The prime function of Hardfacing materials is to protect a component or other material against the forces of wear.
Most hardfacing alloys are iron, nickel, or cobalt-base and can be used in a variety of forms including powder, solid welding rods or wires and tubular rods or wires.
Hardfacing is the application of a hard, wear-resistant material to the surface of a component by welding, thermal spraying or a similar process, mainly to reduce wear. Hardfacing is used on original equipment, as well as for the repair of worn components. Hardfacing consumable materials are acceptable in different forms, such as powder, solid welding rods or wires and tubular rods or wires.
Hardfacing materials include a wide variety of alloys, carbides, and combinations of these materials. Conventional hardfacing materials are normally classified as steels or low-alloy ferrous materials, high-chromium white irons or high alloy ferrous materials, carbides, nickel-base alloys, or cobalt-base alloys. A few copper-base alloys are sometimes used for hardfacing applications, but for the most part, hardfacing alloys are iron, nickel, or cobalt-base.
Nonferrous hardfacing alloys are used either for high resistance to specific types of wear (other than abrasion) or for wear resistance (including abrasion) in environments that are too corrosive or beyond the service temperature of ferrous alloys. The cobalt-base alloys and bronzes are particularly resistant to galling and to those wear processes involving micro-fatigue as the degradation mechanism (such as cavitation erosion). The cobalt-base alloys also possess high resistance to deformation at temperatures in excess of 750°C (1380°F). Typical compositions of the nonferrous hardfacing alloys are presented in Table 1.
Table 1: Composition of selected nonferrous hardfacing alloys
Figure 1: Optical micrographs of the first and third layers of different nickel base hardface alloys: (a–b) ERNiCr-A, (c–d) ERNiCr-B, and (e–f) ERNiCr-C
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Date Published: May-2018