Titanium alloy rolling technology is a vital metal processing method that involves shaping titanium alloy materials into the desired forms and dimensions through the rolling process.
Key Process Aspects
The rolling process is a critical step in titanium alloy production, directly influencing both the material's microstructure and its macroscopic properties.
Here are some key points regarding the titanium alloy rolling process:
1. Rolling Temperature Control:
Titanium alloys have a narrow rolling temperature window and poor thermal conductivity; therefore, controlling the slab temperature is critical. Excessively high initial rolling temperatures or excessive deformation can cause a rapid temperature rise in the core of the workpiece, leading to reduced plasticity and uneven rolling.
2. Multi-pass Rolling:
Rolling titanium alloy plates typically requires multiple hot-rolling passes to control the material's microstructure and properties; intermediate annealing may be required between passes to restore plasticity.
The material thickness is gradually reduced through multiple rolling passes.
3. Reduction Ratio Distribution:
The distribution of reduction ratios during rolling significantly affects the material's anisotropy. For example, a 1:1 reduction ratio distribution between transverse and longitudinal rolling passes can essentially eliminate material anisotropy.
4. Rolling Speed:
Rolling speed affects the slab's temperature distribution, thereby influencing rolling quality and production efficiency. Low speeds are generally used during the initial rolling stage to prevent accidents during the bite process; rolling speed can be increased as the workpiece thins, though it usually remains below a certain limit.
5. Rolling Equipment:
The use of advanced rolling equipment-such as rapid-traverse reversing mills, continuous rolling mills, precision rolling mills, and modular rolling mills-can enhance rolling efficiency and product quality.
6. Automated Control Systems:
Developing fully automated, end-to-end control systems enables automated production with precise temperature and rolling control, thereby raising the level of automation and intelligence in the manufacturing process.
7. New Rolling Processes:
Replacing traditional two-roll mills with three-roll Y-type mills enables single-line, twist-free, micro-tension rolling, resulting in higher rolling speeds.
8. Determination of Rolling Window:
The rolling temperature window for hot-rolling titanium alloys is determined through experiments and simulation analysis, providing the basis for establishing hot-rolling process specifications.
9. Billet Preparation:
Billets for commercially pure titanium and low-alloy grades can be supplied in the form of die-forged blanks, rolled billets, or flat ingots, whereas highly alloyed grades require open-die forging. 10. Formulation of Rolling Schedules:
Formulating rolling schedules involves aspects such as billet design, reduction schedules, speed schedules, and temperature schedules; it requires a comprehensive consideration of material properties, equipment capabilities, and production efficiency.
Technical Characteristics
1. Hot Rolling:
Hot rolling is a process performed above the metal's recrystallization temperature; it significantly reduces the material's deformation resistance and improves rolling efficiency.
Suitable for producing large-sized titanium alloy plates and bars.
2. Cold Rolling:
Cold rolling is performed at room temperature; it enhances surface quality and dimensional accuracy but places higher demands on the material's plasticity.
Typically used to produce high-precision thin sheets and strips.
3. Reversible Rolling:
Reversible rolling involves passing the workpiece through the rolls multiple times, changing its direction after each pass to improve material anisotropy.
4. Near-isothermal Rolling:
An innovative rolling concept that achieves near-isothermal rolling of titanium alloys by controlling the amount of deformation, deformation rate, and rolling cycle, thereby enhancing rolling efficiency and material properties.
5. Non-conventional Pass Sequences and Flexible Rolling:
Allows for the use of various roll pass designs and rolling schedules to accommodate different material properties and production requirements.
6. "Single-Heat" High-Efficiency Rolling Model:
Utilizes innovative rolling concepts and processes to achieve efficient production of aerospace-grade titanium alloys and increases the coil weight of small-gauge wire rods.
7. Large-Scale BDM850 Rapid-Traverse Reversible Rolling Mill:
Equipment designed for rolling large-cross-section titanium alloys, capable of achieving short intervals between passes and high rolling efficiency.
8. Stepping Mills, Helical Rolling Mills, Y-Type Mills, and Planetary Mills:
These rolling mills possess distinct characteristics and are suitable for producing bars of various specifications.
The development of titanium alloy rolling technology continuously drives progress in material processing techniques; improvements in rolling processes and equipment enhance the overall performance of titanium alloy materials, meeting the demands of high-end markets.
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