Hyperspectral Oxide-Layer Characterization on Running Steel Substrate
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Solution Overview
Problem
Existing methods for detecting and identifying oxide layers on steel substrates are slow and cannot be implemented on-line at production facilities, particularly affecting high strength steels with elements like Si, Mn, Al, Cr, B, and P, leading to poor wetting issues during galvanization due to oxide formation.
Innovation Solution
A method using a hyperspectral camera to collect and analyze light from the oxide layer on a steel substrate, allowing for rapid identification of oxide composition and thickness, utilizing infrared light reflection or emission to generate hyperspectral images for analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If infrared spectrometry or ellipsometry is used to characterize oxide layers, then measurement precision is improved, but acquisition time increases making on-line implementation impossible
Solution Approach 1:
The patent extracts only the essential spectral information needed for oxide characterization using a simplified optical setup with a spectrometer that captures reflectance spectra in the visible-near infrared range. This extracted approach avoids the complexity and time-consuming nature of full ellipsometry while maintaining sufficient precision for oxide layer detection and thickness measurement.
Solution Approach 2:
The patent replaces the mechanical scanning and complex optical systems of ellipsometry with a stationary spectrometer-based optical reflection system. This substitution uses spectral analysis instead of mechanical measurement procedures, dramatically reducing acquisition time while maintaining characterization capability.
2Reliability
If conventional optical techniques are used, then nondestructive measurement is achieved, but they cannot work on hot products or cold products at pickling line exit
Solution Approach 1:
The patent creates a universal measurement system that functions across a wide temperature range by using a spectrometer with broad spectral response. The system can measure both hot products directly from the annealing line and cold products at the pickling line exit, making it adaptable to multiple process stages without requiring temperature-specific equipment.
Solution Approach 2:
The patent adjusts measurement parameters such as integration time and spectral range based on product temperature and oxide layer characteristics. This allows the same optical system to accurately measure oxide layers on both hot and cold substrates by dynamically optimizing measurement conditions rather than requiring fixed operating parameters.
3Use of energy by moving object
If direct-fired or radiant tube annealing furnaces are used, then heating efficiency is improved, but oxide formation on steel strip surfaces increases
Solution Approach 1:
The patent implements a feedback system where the spectrometer continuously monitors oxide layer formation on the steel strip during and after annealing. This real-time information is fed back to process control, allowing adjustment of annealing parameters or pickling conditions to minimize harmful oxide formation while maintaining heating efficiency.
Solution Approach 2:
The patent converts the harmful effect of oxide formation into a useful measurement signal. The same oxide layers that cause wetting problems during galvanization are precisely what the spectrometer detects and characterizes, providing valuable process control information that can prevent defects and optimize subsequent coating operations.
4Productivity
If hyperspectral imaging is used for rapid oxide detection, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential spectral bands needed for oxide characterization from the full hyperspectral range, using a simplified spectrometer setup rather than a complete hyperspectral imaging system. This extraction approach maintains rapid measurement capability for on-line implementation while significantly reducing device complexity and cost.
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
Enables fast, on-line characterization of oxide layers, ensuring accurate identification and thickness measurement, preventing defects in coated steel products by optimizing the galvanization process.
Implementation Method 1
collecting light from an oxide surface formed by the layer
Implementation Method 2
using the collected light in order to obtain the composition of this layer
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
AI summary
Method for the fabrication of a steel product comprising a step of characterization of a layer of oxides (22) present on a running steel substrate (21), the characterization comprising the steps of: - providing a portion of the steel substrate comprising a layer of oxides wherein the portion defines an oxide surface, - collecting light (Lr) from said oxide surface using a hyperspectral camera (20) in order to obtain intensity values (Iλ,M) respectively representative of an intensity of a part (Lrλ,M) of the collected light, wherein each part is respectively collected from one of a plurality of points (M) located on said oxide surface and respectively has a wavelength (λ) from a plurality of wavelengths, - comparing the obtained intensity values with reference intensity values obtained for reference oxides, and - calculating amounts of reference oxides in the layer.