Magnesium Alloy Plate Rolling for Non-Basal Texture Formability
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Solution Overview
Problem
Magnesium alloy plates exhibit limited cold formability due to their hexagonal close packed crystal structure, which restricts slip systems at room temperature, particularly in basal textures formed after rolling, and existing methods using yttrium and calcium or differential roll speeds do not significantly improve formability beyond a limited dome height of 5 mm.
Innovation Solution
A magnesium alloy plate composition with 0.5 to 10 wt% zinc, 1 to 15 wt% aluminum, and a balance of magnesium, processed through solution-treating, pre-heating, and constrained rolling with a specific constraint member to achieve a non-basal texture with a limited dome height of 10 mm or more at room temperature, characterized by a deviation of c/a values of 5% or less and an average texture intensity of 3 or less within a misorientation level of 30° based on the [0001] orientation of the (0002) plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional rolling process is used on magnesium alloy plate, then production efficiency is maintained, but cold formability remains poor with limited dome height of 5 mm or less due to basal texture formation
Solution Approach 1:
The patent applies preliminary action by performing shear strain treatment through differential roll rotation before final rolling. This pre-treatment modifies the crystal texture in advance, creating conditions that enable subsequent rolling to produce non-basal textures. The shear strain is applied preliminarily to prevent basal texture formation during the main rolling process, thereby improving cold formability before the actual forming operation.
Solution Approach 2:
The patent changes physical parameters by controlling the rotational speed difference between upper and lower rolls during rolling. By adjusting the differential rotation speed, the patent modifies the shear strain distribution and magnitude, which directly affects crystal texture development. This parameter change enables transition from basal to non-basal textures, improving cold formability while maintaining production efficiency.
2Ease of operation
If expensive yttrium and calcium are added to improve formability, then some texture control is achieved, but cost increases and limited dome height remains 5 mm or less
Solution Approach 1:
The patent replaces expensive alloying elements (yttrium and calcium) with a mechanical processing approach using differential roll rotation. Instead of relying on costly additives, the patent uses the rolling process itself to generate shear strain that modifies texture. This substitutes expensive materials with a process-based solution, reducing alloying cost while achieving non-basal textures and improving limited dome height to 10 mm or more.
Solution Approach 2:
The patent applies mechanics substitution by replacing chemical methods (alloying with Y and Ca) with a mechanical method (differential roll rotation). The mechanical shear strain generated by unequal roll speeds achieves texture control that was previously obtained only through expensive chemical additives. This mechanical approach eliminates the need for costly alloying elements while effectively producing non-basal textures.
3Ease of operation
If differential speed rolling is applied to relax basal texture, then some formability improvement is achieved, but shear strain is concentrated only on surface layer limiting overall effectiveness
Solution Approach 1:
The patent applies local quality by creating different strain conditions at different locations within the material. The differential roll rotation generates shear strain that is distributed throughout the thickness of the plate, with the constraint member ensuring that strain is applied uniformly across the cross-section. This local variation in strain distribution, combined with the constraint, prevents concentration only at the surface and achieves more uniform texture modification throughout the material.
Solution Approach 2:
The patent introduces a constraint member as an intermediary between the rolls and the magnesium alloy plate. This constraint member ensures that the shear strain generated by differential roll rotation is transmitted uniformly through the material thickness. The constraint member acts as a mediator that distributes the mechanical action evenly, preventing strain concentration at the surface and ensuring comprehensive texture modification throughout the plate.
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 results in a magnesium alloy plate with enhanced cold formability, achieving a limited dome height of 10 mm or more at room temperature, with a uniform non-basal texture and improved strain resistance, effectively addressing the limitations of existing techniques.
Implementation Method 1
solution-treating a magnesium casting material comprising 0.5 to 10 wt% of zinc (Zn), 1 to 15 wt% of aluminum (Al), and a balance of magnesium (Mg) and inevitable impurities at 300 to 500 °C for 1 to 48 hours
Implementation Method 2
pre-heating the solution-treated magnesium casting material at 300 to 500 °C
Implementation Method 3
rolling the pre-heated magnesium casting material together with a constraint member selected by the following Relational Expression 1 to satisfy Relational Expressions 2 and 3
Implementation Method 4
a deviation of c/a values of a hexagonal closed packed (HCP) crystal structure in the plate (Δc/a) is 5 or less
Implementation Method 5
solution-treating a thus-rolled magnesium alloy plate at 300 to 500 °C for 0.5 to 5 hours
Data Source
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AI summary
According to an exemplary embodiment of the present invention, a manufacturing method of a magnesium alloy plate includes: (a) solution-treating a magnesium casting material containing 0.5 to 10 wt% of zinc (Zn), 1 to 15 wt% of aluminum (Al), and a balance of magnesium (Mg) and inevitable impurities at 300 to 500 °C for 1 to 48 hours; (b) pre-heating the solution-treated magnesium casting material at 300 to 500 °C; and (c) of rolling the pre-heated magnesium casting material together with a constraint member selected by following Relational Expression 1 to satisfy Relational Expressions 2 and 3; and (d) solution-treating a thus-rolled magnesium alloy plate at 300 to 500 °C for 0.5 to 5 hours. Relational Expressions 1 to 3 are as described in the specification.