Laser welding method capable of eliminating hot rolling delta-TRIP steel weld cracks

Abstract

The invention discloses a laser welding method capable of eliminating hot rolling delta-TRIP steel weld cracks. The laser welding method comprises the steps of splicing a tape head of a to-be-welded steel coil without pickling with a tape tail of the other steel coil; preheating the spliced seam; carrying out conventional laser welding on the spliced seam; heating the laser welding seam in a heating section of an annealing furnace; carrying out annealing in an annealing section of the annealing furnace; and performing normal post-process of the steel sheet. According to the laser welding method, a laser welding machine can not only perform the characteristics of laser welding, but also prevent crack spreading or even fracture on the laser welding joint, and the welding efficiency and the welding qualification rate can be obviously improved. During welding, the problems of low welding line energy of preheating and post-heating caused by high welding speed in the prior art are avoided, so that the welding speed is improved, and the welding time is shortened; and the qualified rate of the welding seam is ensured, and the cupping test value is increased from the original 1 mm to 4 mm at lowest.

Description

technical field

[0001] The invention relates to a steel welding method, which belongs to a steel laser welding method, in particular to a laser welding method capable of eliminating weld cracks in hot-rolled δ-TRIP steel. Background technique

[0002] The cold-rolling and acid-rolling unit uses a laser welding machine to weld the head and tail of the hot-rolled raw material strip to ensure the continuous operation of the production line. At present, laser welding of δ-TRIP steel before pickling is relatively difficult, that is, there are problems of high weld strength, high brittleness, and easy fracture. This is because δ-TRIP steel is a new type of automotive lightweight material, and its structure is dendritic δ-ferrite and bainite. High-power laser welding has the characteristics of large penetration depth, large depth-to-width ratio, fast welding speed, and low heat input. However, the cooling speed of laser welding is too fast, and the weld is easy to form a hardened ...