Macrostructure of Type 316L stainless steel welded joints (6-mm-thick) made by TIG and A-TIG welding

Macrostructure of Type 316L stainless steel welded joints (10-mm-thick) made by TIG and A-TIG welding on two sides

Welding Super Duplex Stainless Steel: A-TIG and TIG thermal efficiencies are the same, namely 0,5. The A-TIG welding energy transferred to the material is used better to increase the performances of the process. The nitrogen transfer in the molten pool is stronger in the A-TIG welding process than in the TIG process.

The A-TIG process is metallurgically more effective than other welding methods without filler material:

• reduction of the ferrite ratio in the molten metal;
• increase of CPT (critical pitting temperature) in a 6% FeCl₃ solution (according to ASTM G48A).

The impact strength resistance of the A-TIG molten metal remains high in spite of an oxygen content a little stronger than in TIG.

Macrostructure of SuperduplexUR52N+ stainless steel welded joints (7-mm-thick) made by TIG welding and A-TIG welding

Single-pass Metal Inerte Gaz welding via returne polarity constant current through activating flux layer without preliminary preparation of welding materials.

“MIG Welding Methode of Articles from Construction Metals (A-MIG)” - International Patent PCT/UZ99/00002. 1999 (No Publication WO0032345, Date 2000-06-08).

Advantages:

• possibility produce single-pass, square-groove, full penetration welds up to 10 mm without lining;
• decrease in heat effect on structural transformation in the field of thermal influence;
• decrease in welding deformations;
• high productivity;
• reduction in labour input;
• saving on electric energy and welding materials.

Macrostructure of Type 316L stainless steel welded joints (6-mm-thick) made by MIG and A-MIG welding