A method for manufacturing low-temperature pipeline transition joints using 3D printing technology

Abstract

A method for manufacturing a low-temperature pipeline transition joint using 3D printing technology, characterized in that the method uses five kinds of metal material powders such as stainless steel, nickel, titanium, aluminum, and aluminum alloy and four kinds of mixed metal powders such as stainless steel / nickel, nickel / titanium, titanium / aluminum, and aluminum / aluminum alloy as powder materials for 3D printing. According to the three-dimensional model of the transition joint, the nine kinds of metal powders are placed in the silo of the 3D printing equipment in sequence, and only one kind of metal powder is placed each time. The 3D printing equipment is started to laser scan the nine kinds of metal powders layer by layer and melt them together to form a transition joint. The manufacturing process of the present invention is safer and more environmentally friendly.

Description

Technical Field

[0001] The present invention relates to a cryogenic fluid pipeline transition joint, and in particular to a method for manufacturing a dissimilar metal cryogenic pipeline connection transition joint, and specifically to a method for manufacturing a cryogenic pipeline transition joint by using 3D printing technology. Background Art

[0002] Aluminum alloy heat exchangers are often used in production areas such as air separation plants and liquefied natural gas (LNG) receiving stations. The pipelines for cryogenic products such as liquid nitrogen, liquid oxygen, and LNG connected to them are generally austenitic stainless steel. The expansion coefficients of aluminum alloy and stainless steel are quite different. If the two are connected by flanges, they are prone to leakage. Especially for flammable and explosive dangerous media such as liquefied natural gas under high pressure, the reliability of the connection seal is higher. Welding is a more reliable sealing method than flange connection, but aluminum alloy and stainless steel cannot be connected by welding. In order to achieve the purpose of welding and connecting the aluminum alloy heat exchanger pipe with the stainless steel pipe, the existing technology is to use a transition joint to weld and connect the aluminum alloy pipe with the stainless steel pipe. The transition joint is processed by explosive composite plates of 5 layers of metal materials such as aluminum alloy, aluminum, titanium, nickel, and stainless steel in sequence. The aluminum alloy end of the transition joint is welded to the aluminum alloy pipe, and the stainless steel end is welded to the stainless steel pipe.

[0003] The transition joint of the prior art is manufactured by the method of explosive compounding. In order to ensure that each layer of metal fits tightly, 5 layers of metal plates are usually compounded into a composite plate by explosive compounding one by one. Each time a layer of metal plate is explosively compounded, the bonding rate is checked by an ultrasonic instrument to be 100% qualified before the next layer of metal plate is explosively compounded. For example, the utility model patent CN201920557461.7 adopts this layer-by-layer explosive compounding method. The utility model patent CN201220648526.7 stacks 5 layers of metal together and then explosively compounds them together at one time. Although the efficiency of explosive compounding is improved, the probability of interlayer bonding defects is higher. Only the explosively compounded plates that pass the interface bonding rate inspection can be used to process transition joints. The qualified explosively compounded plates are machined into transition joints according to the requirements of the drawings.

[0004] The existing explosive bonding method for manufacturing transition joints is very complicated, has a long cycle and high cost. Explosives and detonators are used in the explosive bonding process, which requires a special production environment and safety measures to ensure safety. The multi-layer metal explosive bonding process is prone to produce scrapped materials, and the machining process produces edges and metal cutting waste, which wastes metal materials. Summary of the invention

[0005] The purpose of the present invention is to provide a method for manufacturing low-temperature pipeline transition joints using 3D printing technology that is safe, efficient, low-cost, and free of metal material waste, in view of the fact that the existing explosive composite method used to manufacture transition joints has complex processes, long cycles, high costs, requires the use of highly dangerous explosives and detonators, and requires special production environments and safety measures to ensure safety. In addition, scrapped materials are easily generated during the multi-layer metal explosive composite process, and edges and metal cutting waste are generated during machining, which wastes metal materials. The present invention provides a method for manufacturing low-temperature pipeline transition joints using 3D printing technology that is safe, efficient, low-cost, and free of metal material waste. The method uses 3D printing technology to manufacture transition joints, and the processing technology and time are not limited by the site environment, and the three-dimensional model is quickly transformed into a product, the processing cycle is greatly shortened, and the cost is reduced.

[0006] The technical solution of the present invention is:

[0007] A method for manufacturing a cryogenic pipeline transition joint using 3D printing technology, characterized in that the method comprises the following steps:

[0008] Step 1: Prepare five kinds of metal material powders, namely stainless steel, nickel, titanium, aluminum and aluminum alloy, wherein the metal powder is spherical powder and the particle size of the powder is 15-60 μm.

[0009] Step 2, take out a portion of each base metal material powder in step 1; mix the taken out stainless steel powder and nickel powder, nickel powder and titanium powder, titanium powder and aluminum powder, aluminum powder and aluminum alloy powder respectively to obtain 4 kinds of mixed metal powders, namely stainless steel / nickel, nickel / titanium, titanium / aluminum, and aluminum / aluminum alloy powder; the mass ratio of stainless steel powder in stainless steel / nickel powder is 1:1-2, the mass ratio of nickel in nickel / titanium powder is 1:1-2, the mass ratio of titanium in titanium / aluminum powder is 1:1-2, and the mass ratio of aluminum in aluminum / aluminum alloy powder is 1:1-2;

[0010] Step 3: Use the 5 single metal material powders in step 1 and the 4 mixed metal powders obtained in step 2 as powder materials for 3D printing. Put the 9 metal powders into the silo of the 3D printing device in sequence according to the 3D model of the print part, only put one metal powder at a time, start the 3D printing device to perform laser melting of the metal powder in the selected area of ​​the powder bed, and finally melt the 9 metal powders layer by layer to form a transition joint.

[0011] The order in which the 9 kinds of metal powders described in step 3 of the above-mentioned transition joint manufacturing method are added to the silo is: stainless steel, stainless steel / nickel, nickel, nickel / titanium, titanium, titanium / aluminum, aluminum, aluminum / aluminum alloy, and aluminum alloy.

[0012] The above-mentioned transition joint manufacturing method is characterized in that the stainless steel grade is S31603 / S31608, S30403 / S30408, the nickel grade is N4, N5 or N6, the titanium grade is TA1 or TA2, the aluminum grade is 1050, 1060, 1070, 1100, and the aluminum alloy grade is 5083, 5052, etc.

[0013] The above-mentioned transition joint manufacturing method is characterized in that the four mixed metal powders mentioned in step 2 are obtained by physical mixing at room temperature.

[0014] The above-mentioned transition joint manufacturing method is characterized in that the printing scanning line width used in the selective powder bed laser melting forming in step 3 is 60μm to 100μm, the laser power is 80W to 500W, the scanning speed is 300mm / s to 1000mm / s, and the powder layer thickness is 20 to 80μm. The present invention adopts inert gas protection during the selective powder bed laser melting forming process to avoid chemical reactions with other gases when the metal is molten.

[0015] The above-mentioned transition joint manufacturing method is characterized in that the stainless steel layer of the transition joint formed in step 3 is greater than 50 mm in length, the nickel layer is 1.5 to 4.5 mm in length, the titanium layer is 2 to 5 mm in length, the aluminum layer is 8 to 10 mm in length, and the aluminum alloy layer is greater than 30 mm in length. The sintered thickness of the mixed metal powder between the two layers of single metal is 40 to 100 μm. The sintered layer of mixed metal powder can increase the mutual fusion degree of the interface between the two layers of single metal and enhance the bonding strength between the two layers of metal.

[0016] The beneficial effects of the present invention are:

[0017] The present invention adopts laser 3D printing technology to manufacture transition joints, quickly realizes the transformation from three-dimensional models to products, greatly shortens the processing cycle, and reduces costs.

[0018] The present invention provides a mixed metal powder sintering layer between two layers of single metal, which can increase the degree of mutual fusion of the interface between the two layers of single metal and enhance the bonding strength between the two layers of metal.

[0019] The present invention is an additive manufacturing method, and no metal waste is generated during the manufacturing process.

[0020] The manufacturing process of the invention is safer and more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a side structural schematic diagram of the transition joint of the present invention.

[0022] Figure 2 It is a schematic diagram of the top view of the transition joint of the present invention.

[0023] In the figure, 1-stainless steel layer, 2-nickel layer, 3-titanium layer, 4-aluminum layer, 5-aluminum alloy layer. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Embodiment 1

[0025] A method of manufacturing using 3D printing technology Figure 1 , 2 The method of low temperature pipe transition joint shown:

[0026] Step 1: Prepare five kinds of metal powders: stainless steel, nickel, titanium, aluminum, and aluminum alloy. The metal powder is spherical powder with a particle size of 15-50 μm. The stainless steel grade is S30403 / S30408, the nickel grade is N02200, the titanium grade is TA1, the aluminum grade is 1100, and the aluminum alloy grade is 5083.

[0027] Step 2: Take out a portion of each metal material powder in step 1. Physically mix the stainless steel and nickel powder, nickel and titanium powder, titanium and aluminum powder, and aluminum and aluminum alloy powder at a ratio of 1:2 (mass ratio) at room temperature to obtain four kinds of mixed metal powders, namely stainless steel / nickel, nickel / titanium, titanium / aluminum, and aluminum / aluminum alloy powders.

[0028] Step 3: Use the 5 single metal material powders in step 1 and the 4 mixed metal powders obtained in step 2 as powder materials for 3D printing. According to the 3D model of the transition joint, the 9 metal powders are placed in the silo of the 3D printing equipment one by one, and only one metal powder is placed each time. Start the 3D printing equipment to perform laser melting of the selected powder bed of the metal powder. The laser scans a layer of metal powder laid in advance along a given path, and the layer of metal powder is melted on the previous layer to form a metallurgical bond. After completing the scanning of one layer, the powder spreader lays a layer of powder again, and the laser beam scans and melts again, and accumulates layer by layer until the entire transition joint is 3D printed. The metal powder is completely melted to obtain a transition joint with a dense metallurgical structure. The entire processing process is carried out in a processing chamber protected by an inert gas (argon) to prevent the metal from reacting with other gases at high temperatures.

[0029] The selected area powder bed laser melting forming in step 3 adopts a printing scanning line width of 80μm, a laser power of 300W, a scanning speed of 600mm / s, and a powder layer thickness of 40μm. The order of adding 9 kinds of metal powders into the hopper is: stainless steel, stainless steel / nickel, nickel, nickel / titanium, titanium, titanium / aluminum, aluminum, aluminum / aluminum alloy, and aluminum alloy. Specifically, firstly, the stainless steel powder is spread layer by layer and melted by laser beam scanning; the stainless steel / nickel mixed powder is spread layer by layer on the stainless steel layer and melted by laser beam scanning; then the nickel powder is spread layer by layer and melted by laser beam scanning; the nickel / titanium mixed powder is spread layer by layer on the nickel surface and melted by laser beam scanning; then the titanium powder is spread layer by layer and melted by laser beam scanning; the titanium / aluminum mixed powder is spread layer by layer on the titanium surface and melted by laser beam scanning; then the aluminum powder is spread layer by layer and melted by laser beam scanning; the aluminum / aluminum alloy mixed powder is spread layer by layer on the aluminum surface and melted by laser beam scanning; finally, the aluminum alloy powder is spread layer by layer and melted by laser beam scanning. The length of the stainless steel layer of the transition joint obtained is 75mm, the length of the nickel layer is 2.5mm, the length of the titanium layer is 3mm, the length of the aluminum layer is 9mm, and the length of the aluminum alloy layer is greater than 50mm. The mixed metal powder between the two single metal layers is sintered to a thickness of 80 μm. Embodiment 2

[0030] The difference between this embodiment and the first embodiment is that in step 2, the stainless steel and nickel powder, nickel and titanium powder, titanium and aluminum powder, aluminum and aluminum alloy powder are physically mixed at a ratio of 1:1 (mass ratio) at room temperature to obtain four kinds of mixed metal powders, namely stainless steel / nickel, nickel / titanium, titanium / aluminum, and aluminum / aluminum alloy powders. The protection content of the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the inventive concept, the changes and advantages that can be thought of by those skilled in the art are included in the present invention, and the attached claims are the scope of protection.

[0031] The present invention does not involve parts that are the same as the prior art or can be implemented by using the prior art.

Claims

1. A method for manufacturing a cryogenic pipeline transition joint using 3D printing technology, characterized in that: The method comprises the following steps: Step 1: Prepare five basic metal material powders: stainless steel, nickel, titanium, aluminum, and aluminum alloy; Step 2, take out a portion of each base metal material powder in step 1; mix the taken out stainless steel powder and nickel powder, nickel powder and titanium powder, titanium powder and aluminum powder, aluminum powder and aluminum alloy powder respectively to obtain 4 kinds of mixed metal powders, namely stainless steel / nickel, nickel / titanium, titanium / aluminum, and aluminum / aluminum alloy powder; the mass ratio of stainless steel powder in stainless steel / nickel powder is 1:1-2, the mass ratio of nickel in nickel / titanium powder is 1:1-2, the mass ratio of titanium in titanium / aluminum powder is 1:1-2, and the mass ratio of aluminum in aluminum / aluminum alloy powder is 1:1-2; Step 3: Use the five basic metal material powders in step 1 and the four mixed metal powders obtained in step 2 as powder materials for 3D printing; put the nine metal powders into the silo of the 3D printing device in sequence according to the three-dimensional model of the printed part, and put only one metal powder at a time, start the 3D printing device to perform laser melting of the metal powder in the selected area of ​​the powder bed, and finally melt the nine metal powders together layer by layer to form a transition joint; The four mixed metal powders described in step 2 are obtained by physical mixing at room temperature; the order in which the nine metal powders are added to the silo in step 3 is: stainless steel, stainless steel / nickel, nickel, nickel / titanium, titanium, titanium / aluminum, aluminum, aluminum / aluminum alloy, and aluminum alloy; the stainless steel layer length of the transition joint formed in step 3 is greater than 50 mm, the nickel layer length is 1.5~4.5 mm, the titanium layer length is 2~5 mm, the aluminum layer length is 8~10 mm, and the aluminum alloy layer length is greater than 30 mm; the sintering thickness of the mixed metal powder between the two layers of single metals is 40~100 μm.

2. The method according to claim 1, characterized in that The stainless steel grades of the five basic metal materials are S31603 / S31608, S30403 / S30408, the nickel grade is N4, N5 or N6, the titanium grade is TA1 or TA2, the aluminum grade is 1050, 1060, 1070, 1100, and the aluminum alloy grade is 5083, 5052.

3. The method according to claim 1, characterized in that In step 1, the base metal powder is a spherical powder, and the particle size of the powder is 15-60 μm.

4. The method according to claim 1, characterized in that The printing scanning line width of the selected area powder bed laser melting forming used in step three is 60μm~100μm, the laser power is 80W~500W, the scanning speed is 300mm / s~1000mm / s, and the powder layer thickness is 20~80μm.

5. The method according to claim 1, characterized in that The method is carried out under the protection of inert gas.

Images