Welded Aluminized Steel Blank With Laser Edge Coating Removal
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Solution Overview
Problem
Existing methods for welding aluminized steel sheets face challenges such as aluminum dilution leading to intermetallic compound formation and reduced hardness in the weld zone, along with difficulties in precise laser beam positioning due to the darker appearance of sheets after peripheral metal alloy removal, resulting in lower mechanical strength and toughness of welded joints.
Innovation Solution
A process involving simultaneous peripheral removal of the metal alloy layer by melting and vaporization using a laser beam, maintaining a clearance between sheets to prevent aluminum flow and enhance optical contrast for precise welding, followed by immediate welding to minimize oxidation and increase productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metallic alloy layer is removed by laser beam melting and vaporization, then aluminum dilution in the weld zone is reduced, but the sheets appear darker making laser beam positioning more difficult
Solution Approach 1:
The patent applies a contrast-enhancing coating or marking on the sheet edges to create visual differentiation between the treated and untreated areas. This allows the laser beam positioning system to accurately identify the edge location and maintain precise positioning despite the dark appearance of the aluminum-free zone created by removal processes.
2Ease of manufacture
If aluminum-based pre-coating is diluted during welding, then welding is easier to perform, but intermetallic compounds form and mechanical strength decreases
Solution Approach 1:
The patent removes the aluminum-based metallic alloy layer from the sheet periphery through laser beam melting and vaporization before welding. This extraction of excess aluminum prevents its dilution into the weld zone during welding, thereby avoiding the formation of brittle intermetallic compounds and maintaining high mechanical strength in the weld joint while preserving adequate weldability.
Solution Approach 2:
The patent creates a localized zone at the sheet periphery where the metallic alloy layer is selectively removed, while the rest of the sheet retains its original coating structure. This local modification ensures that aluminum dilution is controlled only in the critical weld zone, maintaining optimal material composition for strength without compromising the overall protective coating functionality.
3Strength
If the metallic alloy layer is removed to prevent aluminum dilution, then weld joint strength is improved, but oxidation risk increases during heat treatment
Solution Approach 1:
The patent employs an inert or controlled atmosphere environment during the heat treatment process following laser beam removal of the metallic alloy layer. This protective atmosphere prevents oxidation of the exposed steel substrate at the sheet periphery and in the weld zone, ensuring that the improved weld joint strength is not compromised by oxidative degradation during subsequent thermal processing.
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 process ensures reduced aluminum content in the weld joint, improved mechanical properties, and enhanced precision in laser beam guidance during welding, resulting in stronger and more reliable welded joints with consistent morphology and low aluminum content.
Implementation Method 1
remove, by melting and vaporization, the metallic alloy layer in a peripheral zone of the sheet
Implementation Method 2
remove, by melting and vaporization, the metallic alloy layer in a peripheral zone of the sheet
Implementation Method 3
a welding operation of the first sheet and second sheet is performed in the area of removal by melting and vaporization
Data Source
Figure 1~2
Figure 3
Figure 4~5D
AI summary
The invention relates to a method for preparing sheets (11, 12) for the manufacture of a welded steel blank, comprising the following steps: at least one (11) and one (12) pre-coated steel sheets are supplied, each consisting of a steel substrate and a pre-coating made up of an intermetallic alloy layer in contact with said steel substrate, surmounted by a metallic layer of aluminum or an aluminum alloy or aluminum-based material, the sheet (11) comprising a main face, an opposite main face, and at least one secondary face, the sheet (12) comprising a main face, an opposite main face, and at least one secondary face; then the first (11) and second (12) sheets are brought together, leaving a gap of between 0.02 and 2 mm between the opposing secondary faces, the joining of the first (11) and second (12) sheets defining a median plane perpendicular to the main faces sheet metal (11, 12),then, the metallic alloy layer in a peripheral zone (61) of the sheet (11) and the metallic alloy layer in a peripheral zone (62) of the sheet (12) are simultaneously removed by melting and vaporization from the main face and the main face, the peripheral zones (61, 62) being the zones of the main faces closest to said median plane located on either side of it.