WAAM (Wire and Arc Additive Manufacturing) is becoming an increasingly popular method to produce components from metals which are usually not so suitable for conventional production methods. One of the good examples is duplex stainless steels (DSS), which are quite complex for welding and machining. Excessive ferrite amount is a common problem for them and controlling an interlayer temperature could offer a solution. However, using too low interlayer temperature will slow down the whole process and compromise one of the WAAM’s main advantages - the high productivity. Aim of this study is to find the relationship between interlayer temperature and process duration and to determine the influence of the interlayer temperature on product structure and other properties. Three samples (walls) were made using different interlayer temperatures (50 °C, 100 °C and 150 °C) and they were tested to analyze their surface texture, chemical composition, ferrite amount, the appearance of porosity and the hardness. Ferrite amount was higher and there was more porosity on lower interlayer temperatures, while there is no significant difference between surface texture and chemical composition for the samples. Considering the fact that higher interlayer temperatures provide a faster process, they should be preferred to produce duplex stainless steel products.
Growth and evolution of the modern industries always bring the need for developing and researching the new technologies and the novel production methods. In the latest years, AM (additive manufacturing) technologies caught the eye of researchers, thanks to their possibility to produce the complex geometries with more design freedom, high productivity and less waste. However, the majority of these technologies are still limited to produce only the prototypes and they often use only polymer materials. The appearance of the WAAM technology and its development could be a potential solution for some problems and challenges which are the main drawbacks for conventional AM technologies, like excessive porosity, limited choice of the materials, low mechanical properties, etc.
An experiment was carried out in Welding Laboratory at the Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb. WAAM system was constructed particularly for this study, by combining welding robotic hand OTC Almega AX-V6 (six axes of freedom) with MIG welding machine DP-400 (conventional power source) and wire feeder CM-7401 (all three devices were supplied by Daihen Varstroj). Welding wire used as a feedstock was 1.2 mm diameter duplex stainless steel solid wire Avesta 2205 (Voestalpine Böhler Welding, designed for welding DSS grade 2205 or 1.4462). Shielding gas mixture was prepared by Messer Croatia Plin, containing 98% Ar and 2% N2. The substrate was austenitic (grade 304 or 1.4301) stainless steel plate, with dimensions 300x150x8 mm.
As a result of this study, conclusions are as following.