Galvanized Steel Sheet Hardness via Mg-Enriched Columnar Zinc

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Solution Overview

Problem

Vacuum deposition methods for zinc coating result in low-density zinc layers with columnar structures, leading to reduced hardness and galling resistance due to empty spaces between growing columns, which is not effectively addressed by existing techniques.

Innovation Solution

A zinc coated steel sheet with a columnar zinc layer formed using electromagnetic levitation induction heating, incorporating a Zn—Mg alloy or mixture with 0.1 to 0.4 wt% Mg content, where Mg is distributed mainly in grain boundaries, enhancing the density and mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If vacuum deposition method is used to form zinc coated layer, then coating efficiency and uniformity are improved, but the zinc layer forms columnar structure with empty spaces between columns resulting in low density

Engineering Contradiction:

Improvecoating efficiencyVSAvoiddensity of zinc coated layer

Core Design Contradiction:

ProductivityVSVolume of stationary object

Solution Approach 1:

The patent changes the chemical composition parameters of the zinc coating by adding magnesium (0.1-0.4 wt%) to the zinc coating material. This compositional parameter change modifies the deposition process and resulting microstructure, transforming the low-density columnar structure into a high-density structure while preserving the vacuum deposition method's efficiency advantages.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If conventional zinc coating methods are used, then coating process is simple, but the zinc layer has low hardness and poor galling resistance due to low density

Engineering Contradiction:

Improvecoating process complexityVSAvoidhardness and galling resistance

Core Design Contradiction:

Device complexityVSStrength

Solution Approach 1:

The patent creates a composite coating material system by combining zinc with magnesium (0.1-0.4 wt%). This composite approach leverages the beneficial properties of both elements: zinc provides the base coating functionality while magnesium enhances density, hardness, and galling resistance. The composite Zn-Mg coating maintains process simplicity while achieving superior mechanical properties.

Inventive Principle:

Principle #40Composite materials

3Volume of stationary object

If magnesium is added to zinc coating to improve density, then grain refinement occurs, but magnesium cannot be added alone in hot-dip plating due to fluidity and stability issues

Engineering Contradiction:

Improvedensity of zinc coated layerVSAvoidcoating process feasibility

Core Design Contradiction:

Volume of stationary objectVSEase of manufacture

Solution Approach 1:

The patent replaces the hot-dip plating process with a vacuum deposition process. This substitution eliminates the fundamental limitations of hot-dip plating regarding magnesium addition (fluidity and stability issues in molten metal). Vacuum deposition allows precise control of coating composition and structure, enabling the use of magnesium (0.1-0.4 wt%) to achieve grain refinement and high density without the manufacturing difficulties encountered in hot-dip plating.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 results in a high-density zinc coated layer with improved hardness and galling resistance, achieving better mechanical properties and adhesion compared to conventional methods.

Implementation Method 1

forming a zinc coated layer through spraying vapor generated by electromagnetic levitation induction heating of a coating raw material

Methodology Applied

Scientific EffectElectromagnetic induction heating: Electromagnetic Induction

Implementation Method 2

spraying vapor generated by electromagnetic levitation induction heating of a coating raw material

Methodology Applied

Scientific EffectInduction heating: Induction Heating

Implementation Method 3

spraying vapor generated by electromagnetic levitation induction heating of a coating raw material

Methodology Applied

Scientific EffectVaporization: Evaporation

Implementation Method 4

forming a zinc coated layer through spraying vapor generated by electromagnetic levitation induction heating

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentUS11781207B2Galvanized steel sheet having excellent hardness and galling resistance

Publication Date: 2023.10.10 POHANG IRON & STEEL CO LTD

AI summary

Provided is a galvanized steel sheet plated by vacuum deposition and, more specifically, to a galvanized steel sheet having excellent hardness and galling resistance, and a method for manufacturing same. The zinc coated steel sheet includes: a base steel sheet; and a zinc coated layer formed on the base steel sheet. The zinc coated layer is formed of a columnar structure, and a content of Mn included in the zinc coated layer is 0.1 to 0.4 wt %.