CN110280880B - Resistance spot welding method for 6061-T6 aluminum alloy and TRIP980 high-strength steel dissimilar alloy - Google Patents

Resistance spot welding method for 6061-T6 aluminum alloy and TRIP980 high-strength steel dissimilar alloy Download PDF

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CN110280880B
CN110280880B CN201910594767.4A CN201910594767A CN110280880B CN 110280880 B CN110280880 B CN 110280880B CN 201910594767 A CN201910594767 A CN 201910594767A CN 110280880 B CN110280880 B CN 110280880B
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welding
aluminum alloy
trip980
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strength steel
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CN110280880A (en
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陈芙蓉
郑纲
王金财
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Inner Mongolia University of Technology
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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
    • 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
    • B23K11/16—Resistance welding; Severing by resistance heating taking account of the properties of the material to be welded
    • B23K11/18—Resistance welding; Severing by resistance heating taking account of the properties of the material to be welded of non-ferrous metals
    • B23K11/185—Resistance welding; Severing by resistance heating taking account of the properties of the material to be welded of non-ferrous metals of aluminium or aluminium alloys
    • 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
    • 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
    • B23K2103/18—Dissimilar materials
    • B23K2103/20—Ferrous alloys and aluminium or alloys thereof

Abstract

The invention discloses a resistance spot welding method for 6061-T6 aluminum alloy and TRIP980 high-strength steel dissimilar alloy, wherein the welding conditions of the resistance spot welding are as follows: the welding current is 6.5kA-10.5kA, the welding time is 15cyc-60cyc, and the electrode pressure is 1kN-3.5 kN. The addition of Cu can effectively improve the plasticity and toughness of the joint under the condition of improving the tensile force of the joint, the fracture mode is that the button fractures and is in a toughness and brittleness mixed fracture mode, the preheating step of the butt welding joint is added, the cooling speed after welding is reduced, and the welding stress is reduced; on the other hand, the increase of the preheating current can improve the plasticity of the metal, so that the workpiece is easy to be tightly attached, the splashing is prevented, the occurrence of cracks is prevented, and the mechanical property of the spot-welded joint is improved.

Description

Resistance spot welding method for 6061-T6 aluminum alloy and TRIP980 high-strength steel dissimilar alloy
Technical Field
The invention relates to the technical field of metal welding machines. In particular to a resistance spot welding method for a dissimilar alloy of 6061-T6 aluminum alloy and TRIP980 high-strength steel.
Background
In recent years, because of the increasing severity of the problems of energy crisis, automobile exhaust emission and the like, the light weight of automobiles is receiving more and more attention. The connection of the aluminum alloy and the high-strength steel is an important research direction for the development of lightweight automobiles. However, for both, the interface is liable to generate thick and brittle Fe — Al intermetallic compounds due to metallurgical incompatibility, thereby deteriorating the mechanical properties of the joint. In contrast, researchers have studied new methods suitable for joining aluminum/steel dissimilar metals by laser brazing, explosion welding, friction stir welding, and the like, but the wide application of these techniques is limited by the cost and the applicability of the techniques.
The resistance spot welding has the advantages of low cost, high automation degree and the like, and is a main welding method for the current automobile body thin plate. In order to realize energy conservation and emission reduction, people such as Chongyueli and the like perform resistance spot welding tests on DP590 high-strength dual-phase steel and 6061 aluminum alloy, and the maximum tensile force of a joint reaches 3kN and is broken at one side of an aluminum base material. The dissimilar welding of aluminum alloy and stainless steel by Shih Hongxi et al shows that the interface reaction layer can weaken the tensile strength of the joint. However, if aluminum/steel is directly subjected to dissimilar welding, the process window range is small, the welding quality is not easy to control, and the joint brittleness is large. And the performance of the aluminum/steel dissimilar joint can be improved to a certain extent by adopting the intermediate interlayer. Oikawa et al use 0.77mm aluminum clad steel as the interlayer, using a composite panel with tensile properties far greater than that of the non-interlayer. I.Ibrahim et Al, used an 80um Al-Mg interlayer to join austenitic stainless steel to 6061 aluminum alloy, and the joint achieved good joint. But still has the problems of high interlayer cost, large brittleness of the dissimilar spot welding joint of the aluminum alloy and the high-strength steel, poor mechanical property and the like.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to provide a resistance spot welding method for 6061-T6 aluminum alloy and TRIP980 high-strength steel dissimilar alloy, which improves the plasticity and toughness of a joint and increases the tensile force.
In order to solve the technical problems, the invention provides the following technical scheme:
the resistance spot welding method of the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy comprises the following welding conditions of resistance spot welding: the welding current is 6.5kA-10.5kA, the welding time is 15cyc-60cyc, and the electrode pressure is 1kN-3.5 kN.
According to the resistance spot welding method for the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy, the welding conditions of the resistance spot welding are as follows: the welding current was 9.5kA, the welding time was 35cyc, and the electrode pressure was 1.5 kN.
According to the resistance spot welding method for the dissimilar alloy of the 6061-T6 aluminum alloy and the TRIP980 high-strength steel, a pure copper sheet or a pure copper sheet with lanthanum powder or gadolinium powder and lanthanum powder coated on the surface is lapped between the 6061-T6 aluminum alloy and the TRIP980 high-strength steel.
According to the resistance spot welding method for the dissimilar alloy of the 6061-T6 aluminum alloy and the TRIP980 high-strength steel, one side of the pure copper sheet coated with the lanthanum powder or the mixed powder of the gadolinium powder and the lanthanum powder faces the TRIP980 high-strength steel.
According to the resistance spot welding method for the 6061-T6 aluminum alloy and TRIP980 high-strength steel dissimilar alloy, the coating amount of lanthanum powder is 0.15-0.3% of the mass of a copper sheet; the coating amount of the mixed powder of the gadolinium powder and the lanthanum powder is 0.1-0.2% of the mass of the copper sheet, and the mass ratio of the gadolinium powder to the lanthanum powder is 1 (5-10).
According to the resistance spot welding method for the dissimilar alloy of the 6061-T6 aluminum alloy and the TRIP980 high-strength steel, the lap joint length of the pure copper sheet is more than or equal to 30mm, burrs on the edges of the 6061-T6 aluminum alloy and the TRIP980 high-strength steel are removed by using an angle grinder before welding, a surface oxidation film is removed by using abrasive paper, and then surface impurities and oil stains are wiped by using absolute ethyl alcohol and acetone.
According to the resistance spot welding method for the 6061-T6 aluminum alloy and TRIP980 high-strength steel dissimilar alloy, a butt joint needs to be preheated before welding; the conditions for preheating the butt joint are as follows: the preheating current is 6kA-8 kA; the preheating time is 10-20 cyc.
According to the resistance spot welding method for the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy, the welding conditions of the resistance spot welding are as follows: the welding current is 15kA-17kA, the welding time is 10cyc-20cyc, and the electrode pressure is 1kN-3.5 kN.
According to the resistance spot welding method for the 6061-T6 aluminum alloy and TRIP980 high-strength steel dissimilar alloy, the conditions for preheating the butt joint are as follows: preheating current is 6kA-8kA, and preheating time is 10-20 cyc; the welding conditions for resistance spot welding were as follows: the welding current is 15kA-17kA, the welding time is 10cyc-20cyc, and the electrode pressure is 1kN-3.5 kN.
According to the resistance spot welding method for the 6061-T6 aluminum alloy and TRIP980 high-strength steel dissimilar alloy, the conditions for preheating the butt joint are as follows: preheating current is 8kA, and preheating time is 20 cyc; the welding conditions of the resistance spot welding were: the welding current was 16kA, the welding time was 20cyc and the electrode pressure was 2.7 kN.
The technical scheme of the invention achieves the following beneficial technical effects:
(1) the addition of Cu changes the components of intermetallic compounds, replaces a part of Fe element in Fe-Al electron pairs to form Fe-Al-Cu ternary compounds, so that the compound has good comprehensive performance and the brittleness of joints is improved. The addition of Cu can effectively improve the plastic toughness of the joint under the condition of improving the tensile force of the joint, and the fracture mode is that the button fractures and is in a mixed fracture mode of toughness and brittleness.
(2) Before welding, a butt welding joint preheating step is added, the cooling speed after welding is reduced, and the welding stress is reduced; on the other hand, the increase of the preheating current can improve the plasticity of the metal, so that the workpiece is easy to be tightly attached, the splashing is prevented, the occurrence of cracks is prevented, and the mechanical property of the spot-welded joint is improved.
(3) The maximum value of the stretching force reaches 4.34kN under the conditions of preheating parameters of 8kA and 20 cycles, welding current, welding time and electrode pressure of 16kA, 20 cycles and 2.7kN respectively, and the stretching force is improved by 14 percent compared with that of the copper sheet which is not added.
(4) The lanthanum powder or the mixed powder of the gadolinium powder and the lanthanum powder is coated on the surface of the copper sheet, so that the components of intermetallic compounds are changed, more importantly, the crystallization condition of one side of TRIP980 high-strength steel can be improved, and the thermal stress during the crystallization of a molten pool can be reduced, so that the difference of the crystallization conditions of one side of 6061-T6 aluminum alloy and one side of TRIP980 high-strength steel is reduced, the generation of cracks at a welding seam is reduced, the lanthanum oxide and the lanthanum also have the function of refining grains, and the grains at two sides of the welding seam are uniformly refined due to the two reasons; the gadolinium-doped powder is beneficial to strengthening the crystallization condition improvement and the grain refinement effect of one side of TRIP980 high-strength steel of lanthanum and lanthanum oxide, thereby greatly improving the tensile force.
Drawings
FIG. 1-1 shows the surface morphology of the joint interface of the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy under different welding currents; (a) the welding current is 6.5kA, the surface appearance of the TRIP980 high-strength steel joint interface, (b) the welding current is 6.5kA, and the surface appearance of the 6061-T6 aluminum alloy joint interface, (c) the welding current is 10.5kA, and the surface appearance of the TRIP980 high-strength steel joint interface, (d) the welding current is 10.5kA, and the surface appearance of the 6061-T6 aluminum alloy joint interface;
FIG. 1-2 shows the surface morphology of the joint of the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy under different welding currents; (a) the welding current is 7kA, the surface appearance of the TRIP980 high-strength steel joint, (b) the welding current is 7kA, the surface appearance of the 6061-T6 aluminum alloy joint, (c) the welding current is 10.5kA, the surface appearance of the TRIP980 high-strength steel joint, (d) the welding current is 10.5kA, and the surface appearance of the 6061-T6 aluminum alloy joint;
FIGS. 1-3 are plots of indentation diameters on both sides of steel/aluminum for different welding currents for a 6061-T6 aluminum alloy of the present invention and a TRIP980 high strength steel dissimilar alloy;
FIGS. 1-4A-C show the macroscopic morphology of the cross section of a steel/aluminum spot-welded joint of the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy under different welding currents: (a) welding current is 7.5kA, (b) welding current is 9.5kA, and (c) welding current is 10.5 kA;
FIGS. 1-5 shows the nugget diameters of the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy under different welding currents;
FIGS. 1-6 illustrate the effect of welding current of dissimilar alloys of 6061-T6 aluminum alloy and TRIP980 high strength steel on the tensile force of a steel/aluminum dissimilar spot welded joint;
FIGS. 1-7 show the surface topography of a steel/aluminum spot-welded joint of a 6061-T6 aluminum alloy and a TRIP980 high-strength steel dissimilar alloy at different welding times: (a) the method comprises the following steps of (a) welding time is 20cyc, the surface appearance of a TRIP980 high-strength steel joint, (b) welding time is 20cyc, the surface appearance of a 6061-T6 aluminum alloy joint interface, (c) welding time is 35cyc, the surface appearance of a TRIP980 high-strength steel joint, (d) welding time is 35cyc, the surface appearance of a 6061-T6 aluminum alloy joint interface, (e) welding time is 60cyc, the surface appearance of a TRIP980 high-strength steel joint, and (f) welding time is 60cyc, and the surface appearance of a 6061-T6 aluminum alloy joint interface;
FIGS. 1-8 impression diameters of the 6061-T6 aluminum alloy of the present invention and TRIP980 high strength steel dissimilar alloy on both sides of the steel/aluminum at different welding times;
FIGS. 1-9A-C show the macroscopic morphology of the cross section of a steel/aluminum spot-welded joint of the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy at different welding times: (a)15cyc, (b)30cyc, (c)50 cyc;
FIGS. 1-10-1 shows the nugget diameters of the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy at different welding times;
FIGS. 1-10-2 illustrate the effect of the 6061-T6 aluminum alloy of the present invention and the TRIP980 high strength steel dissimilar alloy on the tensile force of the steel/aluminum dissimilar spot welded joint at different welding times;
FIGS. 1-11 show the surface topography of a steel/aluminum spot welded joint of 6061-T6 aluminum alloy and TRIP980 high strength steel dissimilar alloy under different electrode pressures: (a) the electrode pressure is 1kN, the surface appearance of the TRIP980 high-strength steel joint interface, (b) the electrode pressure is 1kN, the surface appearance of the 6061-T6 aluminum alloy joint interface, (c) the electrode pressure is 3.5kN, the surface appearance of the TRIP980 high-strength steel joint interface, (d) the electrode pressure is 3.5kN, and the surface appearance of the 6061-T6 aluminum alloy joint interface;
FIGS. 1-12-1 impression diameters of a 6061-T6 aluminum alloy of the present invention and a TRIP980 high strength steel dissimilar alloy for a steel/aluminum spot weld joint at different electrode pressures;
1-12-2 the cross-sectional macro-morphology of the 6061-T6 aluminum alloy and TRIP980 high-strength steel dissimilar alloy of the invention steel/aluminum spot welding joint under different electrode pressures: (a)1kN, (b)1.5kN, (c)3 kN;
FIGS. 1-13 shows the nugget diameters of the 6061-T6 aluminum alloy of the present invention and the TRIP980 high strength steel dissimilar alloy at different electrode pressures;
FIGS. 1-14 illustrate the effect of different alloys of 6061-T6 aluminum alloy and TRIP980 high strength steel on the tension of a steel/aluminum dissimilar spot welded joint at different electrode pressures;
FIG. 2-1 shows the effect of welding current after lapping pure copper between a 6061-T6 aluminum alloy and a TRIP980 high-strength steel dissimilar alloy on the tension of a point welding joint and the size of a nugget;
FIG. 2-2 shows the appearance of the spot-welded joint interface under different welding currents after pure copper is lapped between the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy of the invention: (a) when the welding current is 15kA, the appearance of the interface of the aluminum/steel spot welding joint,
2-3 the appearance of the spot-welded joint interface under different welding currents after pure copper is lapped between the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy of the invention: (b) when the welding current is 17kA, the appearance of the interface of the aluminum/steel spot-welded joint is ensured;
2-4, after pure copper is lapped between the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy, the preheating current is 5kA, and the influence of different welding currents on joint stretching force and nugget diameter is realized when the preheating time is 20 cycles;
FIGS. 2-5 are graphs showing the effect of different welding times after pure copper is lapped between a 6061-T6 aluminum alloy and a TRIP980 high-strength steel dissimilar alloy on the mechanical property and the nugget diameter of an aluminum/steel spot-welded joint;
2-6 the interface topography of the aluminum/steel spot welding joint under the conditions of 6kA preheating current, 20 cycles preheating time, 16kA welding current, 20 cycles welding time and 1.5kN electrode pressure after pure copper is lapped between the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy;
FIGS. 2-7 are graphs showing the effect of different preheating currents on the tensile force and nugget diameter of an aluminum/steel spot-welded joint after pure copper is lapped between a 6061-T6 aluminum alloy and a TRIP980 high-strength steel dissimilar alloy;
FIG. 3 shows the effect of different electrode pressures on the tensile force and nugget diameter of an aluminum/steel spot-welded joint after pure copper is lapped between a 6061-T6 aluminum alloy and a TRIP980 high-strength steel dissimilar alloy;
FIG. 4 shows the interface morphology of the spot-welded joint of aluminum/steel points under conditions of preheating current of 8kA, preheating time of 20 cycles, welding current, welding time and electrode pressure of 16kA, 20 cycles and 2.7kN after pure copper is lapped between the 6061-T6 aluminum alloy and the TRIP980 high-strength steel dissimilar alloy.
Detailed Description
Example 1 Effect of welding conditions on mechanical Properties of aluminum/Steel Spot welded joints
The influence of welding current, welding time and electrode pressure on the mechanical property of the steel/aluminum spot-welded joint is respectively researched according to a single-factor rule by using a conical flat electrode head with the diameter of 8 mm. In the experimental process, 3 samples are welded under each group of parameters, and the stability of the test result is ensured. And determining the better parameters of the 6061-T6 aluminum alloy and the TRIP980 high-strength steel under the condition of dissimilar resistance spot welding according to the magnitude of the tensile force and the welding quality.
1.1 Effect of welding Current
The influence of welding current (6.5-10.5kA) on the mechanical properties of the steel/aluminum dissimilar joint is studied under the stable conditions of maintaining the welding time (30cyc) and the electrode pressure (2 kN).
1.1.1 Effect of welding Current on Joint organization
FIG. 1-1 shows the surface topography of the joint interface at different welding currents. As shown in fig. 1-1(a) and (b), when the welding current is 6.5kA, the forming quality at the interface is good, no nugget splash is generated, an obvious plastic ring can be observed at the aluminum alloy interface, and the influence (aluminum alloy oxidation) on the welding seam forming process caused by external factors is effectively prevented; when the welding current is increased to 10.5kA, as shown in figures 1-1(c) and (d), the temperature of a welding area is increased due to a large increase of heat input, so that the surface yield strength of the steel-aluminum joint is reduced, the aluminum alloy is rapidly melted and expanded, the molten aluminum alloy is extruded under the action of electrode pressure, a large amount of splashes are generated at the interface to rush out a plastic ring, and aluminum alloy splashing and sticking phenomena occur, so that the mechanical property of the joint is seriously influenced.
Fig. 1-2 are topographical views of the joint surface at different welding currents. From the observation of the figure, it is clear that the welding current has a very important influence on the indentation diameter. As shown in fig. 1-2(a), (b), when the welding current was 7kA, the indentation diameter on the aluminum alloy side was 4.675mm, and the indentation diameter on the high-strength steel side was 4.135 mm. Along with the increase of welding current, the increase amplitude of the indentation diameter of one side of the aluminum alloy is greatly improved, and the indentation diameter of one side of the high-strength steel is also increased but is not obvious on one side of the aluminum alloy. As shown in fig. 1-2(c), (d), when the welding current was increased to 10.5kA, the indentation diameter of the aluminum alloy side was increased to 7.445mm, and the indentation diameter of the high strength steel side was 6.375 mm. Generally speaking, under the action of welding thermal cycle, the temperature of the surface of the aluminum alloy contacted with the electrode tip is increased, the yield strength is obviously reduced, the effect of the aluminum alloy surface resisting electrode pressure is reduced, the elongation of the aluminum alloy at high temperature is higher than that of high-strength steel, and the trend of increasing the indentation diameter is obvious under the action of the electrode pressure and the surface of the electrode tip; the yield strength reduction trend of one side of the reverse high-strength steel is not obvious under the action of welding thermal cycle, the indentation depth is almost zero under the action of electrode pressure, and the surface has obvious copper adhesion and oxidation. Therefore, the indentation diameter of the aluminum alloy side is larger than that of the high-strength steel side, but the total indentation depth is not obvious, and the surface forming quality is good. Fig. 1-3 show the indentation diameters on both sides of steel/aluminum at different welding currents.
Fig. 1-4 are cross-sectional macro-features of a steel/aluminum spot weld joint at different welding currents. It can be seen from the figure that as the welding current increases, the nugget diameter gradually increases, and the nugget height also increases, from 0.7mm at 7.5kA to 1.53mm at 10.5 kA. When the current is 7.5kA, the volume of the molten aluminum alloy is smaller due to small welding heat input, so that the diameter and the height of the aluminum alloy nugget are smaller; when the welding current is increased to 10.5kA, the heat input is rapidly increased, the melting volume of the aluminum alloy is correspondingly increased, and the diameter of the aluminum alloy nugget and the height of the nugget are obviously increased. As can be seen from fig. 1-4(c), the high-strength steel of TRIP980 has a convex steel plate on one side, the more the steel plate is close to the center of the welding point, the more the steel plate is convex, and the interface becomes smooth gradually as the steel plate is farther from the center of the welding point. The phenomenon is probably because when the aluminum alloy is heated and melted, the temperature of the central area of the welding spot is highest, and the aluminum alloy is heated and melted, so that the yield strength of one side of the aluminum alloy is obviously reduced; at this time, the surface of one side of the steel is kept in a solid state, and due to thermal expansion, the aluminum alloy side is raised under the action of the pressure of the electrode. Generally, the drawing force of steel-aluminum spot welding is mainly determined by the diameter of a nugget and the height of the nugget, but after the welding current is increased to 10kA, the obvious aluminum alloy splashing phenomenon appears at the joint interface, so that the mechanical property of the joint is reduced, and meanwhile, the defects of cracks, shrinkage cavities and the like are generated, so that the welding seam is not favorably formed.
Fig. 1-5 show the nugget diameters at different welding currents. As can be seen from fig. 1-5, as the welding current increases, the welding heat input also increases accordingly, and more aluminum alloy participates in melting under the same electrode pressure and welding time, and the melting volume of the aluminum alloy increases, resulting in an increase in the nugget diameter. At 6.5-9.5kA, the diameter of the nugget is increased in linear proportion, and the mechanical property of the joint is stably increased. However, when the welding current is 9.5-10.5kA, the nugget diameter has a tendency of rising steeply, although the maximum value of 6.265mm is reached at 10.5kA, which is far beyond the specified standard of the nugget diameter in the lap joint mode
Figure GDA0002935630660000082
(European standard for the diameter of a nugget is adopted, t is the thickness of a thin plate), but aluminum alloy splash at the interface and shrinkage cavity crack defects are generated while the diameter of the nugget is increased, and the mechanical property of the joint is greatly reduced.
1.1.2 influence of welding Current on mechanical Properties of joints
Table 1-1 shows the tensile test results for steel/aluminum spot welded joints at different welding currents. The test result shows that: under the condition of keeping the welding time and the electrode pressure unchanged, the shearing resistance of the joint is increased along with the increase of the welding current. When the welding current reached 9.5kA, the joint tensile force reached a maximum (3.33 kN). When the welding current is further increased to 10.5kA, the joint tensile force is reduced to 2.082 kN. The effect of the welding current on the mechanical properties of the joint is mainly related to the nugget diameter, the thickness of the intermetallic layer and the weld defects due to heat input. When the welding current is 6.5-9.5kA, more aluminum alloy participates in melting along with the increase of heat input, the diameter of a nugget is increased, and the joint tensile force is increased. Further increase of the welding current (9.5-10.5kA) increases the nugget diameter, but due to the large heat input, the thickness of the interface intermetallic compound layer increases, the steel/aluminum interface splashes, the mechanical properties of the weld are reduced, and therefore the tensile force is reduced.
TABLE 1-1 tensile force of joints under different welding currents
Figure GDA0002935630660000081
Figure GDA0002935630660000091
According to the results of welding current on the mechanical properties of the joint, under the test conditions, as shown in fig. 1 to 6, the welding current of 9.5kA is beneficial to improving the mechanical properties of the joint.
1.2 Effect of welding time
The influence of the welding time on the mechanical properties of the steel/aluminum dissimilar joint is studied under the stable conditions of maintaining the welding current (9.5kA) and the electrode pressure (2 kN).
1.2.1 Effect of weld time on Joint organization
Fig. 1-7 show photographs of the topography of the steel/aluminum spot weld joint surface at different weld times. As can be seen from fig. 1-7, the welding time has a significant effect on the indentation diameter of the resistance spot welding of steel and aluminum dissimilar metals. Under the conditions that the welding current (9.5kA) and the electrode pressure (2kN) are kept unchanged, when the welding time is 20cyc, the indentation diameter of one side of the aluminum alloy is 5.76mm, and the indentation diameter of one side of the high-strength steel is 4.755 mm; when the welding time was increased to 35cyc, the indentation diameter of the aluminum alloy side was 7.45mm, and the indentation diameter of the high strength steel side was 5.35 mm; along with the increase of the welding time, the welding heat input is obviously increased, the yield strength of the two sides of the steel and the aluminum is reduced, and when the welding time is 60cyc, the indentation diameter of one side of the aluminum alloy is 8.5mm, and the indentation diameter of one side of the high-strength steel is 6.75 mm. However, as can be seen from the test observation later, although the welding heat input is obviously increased along with the increase of the welding time, under the same electrode pressure, the pressure resistance of the liquid aluminum alloy to the electrode pressure is reduced, and the indentation depth of one side of the aluminum alloy is increased; since the surface of the steel side is kept in a solid state, although the yield strength of the steel side is reduced due to the increase in the temperature of the welding area, the pressure resistance of the steel side against the electrode pressure is not reduced, and thus the indentation depth of the steel side has little effect.
Therefore, in order to better explain the influence degree of the spot-welded joint indentation on one side of the aluminum alloy, the concept of the indentation ratio lambda is introduced, and the calculation mode is as follows:
λ＝H0/H1
(wherein H is0Indicating the indentation depth, H, of one side of the aluminum alloy1Thickness of mother material of aluminum alloy
When the welding time is 15cyc, the indentation depth of one side of the aluminum alloy is 0.12mm, and the indentation rate is calculated by using a formula to be 6%; the welding time is increased to 30cyc, the indentation depth of one side of the aluminum alloy is increased to 0.13, the increase amplitude is not obvious, and the indentation is formed at the momentThe rate is 6.5%; as the welding time further increases, Q-I is determined according to Joule's law2Rt, when the electrode pressure is unchanged, the contact area between the electrode tip and the two sides of the steel and the aluminum and between the electrode tip and the steel and the aluminum is unchanged, the resistance is kept basically unchanged, and under the condition of the same welding current, the longer the welding time is, the higher the temperature of a welding area is, and the more obvious the indentation depth of one side of the aluminum alloy is at the moment. When the welding time is increased to 60cyc, the indentation depth of one side of the aluminum alloy is 1.6mm, the indentation rate is 17%, and the change trend is obvious. According to the quality inspection standard of resistance spot welding joints, the indentation rate of welding spots is not more than 30%, and the surface quality and the mechanical properties of the joints are influenced by the excessive indentation rate. The effect of welding time on the indentation rate of steel aluminum spot welds is primarily due to changes in the welding heat input. Figures 1-8 show the indentation diameters on both sides of the steel and aluminum at different weld times.
Fig. 1-9 show the macroscopic morphology of the cross-section of a steel/aluminum spot weld joint at different weld times. As seen from fig. 1 to 9, when the welding time was 15cyc, the nugget diameter was 4.495, the nugget height was 0.82mm, and at this time, the welding heat input was small, and the volume of the molten aluminum alloy in the welding temperature region was small, resulting in the nugget diameter not meeting the specified standard for steel aluminum spot welding; when the welding time is further increased to 30cyc, along with the increase of welding heat input, the melting volume of the aluminum alloy is increased, the diameter of a nugget reaches 5.625mm, the melting height is 0.94mm, the melting height exceeds the nugget diameter standard of steel-aluminum spot welding specified by European Union, but the increase amplitude of the melting height is not obvious; with the continuous increase of the welding time, under the condition that the electrode pressure and the welding current are kept unchanged, the welding heat input is rapidly increased, the melting volume of the aluminum alloy is further increased, when the welding time is 50cyc, the diameter of a nugget reaches 5.99mm, the melting height is 1.44mm, and the increase amplitude is obvious. The effect of welding time on the nugget diameter of a steel-aluminum spot weld joint is also primarily due to changes in the welding heat input. Fig. 1-10 show nugget diameters at different welding times.
1.2.2 Effect of weld time on mechanical Properties of joints
Tables 1-2 show the tensile test results for steel/aluminum spot welded joints at different weld times. The test result shows that: while maintaining welding current, electricityWhen the extreme pressure was not changed, the joint tensile force was 2.021kN at a welding time of 10cyc, and the joint tensile force was increased with the increase of the welding time, and the maximum tensile force was 3.4kN at a welding time of 35 cyc. The joint tensile force is reduced with further increase of the welding time, and is reduced to 1.921kN when the welding time is 50 cyc. At welding times of 10-35cyc, the increase in joint tensile force was primarily associated with an increase in nugget diameter. As the welding time further increases, the welding heat input increases (Q ═ I) while the welding current and electrode pressure remain unchanged2RT), Fe/Al elements between interfaces have more sufficient time to participate in diffusion, intermetallic compounds with complex structures are generated at the interfaces, the thickness is increased, and the hard and brittle intermetallic compounds cause the reduction of the mechanical property of the joint in the process of carrying out a tensile test.
TABLE 1-2 results of tensile force of joint at different welding times on mechanical properties of joint according to welding time
Figure GDA0002935630660000111
As can be seen from fig. 1-11, under the present test conditions, a weld time of 35cyc is beneficial in improving the tensile properties of the steel/aluminum dissimilar joint.
1.3 influence of electrode pressure
The influence of the electrode pressure on the mechanical properties of the steel/aluminum dissimilar joint is studied under the test conditions of maintaining the welding current (9.5kA) and the welding time (35 cyc).
1.3.1 Effect of electrode pressure on Joint tissue
Electrode pressure is an important parameter that indirectly changes the heat input to the weld. The effect of the electrode pressure on the surface quality of the weld joint and the size of a nugget was studied by changing the electrode pressure (1-3.5kN) under the basic conditions of maintaining the welding current (9.5kA) and the welding time (35 cyc). The smaller the electrode pressure, the smaller the contact area between the steel/aluminum interfaces, and according to the formula R ═ ρ × l/s, the greater the interfacial contact resistance, resulting in a direct increase in the welding heat input. Fig. 1-11 show the indicated morphology of a steel/aluminum spot weld joint at different electrode pressures. As can be seen from the figure, when the electrode pressure is 1kN, from FIGS. 1 to 11(a), (b), the indentation diameter of the aluminum alloy side is 7.505mm, which is an irregular ellipse, while the size of the high-strength steel side reaches 6.745mm, and sparks are generated during welding with a large amount of spatters; when the electrode pressure was increased to 3.5kN, from fig. 1-11(c), (d), the indentation diameter of the aluminum alloy side was reduced to 6.68mm, a regular circle shape was exhibited, and the indentation diameter of the high strength steel side was reduced to 4.225mm, while no sparks and welding spatters were generated. The reason for this phenomenon is mainly that when the electrode pressure is too small, the contact resistance between the interfaces becomes large, so that the welding heat input is greatly increased, more aluminum alloy is melted in the same welding time and current, and meanwhile, the liquid aluminum alloy is punched out of the plastic ring to generate nugget splashing, so that the indentation diameter of the joint surface is increased; similarly, as the electrode pressure increases, the heat between the steel and the aluminum decreases, and the liquid aluminum alloy participating in melting also decreases, resulting in a decrease in the indentation diameter of the joint surface. Figures 1-12 show the surface indentation diameters of steel/aluminum joints at different electrode pressures.
Fig. 1-13 show nugget diameters at different electrode pressures. As can be seen from the figure, the nugget diameter reached a maximum of 6.5mm (shown in FIGS. 1 to 12 (a)) at an electrode pressure of 1kN, at which the fusion height was 1.29 mm.
As the electrode pressure increases, the weld heat input also decreases. When the electrode pressure was 1.5kN, the nugget diameter was 6.16mm and the melt height increased to 1.62 mm. The reason for this phenomenon is that when the electrode pressure is 1kN at the minimum, the compressive capacity of the liquid aluminum alloy is reduced while the welding heat input is increased, more aluminum alloy participates in melting and far exceeds the protection capacity of the plastic ring, so that the nugget splashes, a large amount of sparks occur during welding, and welding defects such as shrinkage cavities are generated at the interface and inside the nugget, and the fusion height is reduced.
When the electrode pressure was large (3kN), the nugget diameter at this time was reduced to 5.41mm, and the nugget height was greatly reduced. In summary, the effect of electrode pressure on nugget diameter is primarily due to changes in weld heat input. Fig. 1-13 show nugget diameters at different electrode pressures.
1.3.2 influence of electrode pressure on mechanical properties of the joint
Tables 1-3 show the tensile test results for steel/aluminum spot welded joints at different electrode pressures. The test result shows that: under the test conditions that the welding current and the welding time are stabilized at 9.5kA and 35cyc, the tensile force of the steel/aluminum dissimilar joint tends to increase and then slowly decrease to be stable along with the increase of the electrode pressure. When the electrode pressure was 1kN, the joint tensile force was 3.17 kN. The interface contact area is sharply increased due to the smaller electrode pressure, according to
Figure GDA0002935630660000132
The interface contact area is reduced and the resistance is increased, thereby generating a large amount of resistance heat. Excessive heat input causes welding defects such as nugget splashing, shrinkage cavity and the like, and greatly reduces the mechanical property of the joint. With the increase of the electrode pressure, the maximum value of 3.793kN is reached when the electrode pressure is 1.5kN, the welding quality is good, and a good welding effect is achieved. Further increasing the electrode pressure, the steel/aluminum dissimilar joint tensile force slowly drops until it stabilizes at a level of 3.1-3.2 kN. On one hand, the welding heat input is reduced along with the increase of the electrode pressure, so that the nugget diameter is reduced, and the mechanical property of the joint is reduced; on the other hand, in experimental observation, there was little change in nugget diameter when the electrode pressure was increased above 2.5kN, resulting in no significant change in tensile properties for the latter experimental design parameters.
TABLE 1-3 tensile forces of joints at different electrode pressures
Figure GDA0002935630660000131
As can be seen from fig. 1-14, under the present test conditions, an electrode pressure of 1.5kN is beneficial for improving the tensile properties of the steel/aluminum dissimilar joint.
In summary, the welding conditions are as follows: the welding current is 9.5kA, the welding time is 35cyc, and the electrode pressure is 1.5kN, so that the mechanical property of the joint is improved, and the tensile property of the steel/aluminum dissimilar joint is improved.
EXAMPLE 2 Effect of Cu on mechanical Properties of aluminum/Steel Spot welded joints
The embodiment respectively researches the influence of welding current, welding time and electrode pressure on the mechanical property of the aluminum/steel spot-welded joint, determines better parameters according to factors such as the size of tensile force, the forming quality of the joint surface and the like, and explains the fracture mechanism of the spot-welded joint.
2.1.1 Effect of welding Current on mechanical Properties of aluminum/Steel Spot welded joints
Because the addition of the copper sheet increases the welding heat input, effective welding can be realized only by selecting larger welding parameters. Compared with the copper sheet, the welding current of 10-17kA is sequentially used, the electrode pressure is kept to be 1.5kN, and the welding time is kept to be 20 cycles. In the experimental process, the tensile force of the spot-welded joint under the welding current of 10-14 kA is found to be less than 1kN, and the test sample is unqualified. When the welding current is increased to 15-17 kA, the tensile force of the spot-welded joint is improved, and the influence of the welding current on the tensile force of the spot-welded joint and the diameter of a nugget is shown in figure 2-1.
As can be seen from FIG. 2-1, when the welding current is 16kA, the joint tensile force is increased to 1.905kN, and with further increase of welding heat input and the welding current is 17kA, the joint tensile force is decreased to 1.623kN, the overall variation trend of the nugget diameter is not obvious, the diameter is maintained at about 6mm, and the standard of the spot welding nugget diameter is achieved
Figure GDA0002935630660000141
But the tensile force of the joint is not obviously improved and is reduced compared with that of the joint without the copper sheet, and the figures 2-3 show the appearance of the spot-welded joint interface under different welding currents.
As can be seen from fig. 2-3, the aluminum/steel spot weld joint interface splashes to various degrees, and cracks are generated on the aluminum alloy nugget side. On one hand, the welding heat input is increased due to the improvement of welding current, and the cooled joint has larger crystallization stress and is accompanied with the generation of thermal cracks under the rapid cooling condition of water cooling of the electrode; on the other hand, under the condition of larger heat input, the aluminum alloy nuggets are punched out of the plastic ring, so that the effective bearing area of the joint is reduced, and the deterioration of the mechanical property of the spot welding joint is caused. Therefore, in order to reduce the problems of large thermal stress, welding spatter and the like of the joint after cooling crystallization, preheating measures are adopted to improve the joint, preheating parameters are preliminarily designed to be 5kA and 20 cycles, and the influence of different welding currents on the tension force of the point welding joint and the nugget diameter under the preheating parameters of 5kA and 20 cycles is shown in figures 2-4.
As can be seen by comparing the joint tensile force and the nugget diameter under the preheating parameters with the comparison of the graphs in FIGS. 2-4 and 2-1, the joint tensile force is 2.585kN and the nugget diameter reaches 7.2mm when the welding current is 16kA, so that the mechanical property is improved to a certain extent. It was therefore preliminarily established that a welding current of 16kA at a welding time of 20 cycles and an electrode pressure of 1.5kN makes it possible to achieve a good connection of the spot-welded joint.
2.1.2 Effect of welding time on mechanical Properties of aluminum/Steel Spot welded joints
The influence of different welding time on the mechanical property of the aluminum/steel spot-welded joint is researched under the condition that the preheating current, the preheating time, the welding current and the electrode pressure are respectively 5kA, 20 cycles, 16kA and 1.5 kN.
Fig. 2-5 are graphs showing the effect of different weld times on the aluminum/steel spot weld joint tensile force and nugget diameter. As can be seen from the graph, the tensile force and the nugget diameter tend to increase with the increase in welding time. When the welding time was 20 cycles, the tensile force was 2.585kN and the nugget diameter was 7.2 mm. However, in the later preheating current parameter optimization test, the preheating parameter optimization process window under the welding time of 20 cycles is found to be small, and effective preheating parameter optimization cannot be realized, so that the welding time of 15 cycles is taken as the basic parameter of the next test. FIGS. 2-6 are graphs of the interface morphology of the aluminum/steel spot-welded joint with preheating parameters of 6kA and 20 cycles, and welding current, welding time and electrode pressure of 16kA, 20 cycles and 1.5kN respectively. As can be seen from fig. 2-6, when the preheating parameter is 6kA and 20 cycles, the burn-through phenomenon has occurred in the spot-welded joint with the welding time of 20 cycles, so that the spot-welded sample fails, and it is further illustrated that the welding time of 15 cycles is the preferred parameter of the test.
2.1.3 Effect of preheating Current on mechanical Properties of aluminum/Steel Spot welded joints
Based on the earlier research results, the influence of the preheating current on the mechanical property of the aluminum/steel spot-welded joint is analyzed under the conditions that the preheating time, the welding current, the welding time and the electrode pressure are respectively 20 cycles, 16kA, 20 cycles and 1.5kN, so that the preheating parameters are further optimized.
Fig. 2-7 illustrate the effect of different preheat currents on the aluminum/steel spot weld joint tensile force and nugget diameter. From the analysis of fig. 2-7, it can be seen that the tension increases with increasing preheat current, and that the spot weld joint tension increases to 2.754kN at 8kA preheat current. The variation trend of the nugget diameter is not obvious, and the average diameter is maintained to be about 7.5 mm. The increase of the preheating current can effectively reduce the cooling speed after welding and reduce the welding stress; on the other hand, the increase of the preheating current can improve the plasticity of the metal, so that the workpiece is easy to be tightly attached, the splashing is prevented, and the mechanical property of the spot welding joint is improved.
2.2.4 Effect of electrode pressure on mechanical Properties of aluminum/Steel Spot welded joints
Based on the earlier research results, the influence of the electrode pressure on the mechanical property of the aluminum/steel spot-welded joint is researched on the basis of the conditions that the preheating parameters are 8kA and 20 cycles, the welding current and the welding time are 16kA and 20 cycles respectively.
Fig. 3 is a graph showing the effect of different electrode pressures on the tensile force and nugget diameter of an aluminum/steel spot weld joint. As can be seen from fig. 3, the tensile force tends to increase first and then decrease with the increase of the electrode pressure, and when the electrode pressure is 2.7kN, the tensile force increases to 4.34kN, and the button is broken; with the further increase of the electrode pressure, the tensile force is in a descending trend, mainly because the indentation rate of the joint surface is also improved with the increase of the electrode pressure, and the excessive increase of the indentation rate further reduces the effective area of the point welding joint bearing load in the tensile process, so that the tensile force is reduced. The diameter of the nugget is reduced along with the increase of the electrode pressure, but the change amplitude is smaller, and the main reason is that the heat input is reduced. The electrode pressure is increased, and the welding heat input is reduced due to the reduction of the actual contact resistance, so that the cooling speed after welding is reduced; on the other hand, in the welding process, the phenomena of electric sparks and welding spatters can be reduced due to the increase of the electrode pressure, the welding quality is improved, the crystallization stress after welding is effectively reduced, the tensile force is further improved to 4.34kN, and is improved by 14% compared with the situation that no copper sheet is added, and the button is broken. FIG. 4 shows the interface morphology of the spot-welded joint under preheating parameters of 8kA and 20 cycles, welding current, welding time and electrode pressure of 16kA, 20 cycles and 2.7kN respectively.
2.2.5 Effect of coating lanthanum powder on mechanical Properties of aluminum/Steel Spot welded joints
Lanthanum powder with the purity of more than or equal to 99 percent and 200 meshes is coated on the copper sheet, and the side coated with the lanthanum powder faces to TRIP980 high-strength steel. The maximum value of the stretching force reaches 4.59kN under the conditions of preheating parameters of 8kA and 20 cycles, welding current, welding time and electrode pressure of 16kA, 20 cycles and 2.7kN respectively, and the stretching force is improved by 21 percent compared with that of the copper sheets which are not added. Lanthanum oxide is formed on the surface of lanthanum powder quickly after one side of a copper sheet is coated with the lanthanum powder, the lanthanum and the lanthanum oxide can improve the crystallization condition of one side of TRIP980 high-strength steel and reduce the thermal stress during the crystallization of a molten pool, so that the difference of the crystallization conditions of one side of 6061-T6 aluminum alloy and one side of TRIP980 high-strength steel is reduced, cracks at a welding seam are reduced, the lanthanum oxide and the lanthanum also have the function of grain refinement, and the grains at two sides of the welding seam are uniformly refined due to the two reasons.
2.2.6 Effect of coating the Mixed powder of gadolinium and lanthanum powders on the mechanical Properties of aluminum/Steel Spot welded joints
The pure copper sheet is coated with mixed powder of gadolinium powder and lanthanum powder, one side coated with the mixed powder faces to TRIP980 high-strength steel, the purity of the gadolinium powder is greater than or equal to 99% and 200 meshes, and the purity of the lanthanum powder is greater than or equal to 99% and 200 meshes; the mass ratio of the gadolinium powder to the lanthanum powder was 1: 7. The maximum value of the stretching force reaches 5.42kN under the conditions of preheating parameters of 8kA and 20 cycles, welding current, welding time and electrode pressure of 16kA, 20 cycles and 2.7kN respectively, and the stretching force is improved by 43 percent compared with that of the copper sheet which is not added. After one side of a copper sheet is coated with mixed powder of gadolinium powder and lanthanum powder, lanthanum oxide is quickly formed on the surface of the lanthanum powder, the lanthanum and the lanthanum oxide can improve the crystallization condition of one side of TRIP980 high-strength steel and reduce the thermal stress during the crystallization of a molten pool, so that the difference of the crystallization conditions of one side of 6061-T6 aluminum alloy and one side of the TRIP980 high-strength steel is reduced, cracks at a welding seam are reduced, the lanthanum oxide and the lanthanum also have the effect of refining crystal grains, and the crystal grains at two sides of the welding seam are uniformly refined due to the two reasons; the gadolinium-doped powder is beneficial to strengthening the crystallization condition improvement and the grain refinement effect of one side of TRIP980 high-strength steel of lanthanum and lanthanum oxide, thereby greatly improving the tensile force.
To summarize: lapping copper sheets, wherein the maximum value of the stretching force is 4.34kN under the conditions that the preheating parameters are 8kA and 20 cycles, the welding current, the welding time and the electrode pressure are respectively 16kA and 20 cycles and 2.7kN, and the stretching force is improved by 14 percent compared with that of the copper sheets which are not added; lapping the copper sheet coated with the lanthanum powder, wherein the maximum value of the stretching force is 4.34kN under the conditions that the preheating parameters are 8kA and 20 cycles, the welding current, the welding time and the electrode pressure are respectively 16kA, 20 cycles and 2.7kN, and the stretching force is improved by 21 percent compared with the copper sheet which is not added; the mixed powder copper sheet of the overlapped gadolinium powder and lanthanum powder has the maximum stretching force of 4.34kN under the conditions of preheating parameters of 8kA and 20 cycles, welding current, welding time and electrode pressure of 16kA and 20 cycles and 2.7kN respectively, and is improved by 43 percent compared with the copper sheet which is not added.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications are possible which remain within the scope of the appended claims.

Claims (6)

  1. The resistance spot welding method for the dissimilar alloy of the 1.6061-T6 aluminum alloy and the TRIP980 high-strength steel is characterized in that a pure copper sheet is lapped between the 6061-T6 aluminum alloy and the TRIP980 high-strength steel, and one side of the pure copper sheet coated with lanthanum powder or mixed powder of gadolinium powder and lanthanum powder faces the TRIP980 high-strength steel; the coating amount of the lanthanum powder is 0.15-0.3% of the mass of the copper sheet; the coating amount of the mixed powder of the gadolinium powder and the lanthanum powder is 0.1-0.2% of the mass of the copper sheet, and the mass ratio of the gadolinium powder to the lanthanum powder is 1 (5-10).
  2. 2. The method for resistance spot welding of dissimilar alloys of 6061-T6 aluminum alloy and TRIP980 high-strength steel, according to claim 1, wherein the lap joint length of pure copper sheets is greater than or equal to 30mm, burrs on the edges of 6061-T6 aluminum alloy and TRIP980 high-strength steel are removed by an angle grinder before welding, a surface oxide film is removed by sand paper, and then surface impurities and oil stains are wiped by absolute ethyl alcohol and acetone.
  3. 3. The method for resistance spot welding of dissimilar alloys of 6061-T6 aluminum alloy and TRIP980 high strength steel according to claim 1, wherein the butt joint is preheated before welding; the conditions for preheating the butt joint are as follows: the preheating current is 6kA-8 kA; the preheating time is 10-20 cyc.
  4. 4. The resistance spot welding method of the 6061-T6 aluminum alloy and TRIP980 high-strength steel dissimilar alloy according to claim 1, characterized in that the welding conditions of the resistance spot welding are as follows: the welding current is 15kA-17kA, the welding time is 10cyc-20cyc, and the electrode pressure is 1kN-3.5 kN.
  5. 5. The resistance spot welding method of 6061-T6 aluminum alloy and TRIP980 high strength steel dissimilar alloy according to claim 1, wherein the conditions for preheating the butt joint are as follows: preheating current is 6kA-8kA, and preheating time is 10-20 cyc; the welding conditions for resistance spot welding were as follows: the welding current is 15kA-17kA, the welding time is 10cyc-20cyc, and the electrode pressure is 1kN-3.5 kN.
  6. 6. The resistance spot welding method of 6061-T6 aluminum alloy and TRIP980 high strength steel dissimilar alloy according to claim 5, wherein the conditions for preheating the butt joint are as follows: preheating current is 8kA, and preheating time is 20 cyc; the welding conditions of the resistance spot welding were: the welding current was 16kA, the welding time was 20cyc and the electrode pressure was 2.7 kN.
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201409232Y (en) * 2009-04-03 2010-02-17 上海汉源特种陶瓷有限公司 Silicon nitride heating element
CN101854749A (en) * 2009-04-03 2010-10-06 上海汉源特种陶瓷有限公司 Silicon nitride heating element and making method thereof
CN102909490A (en) * 2012-11-09 2013-02-06 高金菊 Flux-cored wire for welding austenitic stainless steel
CN103753005A (en) * 2013-10-16 2014-04-30 吉林大学 High strength steel-aluminum alloy dissimilar metal connecting method
CN107081517A (en) * 2017-06-28 2017-08-22 合肥工业大学 A kind of law temperature joining method of TZM and WRe different alloys
CN108950508A (en) * 2018-07-23 2018-12-07 河北工业大学 A kind of high strength anti-corrosion aluminium containing middle layer/magnesium different alloys connector and preparation method thereof

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201409232Y (en) * 2009-04-03 2010-02-17 上海汉源特种陶瓷有限公司 Silicon nitride heating element
CN101854749A (en) * 2009-04-03 2010-10-06 上海汉源特种陶瓷有限公司 Silicon nitride heating element and making method thereof
CN102909490A (en) * 2012-11-09 2013-02-06 高金菊 Flux-cored wire for welding austenitic stainless steel
CN103753005A (en) * 2013-10-16 2014-04-30 吉林大学 High strength steel-aluminum alloy dissimilar metal connecting method
CN107081517A (en) * 2017-06-28 2017-08-22 合肥工业大学 A kind of law temperature joining method of TZM and WRe different alloys
CN108950508A (en) * 2018-07-23 2018-12-07 河北工业大学 A kind of high strength anti-corrosion aluminium containing middle layer/magnesium different alloys connector and preparation method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
中间层铜对铝/钢电阻点焊接头性能的影响;郑纲等;《机械制造文摘—焊接分册》;20190630;参见第10页的左下栏，附图1 *

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