One side welding with ceramic backings

applications fixation

Since their development for shipbuilding the use of ceramic backings for the high speed welding of root passes has spread to the fabrication of bridges, pressure vessels and general steel components. This has been accompanied by an increasing use of flux and metal cored wires to maximise welding productivity.
Process advantages are :

Higher welding currents resulting in higher deposition rates and increased welding speeds

Ceramic weld metal supports have no adverse influence on the chemical composition or mechanical properties of the weld metal. They are non hydroscopic and therefore complement the use of low hydrogen welding consumables.

Centerline cracking when using ceramic backing

 
When welding root runs on ceramic backing strips centerline cracking may occur at high heat inputs. This is a characteristic aspect of all rutile cored wires.
The concave bead shape promotes an unfavouable solidification pattern making the weld prone to hot cracking especially when shrinkage forces are high. For crack free welding the following guidelines should be followed:
 
  • Apply a joint angle of 45-60 with a root gap opening of 5mm   Use ceramic strips with a rectangular groove to accomodate the slag
  • Use backing with a groove width of approximately 15mm
  • Use welding currents below 180A (1,2mm). This gives a more oval weld pool instead of the unfavourable arrow shape.
  • Minimize weaving to limit the thickness of the weld bead whilst keeping the arc in front of the weld pool to ensure sufficient penetration.

    Copyright 2006 deppe Keramik GmbH