ensures the taper requirement of 1.7°-2.0° of the process, and ensures the roughness of Ra1.6-Ra3.2.

[0042] The tapered expansion core 5 is made of high-temperature alloy 2520 stainless steel material, and the taper is matched with the 1.7°-2.0° taper hole of the expansion sleeve 1, and the distance between the large head end surface of the expansion core and the large head end surface of the expansion sleeve is 48-50 mm (to ensure that the compression amount between the flow passage throat pipe and the throat support and the shell is 1.4-1.6 mm after heat processing is completed).

[0043] ⑥ The base 6 is made of 304 stainless steel and is processed in one go. Its upper countersunk platform matches the bottom copper platform of the flow channel throat (fitting clearance 0.5-1.5mm). The bottom surface of the copper platform of the flow channel throat is in close contact with the two platforms of the base support. The size of the small hole in the base support ensures that the small end of the expansion core has sufficient free play.

[0044] The assembly process and sequence of steps for the larynx segment are as follows:

[0045] Step 1: As Figure 2 As shown, the connecting surfaces of the outer shell 1, throat support 2, and flow channel throat tube 3 all need to be surface treated (to remove oxide film and impurities) to ensure that their connecting surfaces are clean and free from contamination. The expansion sleeve 4, tapered expansion core 5, and base 6 are surface oxidized and coated with release agent (to ensure that they do not stick together in a high-temperature environment).

[0046] Step 2: As Figure 4 As shown, Figure 4 The throat support 2 is assembled with the positioning pin 8 and positioning hole 7 through a transition fit. Figure 5 The outer circumference of the flow channel throat is designed to ensure a tight fit, with a clearance of 0-0.05mm.

[0047] Step 3: After assembling the throat support 2, lay TCr1-0.15 copper foil on the outer circular surface (to remove oxide film and impurities, ensuring cleanliness and no contamination), and reinforce it with cold welding;

[0048] Step 4: After completing the above steps, assemble the whole assembly. Figure 3 Inner hole of the outer casing;

[0049] Step 5: As Figure 5 and 6 As shown, the expansion sleeve 4 is composed of fourteen petal-shaped parts. The fourteen petal-shaped parts of the expansion sleeve 4 are assembled into the inner hole of the flow channel throat 3 in the order of large and small heads, and are made flat and in place by fitter work.

[0050] Step 6: As Figure 7 As shown, the tapered expansion core 5 is assembled into the inner hole of the expansion sleeve 4 in the order of large and small ends and pre-pressed (to ensure that a pre-tightening force of 5-8T is applied between each connecting surface);

[0051] Step 7: As Figure 8 As shown, the base 6 is placed at the bottom of the throat section and is positioned by spot welding.

[0052] Step 8: Using a press to... Figure 7 The core expansion is pre-pressurized in increments of 1T according to the process requirements, up to a pre-pressurization of 28T. The pressure is determined based on the height of the core expansion end face. Figure 6 The end face of the expansion sleeve is 48-50mm, and the real-time pressure value is recorded.

[0053] Assembly complete.

[0054] The throat section diffusion connection requirements are as follows:

[0055] The test checks the vacuum furnace (ZKL-1300-500KW vacuum diffusion connection equipment): the limit vacuum degree is 6.67x10 -3 Pa; the pressure range is 5-100T (adjustable, can manually and automatically increase, decrease and maintain pressure), the pressure control precision level is 0.01MPa; the temperature control range is 25℃-2200℃ (the temperature rising speed can be adjusted by changing the heating power), the furnace temperature uniformity is ±3℃ (the intermediate frequency heating body is a graphite cylinder); the rated heating power is 380V, 500KW (the power is adjustable); the maximum displacement stroke of the pressure head is 150mm (two-way up and down pressure head pressing), and each function and performance index is ensured to be intact;

[0056] The graphite heating plate is placed at the bottom of the furnace body, the workpiece to be connected is placed in the middle of the furnace body, and the graphite heating block is placed on the top of the workpiece;

[0057] The hydraulic device is operated to close the furnace cover and pressurize to the original pre-pressing value, and the vacuum system is operated to ensure that the vacuum degree is 2x10 -3 Pa-3x10 -3 Pa;

[0058] After entering the furnace, the heating power is set to 80% of the rated power according to the hot working process;

[0059]

[0060] The execution status of program No. 5 is focused on (according to the amount of expansion and trial pressure, the material diffusion condition is accurately judged, and the holding time and pressure are adjusted in real time).

[0061] The throat section diffusion connection after the furnace demolding requirements are as follows:

[0062] The workpiece is cooled to below 200℃ with the furnace (the pressure is maintained at 5T during the cooling process);

[0063] The equipment is operated, the workpiece is hoisted out of the furnace, the bottom support is removed, the workpiece is inverted, the core and the sleeve are demolded. The throat section diffusion connection finishing (finished product) detection requirements are as follows;

[0064] The diffusion connection is determined to be intact without defects through ultrasonic flaw detection (preliminary same material sample experiment, the connection strength reaches 80%-90% of the base metal strength);

[0065] The sealing property of the interlayer flow channel reaches 3MPa through water pressure test, and there is no leakage after pressure maintaining for 15 minutes; the flow channel geometric size meets the requirements, there is no deformation and abnormal flow resistance (preliminary same material sample experiment, the sealing property has reached 6Mpa-8Mpa).

[0066] The diffusion connection method of the throat section special-shaped surface multi-metal whole of the application has high connection strength of the workpiece connected through diffusion connection, and the sealing property and the precision of the flow passage geometric dimension are improved to a certain extent.

Claims

1. A method of diffusion bonding of a throat section profiled multi-metal monolith, characterised in that, Wherein, The throat section profiled surface multi-metal whole comprises an outer shell (1), a base (6) assembled at the bottom end of the outer shell (1), a flow passage throat pipe (3), a swelling sleeve (4) and a tapered swelling core (5) sequentially arranged in the outer shell (1) along the center of the circle; a throat support (2) is further connected between the outer shell (1) and the flow passage throat pipe (3); Wherein, the diffusion bonding method is specifically performed according to the following steps: Step 1: the connecting surfaces of the outer shell (1), the throat support (2) and the flow passage throat pipe (3) are all pretreated, the surfaces of the swelling sleeve (4), the tapered swelling core (5) and the base (6) are secondly pretreated; the throat support (2) is fixedly assembled on the outer side of the flow passage throat pipe (3); then copper foil is laid on the outer side, and cold welding is used for reinforcement to obtain an A structure; Step 2: the A structure is assembled in the inner hole of the outer shell (1); the swelling sleeve (4) is assembled in the inner hole of the flow passage throat pipe (3); the tapered swelling core (5) is assembled in the inner hole of the swelling sleeve (4) and is pre-pressed; the base (6) is placed at the bottom of the outer shell (1) and is positioned by spot welding; the tapered swelling core (5) is pre-pressed by a press machine, the tapered swelling core (5) is extended from the swelling sleeve (4) by 48-50mm at the top of the outer shell (1), and the real-time pressure value is recorded to obtain an assembled workpiece; Step 3: a vacuum furnace is inspected, graphite heating plates are laid at the bottom of the vacuum furnace, and the workpiece is placed in the middle of the vacuum furnace, and graphite heating blocks are placed on the top of the workpiece; Step 4: operate the hydraulic device to close the furnace cover of the vacuum furnace and pressurize to the original pre-pressurization value, control the vacuum degree in the furnace body to 2x10 -3 pa-3x10 -3 pa, control the temperature in the furnace to 280-1043℃, the pressure to 2-20T, and the holding time to 5-260min, to perform diffusion bonding; Step 5: the workpiece is cooled to below 200℃ with the furnace, the pressure is maintained for 5T during the cooling process, the workpiece is hoisted out of the furnace, the base (6) is removed, the swelling sleeve (4) and the tapered swelling core (5) are demolded, and finally a throat section profiled surface multi-metal whole is obtained; In step 1, the throat support (2) is assembled on the outer side of the flow passage throat pipe (3) through the positioning pin (8) and the positioning hole (7); In step 1, the cold welding reinforcement is specifically spot welding reinforcement by using a cold welding machine; The swelling sleeve (4) is composed of fourteen petal-shaped parts; In step 1, the copper foil is TCr1-0.

15.

2. The method of diffusion bonding a throat segment profiled multi-metal monolith of claim 1, wherein, In step 1, the first pretreatment is to remove the oxide film and impurities, and the second pretreatment is to perform surface oxidation treatment and coating of a demolding agent.

3. The method of diffusion bonding a throat segment profiled multi-metal monolith of claim 1, wherein, In step 2, the pre-pressing value of the press machine is controlled to be 24-28T.

4. The method of diffusion bonding a throat segment profiled multi-metal monolith of claim 1, wherein, In step 3, the vacuum furnace is controlled by the following parameters: limit vacuum degree 6.67 x 10 -3 pa; pressure range 5T-100T, pressure control accuracy level 0.01 MPa; temperature control range: 25-2200℃, furnace temperature uniformity ±3℃; rated heating power: 380V, 500KW; maximum displacement stroke of pressure head: 150mm.

Images