Plated Steel Sheet Fine Zn Texture Rapid Cooling
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Solution Overview
Problem
Existing plated steel sheets often have coarse and uneven plating textures, leading to surface defects, reduced corrosion resistance, and increased susceptibility to cracking, due to inadequate cooling methods that result in incomplete solidification and poor distribution of Zn single-phase and MgZn2 phases.
Innovation Solution
A plated steel sheet manufacturing method involving hot-dipping followed by contact-type pressure cooling with cryogenic liquids, such as liquid nitrogen or liquid helium, to achieve a Zn-based plating layer with a Zn single-phase texture of 5 µm or less, and a MgZn2 phase with a (112)/(201) ratio of 0.6 or more, ensuring even distribution and precise control of plating adhesion, thereby forming a fine and even plating texture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cooling methods are used after hot-dipping, then the cooling process is simple and fast, but the plating texture becomes coarse and uneven with large Zn single-phase particles
Solution Approach 1:
The patent applies parameter changes by controlling the cooling rate (≥20°C/sec) and final temperature (≤150°C) to transform the plating layer microstructure. This rapid cooling process changes the thermal parameters to achieve fine and even plating texture with small Zn single-phase particles (≤5μm), resolving the contradiction between simple cooling and high precision plating texture.
Solution Approach 2:
The patent utilizes phase transitions during rapid cooling to achieve the desired plating structure. The quick cooling rate causes phase transformation in the plating layer, forming fine Zn single-phase particles and controlling the crystal structure, which resolves the contradiction between simple cooling processes and high-quality plating texture.
2Manufacturing precision
If rapid cooling is applied to achieve fine plating texture, then the plating quality improves, but the cooling process becomes more complex and time-consuming
Solution Approach 1:
The patent optimizes cooling parameters by setting specific cooling rate (≥20°C/sec) and final temperature (≤150°C) thresholds. This controlled parameter approach achieves fine plating texture (Zn single-phase ≤5μm) while minimizing cooling time, resolving the contradiction between plating quality and production efficiency.
3Reliability
If inadequate cooling is used, then the process is simple and fast, but the plating layer develops surface defects and poor corrosion resistance
Solution Approach 1:
The patent establishes specific cooling parameters (rate ≥20°C/sec, final temperature ≤150°C) that transform the plating layer structure to improve corrosion resistance and eliminate surface defects. This controlled thermal parameter change resolves the contradiction between simple cooling processes and high reliability plating layers.
Solution Approach 2:
The rapid cooling process induces phase transitions in the plating layer that create a dense, fine-grained structure with small Zn single-phase particles. This phase transformation improves corrosion resistance and eliminates surface defects without requiring complex cooling systems.
4Manufacturing precision
If slow cooling is applied, then the equipment requirements are simple, but the Zn single-phase particles become large and distribution becomes uneven
Solution Approach 1:
The patent controls the cooling rate parameter (≥20°C/sec) to achieve uniform Zn single-phase distribution with particle size ≤5μm. This specific parameter control ensures fine and even plating texture throughout the plating layer, resolving the contradiction between simple cooling equipment and high precision microstructure control.
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 method produces plated steel sheets with minimal surface defects, enhanced corrosion resistance, and improved crack resistance, achieving a high-quality finish with precise control over plating thickness and texture uniformity.
Implementation Method 1
cooling the plating layer by contacting the cooling belt to the plating layer
Implementation Method 2
cooling the cooling belt by supplying a cryogenic liquid including liquid nitrogen or liquid helium to the cooling belt
Implementation Method 3
quenching the steel sheet at a cooling rate of 20°C/sec or more
Data Source
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AI summary
Provided is a plated steel sheet having an excellent quality with fine and even plating texture, the plated steel sheet including a base steel sheet and a Zn plating layer formed on the base steel sheet, wherein a Zn crystal in the plating layer has a size of 5 µm or less.