Ι.Preheating and Temperature Control: Precise temperature control is the first step in preventing cracking.
•GR5 titanium alloy has a unique temperament: it exhibits extremely low plasticity at room temperature, and bending at low temperatures almost inevitably leads to cracking. Therefore, preheating treatment before bending is an absolutely indispensable step.
• Preheating temperature must be strictly maintained between 200-400°C. It should not fall below 200°C (insufficient plasticity still leads to cracking) nor exceed 500°C-once temperatures surpass 500°C, TC4 titanium alloy grains rapidly coarsen, causing a precipitous decline in mechanical properties that cannot be recovered through subsequent processing.
II. Bending Speed and Pressure Control: Low Speed + Precise Compensation to Avoid Springback and Defects
• Speed must be "slow": Bending speed must be controlled at ≤5mm/s. Treat the material like precision instruments-apply gentle pressure and bend slowly. This allows internal stresses to release gradually, preventing stress concentration.
• Pressure must be "precise": Insufficient pressure causes severe springback (GR5 titanium alloy exhibits significantly higher springback than standard steel), requiring a 10%-15% compensation margin during processing.
III. Mold and Lubrication Selection: Choose the Right "Partner" to Reduce Friction and Maintain Precision
• Select the Right Mold Material: Prioritize H13 hot-work tool steel, which combines high wear resistance and thermal stability. This material can withstand the high-hardness impact of TC4 titanium alloy and maintain precision during long-term machining.
•Proper Lubricant Selection: Prior to bending, apply a high-temperature lubricant specifically formulated for titanium alloys (such as molybdenum-based lubricants) to all contact points between the workpiece and the die.
IV. Post-Processing and Quality Inspection: Stress Relief + Rigorous Quality Control
Following the bending of GR5 titanium alloy, subsequent stress relief annealing is required. Rigorous inspection of bending angle tolerances and surface defects must be conducted, followed by mechanical property testing.