Laser directed energy deposition of water-atomized iron powder: Process optimization and microstructure of single-tracks

Although iron, as a basic metal, has been used commonly in industry, the use of an advanced technique such as additive manufacturing (AM) may offer more opportunities. For example, AM of iron-based powders for functional prototypes would likely be beneficial in the automotive industry, since this industry has commonly used iron alloys for prototypes and functional parts produced by conventional technologies. This paper presents Laser Directed Energy Deposition through Powder Feeding (LDED-PF), a class of AM, of irregular-shape inexpensive water-atomized iron powder. A setup with a lateral powder-fed nozzle was deployed to deposit single-tracks using different processing parameters. The experimental design and optimization model were implemented based on the response surface methodology when the regression model was tested by the variance analysis. The desirability function was used to identify the optimal processing window to obtain the single-tracks with a minimized dilution and a maximized bead height and high powder efficiency. The results showed that the geometrical characteristics of the single-tracks have a high dependency on the key LDED-PF processing parameters. In addition, the microstructure and phase composition of the single-tracks were investigated by SEM and EDS, revealing that the deposits were generally composed of the ferrite phase.