Tempering weld bead repairing process for low alloy steel postweld-free heat treatment

Abstract

The invention provides a tempering weld bead repairing process for low alloy steel post-weld-free heat treatment. The tempering weld bead repairing process comprises the steps that a to-be-repaired area of base metal is polished to be in metallic luster; the area to be repaired is preheated to 180-230 DEG C in a flame heating or heat radiation heating mode; a welding material and a corresponding welding process are selected for welding in the to-be-repaired area to form a first transition layer; a second transition layer is formed on the first transition layer through welding by selecting a welding material and a welding process which are the same as those for welding the first transition layer; a welding material and a welding process which are the same as those for welding the first transition layer are selected to weld and form a filling layer on the second transition layer until the to-be-repaired area is filled with the filling layer; a covering layer is formed on the filling layer through welding; and the cover surface layer is polished and removed, and welding repair is completed. According to the method, the existing RCC-M and RSE-M standard requirements are broken through, the optimized process more reasonable than the standard requirements is obtained, and the better welding joint performance is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a tempering weld repair process for low alloy steel without post-weld heat treatment. Background Art

[0002] Pressure-bearing special equipment will inevitably be damaged or even defective during service. Usually, welding repair or replacement of spare parts is used to eliminate the damage or defect to ensure the integrity of the equipment structure. During the welding repair process, due to the effect of welding thermal cycle, the residual stress of the repaired part increases, the hardness increases, and the toughness of the heat-affected zone deteriorates. Post-weld heat treatment is usually required to improve the performance. However, some objective conditions limit the application of post-weld heat treatment, so a welding repair technology without post-weld heat treatment came into being - Temper Bead Welding (TBW).

[0003] Tempering bead welding technology: the weld bead is clad at a specific position or weld surface, the purpose is to affect the metallurgical properties of the heat-affected zone or the previously clad weld metal. Tempering bead welding technology can effectively improve the microstructure and properties of the heat-affected zone of the multi-layer multi-pass weld base material by reasonably controlling the geometric size of the weld bead, the weld bead overlap and the welding heat input. There are many parameters that affect the microstructure and properties of the tempering bead technology after welding, such as electrode diameter, welding heat input, weld bead overlap, weld bead grinding, etc. Among them, the heat input, weld bead overlap, etc. directly affect the geometric size distribution of the weld bead, and then affect the distribution of the hardened microstructure generated between adjacent welds, which directly determines the success of the tempering bead welding technology. Summary of the invention

[0004] In view of the shortcomings of the prior art mentioned above, the purpose of the present invention is to provide a tempering weld repair process for low alloy steel without post-weld heat treatment. Under the premise of not performing high-temperature tempering heat treatment, high-temperature tempering heat treatment of the heat affected zone and weld of low alloy steel is achieved through welding to obtain qualified weld joint structure and performance.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a tempering weld repair process for low alloy steel without post-weld heat treatment, comprising:

[0006] Polish the area to be repaired of the base material to a metallic luster;

[0007] Preheat the area to be repaired to 180℃-230℃ by flame heating or thermal radiation heating;

[0008] Select welding materials and corresponding welding processes to weld the area to be repaired to form a first transition layer;

[0009] Select the same welding material and welding process as that for welding the first transition layer to weld on the first transition layer to form a second transition layer;

[0010] Select the same welding material and welding process as that for welding the first transition layer to weld on the second transition layer to form a filling layer, and until the filling layer fills the area to be repaired;

[0011] Welding the filling layer to form a capping layer;

[0012] The cover layer is removed by grinding to complete the welding repair.

[0013] In a preferred embodiment of the present invention, the welding method is manual arc welding, the welding material is welding rod E7018, and the diameter of the welding material is 2.5 mm or 3.2 mm.

[0014] In a preferred embodiment of the present invention, when the diameter of the welding material is 2.5 mm, the welding process is a welding current of 85 A, a welding voltage of 22 V to 24 V, a welding rate of 2.2 mm / s to 2.6 mm / s, and an interpass temperature of 180° C. to 230° C.;

[0015] When the welding material diameter is 3.2 mm, the welding process is as follows: the welding current is 110 A, the welding voltage is 22 V to 25 V, the welding rate is 2.2 mm / s to 2.6 mm / s, and the interpass temperature is 180° C. to 230° C.

[0016] In a preferred embodiment of the present invention, when the first transition layer and the second transition layer are formed by welding, the interlayer temperature is controlled between 180°C and 230°C.

[0017] In a preferred embodiment of the present invention, the distance between the weld toe of the second transition layer and the weld toe of the first transition layer is set between 3 mm and 5 mm.

[0018] In a preferred embodiment of the present invention, the distance between the weld toe of the filling layer and the weld toe of the first transition layer is set to be greater than or equal to 3 mm.

[0019] In a preferred embodiment of the present invention, the thickness of the first transition layer and the thickness of the second transition layer are less than or equal to the diameter of the welding material;

[0020] The width of each weld bead in the first transition layer and each weld bead in the second transition layer is 3 to 4 times the diameter of the welding material.

[0021] In a preferred embodiment of the present invention, the overlap ratio between the weld beads in the first transition layer and the overlap ratio between the weld beads in the second transition layer are set between 40% and 50%.

[0022] In a preferred embodiment of the present invention, after the first transition layer thickness is formed by welding, the first transition layer is ground, and the grinding amount is less than or equal to 0.5 mm.

[0023] In a preferred embodiment of the present invention, after the cover layer is removed by grinding and the welding repair is completed, it is subjected to a dehydrogenation treatment at 300° C. for 4 hours.

[0024] The present invention proposes a tempering weld repair process for low alloy steel without post-weld heat treatment. Under the premise of no post-weld heat treatment, the process of controlling the tempering weld technology of low alloy steel mainly includes welding material specifications, welding current, welding speed, welding layer thickness, and weld overlap rate, so that the heat affected zone and weld in the repair area are subjected to high-temperature tempering heat treatment, which can not only obtain high-quality tempering microstructure morphology, but also obtain joint performance equivalent to that of the same material after post-weld heat treatment. Compared with the existing RCC-M and RSE-M standard requirements, the present invention breaks through the existing RCC-M and RSE-M standard requirements, obtains a more reasonable optimization process than the standard requirements, and obtains better welding joint performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0026] Figure 1 The present invention is a schematic flow chart of a tempering weld repair process for low alloy steel without post-weld heat treatment in one embodiment.

[0027] Figure 2 FIG. 1 is a schematic diagram of welding the first transition layer in one embodiment of the present invention.

[0028] Figure 3 FIG. 1 is a schematic diagram of welding the second transition layer in one embodiment of the present invention.

[0029] Figure 4 FIG. 1 is a schematic diagram of a welding filling layer in one embodiment of the present invention.

[0030] Figure 5 This is a schematic diagram of welding completion in one embodiment of the present invention.

[0031] Figure 6 a is a schematic diagram of the microstructure of the base material in the joint after welding by the tempering weld repair process of the present application in one embodiment of the present invention.

[0032] Figure 6 b is a schematic diagram of the microstructure of the base material in the joint of medium alloy steel conventional welding + post-weld heat treatment process.

[0033] Figure 7 a is a schematic diagram of the microstructure of the fine grain area in the joint after welding by the tempering weld repair process of the present application in one embodiment of the present invention.

[0034] Figure 7 b is a schematic diagram of the microstructure of the fine grain zone in the joint of medium alloy steel conventional welding + post-weld heat treatment process.

[0035] Figure 8 a is a schematic diagram of the microstructure of the coarse-grained area in the joint after welding by the tempering weld repair process of the present application in one embodiment of the present invention.

[0036] Figure 8 b is a schematic diagram of the microstructure of the coarse-grained zone in the joint of medium alloy steel conventional welding + post-weld heat treatment process.

[0037] Fig. 9 a is a schematic diagram of the microstructure at the fusion line in the joint after welding by the tempering weld repair process of the present application in one embodiment of the present invention.

[0038] Fig. 9 b is a schematic diagram of the microstructure at the fusion line in the joint of medium alloy steel conventional welding + post-weld heat treatment process.

[0039] Fig.10 a is a schematic diagram of the microstructure of the weld in the joint after welding by the tempering weld repair process of the present application in one embodiment of the present invention.

[0040] Fig.10 b is a schematic diagram of the microstructure of the weld in the joint of medium alloy steel conventional welding + post-weld heat treatment process.

[0041] Fig.11 a is a schematic diagram of the hardness measurement values ​​at different positions of the coarse grain zone after welding by the tempering weld repair process of the present application in one embodiment of the present invention.

[0042] Fig.11 b is a schematic diagram of the hardness measurement values ​​at different positions in the coarse grain zone of the medium alloy steel conventional welding + post-weld heat treatment process joint.

[0043] Fig.12 a is a schematic diagram of the hardness measurement values ​​at different positions of the weld toe after welding by the tempering weld repair process of the present application in one embodiment of the present invention.

[0044] Fig.12 b is a schematic diagram of the hardness measurement values ​​at different positions of the weld toe in the joint of medium alloy steel conventional welding + post-weld heat treatment process.

[0045] Fig.13 This is a schematic diagram of a welding sample in one embodiment of the present invention.

[0046] Fig.14 Schematic diagram of the hardness distribution at different positions of the joint of specimen A.

[0047] Fig.15 Schematic diagram of the hardness distribution at different positions of the joint of specimen B.

[0048] Fig.16 Schematic diagram of the hardness distribution at different positions of the specimen C joint. DETAILED DESCRIPTION

[0049] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0050] It should be noted that the illustrations provided in the following embodiments are only used to illustrate the basic concept of the present invention in a schematic manner, and thus the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0051] With the mature development of tempering weld technology, this technology is increasingly used in the welding repair of thick-walled components in the fields of thermal power, nuclear power, petrochemicals, etc., and tempering weld welding technologies that do not require post-weld tempering heat treatment, such as half-weld tempering technology, controlled deposition technology, consistent weld layer technology, double-layer tempering weld technology, and weld toe tempering technology, have been developed successively. ASME, RCC-M, and RSE-M specifications have also included tempering weld bead welding technology. ASME standards stipulate that tempering weld bead technology is applicable to carbon steel and low alloy steel such as P-1, 3, 12A, 12B, and 12C. QW-290 stipulates that tempering weld bead technology is limited to SMAW, GTAW, SAW, GMAW (including FCAW) and PAW welding methods. In Volume IX, Chapter II "Welding Procedure Qualification", QW-290 and Volume XI "Rules for In-service Inspection of Nuclear Power Plant Components" respectively formulate requirements for welding procedure qualification, defect removal, selection of welding methods, selection of welding rods, and tempering weld bead repair dimensions for tempering weld bead welding technology. In France, RCC-M Volume IV S7600 "Welding Repair" also formulates relevant standards for tempering weld bead welding technology. Unlike the ASME specification, RCC-M additionally requires the analysis of the influence of the welding repair part on the stress of the overall component. The French RSE-M "Corrective Maintenance Method" elaborates on the tempering weld processes for welding of the same material, cladding, and dissimilar materials, and takes the manual arc welding repair process of coated electrodes without heat treatment as an example: the first layer of welds is welded with a Φ2.5mm electrode and then processed to a certain thickness, the second layer of welds is welded with a Φ3.2mm electrode, and the thickness of the weld is not more than Φ4.0mm. Relevant regulations are also made for preheating temperature, post-heating, weld width, overlap, and reinforcement of welds. The existing technology basically performs welding repairs based on the RCC-M and RSE-M standards. This application proposes a tempering weld repair process for low-alloy steel without post-weld heat treatment, which breaks through the existing RCC-M and RSE-M standard requirements, obtains a more reasonable optimization process than the standard requirements, and obtains better welding joint performance.

[0052] See also Figure 1 As shown, Figure 1 The flow chart of the tempering weld bead repair process for low alloy steel without post-weld heat treatment in one embodiment of the present invention is shown. Take the base material 18MND5 low alloy steel for nuclear power plants as an example for explanation: The 18MND5 low alloy steel to be repaired is analyzed for hardenability by carbon equivalent. The carbon equivalent is 0.6, the hardening tendency is small, and it is suitable for tempering weld bead repair. The chemical elements of 18MND5 low alloy steel are shown in Table 1.

[0053] Table 118 Chemical elements of MND5 low alloy steel / %

[0054] Steel Type C Mn Cr Mo V Ni Cu Carbon Equivalent CE 18MND5 0.19 1.43 0.11 0.48 0.005 0.80 0.03 0.6

[0055] Among them, CE=[C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15]*100%.

[0056] The present application proposes a tempering weld repair process for low alloy steel without post-weld heat treatment, which specifically includes the following steps:

[0057] S1. The area to be repaired of the base material 11 is polished to a metallic luster; defects of the 18MND5 steel to be repaired are removed by machining and polishing, and after the defects are eliminated, the surface near the area to be repaired for welding is polished to a metallic luster.

[0058] S2. Preheat the area to be repaired to 180℃-230℃ by flame heating or thermal radiation heating;

[0059] S3, selecting welding materials and corresponding welding processes to perform welding on the area to be repaired to form a first transition layer 12;

[0060] See also Figure 1 and Figure 2 As shown, Figure 2 The schematic diagram of welding the first transition layer in one embodiment of the present application is shown. In step S3, for example, a manual arc welding method is used, and a matching electrode E7018 is selected, and the diameter of the electrode is 2.5 mm or 3.2 mm, wherein, when the diameter of the welding material is 2.5 mm, the welding process is a welding current of 85 A, a welding voltage of 22 V to 24 V, a welding rate of 2.2 mm / s to 2.6 mm / s, and an interpass temperature of 180°C to 230°C; when the diameter of the welding material is 3.2 mm, the welding process is a welding current of 110 A, a welding voltage of 22 V to 25 V, a welding rate of 2.2 mm / s to 2.6 mm / s, and an interpass temperature of 180°C to 230°C, and the corresponding welding process is selected according to the selected welding material diameter.

[0061] S4, selecting the same welding material and welding process as for welding the first transition layer 12, and welding on the first transition layer 12 to form a second transition layer 13;

[0062] See also Figure 1 and Figure 3 As shown, Figure 2 The schematic diagram of welding the second transition layer in one embodiment of the present application is shown. When welding the first transition layer 12 and the second transition layer 13, the interlayer temperature is controlled between 180°C and 230°C, and the distance between the weld toe of the second transition layer 13 and the weld toe of the first transition layer 12 is set between 3mm and 5mm.

[0063] In this embodiment, when the first transition layer 12 and the second transition layer 13 are formed by welding, the parameters of the transition layers are as follows: the thickness of the first transition layer 12 and the thickness of the second transition layer 13 are less than or equal to the diameter of the welding material; the width of each weld bead in the first transition layer 12 and the width of each weld bead in the second transition layer 13 are 3 to 4 times the diameter of the welding material; the overlap rate between each weld bead in the first transition layer 12 and the overlap rate between each weld bead in the second transition layer 13 are set between 40% and 50% to ensure uniform forming of each pass.

[0064] In this embodiment, after the first transition layer 12 is formed by welding, the first transition layer 12 is polished, and the polishing amount is less than or equal to 0.5 mm.

[0065] S5, selecting the same welding material and welding process as that for welding the first transition layer 12 to weld on the second transition layer 13 to form a filling layer 14, and until the filling layer 14 fills the area to be repaired;

[0066] See also Figure 1 and Figure 4 As shown, Figure 4 The schematic diagram of the welding filling layer in one embodiment of the present application is shown. Specifically, after the transition layer of the repaired area is welded, the same matching welding material is selected to fill the repaired area until the repaired area is filled. In this process, the welding process parameters of the filling layer are ensured to be the same as those of the transition layer, which can optimize the structure and stress distribution of the weld. In this embodiment, the distance between the weld toe of the filling layer 14 and the weld toe of the first transition layer 12 is set to be greater than or equal to 3mm.

[0067] S6. Forming a capping layer by welding on the filling layer; specifically, after the metal is filled in the repaired area, an additional layer of weld is added as the capping layer to achieve tempering treatment of the weld of the filling layer.

[0068] S7, grinding and removing the cover layer to complete the welding repair. Figure 1 and Figure 5 As shown, Figure 4 The schematic diagram of the welding process in one embodiment of the present application is shown. After the cap layer is removed by grinding and the welding repair is completed, a dehydrogenation treatment is performed at 300°C for 4 hours. The dehydrogenation treatment heats the weld and the heat-affected zone to allow hydrogen to escape from the metal, thereby reducing the hydrogen content in the weld, eliminating or reducing hydrogen-induced cracks, and improving the toughness and crack resistance of the weld. For example, it includes:

[0069] Preheating: Before dehydrogenation treatment, the weldment usually needs to be preheated to avoid thermal stress caused by excessive temperature difference.

[0070] Heating: Heat the weldment to 300°C, usually using a resistance furnace, flame heating or other heating equipment.

[0071] Insulation: Maintain at 300℃ for 4 hours to ensure that the weld and heat affected zone are fully heated.

[0072] Cooling: After the insulation is completed, cool the weldment naturally or control the cooling speed to avoid stress concentration caused by rapid cooling.

[0073] The process evaluation was carried out on the weld joints of 18MND5 steel manufactured by the tempering weld bead heat treatment-free process, and the results were compared with the joints in the normal post-weld heat treatment state:

[0074] See also Figures 6 to 10 As shown, Figure 6 a is a schematic diagram showing the microstructure of the base material in the joint after welding by the tempering weld repair process of the present application in one embodiment of the present application; Figure 6 b shows the microstructure diagram of the base material in the joint of medium alloy steel conventional welding + post-weld heat treatment process; Figure 7 a is a schematic diagram showing the microstructure of the fine grain area in the joint after welding by the tempering weld repair process of the present application in one embodiment of the present application; Figure 7 b shows the microstructure diagram of the fine grain area in the joint of medium alloy steel conventional welding + post-weld heat treatment process; Figure 8 a is a schematic diagram showing the microstructure of the coarse grain area in the joint after welding by the tempering weld repair process of the present application in one embodiment of the present application; Figure 8 b shows the microstructure diagram of the coarse grain area in the joint of medium alloy steel conventional welding + post-weld heat treatment process; Fig. 9 a is a schematic diagram showing the microstructure at the fusion line in a joint welded by the tempering weld repair process of the present application in one embodiment of the present application; Fig. 9 b shows the schematic diagram of the microstructure at the fusion line in the joint of medium alloy steel conventional welding + post-weld heat treatment process; Fig.10 a is a schematic diagram showing the microstructure of the weld in the joint after welding by the tempering weld repair process of the present application in one embodiment of the present application; Fig.10 b shows the microstructure diagram of the weld in the conventional welding + post-weld heat treatment process of medium alloy steel. Figure 6 a to Fig.10 It can be seen from b that the metallographic structure characteristics of the joint after welding by the tempering weld repair process of this application are consistent with those of the joint by conventional welding + post-weld heat treatment process. The weld structure is tempered bainite with a small amount of ferrite, the coarse-grained zone structure of the heat-affected zone is tempered bainite, the parent material structure is ferrite and bainite, the weld and the parent material are well fused, and no cracks, hardened martensite structure and overheated structure are found.

[0075] See also Figure 11 to Figure 12 As shown, Fig.11 a is a schematic diagram showing hardness measurement values ​​at different positions of the coarse grain zone after welding by the tempering weld repair process of the present application in one embodiment of the present application; Fig.11 b is a schematic diagram showing the hardness measurement values ​​at different positions of the coarse grain zone in the conventional welding + post-weld heat treatment process joint of the medium alloy steel in this application; Fig.12 a is a schematic diagram showing hardness measurement values ​​at different positions of the weld toe after welding by the tempering weld repair process of the present application in one embodiment of the present application; Fig.12 b shows the hardness measurement values ​​of different positions of the weld toe in the conventional welding + post-weld heat treatment process of the alloy steel in this application. Fig.11 a to Fig.12 It can be seen from b that the microhardness distribution of the joint after welding by the tempering weld repair process of the present application is consistent with that of the joint by conventional welding + post-weld heat treatment process. The hardness values ​​at the 1.5mm position on the surfacing surface and the middle position of the surfacing are not much different, and the hardness value in the coarse-grained area is not much different. The tempering weld has obvious improvements on the heat-affected zone and weld hardness of the weld joint.

[0076] As shown in Table 2, Table 2 shows the hardness values ​​of the heat affected zone under different processes. It can be seen from Table 2 that the impact properties of the heat affected zone of the material repaired by the tempering weld process and the conventional welding heating treatment process are almost the same: the 0°C impact test results of the heat affected zone at 1mm and 4mm from the fusion line are higher than the performance requirements of the standard for 18MND5 steel welded joints.

[0077] Table 2 Hardness values ​​of heat affected zone under different processes

[0078]

[0079]

[0080] See also Fig.13 As shown, in a specific embodiment, a welding specimen is welded by using a welding rod with a diameter of 2.5 mm and a corresponding tempering weld bead repair process of the welding process of the present invention, a welding specimen is welded by using a welding rod with a diameter of 3.2 mm and a corresponding tempering weld bead repair process of the welding process, and a welding specimen of the standard recommended process for comparison. The schematic diagram of the planned welding specimen is shown in 13. The welding specimens are respectively the first layer weld bead 101, the second layer weld bead 101 and the third layer weld bead 103 from the surface of the base material upward, and the tempering weld bead specimen planning table is shown in Table 3.

[0081] Table 3 Tempering weld sample planning table

[0082]

[0083] See also Figures 13 to 16 As shown, Fig.13 Shown is a schematic diagram of a welding sample in one embodiment of the present application; Fig.14 A schematic diagram showing the distribution of hardness at different positions of the joint of specimen A; Fig.15 Schematic diagram showing the distribution of hardness at different positions of the joint of specimen B; Fig.16 Schematic diagram showing the distribution of hardness at different positions of the joint of specimen C. The surfacing specimen was manufactured using the tempering weld process recommended by the standard process, with the first layer of Φ2.5mm welding rod, the second layer of Φ3.2mm welding rod, and the third layer of Φ3.2mm welding rod. The thermal cycle of the second layer of weld did not reduce the hardness of the first layer of weld, but instead worsened the hardness of the joint. However, the thermal cycle of the third layer had the effect of reducing the hardness.

[0084] According to the test results of the hardness of the cladding specimens welded with the same specifications of 2.5mm diameter welding rods and the corresponding welding process of tempering weld bead repair process, and the test results of the hardness of the cladding specimens welded with 3.2mm diameter welding rods and the corresponding welding process of tempering weld bead repair process, the second and third layers of welds can further reduce the hardness of the heat affected zone of the first layer of welds. Therefore, it is concluded that cladding with different diameter welding rods cannot reduce the hardness of the welds, cladding with the same diameter welding rod can reduce the hardness of the bottom layer of welds, and two or more layers of tempering welds can more effectively reduce the hardness of the first layer of welds.

[0085] The above embodiment is an embodiment based on manual arc welding. If the welding method is changed to argon arc welding and the welding material is replaced with welding wire, this technical requirement can also be achieved.

[0086] In summary, the present invention proposes a tempering weld repair process for low alloy steel without post-weld heat treatment. Under the premise of no post-weld heat treatment, the process of controlling the tempering weld technology of low alloy steel mainly includes welding material specifications, welding current, welding speed, welding layer thickness, and weld overlap rate, so that the heat affected zone and weld in the repair area are subjected to high-temperature tempering heat treatment, which can not only obtain high-quality tempering microstructure morphology, but also obtain joint performance equivalent to that of the same material after post-weld heat treatment. Compared with the existing RCC-M and RSE-M standard requirements, the present invention breaks through the existing RCC-M and RSE-M standard requirements, obtains a more reasonable optimization process than the standard requirements, and obtains better welding joint performance.

[0087] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

[0088] In the description herein, many specific details, such as examples of components and / or methods, are provided to provide a complete understanding of embodiments of the present invention. However, those skilled in the art will recognize that embodiments of the present invention may be practiced without one or more of the specific details or with other devices, systems, components, methods, components, materials, parts, etc. In other cases, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments of the present invention.

[0089] References throughout this specification to "one embodiment," "an embodiment," or "a specific embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, and not necessarily in all embodiments. Thus, various appearances of the phrases "in one embodiment," "in an embodiment," or "in a specific embodiment" in different places throughout this specification do not necessarily refer to the same embodiment. In addition, the particular features, structures, or characteristics of any specific embodiment of the invention may be combined with one or more other embodiments in any suitable manner. It should be understood that other variations and modifications of the embodiments of the invention described and illustrated herein may be possible in light of the teachings herein and are to be considered part of the spirit and scope of the invention.

[0090] It should also be understood that one or more of the elements shown in the figures may also be implemented in a more separate or more integrated manner, or even removed because they are inoperable in certain circumstances or provided because they may be useful depending on the application.

[0091] In addition, unless otherwise explicitly indicated, any marking arrows in the drawings should be regarded as exemplary only and not limiting. In addition, unless otherwise indicated, the term "or" used herein is generally intended to mean "and / or". In the case where the term is not clear because it is anticipated that the ability to separate or combine is provided, the combination of components or steps will also be regarded as indicated.

[0092] As used in the description herein and throughout the claims that follow, "a," "an," and "the" include plural references unless otherwise indicated. Likewise, as used in the description herein and throughout the claims that follow, the meaning of "in" includes "in" and "on," unless otherwise indicated.

[0093] The above description of the illustrated embodiments of the present invention (including the contents described in the Abstract) is not intended to be an exhaustive list or to limit the present invention to the precise form disclosed herein. Although specific embodiments of the present invention and examples of the present invention are described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the present invention as will be recognized and appreciated by those skilled in the art. As noted, these modifications may be made to the present invention in accordance with the above description of the embodiments described in the present invention, and these modifications will be within the spirit and scope of the present invention.

[0094] Systems and methods have been generally described herein as details that aid in understanding the present invention. In addition, various specific details have been given to provide an overall understanding of embodiments of the present invention. However, those skilled in the relevant art will recognize that embodiments of the present invention may be practiced without one or more of the specific details, or may be practiced using other devices, systems, accessories, methods, components, materials, parts, etc. In other cases, well-known structures, materials, and / or operations are not specifically shown or described in detail to avoid confusion with various aspects of embodiments of the present invention.

[0095] Thus, although the invention has been described herein with reference to specific embodiments thereof, freedom of modification, various changes and substitutions are also within the foregoing disclosure, and it should be understood that in some cases, some features of the invention will be employed without the corresponding use of other features without departing from the scope and spirit of the proposed invention. Thus, many modifications may be made to adapt a particular environment or material to the essential scope and spirit of the invention. The invention is not intended to be limited to the specific terms used in the claims below and / or the specific embodiments disclosed as the best mode contemplated for carrying out the invention, but the invention will include any and all embodiments and equivalents falling within the scope of the appended claims. Thus, the scope of the invention will be determined solely by the appended claims.

Claims

1. A tempering weld repair process for low alloy steel without post-weld heat treatment, characterized in that: include: Polish the area to be repaired of the base material to a metallic luster; Preheat the area to be repaired to 180℃-230℃ by flame heating or thermal radiation heating; Select welding materials and corresponding welding processes to weld the area to be repaired to form a first transition layer; Select the same welding material and welding process as that for welding the first transition layer to weld on the first transition layer to form a second transition layer; Select the same welding material and welding process as that for welding the first transition layer to weld on the second transition layer to form a filling layer, and until the filling layer fills the area to be repaired; Welding the filling layer to form a capping layer; The cover layer is removed by grinding to complete the welding repair.

2. The tempering weld repair process for low alloy steel without post-weld heat treatment according to claim 1 is characterized in that: The welding method is manual arc welding, the welding material is welding rod E7018, and the diameter of the welding material is 2.5mm or 3.2mm.

3. The tempering weld repair process for low alloy steel without post-weld heat treatment according to claim 2 is characterized in that: When the diameter of the welding material is 2.5 mm, the welding process is as follows: the welding current is 85 A, the welding voltage is 22 V to 24 V, the welding rate is 2.2 mm / s to 2.6 mm / s, and the interpass temperature is 180° C. to 230° C.; When the welding material diameter is 3.2 mm, the welding process is as follows: the welding current is 110 A, the welding voltage is 22 V to 25 V, the welding rate is 2.2 mm / s to 2.6 mm / s, and the interpass temperature is 180° C. to 230° C.

4. The tempering weld repair process for low alloy steel without post-weld heat treatment according to claim 1 is characterized in that: When the first transition layer and the second transition layer are formed by welding, the interlayer temperature is controlled between 180°C and 230°C.

5. The tempering weld repair process for low alloy steel without post-weld heat treatment according to claim 1, characterized in that: The distance between the weld toe of the second transition layer and the weld toe of the first transition layer is set between 3 mm and 5 mm.

6. The tempering weld repair process for low alloy steel without post-weld heat treatment according to claim 1, characterized in that: The distance between the weld toe of the filling layer and the weld toe of the first transition layer is set to be greater than or equal to 3 mm.

7. The tempering weld repair process for low alloy steel without post-weld heat treatment according to claim 1, characterized in that: The thickness of the first transition layer and the thickness of the second transition layer are less than or equal to the diameter of the welding material; The width of each weld bead in the first transition layer and each weld bead in the second transition layer is 3 to 4 times the diameter of the welding material.

8. The tempering weld repair process for low alloy steel without post-weld heat treatment according to claim 1, characterized in that: The overlap ratio between each weld bead in the first transition layer and the overlap ratio between each weld bead in the second transition layer are set between 40% and 50%.

9. The tempering weld repair process for low alloy steel without post-weld heat treatment according to claim 1, characterized in that: After the first transition layer is formed by welding, the first transition layer is ground, and the grinding amount is less than or equal to 0.5 mm.

10. The tempering weld repair process for low alloy steel without post-weld heat treatment according to claim 1, characterized in that: After the cover layer is removed by grinding and welding repair is completed, a dehydrogenation treatment is performed at 300° C. for 4 hours.

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