Laser welding method for plate composed of steel base body and pre-plating layer

Abstract

The invention discloses a laser welding method for a plate composed of a steel base body and a pre-plating layer. According to the laser welding method, firstly, a preheating heat source is adopted for preheating areas on the two sides of the butt joint position of adjacent plates, the pre-plating layer on the surface of a heat affected zone of the heated plate is melted and flows to the positionnearby a hot melting area formed after preheating, then the plate is subjected to laser welding, accordingly, the plating layer amount of the surface of a weld joint formed after plate welding is reduced, the plate is away from the weld joint, especially the heat affected zone, intermetallic compounds of the plate in the weld joint area are reduced, and the strength of the weld joint is improved.

Description

technical field [0001] The invention relates to a laser welding method for a plate composed of a steel substrate and a pre-coated layer, in particular to a method for laser welding a coated steel plate in the fields of automobiles, aerospace, ships and the like. Background technique [0002] In the fields of automobiles, aerospace and other fields, it is generally required that the plates for manufacturing parts have high corrosion resistance. Coating zinc, aluminum and other coatings on the surface of the plates can increase the corrosion resistance of the plates, so more and more surfaces have Coated sheets are applied. Because the steel coated with aluminum or aluminum alloy on the surface manufactured by cold rolling or hot rolling not only has good corrosion resistance, but also has high temperature resistance, so the steel plate coated with aluminum alloy is often used in In the manufacture of automobile bodies, such as door reinforcements, B-pillar structural parts, ...

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Problems solved by technology

[0004] However, when laser welding a plate coated with aluminum or aluminum alloy on the surface, the coating on the surface of the plate will enter the melting zone, especially into the heat-affected zone of the weld, and the coating entering the heat-affected zone will be on the steel substrate. In the dendrite space of the material, during the austenitization process of the subsequent heating base material, aluminum will interdiffuse with iron or other components and alloy to form an intermetallic compound remaining in the heat affected zone, and due to the strength of the heat affected zone of the weld Weaker, under the action of mechanical load in the future, the weld failure zone of the welded part is often in the heat-affected zone, and these intermetallic compounds will become the initial position of the failure crack, seriously weakening the bearing capacity of the welded joint, so It is necessary to remove or reduce the penetration of coatings into the heat-affected zone of the weld

[0005] At present, the method of eliminating the above-mentioned effects is mainly to remove the coating layer on the surface in advance by mechanical methods, laser methods or other methods, so as to prevent it from entering the weld, but this method has problems such as high cost and complicated process, so it is necessary A better way to achieve high-efficiency laser welding of surface-coated panels

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