Cladding (metalworking)

As a cladding, the method of hard facing is referred to, in which a high-alloy steel is applied as a surface protection for highly stressed metal components. In addition to conventional light welding processes, laser cladding and plasma transferred arc welding are increasingly used.

The main application area of the cladding is the power plant construction. Especially diaphragm walls and platen heating, which are acted upon in power plants with very aggressive exhaust gases, subject to a very strong material removal. Particularly affected are waste incineration plants and biomass power plants for highly loaded waste wood, which have a high sulfur and halogen content in the flue gas. The strongest erosion occur here in the region with the highest flue gas temperatures, unprotected heating surfaces and in the superheater area.

In the method, a high-alloy protective coating is applied to a low -alloy base material. Preferably, nickel-based alloys such as Alloy 625 and Alloy 686 or Alloy 59 can be applied. The thickness of the protective layer is 2-3 mm for typical wall thicknesses of the membrane walls of 4-5 mm. The protective layer is applied in two layers or mixed. The base material must be sanded before Cladden and are directly provided with a temporary protective coating. As a contract method, the MAG welding process is used. For long times the layer thickness of the order the material must be applied uniformly and the Fe dilution (diffusion of iron in the coating during melting ) must be low. The cladding process is also used for upgrading of corrosion and abrasion -damaged components as well as new components. As typical removal rate in waste incineration plants 0,1 mm / 10000 Hours are listed.