CN115555695A - Resistance spot welding method for steel parts - Google Patents
Resistance spot welding method for steel parts Download PDFInfo
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- CN115555695A CN115555695A CN202211114855.8A CN202211114855A CN115555695A CN 115555695 A CN115555695 A CN 115555695A CN 202211114855 A CN202211114855 A CN 202211114855A CN 115555695 A CN115555695 A CN 115555695A
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- 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
- B23K11/00—Resistance welding; Severing by resistance heating
- B23K11/10—Spot welding; Stitch welding
- B23K11/11—Spot welding
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- 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
- B23K11/00—Resistance welding; Severing by resistance heating
- B23K11/34—Preliminary treatment
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- 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
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Abstract
The application relates to the technical field of resistance spot welding, and discloses a resistance spot welding method for a steel part, which comprises the following steps: obtaining parts to be welded, wherein the parts to be welded comprise a first part and a second part; carrying out local heat treatment on at least one to-be-welded position of the to-be-welded part to enable metal elements in the metal coating and iron elements in the part to generate alloying reaction and form an alloy layer at the to-be-welded position; and enabling the position to be welded of the first part to be in contact with the position to be welded of the second part, and welding the position to be welded through a resistance spot welding device to form a weld nugget. The technical scheme that this application provided can solve the steel part that plates low melting point coating material and appear piling zinc defect's problem when carrying out resistance spot welding to avoid forming and pile the processing of polishing after the zinc defect.
Description
Technical Field
The application relates to the technical field of resistance spot welding, and discloses a resistance spot welding method for a steel part.
Background
Resistance spot welding is a method in which a current is passed through a material composition to be welded under pressure, and the resulting resistance heat is used as a heat source to locally heat the material composition to be welded, thereby finally forming a connection. At present, resistance spot welding has been widely used for joining metal materials, and has become a main welding mode in the automobile manufacturing industry.
Due to the continuous improvement of corrosion resistance, the coating material with low melting point is more and more widely applied in the automobile manufacturing. The melting point of a pure zinc coating GI plate is 420 ℃; the ZM plating plate is formed by Zn-Al-Mg elements, and the melting point of the plating layer is 380-390 ℃. Since the plating layers of the GI plate and the ZM plate have a low melting point, there is a deterioration in the welding performance as compared with the continuous annealing product, which mainly includes: (1) after the plating layer is melted, the plating layer is extruded out of a welding area under the action of electrode pressure, and the zinc accumulation defect is easily formed around a welding spot under the action of a magnetic field; (2) the zinc in the plating layer reacts with the copper in the electrode to cause premature failure of the electrode and reduce the service life; (3) because the melting point of the coating is low, the coating is melted in the resistance spot welding process, the current density is reduced, and the welding current needs to be improved; the lower the melting point of the plating, the more significant the reduction in current density.
Therefore, it is necessary to develop a resistance spot welding method to solve the welding problem of the low melting point coating material and form a welding spot with good welding appearance quality.
Disclosure of Invention
The embodiment of the application provides a resistance spot welding method for a steel part. The problem of zinc piling defect of the steel part plated with the low-melting-point coating material during resistance spot welding can be solved, and polishing treatment after the zinc piling defect is formed is avoided.
Other features and advantages of the present application will be apparent from the following detailed description, or may be learned by practice of the application.
According to an aspect of an embodiment of the present application, there is provided a resistance spot welding method for a steel part having a low melting point metal coating applied thereto, the method including: obtaining parts to be welded, wherein the parts to be welded comprise a first part and a second part; carrying out local heat treatment on at least one to-be-welded position of the to-be-welded part to enable metal elements in the metal coating and iron elements in the part to generate alloying reaction and form an alloy layer at the to-be-welded position; and enabling the position to be welded of the first part to be in contact with the position to be welded of the second part, and welding the position to be welded through a resistance spot welding device to form a weld nugget.
In an embodiment of the application, based on the foregoing solution, after the local heat treatment of at least one to-be-welded position of the parts to be welded, the method further includes: detecting whether the content of the iron element in the metal coating at the position to be welded after the local heat treatment is less than an iron element content threshold value; and if the content of the iron element in the metal coating at the position to be welded after the local heat treatment is less than the threshold value of the content of the iron element, performing local heat treatment again on the position to be welded after the local heat treatment.
In one embodiment of the present application, the threshold iron content is 8% based on the foregoing scheme.
In one embodiment of the application, based on the foregoing scheme, the diameter of the heat treatment area is controlled to be 8mm to 50mm during the local heat treatment of at least one to-be-welded position of the to-be-welded part.
In one embodiment of the application, based on the scheme, in the process of carrying out local heat treatment on at least one to-be-welded position of the to-be-welded parts, the temperature of the surface of the metal coating is controlled to be 400-907 ℃.
In one embodiment of the application, at least one to-be-welded position of the parts to be welded is locally heat-treated by a heating device, wherein the heating device comprises any one of an induction heating device, a laser heating device, a resistance heating device, and an arc heating device.
In an embodiment of the application, based on the foregoing solution, when the heating device is a laser heating device, the performing, by the heating device, a local heat treatment on at least one to-be-welded position of the to-be-welded part includes: according to the technical scheme, the method comprises the steps of according to the fact that the diameter of a laser spot of a laser heating device is 15mm, the output power of laser is 500W, a pulse mode is adopted, the frequency is 3.3Hz, the duty ratio is 50%, the heating time is 20 seconds, the temperature of the surface of a metal coating is controlled to be 700 ℃, and local heat treatment is conducted on at least one to-be-welded position of a to-be-welded part.
In an embodiment of the application, based on the foregoing scheme, the resistance spot welding device includes a first electrode and a second electrode, the first electrode and the second electrode are oppositely disposed, wherein the first electrode includes a first electrode base body, a first electrode end face, and a first electrode transition area, the first electrode transition area is used for connecting the first electrode base body and the first electrode end face, the second electrode includes a second electrode base body, a second electrode end face, and a second electrode transition area, the second electrode transition area is used for connecting the second electrode base body and the second electrode end face, and during welding, a position to be welded after local heat treatment of a part to be welded is in contact with the first electrode.
In an embodiment of the present application, based on the foregoing, a diameter of the first electrode end face is greater than or equal to a diameter of the second electrode end face, and a radius of curvature of the first electrode end face is greater than or equal to a radius of curvature of the second electrode end face.
In an embodiment of the present application, based on the foregoing scheme, the diameter of the nugget satisfies the following formula:
wherein d represents the diameter of the nugget; t represents the thickness of the part to be welded at the position to be welded.
In some embodiments of the present application, a part to be welded is obtained, and at least one position to be welded of the part to be welded is subjected to local heat treatment, so that a metal element in a metal coating and an iron element in the part are subjected to an alloying reaction, an alloy layer is formed at the position to be welded, the position to be welded of the first part and the position to be welded of the second part are brought into contact, and the position to be welded is welded by a resistance spot welding device, so that a weld nugget is formed. The local heat treatment is carried out on the position to be welded of the part to be welded, so that the melting point of the coating is improved, the area of the coating on the surface of the welding spot in the subsequent welding process is greatly reduced, the zinc stacking defect is avoided or inhibited, and the polishing treatment is required after the zinc stacking defect is formed.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and, together with the description, serve to explain the principles of the application. It is obvious that the drawings in the following description are only some embodiments of the application, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:
FIG. 1 shows a flow chart of a method of resistance spot welding of a steel part in an embodiment of the application;
FIG. 2 shows a schematic view of a partial heat treatment of a first part according to a first embodiment of the invention;
FIG. 3 shows a schematic view of a partial heat treatment of a first part according to a second embodiment of the invention;
FIG. 4 shows a schematic view of a partial heat treatment of a first part according to a third embodiment of the invention;
FIG. 5 is a schematic view showing a resistance spot welding process according to the first and third embodiments of the present invention;
FIG. 6 shows a schematic view of a resistance spot welding process in a second embodiment of the invention;
FIG. 7 is a photograph showing the appearance of resistance spot welding after resistance spot welding in the first embodiment of the invention;
FIG. 8 is a photograph showing the appearance of resistance spot welding after resistance spot welding in the second embodiment of the present invention;
FIG. 9 is a photograph showing the appearance of resistance spot welding after resistance spot welding in the third embodiment of the present invention;
FIG. 10 is a photograph showing the appearance of a spot after resistance spot welding in a comparative example of the present invention.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the embodiments of the present application can be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known methods, devices, implementations, or operations have not been shown or described in detail to avoid obscuring aspects of the application.
The flow charts shown in the drawings are merely illustrative and do not necessarily include all of the contents and operations/steps, nor do they necessarily have to be performed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the actual execution sequence may be changed according to the actual situation.
The schematic diagrams shown in the figures are only intended to generally describe or represent the shape, relative size, relationship or relationship of objects to one another, and the actual objects do not necessarily have to be the same as the shape, relative size, relationship or relationship of objects to one another as shown in the figures.
It should be noted that: reference herein to "a plurality" means two or more. "and/or" describe the association relationship of the associated objects, meaning that there may be three relationships, e.g., A and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the foregoing drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the objects so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in other sequences than those illustrated or described herein.
The implementation details of the technical solution of the embodiment of the present application are set forth in detail below:
FIG. 1 shows a flow chart of a method of resistance spot welding of a steel part in an embodiment of the present application.
As shown in FIG. 1, the resistance spot welding method for a steel part includes at least steps 110 to 150.
The following will explain steps 110 to 150 shown in fig. 1 in detail:
in step 110, a part to be welded is obtained, the part to be welded comprising a first part and a second part.
In the application, the surface of the part to be welded is plated with a low-melting-point metal plating layer, the metal plating layer can be a pure zinc plating layer, the melting point of the plating layer is 420 ℃, and the metal plating layer can also be a zinc-magnesium-aluminum plating layer consisting of zinc-magnesium-aluminum elements, and the melting point of the plating layer is 380-390 ℃.
With continued reference to fig. 1, in step 130, at least one to-be-welded position of the to-be-welded part is locally heat-treated to cause an alloying reaction between the metal element in the metal coating and the iron element in the part to form an alloy layer at the to-be-welded position.
In this application, it should be noted that the number of the positions to be welded may be one or more.
In the method, local heat treatment is carried out on one or more positions to be welded of a part to be welded, so that a metal element in a metal coating and an iron element in the part are subjected to an alloying reaction, an alloy layer is formed at the position to be welded, and the melting point of the alloy layer is greatly increased compared with that of the metal coating before the local heat treatment, so that the area of the coating melted in the subsequent welding step is greatly reduced.
For example, a pure zinc coating is plated on the surface of the part to be welded, the melting point of the pure zinc coating is 420 ℃, local heat treatment is carried out on a part to be welded of the part to be welded, so that an alloying reaction is carried out between zinc elements in the pure zinc coating and iron elements in the part, a heating part forms a zinc-iron alloy, and the melting point of the coating is increased from 420 ℃ or lower to more than 600 ℃.
With continued reference to fig. 1, in step 150, the to-be-welded position of the first part and the to-be-welded position of the second part are brought into contact, and the to-be-welded positions are welded by a resistance spot welding device to form a nugget.
In some embodiments of the present application, during step 130 shown in fig. 1, i.e. after the local heat treatment of at least one to-be-welded position of the parts to be welded, the method further comprises: detecting whether the content of the iron element in the metal coating at the position to be welded after the local heat treatment is less than an iron element content threshold value; and if the content of the iron element in the metal coating at the position to be welded after the local heat treatment is less than the threshold value of the content of the iron element, performing local heat treatment again on the position to be welded after the local heat treatment.
According to the method, after local heat treatment is carried out on the to-be-welded position of a part to be welded, whether the content of an iron element in a metal coating of the to-be-welded position after the local heat treatment is smaller than an iron element content threshold value or not is detected by using a glow spectrometer, if the content of the iron element in the metal coating of the to-be-welded position after the local heat treatment is smaller than the iron element content threshold value, the to-be-welded position after the local heat treatment is subjected to local heat treatment again, and if the content of the iron element in the metal coating of the to-be-welded position after the local heat treatment is larger than or equal to the iron element content threshold value, the local heat treatment on the to-be-welded position of the part to be welded is successful without performing local heat treatment again.
In some embodiments of the present application, the threshold iron content is 8%.
In some embodiments of the present application, the diameter of the heat treatment area is controlled to be 8mm to 50mm during the local heat treatment of at least one to-be-welded position of the parts to be welded.
In this application, it should be noted that if the diameter of the heat treatment area is larger than 50mm, the part subjected to the partial heat treatment will have a problem of deformation of the part due to an excessively large heating area.
In some embodiments of the present application, the temperature of the surface of the metallic coating is controlled to be between 400 ℃ and 907 ℃ during the local heat treatment of at least one to-be-welded position of said parts to be welded.
In the application, it should be noted that, when the metal coating of the part to be welded is a pure zinc coating or a zinc-magnesium-aluminum coating, in the process of performing local heat treatment, because the melting point of the pure zinc coating is 420 ℃, the melting point of the zinc-magnesium-aluminum coating is 380-390 ℃, and the boiling point of zinc is 906 ℃, the heating temperature exceeds 400 ℃ when local heat treatment is required, so that the metal element in the metal coating and the iron element in the part can generate an alloying reaction, and an alloy layer is formed at the position to be welded; when the heating temperature exceeds 907 ℃ during the local heat treatment, the heating temperature exceeds the boiling point of zinc, and the zinc in the pure zinc coating or the zinc-magnesium-aluminum coating is evaporated due to overhigh temperature, so the surface temperature of the metal coating is controlled within 907 ℃ during the local heat treatment.
In some embodiments of the present application, the at least one to-be-welded position of the parts to be welded is locally heat treated by a heating device, wherein the heating device comprises any one of an induction heating device, a laser heating device, a resistance heating device, and an arc heating device.
In some embodiments of the present application, when the heating device is a laser heating device, the locally heat-treating at least one to-be-welded position of the to-be-welded part by the heating device includes: according to the technical scheme, the method comprises the steps of according to the laser heating device, enabling the diameter of a laser spot to be 15mm, enabling the output power of laser to be 500W, adopting a pulse mode, enabling the frequency to be 3.3Hz, enabling the duty ratio to be 50%, enabling the heating time to be 20 seconds, controlling the temperature of the surface of a metal coating to be 700 ℃, and carrying out local heat treatment on at least one position to be welded of a part to be welded.
In some embodiments of the present application, resistance spot welding device includes first electrode and second electrode, the first electrode with the second electrode sets up relatively, wherein, the first electrode includes first electrode base member, first electrode terminal surface, and first electrode transition district, first electrode transition district is used for connecting first electrode base member and first electrode terminal surface, the second electrode includes second electrode base member, second electrode terminal surface, and second electrode transition district, second electrode transition district is used for connecting second electrode base member and second electrode terminal surface, during the welding treat after welding part local heat treatment wait weld the position with first electrode contacts.
In some embodiments of the present application, a diameter of the first electrode end face is greater than or equal to a diameter of the second electrode end face, and a radius of curvature of the first electrode end face is greater than or equal to a radius of curvature of the second electrode end face.
In the application, when the diameter or the curvature radius of the end face of the first electrode is larger than that of the end face of the second electrode, the current density and the pressure intensity of the contact side of the metal coating of the part to be welded and the end face of the first electrode can be reduced, so that the surface temperature and the pressure of the part to be welded are reduced, the occurrence of zinc stacking defects is inhibited, and the indentation depth of a welding spot is reduced.
In some embodiments of the present application, the diameter of the nugget satisfies the following equation:
wherein d represents the diameter of the nugget; t represents the thickness of the part to be welded at the position to be welded.
In order that those skilled in the art will more readily understand the present application, the present application will now be described in terms of specific embodiments.
Referring to fig. 2, 5 and 7, there are shown a schematic view of a partial heat treatment of a first part according to a first embodiment of the present invention, a schematic view of a resistance spot welding process, and an appearance picture of resistance spot welding after resistance spot welding, respectively.
The first embodiment:
specifically, in the embodiment of the present invention, the first test panel 1 includes a first test panel substrate 11, a first test panel first plating layer 12, and a first test panel second plating layer 13. Wherein the first test plate substrate 11 is IF steel with the thickness of 1.4mm; the first plating layer 12 of the first test plate and the second plating layer 13 of the first test plate are GI plating layers, the Zn content in the plating layers is more than 99 percent, the melting point of the plating layers is 420 ℃, and the weight of the single-side plating layer is 50g/m 2 . The second test board 3 includes a second test board base 31, a second test board first plating layer 32, and a second test board second plating layer 33. Wherein, the second test plate matrix 31 is IF steel with the thickness of 1.4mm; the first coating 32 of the second test plate and the second coating 33 of the second test plate are GI coatings, the Zn content in the coatings is more than 99 percent, the melting point of the coatings is 420 ℃, and the weight of the single-side coating is 50g/m 2 。
First, the first test plate 1 and the second test plate 2 are punched to prepare a first part and a second part, respectively.
Then, local heating is applied to the to-be-welded position of the first part. In the present embodiment, the heating device 2 is a high-frequency induction heating device, as shown in fig. 2. The position to be welded of the first part is heated, the heating area being a circular area with a diameter of 40 mm. In this example, the metal plating layer at the position to be welded of the first part was heated to 600 ℃ for 5 minutes, and naturally cooled to room temperature in air after the heating was stopped. In the embodiment, only one position to be welded is provided, and for the condition of a plurality of positions to be welded, the plurality of positions to be welded can be simultaneously heated so as to improve the efficiency. In the coating of the local heat treatment area, the Fe content is more than or equal to 8 percent.
Subsequently, the position to be welded of the second part is locally heated as described above.
Finally, the first part and the second part are combined together, corresponding positions to be welded are contacted, and resistance spot welding is carried out under the action of the first electrode 4 and the second electrode 5, as shown in fig. 5. In this embodiment, the first electrode 4 and the second electrode 5 are the same and are made of chromium-zirconium-copper material. The first electrode 4 includes a first electrode base 41, a first electrode end face 42, and a first electrode transition region 43, and the first electrode transition region 43 is used to connect the first electrode base 41 and the first electrode end face 42. The first electrode end face 42 is a curved surface having a diameter of 6mm and a radius of curvature of 40 mm. The second electrode 5 includes a second electrode base 51, a second electrode end face 52, and a second electrode transition region 53, where the second electrode transition region 53 is used to connect the second electrode base 51 and the second electrode end face 52. The second electrode end face 52 is a curved surface having a diameter of 6mm and a radius of curvature of 40 mm. The first electrode 4 and the second electrode 5 are oppositely arranged, the metal coating at the position to be welded of the first part is contacted with the first electrode 4, and the metal coating at the position to be welded of the second part is contacted with the second electrode 5. The parameters of the resistance spot welding device are as follows: electrode pressure 3kN, welding current 8kA and welding time 200ms. Finally, a nugget 6 having a diameter of 5.9mm is formed between the first part and the second part so that the nugget diameter is equal to or larger than
Wherein t is a plate thickness.
As shown in fig. 7, after welding, the weld indentation still exists, but the zinc stacking defect around the indentation is obviously improved, and no obvious salient point exists. In addition, the electrode was subjected to a continuous welding test, with a spot welding frequency of 30 spots/min, and the electrode life increased from 2200 spots without heat treatment to 3500 spots after local heat treatment.
Referring to fig. 3, 6 and 8, there are shown a schematic view of a partial heat treatment of a first part, a schematic view of a resistance spot welding process and an appearance picture of resistance spot welding after resistance spot welding, respectively, according to a second embodiment of the present invention.
Second embodiment:
the first test board 1 includes a first test board base 11, a first test board first plating layer 12, and a first test board second plating layer 13. Wherein the first test plate substrate 11 is IF steel with the thickness of 1.4mm; the first plating layer 12 of the first test plate and the second plating layer 13 of the first test plate are GI plating layers, the Zn content in the plating layers is more than 99 percent, the melting point of the plating layers is 420 ℃, and the weight of the single-side plating layer is 50g/m 2 . The second test board 3 includes a second test board base 31, a second test board first plating layer 32, and a second test board second plating layer 33. Wherein, the second test plate substrate 31 is IF steel with the thickness of 1.4mm; the first coating 32 of the second test plate and the second coating 33 of the second test plate are GI coatings, the Zn content in the coatings is more than 99 percent, the melting point of the coatings is 420 ℃, and the weight of the single-side coating is 50g/m 2 。
First, the first test plate 1 and the second test plate 2 are punched to prepare a first part and a second part, respectively.
Then, localized heating is applied to the to-be-welded locations of the first part. In this embodiment, the heating device 2 is a laser heat source, as shown in fig. 3. The diameter of a laser spot is 15mm, and the metal coating at the position to be welded of the first part is heated. In the embodiment, the laser output power is 500W, the pulse mode is adopted, the frequency is 3.3Hz, the duty ratio is 50%, the heating time is 20 seconds, the surface temperature of the coating is about 700 ℃, and the coating is naturally cooled to the room temperature in the air after the heating is stopped. The Fe content in the metal coating of the local heat treatment area is more than or equal to 8 percent.
Finally, the first part and the second part are combined together, corresponding positions to be welded are contacted, and resistance spot welding is carried out under the action of the first electrode 4 and the second electrode 5, as shown in fig. 6. In this embodiment, the firstThe first electrode 4 and the second electrode 5 are made of chromium zirconium copper materials. The first electrode 4 includes a first electrode base 41, a first electrode end face 42, and a first electrode transition region 43, and the first electrode transition region 43 is used to connect the first electrode base 41 and the first electrode end face 42. The first electrode end face 42 is a plane having a diameter of 10mm (radius of curvature ∞). The second electrode 5 includes a second electrode base 51, a second electrode end face 52, and a second electrode transition region 53, where the second electrode transition region 53 is used to connect the second electrode base 51 and the second electrode end face 52. The second electrode end face 52 is a curved surface having a diameter of 6mm and a radius of curvature of 40 mm. The first electrode 4 and the second electrode 5 are oppositely arranged, the metal coating at the position to be welded of the first part is contacted with the first electrode 4 during welding, and the metal coating at the position to be welded of the second part is contacted with the second electrode 5. The parameters of the resistance spot welding device are as follows: electrode pressure 3kN, welding current 9.5kA, and welding time 200ms. Finally, a nugget 6 having a diameter of 5.9mm is formed between the first part and the second part so that the nugget diameter is equal to or larger than
Wherein t is a plate thickness.
As shown in fig. 8, after welding, the surface of the welding spot of the first part on the side of the first electrode 4 is almost flat due to further reduction of pressure and temperature of the surface of the welding spot, and there is only color change at the welding spot; the zinc piling defect at the welding point is further reduced, and no obvious salient point exists. Finally, on the first electrode 4 side, a large increase in the appearance quality of the solder joint is achieved.
Referring to fig. 4, 5 and 9, there are shown a schematic view of a partial heat treatment of a first part, a schematic view of a resistance spot welding process and an appearance picture of resistance spot welding after resistance spot welding, respectively, according to a third embodiment of the present invention.
The third embodiment:
specifically, in the embodiment of the present invention, the first test board 1 includes a first test board base 11, a first test board first plating layer 12, and a first test board second plating layer 13. Wherein the first test plate substrate 11 is IF steel with the thickness of 1.8mm; the first plating layer 12 of the first test plate and the second plating layer 13 of the first test plate are GI plating layers, the Zn content in the plating layers is more than 99 percent, the melting point of the plating layers is 420 ℃,the weight of the single-side coating is 50g/m 2 . The second test board 3 includes a second test board base 31, a second test board first plating layer 32, and a second test board second plating layer 33. Wherein, the second test plate matrix 31 is IF steel with the thickness of 1.8mm; the first coating 32 of the second test plate and the second coating 33 of the second test plate are GI coatings, the Zn content in the coatings is more than 99 percent, the melting point of the coatings is 420 ℃, and the weight of the single-side coating is 50g/m 2 。
First, the first test plate 1 and the second test plate 2 are punched to prepare a first part and a second part, respectively.
Then, local heating is applied to the to-be-welded position of the first part. In this embodiment, the heating device 2 is a resistance heating device, as shown in fig. 4. The heating device 2 comprises a heating device first electrode 21, a heating device second electrode 22. The first part is clamped by the first heating device electrode 21 and the second heating device electrode 22 respectively, and the distance between the first heating device electrode 21 and the second heating device electrode 22 is 20mm. And heating the metal coating at the position to be welded of the first part to 750 ℃ by passing a heating current between the first electrode 21 of the heating device and the second electrode 22 of the heating device, keeping the heating state for 3 seconds, stopping heating, and naturally cooling to room temperature. In this embodiment, there is only one position to be welded, and in the case of a plurality of positions to be welded, the plurality of positions to be welded can be simultaneously heated to improve efficiency. In the coating of the local heat treatment area, the Fe content is more than or equal to 8 percent.
Finally, the first part and the second part are combined together, corresponding positions to be welded are contacted, and resistance spot welding is carried out under the action of the first electrode 4 and the second electrode 5, as shown in fig. 5. In this embodiment, the first electrode 4 and the second electrode 5 are the same and are made of chromium-zirconium-copper material. The first electrode 4 includes a first electrode base 41, a first electrode end face 42, and a first electrode transition region 43, where the first electrode transition region 43 is used to connect the first electrode base 41 and the first electrode end face 42. The first electrode end face 42 is a curved surface having a diameter of 6mm and a radius of curvature of 40 mm. The second electrode 5 includes a second electrode base 51, a second electrode end face 52, and a second electrode transition region 53, where the second electrode transition region 53 is used to connect the second electrode base 51 and the second electrode end face 52. The second electrode end face 52 has a diameter of 6mm,A curved surface with a radius of curvature of 40 mm. The first electrode 4 and the second electrode 5 are oppositely arranged, the metal coating at the position to be welded of the first part is contacted with the first electrode 4 during welding, and the metal coating at the position to be welded of the second part is contacted with the second electrode 5. The parameters of the resistance spot welding device are as follows: the electrode pressure is 3.5kN, the welding current is 8.7kA, and the welding time is 400ms. Finally, a nugget 6 having a diameter of 6.1mm is formed between the first part and the second part so that the nugget diameter is equal to or larger than
Wherein t is a plate thickness.
As shown in fig. 9, after welding, the weld indentation still exists, but the zinc stacking defect around the indentation is obviously improved, and no obvious salient point exists.
Comparative example:
in a conventional manner, the first test plate 1, the second test plate 3, the first electrode 4 and the second electrode 5 are the same as those of the first embodiment. The first test plate 1 and the second test plate 2 are respectively punched to prepare a first part and a second part. The position to be welded of the first part and the position to be welded of the second part are not subjected to local heat treatment, resistance spot welding is performed on a welding combination formed by the first part and the second part by using the first electrode 4 and the second electrode 5, and the parameters of the resistance spot welding device are the same as those of the first embodiment.
The effect after resistance spot welding is shown in fig. 10, the appearance of the welding spot has a remarkable indentation, and a remarkable bulge, namely a zinc stacking defect, exists around the indentation.
One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:
before resistance spot welding, the position to be welded of the part to be welded is heated to the temperature of 400-907 ℃ through a heating device, so that the Zn element in the metal coating and the Fe element in the matrix are subjected to alloying reaction, and the formed zinc-iron alloy phase has a higher melting point.
After the part to be welded is subjected to local heat treatment and cooled, in the subsequent resistance spot welding process, the melting point of the coating is increased from below 420 ℃ to above 600 ℃ due to the local heat treatment of the surface with the appearance quality requirement, and the melting area of the coating on the surface of the welding spot is greatly reduced, so that the zinc stacking defect is avoided or inhibited. Meanwhile, due to the improvement of the melting point of the coating, the reaction speed of Zn in the coating and Cu in the electrode is reduced, and the service life of the electrode is prolonged.
When the curvature radius or the diameter of the end face of the first electrode of the resistance spot welding device is larger than that of the end face of the second electrode, the current density and the pressure intensity of the contact side of the metal coating of the part to be welded and the end face of the first electrode can be reduced, so that the surface temperature and the pressure of the part to be welded are reduced, the zinc stacking defect is further inhibited, the indentation depth of a welding spot is obviously reduced, and the surface quality of the welding spot is improved.
Because the part to be welded of the part to be welded is subjected to local heat treatment, and the heat treatment process is positioned after the material stamping deformation process, the impact on the stamping process is avoided, and the zinc powder peeling phenomenon in the stamping process caused by the increase of the iron content and the increase of the hardness in the coating is avoided.
Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains.
Furthermore, the above-described figures are merely schematic illustrations of processes involved in methods according to exemplary embodiments of the present application, and are not intended to be limiting. It will be readily understood that the processes shown in the above figures are not intended to indicate or limit the chronological order of the processes. In addition, it is also readily understood that these processes may be performed synchronously or asynchronously, e.g., in multiple modules.
It will be understood that the present application is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.
Claims (10)
1. A method of resistance spot welding a steel component having a low melting point metal coating applied to a surface of the steel component, the method comprising:
obtaining parts to be welded, wherein the parts to be welded comprise a first part and a second part;
performing local heat treatment on at least one position to be welded of the part to be welded to enable a metal element in the metal coating and an iron element in the part to generate an alloying reaction and form an alloy layer at the position to be welded;
and enabling the position to be welded of the first part to be in contact with the position to be welded of the second part, and welding the position to be welded through a resistance spot welding device to form a weld nugget.
2. A method according to claim 1, characterized in that after the local heat treatment of at least one to-be-welded position of the parts to be welded, the method further comprises:
detecting whether the content of the iron element in the metal coating at the position to be welded after the local heat treatment is less than an iron element content threshold value;
and if the content of the iron element in the metal coating at the position to be welded after the local heat treatment is less than the threshold value of the content of the iron element, performing local heat treatment again on the position to be welded after the local heat treatment.
3. The method according to claim 2, wherein the threshold iron content is 8%.
4. A method according to claim 1, characterized in that the diameter of the heat treatment zone is controlled to be 8-50 mm during the local heat treatment of at least one to-be-welded position of the parts to be welded.
5. A method according to claim 1, characterized in that the temperature of the surface of the metal coating is controlled to be 400-907 ℃ during the local heat treatment of at least one to-be-welded position of the parts to be welded.
6. The method according to claim 1, characterized in that at least one to-be-welded position of the parts to be welded is locally heat treated by a heating device, wherein the heating device comprises any one of an induction heating device, a laser heating device, a resistance heating device, and an arc heating device.
7. The method according to claim 6, wherein, when the heating device is a laser heating device, the locally heat-treating at least one to-be-welded position of the parts to be welded by the heating device comprises:
according to the technical scheme, the method comprises the steps of according to the fact that the diameter of a laser spot of a laser heating device is 15mm, the output power of laser is 500W, a pulse mode is adopted, the frequency is 3.3Hz, the duty ratio is 50%, the heating time is 20 seconds, the temperature of the surface of a metal coating is controlled to be 700 ℃, and local heat treatment is conducted on at least one to-be-welded position of a to-be-welded part.
8. The method according to claim 1, wherein the resistance spot welding device comprises a first electrode and a second electrode, the first electrode and the second electrode being disposed opposite to each other, wherein the first electrode comprises a first electrode base body, a first electrode end surface, and a first electrode transition region for connecting the first electrode base body and the first electrode end surface, and the second electrode comprises a second electrode base body, a second electrode end surface, and a second electrode transition region for connecting the second electrode base body and the second electrode end surface, and a position to be welded after the local heat treatment of the part to be welded is brought into contact with the first electrode during welding.
9. The method of claim 8, wherein the diameter of the first electrode end face is greater than or equal to the diameter of the second electrode end face, and the radius of curvature of the first electrode end face is greater than or equal to the radius of curvature of the second electrode end face.
10. The method of claim 1, wherein the diameter of the nugget satisfies the following equation:
wherein d represents the diameter of the nugget; t represents the thickness of the part to be welded at the position to be welded.
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| CN202211114855.8A CN115555695A (en) | 2022-09-14 | 2022-09-14 | Resistance spot welding method for steel parts |
| PCT/CN2022/142914 WO2024055471A1 (en) | 2022-09-14 | 2022-12-28 | Resistance spot welding method for steel parts |
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| CN202211114855.8A CN115555695A (en) | 2022-09-14 | 2022-09-14 | Resistance spot welding method for steel parts |
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| JP2009061500A (en) * | 2007-08-10 | 2009-03-26 | Nissan Motor Co Ltd | Dissimilar metal bonded member, and method of bonding dissimilar metals |
| CN113134671B (en) * | 2021-03-22 | 2022-11-18 | 首钢集团有限公司 | Resistance spot welding method for welding plate group |
| CN113441826A (en) * | 2021-07-16 | 2021-09-28 | 上海交通大学 | Spot welding process for inhibiting liquid metal brittle cracks of galvanized high-strength steel resistance spot welding joint |
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