Hot Dip Aluminized Steel Sheet Anti-Delamination Diffusion Layer
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Solution Overview
Problem
Hot press formed articles with hot-dip aluminum plated steel sheets often experience delamination due to the formation of intermetallic compound layers, leading to cracking and adhesion issues during the forming process, which affects dimensional accuracy and surface quality.
Innovation Solution
A method involving alloying heat treatment of a hot-dip aluminum plated steel sheet to form a single soft diffusion layer with α-Fe and solid-solubilized Al, controlling heat treatment conditions to achieve a hardness of 300-600 Hv, and maintaining a diffusion layer thickness of 2-10 μm, thereby preventing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hot-dip aluminum plating is applied to steel sheets for hot press forming, then corrosion resistance and surface quality are improved, but intermetallic compound layers form during heating which cause delamination and cracking
Solution Approach 1:
The patent applies parameter changes by controlling the heating temperature range (800-950°C) and heating time (5-30 minutes) to regulate the formation of the diffusion layer. By optimizing these parameters, the plated layer transforms from a multi-layer structure with brittle intermetallic compounds to a single soft diffusion layer with controlled Al concentration gradient, preventing delamination while maintaining corrosion resistance
Solution Approach 2:
The patent implements local quality by creating a non-uniform Al concentration distribution within the diffusion layer. The Al concentration decreases from the steel sheet interface toward the plated layer surface, forming a gradient structure where each region has optimized properties: high Al content near the interface for strong bonding, lower Al content toward the surface for ductility and crack resistance
2Strength
If the plated layer is heated during hot press forming, then the steel sheet achieves ultrahigh strength through quenching, but the plated layer delaminates and forms fine powder that adheres to the mold
Solution Approach 1:
The patent applies preliminary action by pre-forming a single soft diffusion layer with controlled Al concentration gradient before the hot press forming process. This pre-prepared diffusion layer structure prevents delamination during the subsequent heating and quenching operations, eliminating the need for mold corrections and ensuring dimensional accuracy of the formed article
3Strength
If heating time and temperature are increased during hot press forming, then steel sheet strength is improved, but the diffusion layer thickens and intermetallic compound layers form causing cracking
Solution Approach 1:
The patent implements feedback by establishing a controlled heating process that monitors and regulates temperature and time parameters to maintain the diffusion layer within optimal boundaries. The feedback mechanism ensures that the Al concentration gradient remains controlled and the diffusion layer thickness stays within 2-10 μm, preventing the formation of brittle intermetallic compounds even during extended heating periods
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 approach effectively enhances delamination resistance in hot press formed articles by ensuring the plated layer remains intact, reducing dimensional variations and surface defects, and maintaining the strength and precision of the formed products.
Implementation Method 1
a single soft diffusion layer including α-Fe with solid-solubilized Al
Implementation Method 2
after a steel sheet is heated to a predetermined temperature (for example, a temperature at which a phase thereof is changed to an austenite phase)
Implementation Method 3
controlling heat treatment conditions during an alloying heat treatment of a hot-dip aluminum plated steel sheet
Data Source
AI summary
Provided is a hot press formed article having good anti-delamination and having a hot dip aluminized layer formed on the surface of a base steel sheet. The base steel sheet comprises 0.18-0.25 wt % of C, 0.1-0.5 wt % of Si, 0.9-1.5 wt % of Mn, 0.03 wt % or less of P, 0.01 wt % or less of S, 0.01-0.05 wt % of Al, 0.05-0.5 wt % of Cr, 0.01-0.05 wt % of Ti, 0.001-0.005 wt % of B, 0.009 wt % or less of N and the balance of Fe and other impurities. The aluminized layer comprises a single soft diffusion layer comprising α-Fe with solid-solubilized Al, and the hardness of the diffusion layer is 300-600 (Hv).