Alpha-Beta Titanium Alloy Sheet T-Texture Cold Rollability
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Solution Overview
Problem
α+β titanium alloy sheets face issues with edge cracking during cold rolling, leading to sheet fractures and reduced production efficiency, due to high deformation resistance and limited thickness reduction ratios.
Innovation Solution
Stabilizing a hot-rolling texture (T-texture) with specific crystal orientation and chemical composition, including Fe, N, and O, to reduce deformation resistance and enhance ductility, allowing for higher sheet thickness reduction ratios and improved cold rollability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If alloying elements are added to impart high strength, then strength is improved, but deformation resistance increases and cold rollability deteriorates
Solution Approach 1:
The invention changes the crystal orientation parameter by stabilizing T-texture where the c-axis is oriented in the sheet width direction. This parameter change reduces deformation resistance during cold rolling while maintaining high strength through controlled alloying elements (Fe: 0.8-1.5%, N: 0.020% or less, O: 0.030% or less) and hot rolling conditions (temperature: β transformation point +20℃ to +150℃, finishing temperature: β transformation point -200℃ to -50℃, sheet thickness reduction ratio: 90% or more).
Solution Approach 2:
The invention creates a composite microstructure consisting of α-phase and β-phase with specific crystal orientations. The T-texture orientation creates a composite arrangement where the c-axis of the hexagonal basal plane is oriented in the sheet width direction, combining the strength benefits of alloying elements with the ductility benefits of favorable crystal orientation.
2Productivity
If cold rolling reduction ratio is increased, then productivity is improved, but sheet fracture occurs due to edge cracking
Solution Approach 1:
The invention performs preliminary action by stabilizing T-texture during hot rolling before cold rolling. This preliminary crystal orientation arrangement prevents edge cracking during subsequent cold rolling, allowing high sheet thickness reduction ratios (90% or more) without sheet fracture. The T-texture creates favorable stress distribution that prevents crack initiation at sheet edges during high-reduction cold rolling.
3Ease of manufacture
If hot rolling temperature is increased to stabilize T-texture, then cold rollability is improved, but energy consumption increases
Solution Approach 1:
The invention optimizes the temperature parameter within a specific range (β transformation point +20℃ to +150℃) to stabilize T-texture. This parameter optimization achieves the desired crystal orientation for improved cold rollability while minimizing energy consumption. The controlled temperature range ensures sufficient thermal energy for texture stabilization without excessive energy input.
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 stabilization of T-texture in α+β titanium alloy sheets significantly reduces the likelihood of sheet fractures during cold rolling, maintains high ductility, and facilitates efficient cold rolling with reduced deformation resistance, thereby enhancing handling properties and production efficiency.
Implementation Method 1
the normal direction of a hot-rolled sheet is taken as ND, the hot rolling direction is taken as RD, the hot-rolling width direction is taken as TD, the normal direction of the α-phase (0001) plane is taken as c-axis orientation
Implementation Method 2
Stabilizing a hot-rolling texture (T-texture) with specific crystal orientation and chemical composition
Implementation Method 3
an α+β titanium alloy sheet... wherein: (a) the normal direction of a hot-rolled sheet is taken as ND... the normal direction of the α-phase (0001) plane is taken as c-axis orientation
Implementation Method 4
including Fe, N, and O, to reduce deformation resistance and enhance ductility
Implementation Method 5
at the time of hot-rolling an α+β titanium alloy, the titanium alloy prior to hot rolling is heated to a temperature ranging of (β transformation temperature +20℃) or more and (β transformation temperature +150℃) or less
Implementation Method 6
the deformation resistance thereof during the cold rolling is low... facilitating efficient cold rolling with reduced deformation resistance
Data Source
AI summary
An α+β type hot-rolled titanium alloy sheet, wherein: (a) ND represents the normal direction of a hot-rolled sheet; RD represents the hot rolling direction; TD represents the hot rolling width direction; θ represents the angle formed between the orientation of c axis and the ND; Φ represents the angle formed between a plane including the orientation of the c axis and the ND, and a plane including the ND and the TD; (b1) XND represents the highest (0002) relative intensity of the X-ray reflection caused by crystal grains when θ is from 0° to 30° and Φ is within the entire circumference; (b2) XTD represents the highest (0002) relative intensity of the X-ray reflection caused by crystal grains when θ is from 80° to 100° and Φ is ±10°. (c) The α+β type titanium alloy sheet has a value for XTD/XND of at least 5.0.