Hot-Stamped Steel Plating Structure to Prevent Surface Red Rust
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Solution Overview
Problem
Existing hot stamped bodies lack effective corrosion resistance on their surface, especially in the uncoated state, as previous studies focused on corrosion resistance after coating rather than before coating, leaving measures for improving surface corrosion resistance unclear.
Innovation Solution
A hot stamped body is developed with a plating layer comprising a ZnO region on the surface and an Ni—Fe—Zn alloy region beneath, where the ZnO region has an oxygen concentration of 10 mass % or more and the Ni—Fe—Zn alloy region has an oxygen concentration less than 10 mass %, with controlled concentrations of Fe, Mn, and Si in the ZnO region to prevent red rust formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plating layer is formed on the steel sheet surface, then corrosion resistance is improved, but Fe diffusion to the surface causes red rust formation
Solution Approach 1:
The plating layer is designed with non-uniform composition: a ZnO-rich outer layer (0.5-3.0 μm thick) containing less than 5 mass% total Fe, Mn, and Si, transitioning to an Ni-Fe-Zn alloy inner layer. This local differentiation prevents Fe diffusion to the surface while maintaining corrosion resistance.
Solution Approach 2:
The plating layer combines multiple materials (ZnO, Ni, Fe, Zn) in a composite structure where the ZnO region provides corrosion resistance and the controlled Fe content prevents red rust, while the Ni-Fe-Zn alloy region provides structural support and additional corrosion protection.
2Reliability
If the ZnO region thickness is increased to improve corrosion resistance, then surface protection is enhanced, but manufacturing precision becomes difficult to control
Solution Approach 1:
The patent specifies precise parameter ranges: ZnO region thickness of 0.5-3.0 μm and total Fe, Mn, Si content of less than 5 mass%. These controlled parameters ensure optimal corrosion resistance while maintaining manufacturing feasibility through standardized process windows.
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 configuration enhances the corrosion resistance of the hot stamped body's surface by preventing red rust formation and improving overall corrosion resistance, even in the uncoated state, while maintaining a suitable surface appearance.
Implementation Method 1
a ZnO region present on a surface side of the plating layer and having an oxygen concentration of 10 mass % or more... an average concentration of a total of Fe, Mn and Si in the ZnO region is more than 0 mass % and less than 5 mass %
Implementation Method 2
a ZnO region present on a surface side of the plating layer and having an oxygen concentration of 10 mass % or more... having an Ni—Fe—Zn alloy region present on a steel sheet side of the plating layer and having an oxygen concentration of less than 10 mass %
Data Source
AI summary
The present invention relates to a hot stamped body comprising a steel sheet and a plating layer formed on at least one surface of the steel sheet, wherein the plating layer is comprised of a ZnO region present on a surface side of the plating layer and having an oxygen concentration of 10 mass % or more and an Ni—Fe—Zn alloy region present on a steel sheet side of the plating layer and having an oxygen concentration of less than 10 mass %, and an average concentration of a total of Fe, Mn and Si in the ZnO region is more than 0 mass % and less than 5 mass %.