Hardfacing is a metalworking process where harder or tougher material is applied to a base metal. It is welded to the base material, and generally takes the form of specialized electrodes for arc welding or filler rod for oxyacetylene and gas tungsten arc welding. Powder metal alloys are used in plasma-transferred arc (PTA), also called powder plasma welding, and thermal spray processes like high-velocity oxygen fuel coating, plasma spray, spray and fuse, etc. Submerged arc welding, flux core arc welding (FCAW) and metal inert gas (MIG) / metal active gas (MAG) use continuously fed wire varying in diameter depending on the process and current. The strip cladding process uses strips from 50 mm wide to 125 mm with a thickness of 0.5mm. Open arc welding uses a continuously fed tubular electrode which may or may not contain flux.

Hardfacing may be applied to a new part during production to increase its wear resistance, or it may be used to restore a worn-down surface. Hardfacing by arc welding is a surfacing operation to extend the service life of industrial components, preemptively on new components, or as part of a maintenance program.[citation needed] The result of significant savings in machine down time and production costs has meant that this process has been adopted across many industries such as steel, cement, mining, petrochemical, power, sugar cane and food. According to the results of an experimental study, the shielded metal arc welding and the gas metal arc welding hardfacing processes were effective in reducing the wear on the mouldboard ploughshare. With the shielded metal arc welding and gas metal arc welding hardfacing processes, the life span of the ploughshare was increased approximately 2 times.[1]

Extensive work in research has resulted in the development of a wide range of alloys and welding procedures. The optimum alloy selection is made considering the component service conditions and feedback of the service performance.

For each industrial application and wear phenomena, there is a welding electrode to provide wear resistance.

Hardfacing can be deposited by various welding methods:

Commonly applied materials include cobalt-based alloys (such as Stellite), nickel-based alloys, chromium carbide alloys and NOREM. Hardfacing is sometimes followed by hot stamping to refinish the part or add color or instructional information to the part. Foils or films can be used for a metallic look or other protection.[citation needed]

See also

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References

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  1. ^ "Investigation of the reduction of mouldboard ploughshare wear through hot stamping and hardfacing processes" (PDF). www.tubitak.gov.tr. Archived from the original (PDF) on 3 March 2016. Retrieved 9 February 2016.

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Filler metal

deliberately different metal is to be deposited. This is often done for hardfacing excavating tools or digger bucket teeth. A hard, but more expensive and

Stellite

content. Typical applications for Stellite alloys include saw teeth, hardfacing, and acid-resistant machine parts. Stellite alloys were a major improvement

NOREM

NOREM is a hardfacing material developed by the Electric Power Research Institute to deal with radiation safety issues associated with the use of cobalt

Ferroaluminum

aluminium. Applications of ferroaluminum include the deoxidation of steel, hardfacing applications, reducing agent, thermite reactions, AlNiCo magnets, and

Oxy–fuel welding and cutting

non-ferrous metals except brass. Depositing metal to build up a surface, as in hardfacing. Also, oxy-hydrogen flames are used: In stone working for "flaming" where

Grinding (abrasive cutting)

been built and has been heat-treated, it is pre-ground before welding or hardfacing commences. This usually involves grinding the outside diameter (OD) slightly

Plasma arc welding

wire or autogenous up to 6 mm (0.24 in) plates and metal deposition (hardfacing) using specialised torches and powder feeders (PTA) using metal powders

List of laser applications

process applied to mechanical components for reconditioning, repair work or hardfacing Photolithography Optical communications over optical fiber or in free