Dual-Layer Al-Zn Coated Steel Sheet for LME-Resistant Post-Processing
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Solution Overview
Problem
Aluminum alloy-coated steel sheets face limitations in automotive applications due to the inability to receive zinc-based post-processing, leading to increased manufacturing costs and time, and issues with liquid metal embrittlement and galling resistance.
Innovation Solution
A steel sheet with a base steel sheet, an Al-based alloy-coated layer, and a Zn—Al-based coated layer containing 0.5-1.0% Al and a balance of Zn, allowing for phosphating and post-processing like existing Zn-coated steel sheets, with a hardness of 65 Hv or more for improved galling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum alloy coating is applied to steel sheets, then liquid metal embrittlement is prevented and sacrificial protection is improved, but zinc-based post processing becomes impossible and manufacturing complexity increases
Solution Approach 1:
The coating is segmented into two functional layers: an aluminum-based alloy coating layer (5-30 wt% Al) that provides liquid metal embrittlement resistance and sacrificial protection, and a zinc-based coating layer (30-80 wt% Zn) that enables zinc-based post processing. This segmentation allows each layer to perform its specific function without interfering with the other.
Solution Approach 2:
A composite coating structure is created by combining aluminum-based alloy and zinc-based coating materials. The aluminum-based alloy coating layer provides corrosion resistance and LME prevention, while the zinc-based coating layer enables phosphating and other zinc-based post processing, achieving both requirements simultaneously.
2Adaptability or versatility
If zinc-based coating is applied to steel sheets, then zinc-based post processing is enabled, but liquid metal embrittlement occurs during welding and corrosion resistance decreases
Solution Approach 1:
The coating is segmented into two functional layers: an aluminum-based alloy coating layer (5-30 wt% Al) that provides liquid metal embrittlement resistance and sacrificial protection, and a zinc-based coating layer (30-80 wt% Zn) that enables zinc-based post processing. This segmentation allows each layer to perform its specific function without interfering with the other.
Solution Approach 2:
A composite coating structure is created by combining aluminum-based alloy and zinc-based coating materials. The aluminum-based alloy coating layer provides corrosion resistance and LME prevention, while the zinc-based coating layer enables phosphating and other zinc-based post processing, achieving both requirements simultaneously.
3Reliability
If aluminum coating is used instead of zinc coating, then corrosion resistance is improved, but phosphating processing cannot be performed and manufacturing costs increase
Solution Approach 1:
The coating is segmented into two functional layers: an aluminum-based alloy coating layer (5-30 wt% Al) that provides liquid metal embrittlement resistance and sacrificial protection, and a zinc-based coating layer (30-80 wt% Zn) that enables zinc-based post processing. This segmentation allows each layer to perform its specific function without interfering with the other.
Solution Approach 2:
The dual-layer coating structure provides multi-functionality: the aluminum-based layer delivers corrosion resistance and LME prevention, while the zinc-based layer enables phosphating and other zinc-based post processing. This universal design allows the coating to serve multiple purposes, eliminating the need for separate processing lines and reducing manufacturing costs.
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
The solution enables aluminum alloy-coated steel sheets to withstand zinc-based post-processing without liquid metal embrittlement, maintaining excellent galling resistance and enabling continuous production with reduced manufacturing costs.
Implementation Method 1
forming a Zn—Al-based coated layer including Al: 0.5 ̃1.0%, and a balance of Zn and unavoidable impurities in percentage by weight and having an adhesion amount of 3 ̃12 g/m2 on a surface of the aluminum alloy-coated steel sheet using vacuum deposition
Data Source
AI summary
The present disclosure relates to an aluminum-based alloy-coated steel sheet and a method of manufacturing the same and, more particularly, to an aluminum-based alloy-coated steel sheet that can be preferably applied to automotive steel sheets, etc., and a method of manufacturing the same.An embodiment of the present disclosure provides an aluminum-based alloy-coated steel sheet that includes: a base steel sheet; an Al-based alloy-coated layer formed on at least one surface of the base steel sheet; and a Zn—Al-based coated layer formed on the Al-based alloy-coated layer, including Al: 0.5˜1.0%, and a balance of Zn and unavoidable impurities in percentage by weight, and having an adhesion amount of 3˜12 g/m2, and a method of manufacturing the aluminum-based alloy-coated steel sheet.