Assembling parts together often requires welding operations. In the same way as low-alloyed steels, Creusabro grades are suitable for welding using conventional welding technology : manual welding with coated electrode, gas metal arc welding with flux core wire, submerged arc welding.
However some precautions must be taken. Key factor to succeed welding is first of all the respect of basic rules. Cleaning pieces to weld, drying stick electrodes, decreasing stresses of the assembly contribute to have a good final result.
Preheating is necessary for high thicknesses or specific assembly with high internal stresses.
Filler must be chosen according to whether the weld is submitted to abrasion or not.
The ambient atmosphere has a more or less high moisture content.
• Plates temperature: 5°C (50°F) minimum.
• AVOID wind in work area as it will affect the gas shielding.
• Protect the weld with appropriate shelter.
• Warm plates with a burner to remove moisture.
Plate surfaces has several possible sources of Hydrogen. Before welding, it is necessary to remove :
Usual baking conditions for SMAW (electrodes) and SAW (flux):
• DRYING: 350°C (660°F) during 2H.
• STORAGE:150°C (300°F).
|Sequences for a longitudinal weld|
A plate which will not able to deforme during welding inevitably will induce strong residual stresses in the area of welded joints.
• Working on weld sequences.
• Letting degrees of freedom to the assemblies.
• Reducing number of welds.
Preheating conditions depend on Creusabro grade, on welding product choosen and on thicknesses welded. Please to refer to datasheets in order to find preheating tables.
Goals of a preheating are:
• to decrease the cooling rate after welding
• to reduce residual stresses
• to facilitate hydrogen degassing
It is a very efficient means to reduce cold crack sensitivity of the assembly.
Preheating could be carried out :
• with burners
• in a furnace
• electric heating mats