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 (TIG) welding.
Hardfacing is to increase or restore the size of the metal parts, or to obtain a deposited metal with special properties on the surface of the metal parts. There are two meanings: first, the size of the metal parts is changed by the hardfacing method, and the surface performance of the metal parts does not basically change after welding; second, the surface of the metal parts is made to be wear-resistant, heat-resistant, or corrosion-resistant by the hardfacing method. The deposited metal layer with special properties makes the surface properties of the metal parts substantially change (the hardfacing metal layer and the metal parts are mostly different materials).
The advantages of hardfacing are as follows:
1. It can improve the service life of parts and performances such as wear resistance, heat resistance and corrosion resistance.
2. Due to the hardfacing welding, the bimetal layer is manufactured, which saves a lot of alloy materials, and obtains excellent comprehensive performance, which makes the use of materials more reasonable and further reduces the manufacturing cost.
3. Shorten the time for repairing and replacing parts, increase productivity and reduce production costs. Overlay welding mostly belongs to fusion welding. The following issues should be considered during hardfacing; the service conditions of the parts and the causes of failure must be analyzed, and then the material of the hardfacing metal layer should be selected reasonably in order to fully exert the function of the hardfacing layer. During hardfacing welding, the amount of melting of the base material in the hardfacing layer must be reduced, and the required weld metal composition can be achieved with less consumption of the welding material, that is, the dilution rate should be low to improve productivity and ensure the hardfacing metal For the quality, we must choose the appropriate welding method and the correct hardfacing process.
At present, hardfacing has been widely used in the manufacture and repair of equipment in the mining, metallurgy, agricultural machinery, construction, power station, railway, vehicle, petroleum, chemical and other industries, as well as the manufacture and repair of tools and molds.