Plasma transferred arc (PTA) hardfacing is a versatile method of depositing high-quality metallurgically fused deposits on relatively low cost surfaces. Soft alloys, medium and high hardness materials, and carbide composites can be deposited on a variety of substrates to achieve diverse properties such as mechanical strength, wear and corrosion resistance, and creep. PTA hardfacing has several significant advantages over traditional welding processes such as oxyfuel (OFW) and gas tungsten arc (GTAW) welding.
The PTA process:
PTA is easily automated, providing a high degree of reproducibility.
PTA allows precise metering of metallic powder feedstocks. As a result a lesser quantity of material is used when compared to other traditional welding processes.
PTA permits precise control of important weld parameters i.e. powder feed rates, gas flow rates, amperage, voltage, and heat input, ensuring a high degree of consistency from lot to lot. Controlled heat input ensures weld dilutions that can be controlled from 5-7% in most cases.
PTA produces deposits of a given alloy that are tougher and more corrosion resistant then counterparts laid down by GTAW or OFW processes. Weld deposits are characterized by very low levels of inclusions, oxides, and discontinuities.
PTA produces smooth deposits that significantly reduce the amount of post weld machining required.
PTA parameters can be adjusted to provide a variety of deposits in thicknesses from 1.2 to 2.5 mm (0.05 to 0.10 in.) or higher. These can be deposited by a single pass at a rate of 1 kg/h up to 13 kg/h depending upon the torch, powder and application.