Low-alloy high-strength steel laser composite weld hardness control method

Abstract

The invention relates to a method for controlling the hardness of low-alloy high-strength steel laser composite welds, which belongs to the technical field of welding engineering. In the invention, consumable electrode arc is positioned before the laser focus along the welding direction, the distance between the consumable electrode arc and the laser focus is controlled, so as to lead interactionto be maintained between the laser induced plasma of the laser and the plasma of the consumable electrode arc and to form a molten pool; the molten pool is shallow in the covering area of the consumable electrode arc, and deep in the laser induced plasma area; non-consumable electrode arc is positioned behind the laser focus along the welding direction, the distance between the non-consumable electrode arc and the laser focus is controlled, so that no marked interaction can appear between the laser induced plasma and the plasma of the non-consumable electrode arc, and simultaneously the non-consumable electrode arc is stably burnt with the assistance of the laser induced plasma. The method enhances the absorbing capacity of a work piece to the laser power, improves the bridging capabilityof laser welding, reduces the cooling rate of the welding seam and the microhardness of the connector, and improves the mechanical properties of the welding seam.

Description

technical field [0001] The invention relates to a method in the technical field of welding engineering, in particular to a method for controlling the hardness of a laser composite weld of low-alloy high-strength steel. Background technique [0002] Laser welding is a welding method characterized by high energy density, strong penetrating ability, and small heat input. It has been widely used in the connection of metal materials and non-metal materials. However, due to the difference in the laser absorption ability of the material itself and its surface state, the energy conversion efficiency of the laser to the welding workpiece is low, especially for CO 2 Gas laser, with a wavelength of 10.6 microns, has a high reflection coefficient when irradiating metal materials, and usually only a small part of the output laser power can be absorbed by the material as energy to melt the metal. On the other hand, the diameter of the laser beam spot is small, and it is highly sensitive ...

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Problems solved by technology

[0004] After searching, it was also found that in 2004, Ni Yu of Huazhong University of Science and Technology described a hybrid laser and non-melting electrode arc hybrid welding in his master's thesis "Laser Arc Hybrid Welding and Laser Welding Ultra-low Carbon Steel Weld Magnetic Properties Research". The non-melting electrode arc body is placed in front of the laser beam along the welding direction, the workpiece is preheated by the non-melting electrode arc, and the laser beam is then irradiated on the molten pool, which improves the energy transfer efficiency of the laser beam, because the non-melting electrode arc cannot provide additional When welding thicker metal materials, it is often difficult to avoid weld formation defects above the workpiece. It depends entirely on the welding process parameters of the laser beam. Its role is limited to improving the laser energy conversion efficiency and lacks the ability to improve the weld formation. ability

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