Aluminum steel dissimilar metal laser welding-brazing welding method and filled powder

Abstract

The invention discloses an aluminum steel dissimilar metal laser welding-brazing welding method and filled powder. A preset powder filling method is adopted. The method comprises the following steps of: configuring a joint to be in overlap joint and butting of different thicknesses, wherein the overlap joint length is 4-10mm in overlap joint; in butting, assembling the aluminum steel with the clearance-free bottom surface on the same level; striking a laser spot on an aluminum alloy in overlap joint and butting, wherein the distance from the laser spot to the edge of an aluminum plate is 0-0.5mm; coating powder so as to cover the gloss on the surface of the aluminum alloy, wherein the coating width is 2-4mm; and protecting by adopting an inert gas, wherein the protection mode is as follows: frontage protection is adopted for overlap joint, and simultaneous protection of frontage and back surface is adopted for butting. When optimized welding technology parameters are adopted, the aluminum alloy is melted and steel is not melted, thereby forming welding-brazing welding overlap joint and butting connection.

Description

technical field [0001] The invention relates to laser melting and brazing technology of dissimilar metals. Background technique [0002] When welding dissimilar metals of aluminum and steel, due to the great difference in physical and chemical properties of aluminum and steel, it is difficult to form an effective welded joint; and the surface of the aluminum alloy is easily oxidized, and the reflectivity to the laser is high, resulting in the absorption of the laser by the aluminum alloy The rate is very low, and the oxide is difficult to melt to form inclusions, pores and other defects; because the molten liquid aluminum has poor wettability on the steel side, it is difficult to wet and spread on the steel side, resulting in unstable welding process and poor weld formation; Al and Fe are easy to form brittle and hard intermetallic compounds, and too thick intermetallic compound layer will reduce the mechanical properties of welded joints. The Chinese patent (Application No...

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Problems solved by technology

[0002] When welding dissimilar metals of aluminum and steel, due to the great difference in physical and chemical properties of aluminum and steel, it is difficult to form an effective welded joint; and the surface of the aluminum alloy is easily oxidized, and the reflectivity to the laser is high, resulting in the absorption of the laser by the aluminum alloy The rate is very low, and the oxide is difficult to melt to form inclusions, pores and other defects; because the molten liquid aluminum has poor wettability on the steel side, it is difficult to wet and spread on the steel side, resulting in unstable welding process and poor weld formation; Al and Fe are easy to form brittle and hard intermetallic compounds, and too thick intermetallic compound layer will reduce the mechanical properties of welded joints

The Chinese patent (Application No. 201110240318.3) entitled "A Flux-Free Laser Powder Filling Welding Method for Aluminum-Steel Dissimilar Metal Joints" discloses a solution, which uses a layer of powder between the aluminum plate and the steel plate and adopts synchronous feeding Powder technology, although this method improves the absorption rate of the laser, the laser absorption rate is limited due to the divergence of the powder during powder feeding and the reflection still existing on the aluminum alloy surface, and the energy density of the laser beam is not concentrated after defocusing or shaping. The matching accuracy between the size of the powder beam and the size of the laser spot is high, and it is difficult to effectively remove the remaining unmelted powder in the interlayer after powder filling welding

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