Carbon Filament Wire for Stronger Laser Welding of Al-Coated Steel
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Solution Overview
Problem
The challenge lies in laser welding of steel sheets with aluminum-based coating layers, where the increased brittleness of weld zones due to elements like C, Si, and Cr hinders strength, and existing methods either complicate the process or increase costs by requiring additional steps.
Innovation Solution
A carbon filament wire with a resin matrix and multiple carbon filaments is used for laser welding, which suppresses ferrite generation and enhances martensite formation in the weld zone without additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If aluminum or aluminum-silicon coated steel sheets are used to prevent oxidation and decarburization during hot press molding, then surface quality is improved, but the strength of weld zones decreases due to ferrite formation
Solution Approach 1:
The invention extracts and removes the aluminum-based coating layer from the steel sheet surface in the weld zone before laser welding. By eliminating the coating in the specific welding area, it prevents aluminum and silicon from mixing into the weld zone and promoting ferrite formation, thereby maintaining high weld zone strength while preserving the coating's protective function in non-weld areas
Solution Approach 2:
The invention performs preliminary removal of the aluminum-based coating layer before the laser welding process. This advance action prevents the harmful mixing of aluminum and silicon into the weld zone during welding, ensuring that the weld zone can form martensite structure and achieve high strength without the need for post-weld remediation
2Strength
If elements such as C, Si, Cr, Mn are added to increase material strength, then material strength is improved, but the brittleness of weld zone increases due to increased weld hardenability
Solution Approach 1:
The invention applies local quality control by creating a coating-free zone specifically in the weld area while maintaining the coating in other areas. This localized modification allows the weld zone to have different chemical composition characteristics - free from aluminum and silicon that promote ferrite formation - enabling the development of a microstructure with appropriate balance between strength and ductility, rather than uniform brittleness throughout
3Strength
If the plating layer is removed with a brush or laser before welding, then weld zone strength is maintained, but the process becomes complicated and costs increase
Solution Approach 1:
The invention merges the coating removal function with the laser welding process itself. The laser beam serves dual purposes: removing the aluminum-based coating in the weld zone and simultaneously performing the welding operation. This integration eliminates the need for separate mechanical brush removal or additional laser passes, simplifying the overall process while maintaining weld zone strength
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 approach maintains the strength of the weld zone comparable to the base material, improving rigidity and tensile strength while avoiding complications and cost increases associated with existing methods.
Implementation Method 1
laser welding
Implementation Method 2
laser welding
Implementation Method 3
austenite in the material is transformed into martensite by rapid cooling
Implementation Method 4
the carbon component of the plating layer is mixed into the weld zone
Data Source
AI summary
One embodiment of the present invention provides a carbon filament wire for laser welding of a steel sheet having an aluminum-based coating layer, a laser welding method of a steel sheet having an aluminum-based coating layer by using same, and a welded product produced by same, the carbon filament wire comprising: a resin matrix; and two or more carbon filaments provided inside the resin matrix.