Processing and welding of titanium profiles!
1、 Key points of processing technology
1. Tools and cutting parameters
Hard alloy or diamond coated cutting tools should be used to avoid increased tool wear caused by the viscosity of titanium during high-speed cutting; It is recommended to control the cutting speed at 20-50 m/min and the feed rate at 0.05-0.2mm/revolution.
Water based emulsion or specialized cutting fluid must be used for continuous cooling during processing to prevent local high temperatures from causing material oxidation or work hardening.
2. Optimization of molding process
Extrusion molding: The composite extrusion of titanium alloy ingot and carbon steel ingot can reduce surface pollution and prevent metal from entering the profile, increasing the yield to 80% -90%.
Rolling cooling: Titanium plate rolling requires a forced cooling system to prevent grain coarsening at high temperatures from affecting mechanical properties.
2、 Core Welding Technologies and Requirements
1. Welding method
Inert gas shielded welding: commonly used, requiring 99.999% high-purity argon gas protection. The welding gun is equipped with a drag cover to extend the protection time and avoid oxidation of the weld seam.
Laser/electron beam welding: suitable for precision components, with narrow heat affected zone and small deformation, but high equipment cost.
2. Key to process control
Cleanliness: Before welding, it is necessary to thoroughly remove oil stains and oxides with acetone or specialized solvents to prevent porosity and inclusions.
Gas protection: Both sides of the weld seam must be covered with argon gas, and the residual oxygen content must be less than 50 ppm.
Heat input control: using low line energy, interlayer temperature ≤ 150 ℃, to avoid excessive grain growth.
3. Post weld treatment
Annealing is required to eliminate residual stress and improve joint toughness and corrosion resistance.
For key aviation components, penetration testing is required to ensure that the welds are defect free.
3、 Typical Problems and Countermeasures
Weld embrittlement: Oxygen/nitrogen pollution or rapid cooling, strengthen gas protection, and slow cooling after welding;
Cracks in the heat affected zone: if the hydrogen content is too high or stress is concentrated, strictly control hydrogen and optimize structural design;
Processing tool sticking: Titanium chips adhere to the tool at high temperatures, reducing cutting speed and increasing coolant flow rate.
