Typical corrosion resistant clad layers include:
- Copper based weld overlays on steels for seawater corrosion resistance
- Ni Alloy 625 weld overlays onto pump, valve or sealing surfaces exposed to brackish water, sea water or sour gas service
- Stellite®21 or Stellite®6 or ULTIMET® (UNS R31233) weld overlay where a combination of corrosion and wear resistance is required
Weld cladding is typically between 2 and about 20 mm thick. It can be applied using a variety of welding processes including manual metal arc (MMA), gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), submerged arc welding (SAW), flux cored arc welding (FCAW), plasma transferred arc welding (PTAW) and laser deposition.
During weld cladding the integrity of the clad layer and adequate toughness of the heat-affected zone (HAZ) must be ensured whilst simultaneously maintaining the substrate material properties.
For specific base materials such as duplex steels, tool steels, high-carbon steels or martensitic steels, this requires a thorough understanding of the metallurgy of the substrate as well as the hardfacing material.
Another very important consideration is the dilution of the clad layer by the substrate material, as dilution can have a dramatic effect on the corrosion resistance of the cladding.
With world class expertise in all welding processes, as well as metallurgists with knowledge of corrosion-resistant alloys and the welding of ‘difficult’ steels, TWI is able to put together a team of truly independent specialists to advise on any cladding query. We can assist you with materials selection, failure analysis and processing advice.
We can also advise on correct procedures for the weld joining of clad plates or pipes.