Aluminum Alloy Sheet Press-Formability and Shape Fixability
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Solution Overview
Problem
5000 series aluminum alloy sheets face challenges in press-formability and shape fixability due to high yield strength and limitations in plane strain fracture limit, especially when forming complex shapes, and suffer from skin roughness and defects during actual press-forming operations.
Innovation Solution
The development of an aluminum alloy sheet with a composition of Mg: 3.4 to 5.5%, Fe: 0.05 to 0.25%, Ti: 0.005 to 0.10%, and restricted Si content, combined with a metal structure featuring an average grain size of less than 15 μm and specific second phase particles, which is produced through continuous casting and cold rolling followed by annealing to achieve high tensile strength, low yield strength, and enhanced elongation and plane strain fracture limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of the original slab is reduced to 1 to 10 mm to control intermetallic compound size, then formability is improved, but yield strength increases and shape fixability deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the aluminum alloy by precisely controlling the content ranges of Mg (2.0-6.0%), Si (0.1-1.5%), Fe (0.1-1.5%), Mn (0.05-1.0%), and other elements. This compositional adjustment allows the material to achieve both improved formability through controlled intermetallic compound formation and maintained shape fixability through optimized strength properties.
2Ease of manufacture
If conventional 5000 series aluminum alloy sheet is used for press-forming of complicated shapes, then production is simplified, but cracking and defects occur near the plane strain region
Solution Approach 1:
The invention modifies the chemical composition parameters within specific ranges to improve the plane strain fracture limit while maintaining the simplicity of press-forming production. The controlled composition prevents cracking in complicated shape formation.
Solution Approach 2:
The invention creates a composite microstructure consisting of aluminum matrix with controlled intermetallic compounds (Al-Fe-Si phase, Al-Mn phase, and Al-Mg-Si phase) distributed throughout. This composite structure at the micro level provides both the formability needed for complicated shapes and the fracture resistance to prevent cracking during press-forming operations.
3Strength
If high strength aluminum alloy sheet is used to improve structural properties, then strength is increased, but press-formability and shape fixability deteriorate
Solution Approach 1:
The invention optimizes the chemical composition parameters within specific ranges: Mg (2.0-6.0%), Si (0.1-1.5%), Fe (0.1-1.5%), Mn (0.05-1.0%), and controls impurity levels. This parameter optimization achieves a balance where the alloy maintains high structural strength while preserving excellent press-formability and shape fixability, eliminating the need to divide parts into multiple pieces.
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 resulting alloy exhibits improved press-formability, shape fixability, and surface quality, with a plane strain fracture limit of 0.20 or more at a strain rate of 20/sec, effectively addressing the limitations of existing 5000 series aluminum alloys.
Implementation Method 1
final annealing it
Implementation Method 2
has an average size of recrystallized grains of 10 μm or less
Data Source
AI summary
An aluminum alloy sheet which has high strength enabling application to automobile body sheet and which is excellent in press-formability and shape fixability and a method of production of the same are provided. Aluminum alloy sheet having a composition of ingredients which contains Mg, Fe, and Ti, restricts the impurity Si to less than 0.20 mass %, and has a balance of Al and unavoidable impurities and a metal structure with an average grain size of less than 15 μm and having second phase particles with a circle equivalent diameter of 3 μm or more in a number of less than 300/mm2 and having a tensile strength of 240 MPa or more, a yield strength of less than 130 MPa, an elongation of 30% or more, and a plane strain fracture limit at a strain rate of 20/sec of 0.20 or more.