Arc weld surfacing - plasma transferred arc (PTA), submerged arc strip, manual metal arc (MMA), metal inert gas (MIG) and tungsten inert gas (TIG)
All arc welding processes can be used for overlay as well as joining applications. The choice of process depends on the application and the component size and geometry. Overlays are typically in excess of 2mm thick, and can be considerably thicker if required. Good adhesion is secured to the substrate through a metallurgical bond, but it should be noted that weld surfacing involves fusion of the substrate to a certain extent and at the same time dilution of the overlay by the substrate material. Weld surfacing can be used to overlay new components with wear or resistant coatings, or to restore worn components to their original dimensions.| Process | Deposition rate, kg.hr-1 | Manual or mechanised |
|---|---|---|
| Manual metal arc (MMA) | 1-3 | Manual |
| Metal inert gas (MIG) | 2-6 | Both |
| Tungsten inert gas (TIG), micro plasma | 1-2 | Both |
| Plasma transferred arc | 2-10 | Mechanised |
| Submerged arc, open arc, strip cladding | 10-40 | Mechanised |
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Excavator bucket fabricated from wear plate manufactured by open arc welding |
Examples of common applications and typical alloy selection:
- Repair of cast iron tooling (nickel alloys)
- Repair of injection molding tools (martensitic steels)
- Repair of hot work tool steels (high speed steels)
- Engine exhaust valves (cobalt alloys)
- Wear plate for earth moving, mineral extraction and transportation, concast rolls (ferrochromium chromium carbide)
- Screw press flights (martensitic steels, cobalt alloys)
- Gate valves (cobalt alloys)
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