Efficient Multi-Material and High Deposition Coating including Additive Manufacturing by Tandem Plasma Transferred Arc Welding for Functionally Graded Structures

Abstract

Market demands coating processes with high-performance, high reliability, high flexibility for processing of complex geometries and multi-material depositions, as well as increased deposition rates. The systematic coupling of two plasma transferred arc welding systems that interact in the same melt pool to form a tandem Plasma Transferred Arc (PTA) system accomplishes these tasks. Previous research has shown that the deposition rate with the tandem PTA method reaches 240 percent when comparing to the conventional single torch PTA method. Within one layer, up to four different powders and powder fractions can be combined at the same time. This allows for the creation of multi-material coatings that are suitable for sustaining high mechanical loads and wear- and temperature-resistant surfaces by use of tungsten carbides (WC). This study examines and analyzes defined functionally graded structures made from super duplex steel 1.4410 and corrosion resistant austenitic steel 1.4404. The mechanical-chemical properties of the tandem PTA system can be precisely controlled by changing the powder feeding positions. Furthermore, an additively manufactured specimen from previous studies is examined and evaluated. A direct comparison with conventional single torch PTA was performed to demonstrate the benefits of the tandem PTA-process.