Variable-Thickness Hot-Forming Steel Sheet With Selective IR Absorption
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Solution Overview
Problem
Flat steel products with varying thicknesses experience uneven heating during hot forming, leading to inconsistent diffusion of iron into the aluminum-based corrosion protection coating, resulting in disparate properties such as strength and weldability across different areas.
Innovation Solution
A flat steel product with a steel substrate containing 0.1-3% Mn and up to 0.01% B, featuring an aluminum-based corrosion protection coating and an absorption layer in thicker areas with a lower infrared reflectance, ensuring more even heating by absorbing a larger proportion of infrared radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the flat steel product has thicker and thinner areas, then weight optimization and load adaptation are achieved, but uneven heating occurs leading to inconsistent diffusion of iron into the aluminum-based corrosion protection coating
Solution Approach 1:
The patent applies an absorption layer selectively to thicker areas (second region) of the flat steel product, creating local quality differences in infrared absorption properties. This localized treatment compensates for the thickness variation by enhancing heat absorption specifically where needed, thereby achieving uniform heating across the entire surface despite varying thicknesses.
Solution Approach 2:
The patent modifies the infrared optical properties of the steel product surface by introducing an absorption layer with specific infrared absorption characteristics. This parameter change in the surface layer allows thicker areas to absorb more infrared radiation, compensating for their greater thermal mass and achieving uniform heating rates across different thicknesses.
2Weight of moving object
If the flat steel product has thicker and thinner areas, then weight optimization is achieved, but energy consumption increases due to unnecessary heating of thinner areas
Solution Approach 1:
The absorption layer is applied selectively only to thicker areas rather than uniformly across the entire surface. This local quality approach ensures that additional infrared absorption capacity is provided only where needed, preventing unnecessary energy consumption on already adequately heated thinner areas while maintaining uniform heating across the whole product.
3Weight of moving object
If the flat steel product has thicker and thinner areas, then weight optimization is achieved, but property consistency deteriorates due to different diffusion stages in different areas
Solution Approach 1:
By applying the absorption layer selectively to thicker areas, the patent creates local quality differences in heat absorption that compensate for thickness variations. This ensures that iron diffusion into the aluminum-based corrosion protection coating proceeds at consistent rates across all areas, maintaining uniform composition and properties throughout the steel product.
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 approach achieves homogeneous heating across areas of different thicknesses, synchronizing the diffusion process and maintaining the properties of the steel component, such as weldability and corrosion resistance.
Implementation Method 1
an absorption layer is arranged on the corrosion protection coating in the second region, so that the average reflectance R in the infrared range in the second range is smaller than in the first range
Implementation Method 2
the heating also serves to initiate a diffusion process in which iron diffuses from the steel substrate into the aluminum-based corrosion protection coating
Implementation Method 3
The cooling rates are adjusted to create a hardened microstructure in the steel substrate. This microstructure is converted into an at least partially martensitic microstructure
Data Source
AI summary
The invention relates to a flat steel product for manufacturing a steel component by hot forming. The flat steel product comprises a steel substrate consisting of steel containing 0.1-3 wt.% Mn and optionally up to 0.01 wt.% B, and an aluminum-based corrosion protection coating applied to the steel substrate. Furthermore, the flat steel product has a first region with a first thickness di and a second region with a second thickness d2, the second thickness being greater than the first. An absorption layer is also arranged on the corrosion protection coating in the second region, such that the average infrared reflectance R is lower in the second region than in the first region. The invention further relates to a method for manufacturing such a flat steel product by selective rolling.