LSAW Pipe Temperature Requirement And Causes Of Slagging

The calibre of LSAW steel pipe can reach 1500mm, LSAW is the English abbreviation for submerged arc welded straight seam steel pipe, the production process of submerged arc welded straight seam steel pipe has JCOE forming technology, rolled into a type of submerged arc welding technology. When the calibre is large, two steel plates may be rolled, which will form the phenomenon of double weld.

• LSAW pipe requirements for welding temperature:

The material is low carbon steel, the welding temperature is controlled at 1250~1460℃, which can meet the requirement of weld penetration of 3~5mm pipe wall thickness, and the welding temperature is mainly controlled by adjusting the high-frequency eddy current heat power and welding speed.

• When the heat input is insufficient, the heated weld edge does not reach the welding temperature and the metal tissue remains solid, resulting in unfused or unwelded welds. When the input heat is too large, the edge of the heated weld exceeds the welding temperature, resulting in overcooking or molten droplets, causing the weld to form a molten hole.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

• The production characteristics of submerged arc welding LSAW steel pipe can eliminate the cause of slag in the weld due to unclean interlayer in multi-layer welding.
• For more inclusions in the raw material to make the weld slag, take pre-welding inspection of the base material, change the new wire and flux and other measures, the proportion of weld fusion line slag only slightly reduced, indicating that the inclusions in the raw material is not the main cause of the slag.
• Therefore, thick-walled straight seam submerged arc welded steel pipe fusion line slag is the main reason for the main reason is the choice of welding process parameters are not appropriate. Thick-walled straight seam submerged arc welded steel pipe welding process parameters are: line energy, welding current, welding voltage, welding speed, wire spacing, bevel size, etc..

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Slag is the slag remaining inside the weld. From the theoretical analysis, submerged arc automatic welding seam slag produced by the following three main reasons:
1. More inclusions in the raw materials (including base metal, welding wire, flux);
2. More inclusions in raw materials (including base material, welding wire, flux);
3. Inappropriate welding process parameters selected, which is not conducive to the surfacing of slag.