Ι.Temperature Mechanism: The Divide Between Dynamic Recrystallization and Work Hardening
The core characteristic of hot working lies in processing temperatures exceeding the recrystallization temperature of titanium alloys (typically 600–950°C, depending on alloy composition). Within this temperature range, the material undergoes dynamic recrystallization: elevated temperatures activate atomic diffusion capabilities, enabling dislocations accumulated during deformation to rearrange through migration across grain boundaries, forming equiaxed grain structures.
Cold working, however, occurs at room temperature or below the recrystallization temperature, achieving plastic deformation through dislocation multiplication. Without the softening effect of dynamic recrystallization, dislocation density within the titanium plate continuously accumulates, forming a high-density entangled network.
II. Process Objectives: Differentiated Pathways for Macro-Scale Forming and Micro-Scale Control
The core value of hot processing lies in achieving macro-level forming of large-sized billets. Through processes such as hot forging and hot rolling, cast titanium ingots (with diameters exceeding 600mm) can be transformed into plates with uniform thickness or complex cross-section profiles.
Cold processing, however, focuses on microstructural property control and dimensional precision. Through cold rolling, cold drawing, and similar techniques, the thickness tolerance of hot-rolled titanium plate can be reduced from ±0.5mm to ±0.05mm. Simultaneously, material strength can be precisely adjusted by controlling deformation levels.
III. Typical Process Combination: Engineering Practice of Thermal-Cold Synergy
In actual production, a single processing method often fails to meet complex performance requirements, making the combined application of hot and cold processing for titanium plate the mainstream approach. Hot rolling stage: Ingots are heated and subjected to multiple rolling passes to produce basic billets. Cold rolling stage: Hot-rolled sheets undergo acid pickling to remove scale, followed by multiple cold rolling passes at room temperature. Intermediate annealing is incorporated during cold rolling to relieve work hardening and prevent edge cracking. Final treatment: Vacuum annealing eliminates residual stresses, yielding high-performance plates.
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