Laminated laser spot welding method for high-strength steel

Abstract

A high-strength steel lamination laser spot welding method comprises the steps that two or more steel workpieces are stacked to form a lamination combination, and a steel workpiece base body is Qamp; the thickness of the P steel is less than 3.0 mm; air blowing openings are formed in the periphery of the position to be welded, the air blowing openings are flat, the air outlet direction of the air blowing openings is roughly parallel to the welding surface, the vertical distance between the air blowing openings and the welding surface is 0-100 mm, a compressed air source is used, and the air flow is 15-50 L/min; enabling a laser beam to act on the upper surface of the laminated combination along a preset scanning path, setting welding parameters to enable the laser beam not to penetrate through the lower surface of the laminated combination, and melting and connecting a bottom workpiece through heat conduction, the finally formed spot-like welding seam is characterized in that the area of a melting area on the lower surface of the lamination combination does not exceed 70% of the area of a melting area on the upper surface of the lamination combination. The laser energy utilization rate can be increased, the welding quality consistency is guaranteed, and the joint performance is improved.

Description

technical field [0001] The invention belongs to the field of high-strength steel laser welding, in particular to a high-strength steel lamination laser spot welding method. Background technique [0002] In the automobile manufacturing industry, the need to reduce the weight of automobiles to achieve energy saving and emission reduction, and to improve the collision safety of automobiles has prompted the application of higher strength steel in body manufacturing. [0003] In the automobile structure, multi-layer steel plates are usually superimposed to form a laminated combination, and different laminated steel plate combinations need to be welded to realize the manufacture of the car body or parts. The existing production method uses resistance spot welding technology, which requires high welding current and low production efficiency, and there are quality problems in high-strength steel welding that cannot be solved. Laser welding technology is a method of applying laser b...

AI Technical Summary

Problems solved by technology

In the laser welding process, the material is completely melted and then cooled and solidified, resulting in a sharp decrease in the retained austenite content in the weld. At the same time, due to the temperature gradient and structural phase transformation, there is a large thermal stress in the weld and the heat-affected zone, which eventually leads to The performance of welded joints is poor, and the strength and plasticity are at a low level, which is difficult to meet the conditions of production and application

[0006] It is worth noting that in the face of ultra-high-strength steel, such as QP1180 (with a tensile strength of about 1200MPa), resistance spot welding (a method that uses the contact resistance between laminated materials to generate heat under a large welding current) is used for automotive steel welding. Double-sided welding method to achieve welding) also cannot obtain high-quality welded joints

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