CN114833414B - Method for vacuum welding stainless steel based on copper vapor deposition - Google Patents
Method for vacuum welding stainless steel based on copper vapor deposition Download PDFInfo
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- CN114833414B CN114833414B CN202210603534.8A CN202210603534A CN114833414B CN 114833414 B CN114833414 B CN 114833414B CN 202210603534 A CN202210603534 A CN 202210603534A CN 114833414 B CN114833414 B CN 114833414B
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 208
- 229910052802 copper Inorganic materials 0.000 title claims abstract description 207
- 239000010949 copper Substances 0.000 title claims abstract description 207
- 238000003466 welding Methods 0.000 title claims abstract description 168
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 147
- 239000010935 stainless steel Substances 0.000 title claims abstract description 147
- 238000000034 method Methods 0.000 title claims abstract description 86
- 238000007740 vapor deposition Methods 0.000 title claims abstract description 33
- 229910000679 solder Inorganic materials 0.000 claims abstract description 97
- 239000007788 liquid Substances 0.000 claims abstract description 39
- 230000008018 melting Effects 0.000 claims abstract description 28
- 238000002844 melting Methods 0.000 claims abstract description 28
- 238000001816 cooling Methods 0.000 claims abstract description 20
- 238000004321 preservation Methods 0.000 claims description 35
- 238000010438 heat treatment Methods 0.000 claims description 31
- 230000008021 deposition Effects 0.000 claims description 24
- 238000004220 aggregation Methods 0.000 claims description 4
- 230000002776 aggregation Effects 0.000 claims description 4
- 230000008569 process Effects 0.000 abstract description 31
- 230000009471 action Effects 0.000 abstract description 13
- 238000005516 engineering process Methods 0.000 abstract description 9
- 230000007797 corrosion Effects 0.000 abstract description 6
- 238000005260 corrosion Methods 0.000 abstract description 6
- 238000007711 solidification Methods 0.000 abstract description 3
- 230000008023 solidification Effects 0.000 abstract description 3
- 230000008859 change Effects 0.000 abstract description 2
- 238000005265 energy consumption Methods 0.000 abstract description 2
- 239000000047 product Substances 0.000 description 20
- 238000005219 brazing Methods 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 15
- 239000002184 metal Substances 0.000 description 11
- 229910052751 metal Inorganic materials 0.000 description 11
- 239000000945 filler Substances 0.000 description 10
- 230000004907 flux Effects 0.000 description 9
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 8
- 239000010953 base metal Substances 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000012545 processing Methods 0.000 description 6
- 230000001737 promoting effect Effects 0.000 description 6
- 239000000428 dust Substances 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 230000002349 favourable effect Effects 0.000 description 4
- 238000010587 phase diagram Methods 0.000 description 4
- 238000005476 soldering Methods 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
- 230000000630 rising effect Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000013021 overheating Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 206010070834 Sensitisation Diseases 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 229910001338 liquidmetal Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000004021 metal welding Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 230000008313 sensitization Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000009617 vacuum fusion Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K1/00—Soldering, e.g. brazing, or unsoldering
- B23K1/008—Soldering within a furnace
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K1/00—Soldering, e.g. brazing, or unsoldering
- B23K1/20—Preliminary treatment of work or areas to be soldered, e.g. in respect of a galvanic coating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K1/00—Soldering, e.g. brazing, or unsoldering
- B23K1/20—Preliminary treatment of work or areas to be soldered, e.g. in respect of a galvanic coating
- B23K1/206—Cleaning
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K2103/00—Materials to be soldered, welded or cut
- B23K2103/02—Iron or ferrous alloys
- B23K2103/04—Steel or steel alloys
- B23K2103/05—Stainless steel
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention belongs to the technical field of stainless steel vacuum welding, and particularly relates to a method for performing stainless steel vacuum welding based on copper vapor deposition. According to the method for vacuum welding stainless steel by utilizing copper vapor deposition, a large amount of copper vapor is obtained by utilizing the characteristic that pure copper solder can volatilize in an unmelted state at a temperature lower than a melting point to form copper vapor in a large amount; meanwhile, copper vapor is controlled to gather, deposit and release heat at the stainless steel welding joint through copper vapor pressure to form a large amount of liquid copper solder, and then the stainless steel welding joint is filled through capillary action; and then along with the temperature change in the cooling process, the liquid solder at the joint can form a stainless steel welding joint after solidification, and then the welding of the welding joint is completed. The welding method can obtain a better stainless steel welding joint at a lower temperature, can reduce energy consumption and corrosion of liquid solder, and is an efficient, economical and reliable vacuum welding technology.
Description
Technical Field
The invention belongs to the technical field of stainless steel vacuum welding, and particularly relates to a method for performing stainless steel vacuum welding based on copper vapor deposition.
Background
A heat exchanger, also known as a heat exchanger, is a device that transfers a portion of the heat of a hot fluid to a cold fluid, and has wide application in chemical, petroleum, power, food, and many other industrial processes. At present, the heat exchanger is manufactured by adopting a vacuum copper brazing mode, namely copper brazing filler metal with a melting point lower than that of a base metal is adopted, a weldment and the brazing filler metal are heated to a temperature higher than the melting point of the brazing filler metal but lower than that of the base metal, at the moment, the brazing filler metal is melted, the base metal is still kept in a solid state, a gap between solid base metals is filled with liquid brazing filler metal by utilizing capillary action, the brazing filler metal penetrates, diffuses and interacts on the surface of the base metals, and then is cooled and solidified, so that a metallurgically bonded connection method is formed, and different base metal welding processes adopt different production technologies. The brazing mode has the advantages of small deformation, good base metal performance, capability of welding a plurality of parts at the same time, and the like.
However, in the conventional brazing process, since the copper brazing filler metal is largely volatilized at a melting stage in a vacuum high-temperature environment, a large amount of copper vapor is formed at a high temperature, and then deposition is performed in the cavity of the heat exchanger and a large amount of latent heat is released, so that the temperature of a local area of the stainless steel material is higher than the melting temperature of the stainless steel, namely, the local area of the heat exchanger is molten due to overheating, which is also a main reason for failure problems such as insufficient filling of the brazing filler metal in the heat exchanger, partial gap blockage, and overheating and melting corrosion of the local area. In addition, the problem that various soldering fluxes remain is unavoidable in the traditional welding process, after the soldering fluxes remain, the soldering fluxes are used for a long time, copper parts can be corroded to enable products to fail, and the residual soldering fluxes can rapidly generate copper green on the surfaces of the products, so that the appearance of the products is affected.
Therefore, how to improve the heat exchanger welding process is of great importance for improving the performance of the heat exchanger to apply stability, and for the development and production of the heat exchanger.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to provide a method for carrying out stainless steel vacuum welding based on copper vapor deposition, which utilizes a vacuum environment to obtain copper vapor at a temperature close to or lower than the melting point of pure copper solder and deposits the copper vapor at a stainless steel welding joint to form a deposited welding seam so as to solve the problem of unstable application performance of a heat exchanger caused by welding problems in the prior art;
the second technical problem to be solved by the invention is to provide a stainless steel welding product with stable application performance.
In order to solve the technical problems, the method for vacuum welding stainless steel based on copper vapor deposition comprises the following steps:
(1) Placing a stainless steel product to be welded and copper-containing solder in a vacuum environment together, adjusting the temperature of a reaction system, and controlling the volatilization of the pure copper solder to obtain copper vapor;
(2) Heat preservation is carried out when the stainless steel product is hot, and the copper vapor is controlled to be subjected to aggregation deposition and exothermic melting at the joint to be welded of the stainless steel product to form liquid solder;
(3) And cooling the system to solidify the liquid solder to form a weld joint, and finishing welding.
Specifically, in the step (1), the copper-containing solder is a solder capable of generating copper vapor at a high temperature, and more preferably, pure copper solder is used, and the amount of the pure copper solder is required to ensure that a small amount of copper vapor remains after the evaporation deposition of the copper solder, so that the sufficient evaporation amount of the copper vapor is ensured, the copper solder can be reasonably placed according to the length of a welding seam and a reserved gap, and the longer the welding seam, the more the amount of the solder.
Specifically, in the step (1), the step of adjusting the temperature of the reaction system includes a step of heating to perform gradient temperature rise and a step of heating to the highest temperature to perform heat preservation.
Specifically, in the step (1), the gradient heating step includes the following procedures:
the temperature of the system is controlled to be uniformly increased from 0 ℃ to 500-700 ℃ within 70-90 min;
controlling the temperature of the system to be 500-700 ℃ for heat preservation for 5-15min;
and controlling the temperature of the system to rise from 500-700 ℃ to the highest temperature value at a constant speed within 70-90 min.
Specifically, in the step (1), a processing technology curve is designed according to the volatilization characteristic and the melting point of the pure copper solder, and the highest temperature is controlled to be lower than the melting point of the copper solder;
preferably, the highest temperature of the vacuum welding reaction system is controlled to be 900-1100 ℃.
Specifically, in the step (2), the aggregate deposition step includes a step of performing thermal insulation deposition at the highest temperature.
Specifically, the heat preservation time of the reaction system at the highest temperature is controlled to be 10-200min, and the process comprises the process of controlling a large amount of copper vapor obtained in the step (1) and the heat preservation time of copper vapor deposited at the highest temperature in the step (2). In general, the adjustment and control of the heat preservation time can be performed according to the condition of the amount of pure copper solder, in theory, the larger the amount of the solder is, the longer the heat preservation time is required for generating copper vapor, the larger the obtained amount of the copper vapor is, and the more the amount of the solder is deposited at the welding seam, but in the actual welding process, the larger the amount of the solder is, the better the amount of the solder is, so that the adjustment and control of the heat preservation time can be performed according to the condition of the solder which is required conventionally by a person skilled in the art.
Specifically, in the step (3), the cooling step includes the following procedures:
within 40-60min, controlling the system temperature to be uniformly reduced to 40-60 ℃ from the highest temperature;
the temperature of the system is controlled to be 40-60 ℃ for heat preservation for 10-30min.
Preferably, in order to ensure the speed requirement of the whole cooling process, inert gas can be selectively introduced in the cooling process to increase the cooling speed, and preferably, a proper amount of inert gas such as nitrogen, argon and the like can be introduced to accelerate the cooling.
Preferably, in the step (1), the method further comprises a step of performing pretreatment such as degreasing and dust removal on the surface of the joint to be welded of the stainless steel product.
Specifically, in the step (1), the copper vapor deposition welding is performed in a vacuum environment, and the vacuum degree which is most favorable for the volatilization of pure copper solder is selected, and is generally controlled to be higher than 1×10 -1 Pa, the high vacuum degree is favorable for volatilization of the brazing filler metal.
Specifically, in the step (1), the pure copper solder is disposed in the cavity of the to-be-welded joint of the stainless steel product, and because the pure copper solder is disposed in the cavity of the to-be-welded joint of the stainless steel product, copper vapor is formed in the cavity of the stainless steel welding joint after the copper solder volatilizes, so that copper vapor pressure difference is generated between the inside and the outside of the cavity, and the copper vapor is collected at the stainless steel welding joint under the action of the vapor pressure difference, thereby completing deposition, heat release and solidification welding at the welding joint.
The invention also discloses a stainless steel welding product obtained by the vacuum welding method.
According to the method for vacuum welding stainless steel by utilizing copper vapor deposition, based on the research of the applicant on the traditional stainless steel copper welding technology, pure copper can volatilize in a large amount to form copper metal atomic clusters in an unmelted state at a temperature lower than a melting point in a vacuum environment, so that copper vapor generated when copper solder is unmelted or slightly melted in a vacuum welding heating process is utilized, copper vapor is attempted to be controlled by copper vapor pressure to deposit at a stainless steel gap to form a joint with better quality, and because the heat input at the low-temperature copper vapor deposition joint is smaller, the service performance of a heat exchanger can be improved, the production efficiency of the heat exchanger is enhanced, and meanwhile, the production cost of the heat exchanger is reduced. Therefore, the vacuum welding method of the invention utilizes the volatilization and deposition characteristics below the melting point of the brazing filler metal in the vacuum environment to carry out copper vapor deposition welding on the stainless steel welding joint, thereby being beneficial to saving production energy and effectively improving the application stability of the stainless steel welding product.
According to the method for vacuum welding stainless steel by utilizing copper vapor deposition, the characteristic that pure copper solder can volatilize in a large amount to form copper vapor in an unmelted state below a melting point temperature is utilized, and proper processing temperature and vacuum degree parameters are determined according to the characteristic and the melting point of the pure copper solder, so that a large amount of copper vapor is obtained, and favorable conditions are provided for copper vapor deposition; meanwhile, copper vapor is controlled to gather at the stainless steel welding joint through copper vapor pressure, copper vapor is deposited and releases heat to form a large amount of liquid copper solder, and the molten liquid copper solder deposited at the joint can fill the stainless steel welding joint through capillary action; and then along with the temperature change in the cooling process, the liquid solder at the joint can form a stainless steel welding joint after solidification, and then the welding of the welding joint is completed. The welding method can obtain a better stainless steel welding joint at a lower temperature, can reduce energy consumption and corrosion of liquid solder, and is an efficient, economical and reliable vacuum welding technology.
According to the method for vacuum welding stainless steel by utilizing copper vapor deposition, the pure copper solder is placed in the cavity of the to-be-welded joint of the stainless steel product, and the deposition joint is formed by utilizing vapor pressure to control copper vapor deposition at the stainless steel joint at a lower temperature by utilizing proper position setting, so that the use of energy sources can be reduced, and the failure problems of liquid metal corrosion, thermal corrosion and the like of the stainless steel vacuum brazing welding joint can be reduced by utilizing the copper vapor deposition welding at the lower temperature.
According to the method for vacuum welding stainless steel by utilizing copper vapor deposition, disclosed by the invention, the characteristic that pure copper solder can volatilize in a large amount to form copper vapor in an unmelted state below the melting point temperature is utilized, and the copper vapor deposited stainless steel welding joint can be formed at the temperature of 900 ℃ below the melting point of the pure copper solder. In particular, the copper solder is not melted or only slightly melted at a lower heating temperature, and the latent heat released by deposition of copper vapor at the stainless steel welding joint at a low temperature can not enable the temperature of the local stainless steel welding joint to reach the melting temperature of the stainless steel base metal, so that the occurrence of thermal corrosion in the welding process is effectively reduced.
The stainless steel welded product manufactured by the welding method has very slight thermal erosion phenomenon of copper on stainless steel at the copper vapor deposition joint, and compared with the traditional welding methods such as vacuum brazing, vacuum fusion welding and the like, the formed stainless steel welded joint has excellent mechanical properties and can meet the use requirement.
Drawings
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings, in which,
FIG. 1 is a view showing a vapor welding assembly of SUS304 stainless steel copper in example 1;
FIG. 2 is a graph showing a copper vapor welding process of SUS304 stainless steel in example 1;
FIG. 3 is a macroscopic view showing various angles of a copper vapor deposited SUS304 stainless steel welded joint in example 1;
FIG. 4 is a comparison of the golden phase diagrams of a copper vapor deposited SUS304 stainless steel welded joint and a braze welded joint in example 1, wherein (a) is a conventional braze joint and (b) is a copper vapor deposited joint; in fig. (b), the upper part is a copper deposition joint, and the lower part is SUS304 stainless steel;
FIG. 5 is an electron microscopic view of a copper vapor deposited SUS304 stainless steel welded joint in example 1, wherein (a) is a copper vapor deposited joint and (b) is a partially enlarged SEM image of a copper vapor deposited joint interface; wherein, in the figures (a) and (b), the upper part is a SUS304 stainless steel part, and the lower part is a copper deposition joint part;
FIG. 6 is a drawing showing tensile mechanical properties of a copper vapor deposited SUS304 stainless steel welded joint in example 1.
Detailed Description
Example 1
In this embodiment, pure copper solder is selected to perform copper vapor deposition welding on an SUS304 stainless steel weld, and the assembly diagram of the SUS304 stainless steel copper vapor welding is shown in fig. 1 (a) - (b), and the vacuum welding method comprises the following steps:
(1) Carrying out oil removal pretreatment on a joint of an SUS304 stainless steel welding piece by using acetone as a solvent, and carrying out dust removal pretreatment on the joint by using alcohol ultrasonic to obtain a stainless steel welding joint with a good surface environment for later use;
placing the pretreated SUS304 stainless steel welding piece and a sufficient amount of pure copper solder into a vacuum furnace, placing the pure copper solder into a cavity of a joint to be welded of a stainless steel product, volatilizing the copper solder to form copper vapor in the cavity of the stainless steel welding joint, and under a vacuum environment, so that copper vapor pressure difference is generated between the inside and the outside of the cavity, and the copper vapor is favorable for realizing aggregation of the copper vapor at the stainless steel welding joint under the action of the vapor pressure difference, thereby facilitating the subsequent deposition effect, and vacuumizing the vacuum furnaceTreating to make the vacuum degree in the vacuum furnace be 1×10 -2 Pa；
Determining a temperature control curve of a processing technology according to the characteristics and the melting point of the pure copper solder, wherein the temperature control curve is shown in the figure 2, setting the heating maximum temperature to 900 ℃, and heating the pure copper solder in vacuum to obtain a large amount of copper steam in a heating process below the melting point according to the process curve shown in the figure 2;
(2) The heat preservation is carried out at the temperature of 900 ℃ which is the highest temperature, and the generated copper vapor can be quickly and accurately gathered and deposited at the SUS304 stainless steel joint due to the internal and external pressure difference formed by the copper vapor at the welding cavity; in the heat preservation process, a great amount of heat is emitted by copper vapor when the stainless steel welding joint is deposited, so that a deposition layer near the joint is melted to form liquid solder, and the molten liquid copper solder deposited at the joint can fill the stainless steel welding joint through capillary action;
(3) And cooling according to the process curve shown in figure 2, and solidifying the liquid solder at the joint to form a stainless steel welding joint during cooling to finish welding the welding seam.
The temperature profile of the SUS304 stainless steel copper vapor welding process as shown in fig. 2 can be seen from the temperature profile in the drawings:
heating the system temperature in the vacuum furnace at a constant speed in 0-80min after the reaction starts, controlling the system temperature to rise from 0 ℃ to 600 ℃, and then preserving heat at 600 ℃ in a temperature interval of 80-90min, wherein the aim of the step is to control the temperature transmission in the brazing furnace to be more uniform, and simultaneously changing the heating rate; then in the temperature range of 90-170min, the temperature of the system is controlled to be uniformly increased from 600 ℃ to 900 ℃, namely the highest temperature of the whole reaction is reached; in the whole heating process, pure copper solder can start to form copper vapor through volatilization;
then, in the interval of 170-320min, controlling the temperature in the vacuum furnace to maintain 900 ℃ for heat preservation, wherein in the step, on one hand, the pure copper solder can be further promoted to be volatilized continuously to obtain a large amount of copper steam, and meanwhile, the copper steam is promoted to be accumulated and deposited at the SUS304 stainless steel joint; in the heat preservation process, a great amount of heat is emitted by copper vapor when the stainless steel welding joint is deposited, so that a deposition layer near the joint is melted to form liquid solder, and the molten liquid copper solder deposited at the joint can fill the stainless steel welding joint through capillary action;
and then, in the interval of 320-370min, controlling the temperature in the vacuum furnace to be uniformly reduced to 50 ℃ at 900 ℃, and preserving heat in the interval of 370-390min, wherein as the system is reduced in temperature, the liquid solder deposited at the joint can be solidified to form a stainless steel welding joint, so that the welding of the welding seam is completed.
The macroscopic views of the copper vapor deposition SUS304 stainless steel welded joint at different angles are shown in (a) - (c) of fig. 3, and it can be seen that the welded joint obtained by the welding method of the invention has good surface morphology, no obvious holes and cracks at the joint, and no obvious welding defects.
The golden phase diagram of the copper vapor deposited SUS304 stainless steel welded joint according to the present embodiment is shown in FIG. 4, wherein (a) is the golden phase diagram of the joint obtained by the conventional copper brazing method, and (b) is the golden phase diagram of the copper vapor deposited joint according to the present embodiment. Comparing the two figures, the phenomenon that the joint obtained by the traditional copper brazing mode is obviously corroded by stainless steel and the liquid copper solder permeates into the grain boundary can be seen; the copper vapor deposition joint of the embodiment does not have the phenomenon of stainless steel surface melting, and does not have the phenomenon of liquid braze welding flux penetration to the stainless steel grain boundary.
The electron microscopic images of the copper vapor deposited SUS304 stainless steel welded joint according to the present example are shown in fig. 5 (a) - (b). It can be seen that the liquid copper wets well in the stainless steel matrix and the copper vapor deposited joint interface is flat and defect free.
The tensile mechanical properties of the copper vapor deposited SUS304 stainless steel welded joint described in this example are shown in fig. 6 (a) - (b). It can be seen that the copper vapor deposition joint does not have shear fracture but fracture occurs at the SUS304 stainless steel, which indicates that the shear strength of the deposition joint is higher than the tensile strength of the SUS304 stainless steel matrix, and the mechanical properties of the joint meet the use requirements.
Comparative example 1
The stainless steel vacuum welding method of the comparative example is the same as that of example 1, and is only different in that in the heating step of step (1), the temperature of the system in the vacuum furnace is heated in a uniform gradient manner within a time interval of 0-170min, and the temperature of the system is controlled to be raised from 0 ℃ to 900 ℃.
In the welding process of the method described in the comparative example, the vacuum furnace is damaged by the excessively high heating rate at the high temperature of the vacuum furnace.
Comparative example 2
The difference between the stainless steel vacuum welding method of the present comparative example and the stainless steel vacuum welding method of example 1 is that in the heating step of step (1), the temperature of the system in the vacuum furnace is controlled to be uniformly and gradient heated within 0-90min after the reaction starts, the temperature of the system is controlled to be increased from 0 ℃ to 600 ℃, and then the temperature of the system is controlled to be uniformly increased from 600 ℃ to 900 ℃ within a temperature interval of 90-170 min.
In the welding process of the method of the comparative example, the temperature distribution in the cavity is uneven due to the fact that heat preservation at a low temperature stage is not carried out, and the effect of the welding surface of a product is affected.
Comparative example 3
The difference between the stainless steel vacuum welding method of the present comparative example and the stainless steel vacuum welding method of example 1 is that in the heating step of step (1), the temperature of the system in the vacuum furnace is controlled to be uniformly and gradient heated within 0-80min after the reaction starts, the temperature of the system is controlled to be increased from 0 ℃ to 600 ℃, and then the temperature of the system is controlled to be uniformly increased from 600 ℃ to 900 ℃ within the temperature interval of 80-170 min.
In the welding process of the method of the comparative example, the heating rate of the high-temperature section is low, the copper vapor deposition efficiency is affected, and meanwhile, the temperature distribution in the cavity is not uniform due to the fact that the heat preservation in the low-temperature stage is avoided.
Comparative example 4
The stainless steel vacuum welding method of the present comparative example is the same as that of example 1, and is different from that of example 1 only in that in the cooling step of step (3), the temperature in the vacuum furnace is controlled to be cooled to 50 ℃ at a constant speed at 900 ℃ within a period of 320-390 min.
In the welding process of the method of the comparative example, the overlong cooling time can lead to sensitization of the stainless steel matrix, and the quality of weldments is affected.
Comparative example 5
The stainless steel vacuum welding method of this comparative example was the same as example 1 except that the stainless steel weld was placed in a vacuum furnace without contact with the pure copper solder.
In the welding process of the method of the comparative example, copper vapor volatilized by pure copper solder cannot be effectively diffused to the welding joint, and the expected welding effect cannot be formed.
Example 2
In this embodiment, pure copper solder is selected to perform copper vapor deposition welding on an SUS304 stainless steel weld, and the SUS304 stainless steel copper vapor welding assembly structure is the same as that in example 1, and the vacuum welding method includes the following steps:
(1) Carrying out oil removal pretreatment on a joint of an SUS304 stainless steel welding piece by using acetone as a solvent, and carrying out dust removal pretreatment on the joint by using alcohol ultrasonic to obtain a stainless steel welding joint with a good surface environment for later use;
placing the pretreated SUS304 stainless steel welding piece and pure copper welding flux into a vacuum furnace, placing the pure copper welding flux into a cavity of a joint to be welded of the stainless steel product, facilitating copper vapor to gather at the cavity, and vacuumizing the vacuum furnace to ensure that the vacuum degree in the vacuum furnace is 1 multiplied by 10 -2 Pa；
Determining that the highest heating temperature of the processing technology is 1000 ℃ according to the characteristics and the melting point of the pure copper solder, and starting to volatilize a large amount of copper steam in the vacuum in the heating process of the pure copper solder below the melting point to obtain copper steam;
(2) Heat preservation is carried out at the temperature of rising to the highest temperature of 1000 ℃, and copper vapor is accumulated and deposited at the SUS304 stainless steel joint; in the heat preservation process, a great amount of heat is emitted by copper vapor when the stainless steel welding joint is deposited, so that a deposition layer near the joint is melted to form liquid solder, and the molten liquid copper solder deposited at the joint can fill the stainless steel welding joint through capillary action;
(3) And cooling according to the following procedure, and solidifying the liquid solder at the joint to form a stainless steel welding joint during cooling to finish welding the welding seam.
In this embodiment, the temperature control procedure for the whole welding process is as follows:
heating the system temperature in the vacuum furnace at constant speed in 0-70min after the reaction starts, controlling the system temperature to rise from 0 ℃ to 500 ℃, then carrying out 500 ℃ heat preservation in a temperature interval of 70-80min, and then controlling the system temperature to rise from 500 ℃ to 1000 ℃ at constant speed in a temperature interval of 80-170min, so as to achieve the highest temperature of the whole reaction; in the whole heating process, pure copper solder can start to form copper vapor through volatilization;
then, in the interval of 170-320min, controlling the temperature in the vacuum furnace to maintain 1000 ℃ for heat preservation, further promoting the volatilization of the pure copper solder to obtain a large amount of copper vapor, and simultaneously promoting the copper vapor to gather and deposit at the SUS304 stainless steel joint; in the heat preservation process, a great amount of heat is emitted by copper vapor when the stainless steel welding joint is deposited, so that a deposition layer near the joint is melted to form liquid solder, and the molten liquid copper solder deposited at the joint can fill the stainless steel welding joint through capillary action;
and then, in the interval of 320-360min, controlling the temperature in the vacuum furnace to be uniformly reduced to 60 ℃ at 1000 ℃, and preserving heat in the interval of 360-370min, wherein as the system is cooled, the liquid solder deposited at the joint can be solidified to form a stainless steel welding joint, so that the welding of the welding seam is completed.
Example 3
In this embodiment, pure copper solder is selected to perform copper vapor deposition welding on an SUS304 stainless steel weld, and the SUS304 stainless steel copper vapor welding assembly structure is the same as that in example 1, and the vacuum welding method includes the following steps:
(1) Carrying out oil removal pretreatment on a joint of an SUS304 stainless steel welding piece by using acetone as a solvent, and carrying out dust removal pretreatment on the joint by using alcohol ultrasonic to obtain a stainless steel welding joint with a good surface environment for later use;
placing the pretreated SUS304 stainless steel welding piece and pure copper solder into a vacuum furnace, placing the pure copper solder into a cavity of a joint to be welded of the stainless steel product, facilitating copper vapor to gather at the cavity, and vacuumizing the vacuum furnace to ensure that the stainless steel product is trueVacuum degree in empty furnace is 1 x 10 -2 Pa；
Determining that the highest heating temperature of the processing technology is 1100 ℃ according to the characteristics and the melting point of the pure copper solder, and starting to volatilize a large amount of copper steam in the vacuum in the heating process of the pure copper solder below the melting point to obtain copper steam;
(2) Heat preservation is carried out at the temperature of rising to the highest temperature of 1100 ℃, and copper vapor is accumulated and deposited at the SUS304 stainless steel joint; in the heat preservation process, a great amount of heat is emitted by copper vapor when the stainless steel welding joint is deposited, so that a deposition layer near the joint is melted to form liquid solder, and the molten liquid copper solder deposited at the joint can fill the stainless steel welding joint through capillary action;
(3) And cooling according to the following procedure, and solidifying the liquid solder at the joint to form a stainless steel welding joint during cooling to finish welding the welding seam.
In this embodiment, the temperature control procedure for the whole welding process is as follows:
heating the system temperature in the vacuum furnace at constant speed and gradient within 0-90min after the reaction starts, controlling the system temperature to rise from 0 ℃ to 700 ℃, then carrying out 700 ℃ heat preservation within a temperature range of 90-95min, and then controlling the system temperature to rise from 700 ℃ to 1100 ℃ at constant speed within a temperature range of 95-180min, namely, the highest temperature of the whole reaction is reached; in the whole heating process, pure copper solder can start to form copper vapor through volatilization;
then, in the interval of 180-330min, controlling the temperature in the vacuum furnace to maintain 1100 ℃ for heat preservation, further promoting the volatilization of the pure copper solder to obtain a large amount of copper vapor, and simultaneously promoting the copper vapor to gather and deposit at the SUS304 stainless steel joint; in the heat preservation process, a great amount of heat is emitted by copper vapor when the stainless steel welding joint is deposited, so that a deposition layer near the joint is melted to form liquid solder, and the molten liquid copper solder deposited at the joint can fill the stainless steel welding joint through capillary action;
then, in the interval of 330-380min, the temperature in the vacuum furnace is controlled to be uniformly reduced to 40 ℃ at 1100 ℃, and the temperature is kept in the interval of 380-400min, and as the system is reduced in temperature, the liquid solder deposited at the joint is solidified to form a stainless steel welding joint, so that the welding of the welding seam is completed.
Example 4
In this embodiment, pure copper solder is selected to perform copper vapor deposition welding on an SUS304 stainless steel weld, and the SUS304 stainless steel copper vapor welding assembly structure is the same as that in example 1, and the vacuum welding method includes the following steps:
(1) Carrying out oil removal pretreatment on a joint of an SUS304 stainless steel welding piece by using acetone as a solvent, and carrying out dust removal pretreatment on the joint by using alcohol ultrasonic to obtain a stainless steel welding joint with a good surface environment for later use;
placing the pretreated SUS304 stainless steel welding piece and pure copper welding flux into a vacuum furnace, placing the pure copper welding flux into a cavity of a joint to be welded of the stainless steel product, facilitating copper vapor to gather at the cavity, and vacuumizing the vacuum furnace to ensure that the vacuum degree in the vacuum furnace is 1 multiplied by 10 -2 Pa；
Determining that the highest heating temperature of the processing technology is 900 ℃ according to the characteristics and the melting point of the pure copper solder, and starting to volatilize a large amount of copper steam in the vacuum in the heating process of the pure copper solder below the melting point to obtain copper steam;
(2) Heat preservation is carried out at the temperature of rising to the highest temperature of 900 ℃, and copper vapor is accumulated and deposited at the SUS304 stainless steel joint; in the heat preservation process, a great amount of heat is emitted by copper vapor when the stainless steel welding joint is deposited, so that a deposition layer near the joint is melted to form liquid solder, and the molten liquid copper solder deposited at the joint can fill the stainless steel welding joint through capillary action;
(3) And cooling according to the following procedure, and solidifying the liquid solder at the joint to form a stainless steel welding joint during cooling to finish welding the welding seam.
In this embodiment, the temperature control procedure for the whole welding process is as follows:
heating the system temperature in the vacuum furnace at a constant speed in 0-80min after the reaction starts, controlling the system temperature to rise from 0 ℃ to 600 ℃, then carrying out 900 ℃ heat preservation in a temperature range of 80-90min, and then controlling the system temperature to rise from 600 ℃ to 900 ℃ at a constant speed in a temperature range of 90-160min, so as to achieve the highest temperature of the whole reaction; in the whole heating process, pure copper solder can start to form copper vapor through volatilization;
then, in the interval of 160-310min, controlling the temperature in the vacuum furnace to maintain 900 ℃ for heat preservation, further promoting the volatilization of the pure copper solder to obtain a large amount of copper vapor, and simultaneously promoting the copper vapor to gather and deposit at the SUS304 stainless steel joint; in the heat preservation process, a great amount of heat is emitted by copper vapor when the stainless steel welding joint is deposited, so that a deposition layer near the joint is melted to form liquid solder, and the molten liquid copper solder deposited at the joint can fill the stainless steel welding joint through capillary action;
and then, in the interval of 310-360min, controlling the temperature in the vacuum furnace to be uniformly reduced to 50 ℃ at 900 ℃, and preserving heat in the interval of 360-390min, wherein as the system is cooled, the liquid solder deposited at the joint can be solidified to form a stainless steel welding joint, so that the welding of the welding seam is completed.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (8)
1. A method for vacuum welding stainless steel based on copper vapor deposition, comprising the steps of:
(1) Placing a stainless steel product to be welded and pure copper solder in a vacuum environment together, adjusting the temperature of a reaction system, and controlling the volatilization of the pure copper solder to obtain copper vapor;
the step of adjusting the temperature of the reaction system comprises the step of heating to perform gradient temperature rise and the step of heating to the highest temperature to perform heat preservation;
controlling the highest temperature to be lower than the melting point of the pure copper solder;
(2) Heat preservation is carried out when the stainless steel product is hot, and the copper vapor is controlled to be subjected to aggregation deposition and exothermic melting at the joint to be welded of the stainless steel product to form liquid solder;
the aggregation deposition step comprises the step of carrying out heat preservation deposition at the highest temperature;
(3) And cooling the system to solidify the liquid solder to form a weld joint, and finishing welding.
2. The method of vacuum welding stainless steel based on copper vapor deposition according to claim 1, wherein in said step (1), said gradient heating step comprises the following procedure:
the temperature of the system is controlled to be uniformly increased from 0 ℃ to 500-700 ℃ within 70-90 min;
controlling the temperature of the system to be 500-700 ℃ for heat preservation for 5-15min;
and controlling the system temperature to rise from 500-700 ℃ to the highest temperature at a constant speed within 70-90 min.
3. The method for vacuum welding of stainless steel based on copper vapor deposition according to claim 1 or 2, wherein in said step (1), the maximum temperature of said reaction system is controlled to 900-1100 ℃.
4. A method for vacuum welding of stainless steel based on copper vapor deposition according to any of claims 1-3, characterized in that the holding time of the reaction system at the highest temperature is controlled to be 10-200min.
5. The method of vacuum welding stainless steel based on copper vapor deposition according to any one of claims 1 to 4, wherein in said step (3), said cooling step comprises the following procedure:
within 40-60min, controlling the system temperature to be uniformly reduced to 40-60 ℃ from the highest temperature;
the temperature of the system is controlled to be 40-60 ℃ for heat preservation for 10-30min.
6. The method for vacuum welding of stainless steel based on copper vapor deposition according to any one of claims 1 to 5, wherein in said step (1), the vacuum degree of said vacuum atmosphere is controlled to be higher than 1 x 10 -1 Pa。
7. The method of vacuum welding stainless steel based on copper vapor deposition according to any one of claims 1-6, wherein in said step (1), said pure copper solder is placed inside the cavity of the joint to be welded of said stainless steel article.
8. Stainless steel welded article obtainable by the method of vacuum welding according to any one of claims 1-7.
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