Magnesium Alloy Sheet Hot Rolling with Large Pass Reduction

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Solution Overview

Problem

The development of magnesium alloy sheets is hindered by their poor processing performance at room temperature, requiring high-temperature hot rolling with multiple passes, low single-pass reduction, and slow rolling speeds, leading to high production costs and inefficient production, as well as inadequate mechanical properties such as strength and ductility.

Innovation Solution

A high-efficiency rolling process with controlled rolling speeds of 10-50 m/min and rolling reductions of 40-90% per pass, combined with preheating and precise temperature control between 250-450°C, to achieve finer grain structures and improved mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If high-temperature hot rolling with multiple passes is used to process magnesium alloy sheets, then the processing performance is improved, but the production time and costs increase

Engineering Contradiction:
Improveprocessing performanceVSAvoidproduction time
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent applies parameter changes by optimizing rolling temperature (250-450°C), rolling speed (10-50 m/min), and single-pass reduction (40-90%) to achieve both good processing performance and high productivity. This resolves the contradiction by finding optimal parameter ranges that satisfy both ease of manufacture and production efficiency

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses preheating before rolling as a preliminary action to prepare the magnesium alloy for deformation. This preliminary heating treatment enables the material to achieve desired plasticity before the main rolling process, reducing the need for multiple passes and extending production time

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If multiple passes with small reductions are used for rolling magnesium alloy sheet, then the processing quality is maintained, but the number of passes increases to over ten

Engineering Contradiction:
Improveprocessing qualityVSAvoidnumber of passes
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the reduction parameter from small incremental reductions to large single-pass reductions (40-90%), while maintaining processing quality through controlled temperature and speed parameters. This reduces the number of passes required while preserving manufacturing precision

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies excessive action by using larger than conventional single-pass reductions (40-90% compared to typical smaller reductions). This approach achieves the required total reduction in fewer passes while maintaining quality through proper temperature and speed control

Inventive Principle:
Principle #16Partial or excessive action

3Stability of the object's composition

If low rolling speed is used for magnesium alloy rolling, then the plasticity is maintained, but the production efficiency decreases

Engineering Contradiction:
ImproveplasticityVSAvoidproduction efficiency
Core Design Contradiction:
Stability of the object's compositionVSProductivity

Solution Approach 1:

The patent optimizes the rolling speed parameter to 10-50 m/min, which is higher than conventional speeds but maintains plasticity through coordinated temperature control (250-450°C). This resolves the contradiction by finding an optimal speed range that balances plasticity maintenance with improved production efficiency

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses preheating as a preliminary action to prepare the magnesium alloy for high-speed rolling. By heating the material before rolling, the plasticity is maintained even at higher rolling speeds, enabling both good plasticity and high production efficiency

Inventive Principle:
Principle #10Preliminary action

4Productivity

If conventional rolling process is used, then the production cost is high, but the mechanical properties such as strength and ductility are insufficient

Engineering Contradiction:
Improveproduction costVSAvoidmechanical properties
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The patent optimizes multiple parameters simultaneously (temperature 250-450°C, speed 10-50 m/min, reduction 40-90%) to achieve both cost reduction through fewer passes and improved mechanical properties. This multi-parameter optimization resolves the contradiction between production cost and mechanical properties

Inventive Principle:
Principle #35Parameter changes

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 process enhances the strength and ductility of magnesium alloy sheets, reduces production time and costs, and simplifies the rolling process, making it more suitable for large-scale industrial production.

Implementation Method 1

By adopting a relatively fast rolling speed and combining with a relatively large amount of rolling deformation, dynamic recrystallization is accompanied, so that a deformed structure can be obtained in the magnesium alloy sheet

Methodology Applied
Scientific EffectDynamic recrystallization: Crystallisation

Implementation Method 2

the deformation heat generated by the deformation and the frictional heat generated by the contact between the rolled piece and the roller will cause rise of actual temperature of the rolling piece

Methodology Applied
Scientific EffectDeformation heat: Viscoelasticity

Implementation Method 3

the deformation heat generated by the deformation and the frictional heat generated by the contact between the rolled piece and the roller will cause rise of actual temperature of the rolling piece

Methodology Applied
Scientific EffectFrictional heat: Friction

Data Source

PatentEP3391976B1Magnesium alloy sheet rolling and preparation method
Publication Date: 2021.02.10 BAOSHAN IRON & STEEL CO LTD
  • EP3391976B1 patent drawingFigure 1~3
  • EP3391976B1 patent drawingFigure 4~5
  • EP3391976B1 patent drawingFigure 6~7

AI summary

A high-efficient rolling process for magnesium alloy sheet. The process is a rolling process for rolling billets. Parameters of the rolling process are: the rolling speed of each rolling pass is 10∼50 m/min, the rolling reduction of each rolling pass is controlled to be 40∼90%, and both the preheating temperature before rolling and the rolling temperature of each rolling pass are 250∼450 °C. A preparation method for magnesium alloy sheet. The method comprises the steps of: 1) preparing rolling billets; 2) high-efficient hot rolling: controlling the rolling speed of each rolling pass to be 10∼50 m/min, controlling the rolling reduction of each rolling pass to be 40∼90%, and controlling both the preheating temperature before rolling and the rolling temperature of the each rolling pass to be 250∼450°C; and 3) performing annealing. By means of the rolling process, mechanical performance of the sheet can be also effectively improved, and especially, the strength and ductility of the sheet can be greatly improved.