Hot-Rolled Titanium Alloy Sheet Texture Control for Crack Resistance
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Solution Overview
Problem
α+β titanium alloy hot-rolled sheets suffer from edge cracking during hot rolling, leading to sheet fractures during cold uncoiling or recoiling, which reduces production efficiency and safety due to crack propagation in the sheet width direction.
Innovation Solution
A high-strength α+β titanium alloy hot-rolled sheet with a specific crystal texture (T-texture) is developed, where the c-axis of the hexagonal basal plane is strongly oriented in the width direction, reducing crack propagation propensity and enhancing ductility and flexural characteristics by adjusting the content of elements like Fe, Al, O, and N, and controlling the hot rolling process parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If α+β titanium alloy is subjected to hot rolling, then high strength is achieved, but edge cracking occurs in the sheet width direction
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters (Fe: 0.05-1.0%, Al: 2.0-6.0%, V: 0.05-2.0%, Ti: balance) and hot rolling process parameters (temperature range, reduction ratio) to prevent edge cracking while maintaining high strength. The specific compositional ranges and processing conditions transform the material properties to achieve both strength and crack resistance.
2Productivity
If edge cracking remains in hot-rolled coil, then production continuity is maintained, but crack propagates during cold uncoiling or recoiling causing sheet fracture
Solution Approach 1:
The patent applies preliminary anti-action by pre-preventing crack propagation through specific alloy composition design and hot rolling process control. The Fe-Al-V system creates a microstructure that inherently resists crack propagation during subsequent cold handling operations, eliminating the need for reactive measures like trimming or reduced speed processing.
3Reliability
If trimming is performed to remove edge cracking, then sheet integrity is improved, but production yield decreases and production cost increases
Solution Approach 1:
The patent converts the potential harm of edge cracking into a benefit by designing an alloy system where controlled hot rolling produces a microstructure that prevents crack propagation. The Fe-Al-V alloy composition transforms what would be a defect (edge cracking) into an opportunity to achieve both high strength and excellent cold handling properties without material removal.
4Shape
If cold leveling is performed on hot-rolled coil, then flatness is improved, but sheet fracture occurs due to tension fluctuation from trimming scraps plugging
Solution Approach 1:
The patent applies preliminary action by ensuring that the hot rolling process creates a microstructure with high crack propagation resistance before the cold leveling operation. The Fe-Al-V alloy composition and controlled hot rolling parameters prepare the material in advance to withstand the tension fluctuations that occur during cold leveling without fracturing.
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 solution effectively inhibits sheet fractures during uncoiling and recoiling, improving the cold coil handling property and production yield by reducing deformation resistance and promoting plastic deformation, thus ensuring the sheet's integrity and usability.
Implementation Method 1
containing a crystal texture (T-texture) in which a normal direction of a hexagonal basal plane ((0001) plane), that is, a c-axis orientation, of a titanium α phase is strongly oriented in the width direction
Implementation Method 2
adjusting the content of elements like Fe, Al, O, and N
Implementation Method 3
promoting plastic deformation
Data Source
AI summary
A high-strength α+β type hot-rolled titanium alloy sheet containing 0.8 to 1.5 mass % Fe, 4.8 to 5.5 mass % Al, 0.030 mass % N, O and N, wherein cracks are prevented from spreading, wherein: (a) ND represents normal direction of a hot-rolled sheet; RD represents hot rolling direction; TD represents hot rolling width direction; θ represents the angle formed between c axis and ND; φ represents angle formed between plane including c axis and ND, and a plane including ND and TD; (b1) XND represents highest (0002) relative intensity of X-ray reflection by grains when θ is from 0° to 30° ; (b2) XTD represents the highest (0002) relative intensity of the X-ray reflection caused by grains when θ is from 80° to 100° and φ is ±10° . (c) The high-strength α+β type hot-rolled titanium alloy sheet has a value for XTD/XND of at least 4.0. Q(%)=[O]+2.77·[N].