Laser Welding Galvanized Steel Protrusion Zinc Vapor Escape
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Solution Overview
Problem
Laser welding of galvanized steel plates often results in blowholes and pits due to the lower melting point of zinc, which vaporizes and gets trapped in the weld, leading to welding defects and potential explosions.
Innovation Solution
A laser welding control method where the steel plates are overlapped with a protrusion, and the protrusion is irradiated with laser light in a spiral or helical pattern larger than the protrusion's size, creating a path for zinc vapor to escape, thus preventing gas pockets from forming in the weld bead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser welding is performed on galvanized steel plates, then welding speed is improved, but zinc vapor gets trapped in the weld bead causing blowholes and pits
Solution Approach 1:
The laser beam irradiation is divided into multiple segments forming a spiral or circular pattern around the protrusion, rather than a single continuous pass. This segmented approach allows zinc vapor to escape through the center while maintaining high welding speed and preventing gas pocket formation in the weld bead
Solution Approach 2:
A protrusion is formed on one of the steel plates before welding to create a predetermined vapor escape path. This preliminary structural modification enables zinc vapor to escape during laser welding, preventing blowholes and pits while maintaining high welding speed
2Reliability
If zinc vapor is allowed to escape through a gap between plates, then blowholes are prevented, but welding strength may be compromised
Solution Approach 1:
The protrusion serves as an intermediary structure that facilitates zinc vapor escape without creating a direct gap between the steel plates. The spiral laser irradiation pattern further mediates the process by concentrating energy around the protrusion while allowing vapor to escape through its center, maintaining both weld quality and strength
3Reliability
If spiral or circular laser irradiation pattern is used, then zinc vapor discharge is improved, but irradiation time increases
Solution Approach 1:
The laser irradiation is segmented into a spiral or circular pattern that efficiently covers the area around the protrusion. This segmentation allows vapor to escape through the center while maintaining relatively short irradiation time compared to traditional linear scanning patterns
Solution Approach 2:
The spiral or circular laser irradiation pattern provides continuous heating around the protrusion, ensuring efficient zinc vapor discharge throughout the welding process. This continuous action maintains weld quality while minimizing total irradiation time
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively suppresses the occurrence of gas pockets in the weld bead, improving welding performance by ensuring smooth discharge of zinc vapor and maintaining consistent welding strength.
Implementation Method 1
irradiating the protrusion with laser light
Implementation Method 2
an irradiated local portion of plated steel plate 110 melts, and then an irradiated local portion of second plated steel plate 120 melts
Implementation Method 3
zinc vaporizes, and zinc vapor tends to diffuse to an outside through molten pool and molten metal
Implementation Method 4
zinc vapor tends to diffuse to an outside through molten pool and molten metal
Data Source
AI summary
A laser welding control method according to the present disclosure includes: a first step of causing a first steel plate having a protrusion and a second steel plate to overlap so that a tip of the protrusion provided on the first steel plate makes contact with the second steel plate; and a second step of irradiating the protrusion with laser light in an irradiation pattern having a size larger than a size of the protrusion in plan view after the first step. At least one of a surface of the first steel plate that faces the second steel plate and a surface of the second steel plate that faces the first steel plate is plated.