Influence of laser power in direct laser deposition on the proportion of ferrite and austenite in duplex steel SAF2507

Abstract

This work focuses on the effect of laser power on the proportion of austenite and ferrite in duplex steel SAF 2507. Duplex steels combine the advantages of ferritic and austenitic steels, preferably with an optimal proportion of austenite and ferrite. The effect of laser beam power in direct laser deposition on this proportion of microstructure constituents was studied. The proportion also has an impact on mechanical and corrosion properties, which are essential for this type of steel. Duplex steels are often used in corrosive environments and their mechanical properties and corrosion resistance depend on the proportion of austenite and ferrite. Direct laser deposition (DED) was used for making samples. DED operates on the principle of laser melting of a powder which is carried by the shielding gas into a nozzle. This technology can be used as an additive manufacturing process as well as for surface repairs and modification of components. The samples in this experimental study were printed using several different fixed outputs and the same intervals. One sample was printed using the machine’s automatic mode. Microstructural analysis was performed using EBSD, EDS and light microscopy. The proportion of austenite and ferrite was measured by X-ray diffraction (XRD analysis). The differences in the proportion of ferrite and austenite were minimal, on the order of several percentage points.