Plated Steel Interface Microstructure for Adhesion and Sacrificial Protection
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Solution Overview
Problem
Existing plated steel materials used in civil engineering, infrastructure, and automobile components lack adequate adhesion, base metal corrosion resistance, and sacrificial corrosion resistance, despite being effective in red rust resistance.
Innovation Solution
A plated steel material with a specific chemical composition and microstructural design, including a base steel material and a plated layer with defined regions of varying Fe concentrations and alloy phases, enhancing adhesion and corrosion resistance through controlled cooling and dipping plating treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a plated steel material with Zn-Al-Mg-based plated layer is used to improve red rust resistance, then red rust resistance is improved, but adhesion of the plated layer, base metal corrosion resistance, and sacrificial corrosion resistance are insufficient
Solution Approach 1:
The plated layer is segmented into three distinct regions with different Fe concentrations: a first region (Fe < 5 mass%) for red rust resistance, a second region (5 ≤ Fe < 30 mass%) for adhesion, and a third region (30 ≤ Fe ≤ 80 mass%) for base metal corrosion resistance. This segmentation allows each region to fulfill its specific function optimally.
Solution Approach 2:
Different regions of the plated layer are given different local compositions and structures: the first region contains Al-containing phase for red rust resistance, the second region has intermediate Fe concentration for adhesion, and the third region has high Fe concentration for base metal corrosion resistance. Each local area is optimized for its specific purpose.
2Reliability
If the plated layer thickness is increased to improve corrosion resistance, then corrosion resistance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention controls specific parameters including Fe concentration ranges in each region (Fe < 5%, 5 ≤ Fe < 30%, 30 ≤ Fe ≤ 80%), thickness ratios between regions, and Al-containing phase area fraction (≥5%). By controlling these parameters within specific ranges, the complex multi-functional performance is achieved without excessive thickness or manufacturing complexity.
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 material achieves improved adhesion, base metal corrosion resistance, and sacrificial corrosion resistance, maintaining red rust resistance while ensuring effective layer adhesion and structural integrity.
Implementation Method 1
the plated layer includes a first region which is arranged at the surface of the plated steel material and where an Fe concentration is less than 5.0 mass %, a second region which is adjacent to the first region and where an Fe concentration is 5.0 mass % or more and less than 30.0 mass %, and a third region which is arranged between the second region and the base steel material and where an Fe concentration is 30.0 mass % or more and 80.0 mass % or less
Data Source
AI summary
A plated steel material including a plated layer and a base steel material. In a cross section perpendicular to a surface of the plated steel material, a length L of a boundary line between the plated layer and the base steel material satisfies (L−L0)/L0×100≥2.0 (%), wherein L0 is a linear distance between ends of the boundary line in an observation region, and L is a length of the boundary line between the ends. The plated layer includes a first region where an Fe concentration is less than 5.0 mass %, a second region where an Fe concentration is 5.0 mass % or more and less than 30.0 mass %, and a third region where an Fe concentration is 30.0 mass % or more and 80.0 mass % or less, the first region including an Al-containing phase at an area fraction of 5% or more.