CN109290749B - Furnace tube local high-temperature forging and welding method - Google Patents
Furnace tube local high-temperature forging and welding method Download PDFInfo
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- CN109290749B CN109290749B CN201811346706.8A CN201811346706A CN109290749B CN 109290749 B CN109290749 B CN 109290749B CN 201811346706 A CN201811346706 A CN 201811346706A CN 109290749 B CN109290749 B CN 109290749B
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Abstract
A furnace tube local high-temperature forging welding method comprises the following steps: 1) cutting the furnace tube, namely cutting off the welding part of the furnace tube to form an end head to be welded at the cutting position; 2) polishing the end, namely polishing the end part to be welded by using an angle polishing sheet of 1-2 mm through an angle grinder; 3) heating, namely heating the polished end part by using a heat source, and controlling the temperature of the welding part to be 570-630 ℃; 4) knocking and forging, namely immediately adopting a forging device after removing a heat source to knock and forge the heated welding part; 5) and end welding, namely symmetrically welding the forged welding part. The invention causes the coarse grains of carbide precipitated on the metal surface of the old furnace tube to be distorted and deformed and become more compact within a certain depth range, thereby generating larger tensile strength, enabling the metal to effectively absorb and dissolve the shrinkage stress generated in the welding process, improving the crack resistance of the metal and enhancing the weldability of the furnace tube.
Description
Technical Field
The invention relates to a furnace tube local high-temperature forging welding method, and belongs to the technical field of welding.
Background
At present, the most remarkable characteristics of the high-temperature alloy material in the using process are as follows: as the temperature rises until the working temperature is 830-890 ℃ and the material is used for a long time, the carbide in the material in the temperature range completes segregation along the metal grain boundary from 10-1000 hours of the initial work, the precipitation of the carbide is transformed from the initial small block to the coherent large block carbide with longer service time, and the precipitation of the carbide is the final purpose of researching the material, so that the material is more stable in the high temperature resistant process.
With the increase of the service process of the material, carbide is continuously precipitated, the weldability of the material becomes worse and worse, mainly because a large amount of carbide is gathered in the metal crystal boundary of the material, the tensile strength becomes worse, the material is easy to crack along the crystal boundary under the action of welding shrinkage stress or other tensile stress, and in addition, the characteristic of large expansion coefficient and small heat conductivity coefficient of the material is caused by the poor heat conductivity of the material, and the cracking tendency of the material is further caused. Referring to fig. 1, the weldability of the new material is very good, but the furnace tube material increases with the service time, and the precipitates on the metal surface of the furnace tube gradually increase, and when the furnace tube is welded with the new furnace tube, the side close to the old furnace tube cracks along the grain boundary in the heat affected zone.
Referring to fig. 2, the structure crystal grains on the surface of the furnace tube after a period of use become extremely coarse due to precipitation of carbides, resulting in a decrease in mechanical properties such as tensile strength, which is a main cause of cracking encountered during welding of the old and new furnace tubes. In the traditional welding method, the cut end of the furnace tube is melted by an electric arc of argon arc welding on the groove with the current of 100A-120A without filling metal, and then is recrystallized, and is cooled to room temperature and then is subjected to PT inspection, the detection result can indicate the weldability of the metal, if the detection result is one-grade or a very small amount of cracks with the length not exceeding 1mm, the weldability of the metal is better, and if the cracks are serious, the weldability of the metal is very poor. When the whole groove is burnt or spray-shaped splashing is generated under the high temperature of the electric arc of the argon arc welding, the metal does not have weldability.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a method for forging and welding the local part of the furnace tube at high temperature, so that the metal furnace tube can effectively absorb and dissolve the shrinkage stress generated in the welding process, and the crack resistance of the metal furnace tube is improved.
The technical scheme for solving the technical problems is as follows: a furnace tube local high-temperature forging welding method comprises the following steps:
1) cutting the furnace tube, namely cutting off the welding part of the furnace tube to form an end head to be welded at the cutting position;
2) polishing the end, namely polishing the end part to be welded by using an angle polishing sheet of 1-2 mm through an angle grinder;
3) heating, namely heating the polished end part by using a heat source, and controlling the temperature of the welding part to be 570-630 ℃;
4) knocking and forging, namely immediately adopting a forging device after removing a heat source to knock and forge the heated welding part;
5) and (4) end welding, namely welding the forged welding part.
As a preferable scheme of the furnace tube local high-temperature forging welding method, in the step 3), the heat source adopts alkyne oxygen flame or a resistance heating belt.
As a preferable scheme of the furnace tube local high-temperature forging welding method, in the step 4), the forging device adopts a hand hammer or a pneumatic pick, and the hand hammer or the pneumatic pick is wrapped with austenite alloy.
As a preferable scheme of the furnace tube local high-temperature forging welding method, in the step 4), a forging device is adopted to uniformly forge the periphery of the groove of the part to be welded within a range of 50-70 mm.
As a preferable scheme of the furnace tube local high-temperature forging welding method, in the step 4), the forging depth of the welding part is 3-5 mm.
As a preferable scheme of the furnace tube local high-temperature forging welding method, the step 5) further includes performing PT inspection on the forged to-be-welded part, and cleaning the detected groove crack of the welded part.
As a preferable scheme of the furnace tube local high-temperature forging welding method, the step 5) further comprises the steps of plugging a 95-105mm position in the furnace tube by adopting a paper pasting mode, and performing local argon filling backing protection.
As a preferable scheme of the furnace tube local high-temperature forging welding method, the step 5) further comprises the steps of carrying out area equalization on the end to be welded, welding the equalized end in a symmetrical mode, and knocking a welding bead after arc extinguishing welding.
The invention has the beneficial effects that: through the procedures of furnace tube cutting, end polishing, heating treatment, knocking forging, end welding and the like, the polished end part is heated by using a heat source, the temperature of the welding part is controlled to be 570-630 ℃, so that coarse grains of carbide precipitated on the metal surface of an old furnace tube are distorted and deformed and become more compact within a certain depth range, and therefore, the large tensile strength is generated, the metal can effectively absorb and dissolve the shrinkage stress generated in the welding process, the crack resistance of the metal is improved, and the weldability of the furnace tube is enhanced.
Drawings
FIG. 1 is a metallographic view of a new furnace tube material as described in the background;
FIG. 2 is a gold phase diagram of the furnace tube material after use as described in the background art;
FIG. 3 is a flowchart of a furnace tube local high temperature forging and welding method according to an embodiment of the present invention;
FIG. 4 is a metallographic diagram of a furnace tube before being processed according to the embodiment of the present invention;
FIG. 5 is a metallographic image of a furnace tube treated according to the embodiment of the present invention;
fig. 6 is a schematic diagram of welding performed in a symmetrical manner according to an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 3, 4 and 5, in the present embodiment, a furnace tube local high temperature forging welding method is provided, where the welding method includes the following steps:
s1: cutting the furnace tube, namely cutting the welding part of the furnace tube to form an end head to be welded at the cut position;
s2: polishing the end, namely polishing the end part to be welded by using an angle polishing sheet of 1-2 mm through an angle grinder;
s3: heating, namely heating the polished end part by using a heat source, and controlling the temperature of the welding part to be 570-630 ℃;
s4: knocking and forging, namely immediately adopting a forging device after removing a heat source to knock and forge the heated welding part;
s5: and (4) end welding, namely welding the forged welding part.
In one embodiment of the method, the welding is argon arc welding, and the main preparation tool before welding comprises the following steps: an angle grinder; slicing 1-1.2 mm; 1.5-2 pounds of a tip dome throwing hammer, wherein the radius of a small dome is about 3mm (or a pneumatic small air pick); one set of argon arc welding machines which are professional argon arc welding machines with attenuation; the argon meter and the argon are provided with a plurality of bands. And carrying out PT inspection before welding, and if a problem is found, cleaning the small crack of the end groove and carrying out welding. The back lining gas is fully considered before welding, because the whole furnace tube system is large and argon cannot be filled into the whole system for welding, the best method is to paste paper easy to carbonize in the furnace tube about 100mm for plugging, and the back lining is partially filled with argon for protection.
The PT test related to the embodiment, in particular, the PT test after argon arc welding remelting is an important index for evaluating the weldability of the furnace tube. The method comprises the following steps: melting the cut end of the furnace tube by using an electric arc of argon arc welding to the groove with a current of 100A-120A without adding filling metal, then recrystallizing, cooling to room temperature, and then carrying out PT inspection, wherein the detection result can indicate the weldability of the metal, if the detection result is a first-grade crack or a very small amount of cracks with the length not exceeding 1mm, the weldability of the metal is better, and if the cracks are serious, the weldability of the metal is very poor. When the whole groove is burnt or spray-shaped splashing is generated under the high temperature of the electric arc of the argon arc welding, the metal does not have weldability.
The compositions of the furnace tubes to be welded are as follows:
| composition (I) | C | Si | Mn | P | S | Mo |
| ％ | 0.35-0.45 | 1.00-2.00 | 1.00-2.00 | ≤0.30 | ≤0.30 | ≤0.50 |
| Composition (I) | Cr | Ni | Nb | |||
| ％ | 24.0-28.0 | 33.0-37.0 | 0.80-1.50 |
Specifically, after the furnace tube is cut off, the grinding is carried out by using an angle grinder, but an angle grinding plate needs to be carried out by using a 1-1.2mm slice, so that the over-high temperature of local grinding is prevented. Because the old furnace tube can generate cracks due to overhigh local temperature in the grinding process, the cracks are also caused by grain boundary cracking generated by nonuniform heating after carbide of the grain boundary is precipitated. Forging by adopting a heating method. The acetylene oxygen flame or the resistance heating belt is used for heating, the flame heating can not uniformly heat the whole groove, so that the local high-temperature forging is carried out, a throwing hammer or a pneumatic small air pick is generally adopted in the knocking and pressurizing process, and a layer of austenite alloy is added on a handle hammer or an air pick head for forging before forging. The heating temperature is generally within the range of 570-630 ℃, after heating, the flame is removed, and the heating part is rapidly knocked and forged by a hand hammer or a small air pick until the forging is completed uniformly within the range of 50-70mm around the groove, the forging depth is generally within the range of 3-5mm, and the process is finished.
Referring to fig. 6, the area of the end to be welded is equally divided, and the evenly divided end is welded in a symmetrical manner. Through pairing and spot welding, the weld gap is determined according to the diameter of the welding wire, generally phi +1-1.5mm of the diameter of the welding wire, the spot welding position is generally (1.2.3 points), and welding is started at the 4 th point. And (3) adopting symmetrical welding, namely welding the area a, then welding the area b, then welding the area c and finally welding the area d. Multilayer multi-pass welding and the like.
When the method of the embodiment is adopted, during welding, attention is paid to nickel-based welding materials are generally selected when the welding materials are required to be selected again because the strength of the used furnace tube in service is changed. A special welding process is needed during welding: the welding wire is additionally added at the arc closing point to make the welding wire bulge, and the welding channel is knocked after the arc is closed. Specifically, after the bottom layer is finished, the filling layer is welded to one side of the old furnace pipe, and finally the filling layer is welded to one side of the new furnace pipe. And stopping arc after welding for 80-100mm each time, and immediately knocking and forging by using a throwing hammer or a small pneumatic pick to eliminate stress, so that the crack tendency is reduced.
After welding, the welding can be qualified by adopting ray inspection (RT) II or above, and penetration inspection (PT) I grade is qualified. Finally, the air tightness test is carried out, and the test pressure can be carried out according to the design pressure or 1.2-1.5 times of the working pressure.
The local high-temperature forging method is adopted for welding the lower collecting pipe of a certain petrochemical hydrogen production converter and the reinforced joint of the lower collecting pipe, so that the stable operation time of the equipment is obviously increased.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (8)
1. A furnace tube local high-temperature forging welding method is characterized in that: the welding method comprises the following steps:
1) cutting the furnace tube, namely cutting off the welding part of the furnace tube to form an end head to be welded at the cutting position;
2) polishing the end, namely polishing the end part to be welded by using an angle polishing sheet of 1-2 mm through an angle grinder;
3) heating, namely heating the polished end part by using a heat source, and controlling the temperature of the welding part to be 570-630 ℃;
4) knocking and forging, namely immediately adopting a forging device after removing a heat source to knock and forge the heated welding part;
5) and (4) end welding, namely welding the forged welding part.
2. The furnace tube local high-temperature forging welding method according to claim 1, characterized in that: in the step 3), the heat source adopts alkyne oxygen flame or a resistance heating belt.
3. The furnace tube local high-temperature forging welding method according to claim 1, characterized in that: in the step 4), the forging device adopts a hand hammer or a pneumatic pick head, and the hand hammer or the pneumatic pick head is wrapped with austenitic alloy.
4. The furnace tube local high-temperature forging welding method according to claim 1, characterized in that: and in the step 4), uniformly forging the periphery of the groove of the part to be welded within a range of 50-70mm by adopting a forging device.
5. The furnace tube local high-temperature forging welding method according to claim 1, characterized in that: in the step 4), the forging depth of the welding part is 3-5 mm.
6. The furnace tube local high-temperature forging welding method according to claim 1, characterized in that: and the step 5) also comprises the steps of carrying out PT inspection on the forged part to be welded and cleaning the detected groove cracks of the welding part.
7. The furnace tube local high-temperature forging welding method according to claim 1, characterized in that: and the step 5) also comprises the steps of plugging a 95-105mm position in the furnace tube by adopting a paper pasting mode and carrying out local argon filling backing protection.
8. The furnace tube local high-temperature forging welding method according to claim 1, characterized in that: the step 5) also comprises the steps of carrying out area equalization on the end head to be welded, and welding the equalized end head in a symmetrical mode; knocking the welding bead after arc extinguishing.
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| US8353785B2 (en) * | 2009-04-23 | 2013-01-15 | Taylor Made Golf Company, Inc. | Golf club head |
| CN105448308B (en) * | 2014-08-27 | 2019-04-09 | 祥和科技有限公司 | It is used to form the method and apparatus with the hard disk drive substrate for extending height |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1515804A (en) * | 2003-01-02 | 2004-07-28 | 金英基 | Eccentric rotation shaft and electric motor shaft mfg. method |
| CN1872477A (en) * | 2003-05-10 | 2006-12-06 | 韩国电力技术株式会社 | Local heatsink welding device and welding method thereof |
| CN102463402A (en) * | 2010-11-18 | 2012-05-23 | 成都植源机械科技有限公司 | Process for welding medium-high carbon steel without cracking and deformation |
| CN102764988A (en) * | 2011-05-06 | 2012-11-07 | 浦杰 | High temperature resistant alloy furnace tube and machining production line of tube bundle |
| CN105598599A (en) * | 2015-03-26 | 2016-05-25 | 中国科学院金属研究所 | Cylindrical metal construction method |
| CN107322159A (en) * | 2017-06-12 | 2017-11-07 | 广东工业大学 | Metal dual-laser beam impact forges low stress welder and method |
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Effective date of registration: 20190709 Address after: 264006 No. 7, No. 11 Jinshajiang Road, Yantai Economic and Technological Development Zone, Shandong Province Applicant after: Sun Qingguang Address before: 264006 No. 7, No. 11 Jinshajiang Road, Yantai Economic and Technological Development Zone, Shandong Province Applicant before: Yantai Mudi Industrial Technology Co., Ltd. |
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Effective date of registration: 20210121 Address after: Room 907, 9 / F, North building, Lihu science and technology innovation center, 9 Wuhu Avenue, Wuxi City, Jiangsu Province, 214000 Patentee after: Jiangsu Zhijian Industrial Technology Co.,Ltd. Address before: 264006 No. 7, No. 11 Jinshajiang Road, Yantai Economic and Technological Development Zone, Shandong Province Patentee before: Sun Qingguang |