HF Welding Stainless Steel Tube Mill Line

Regarding the high frequency welding stainless steel pipe production line, we can learn the following precautions.

1. Welding process control

Current and voltage regulation ‌. The current parameter is about 20% lower than that of carbon steel welding to avoid intergranular corrosion caused by excessive heating ‌; Strictly control arc length (1-3mm recommended) to reduce oxidation and heat affected zone ‌.

Welding speed and heat input ‌. High frequency welding speed, it is necessary to balance efficiency and quality, to avoid welding seams caused by too fast speed or internal burr residue ‌; Small line energy welding reduces the width of the heat affected zone and reduces the risk of deformation and cracking ‌.

Preheating and interlayer temperature ‌. Thick wall pipe should be preheated to 100-150℃ before welding to prevent cold cracking ‌; The inter-layer temperature should be controlled below 150℃ to avoid carbide precipitation caused by multiple heating ‌.

2. Materials and equipment management

Select the welding material ‌. The welding wire/electrode matching with the base material composition (such as 25-13 series) is preferred to avoid cold cracks ‌; Use ultra-low carbon or stabilizer-free filler to prevent intergranular corrosion ‌.

Gas protection ‌. Adopt pure argon or reducing gas to protect the welding root, avoid CO₂ mixed gas to cause weld carburization ‌;

The purity of argon should be ≥99.99%, and the flow rate should be adjusted according to the current (for example, 50-150A corresponds to 8-10L/min) ‌.

Equipment maintenance ‌. Regularly clean the electrode and guide wheel of the high-frequency welding machine to avoid oil or impurities affecting the conductivity ‌;

Check tungsten and nozzle status to ensure protrusion length and gas coverage meet process requirements ‌.

Third, surface treatment and post-processing

Clean before welding ‌. Thoroughly remove grease, rust and oxide from the surface of the pipe (can be cleaned with alkali water, gasoline or flame) ‌.

Internal burr treatment ‌. After high-frequency welding, remove the internal burrs in time to avoid residual influence on corrosion resistance and subsequent processing ‌.

Post-welding treatment ‌. Annealed or polished to restore weld corrosion resistance and ensure bright surface ‌; If necessary, pickling or passivation treatment to remove oxidation color and residual stress ‌.