Resistance spot welding technology for improving quality of welding spots of dual-phase steel

Abstract

The invention discloses a resistance spot welding technology for improving quality of welding spots of dual-phase steel. The resistance spot welding technology comprises the steps that firstly, the flatness of the to-be-welded dual-phase steel is adjusted to be 1 mm / m or below through pressurization; then, a spot welding machine is connected with a current to preheat the to-be-welded dual-phase steel; after preheating, the welding current is adjusted, and the to-be-welded dual-phase steel is subjected to heating welding; and the welding current is cut off, spot-welded joints quickly cool and form molten cores, and after the molten cores cool to the martensitic structure transformation temperature or below, a temper current is connected, and postwelding temper heat treatment is carried out. According to the resistance spot welding technology for the dual-phase steel provided by the invention, before welding, the flatness of the to-be-welded dual-phase steel is adjusted, spot welding is carried out through the manner of preheating-heating-cooling crystallization-tempering, and the problems that liquid metal in the molten state splashes and affects the welding quality and possibly causes unintentional harm to human bodies during the welding process are avoided; and besides, the welding spots are relatively stable during the welding process, the welding deformation is reduced, a brittle structure is changed, the quality of the welding spots is improved, the welding spots are prevented from having shrinking holes and cracks, and the quality of a product is improved.

Description

technical field [0001] The invention relates to the field of automobile manufacturing, in particular to a resistance spot welding process for improving the quality of dual-phase steel solder joints. Background technique [0002] With the increasingly fierce competition in the automobile industry, automobile lightweight, energy saving and environmental protection have become important issues in the development of automobile design and manufacturing. Due to the characteristics of high strength and good processing performance, dual-phase steel not only shows obvious advantages in automobile lightweight, but also It has the characteristics of high weight reduction potential, high crash resistance, and high fatigue strength, which greatly improves the safety, reliability and comfort of automobiles. Therefore, the research and development and utilization of dual-phase steel materials are gradually emerging in the global automobile industry. However, the existing dual-phase steel i...

AI Technical Summary

Problems solved by technology

However, the existing dual-phase steel is prone to internal defects such as spatter, shrinkage cavity, and cracks during spot welding. When the welding process parameters are improper, problems such as lack of fusion, deep indentation, warping between plates, and surface cracks will also occur.

The above defects can easily lead to a reduction in the bearing capacity of the joints and seriously affect the quality of the dual-phase steel solder joints. These are unstable factors in production and cause safety hazards to the car.

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