The treatment method of titanium tube welding cracks requires systematic process control and quality assurance measures, mainly including the following key steps:
Crack detection and removal
Use penetration testing or ultrasonic testing to locate the crack area accurately
Use mechanical processing or grinding to remove the cracks completely, and the removal range should exceed the end of the crack by 3-5mm
After removal, perform NDT testing again to confirm that the cracks are completely removed
Welding process preparation
Welding material selection: strictly match the welding wire according to the composition of the parent material (pure titanium uses ERTi series, TC4 alloy uses ERTi-6Al-4V)
Shielding gas: Use 99.999% high-purity argon gas, equipped with drag hood protection
Groove preparation: Process 30-35° single V groove, retain 1-2mm blunt edge
Welding process control
Titanium tube welding cracks use a low-current GTAW welding process (recommended parameters: current 80 - 120A, Voltage 10 - 12V)
Strictly control the interlayer temperature, not exceeding 150℃
When implementing multi-layer and multi-pass welding, each pass needs to be cooled to below 50℃
Maintain a shielding gas flow rate of 0.8-1.2L/min
Post-weld treatment and inspection
Maintain post-protection below 200℃ after welding
Perform 100% visual inspection and non-destructive testing (RT+PT)
Perform mechanical property testing and corrosion testing when necessary
Personnel and document requirements
Operated by welders holding NB/T47014 titanium welding qualifications
Record welding parameters and inspection results throughout the process
Establish a complete quality traceability file
Precautions:
Ambient humidity must be controlled below 40%
Avoid working in ventilated areas to prevent shielding gas loss
Chemical composition verification is required before each batch of welding wire is used
The above strictly controlled process measures can effectively solve the problem of titanium tube welding cracking and ensure that the joints meet the requirements of ASME B31.3 and other specifications. For key equipment, it is recommended to conduct welding process qualification (PQR) and process verification tests.
