**5. Conclusion**

Before heat treatment, Ti–6Al–4V specimen has a basket type of microstructure (see **Figure 9**). After annealing, some α‐ and β‐phases stood at grain boundaries, initial martensite of needles enlarged in size, borders become more rounded compared to the sample without annealing.

The study of fractography of fracture surfaces of impact strength specimens showed some

**Figure 10.** Fractography of Inconel 718 (a, c) and Ti–6Al–4V (b, d) specimen fracture surfaces before (a, b) and after

imperfections of SLM process (see **Figure 10**).

232 New Trends in 3D Printing

heat treatment (c, d).

In this chapter, a review of powder production methods, characterization of metal powder with focus on the application and technologies in additive manufacture, which use metal powders as initial material, was presented. The researches in the field of microstructure and properties of samples, which are produced by selective laser melting, also were presented.

The main technologies for mass production of metal powder with spherical or spheroidal particle shape relate to the atomization methods (dispersion of metal melt). However, the other technologies may cost cheaper because of using the waste products (chips, shaving, flakes etc.) as raw materials and the approach of receiving of powders with subsequent plasma spher‐ oidization looks very promising, especially for developing of new alloys that impossible to produce by melting technologies.

Some standardized methods for the characterization of metal powders help to understand differences between powders produced by different technologies, and also they may be used for fixation the evolution of powder properties after reusing in additive manufacturing. Developing of special methods for checking the properties of powder gives an additional information about behavior of powder in AM systems, may significantly expand a range of applicable powder in AM, and allows to better understand requirements for powder for using them in additive manufacturing.

There exist three main technologies for additive manufacturing from metal powders: powder bed fusion, directed energy deposition, and binder jetting. Every of them has advantages and disadvantages, and at this moment, they all are in intensive developing phase all around the world. The main advantage of all types of additive manufacturing is a possibility to produce parts with design that impossible to manufacture by traditional technologies. It is necessary to conduct huge researches and tests to be sure that produced by AM parts have reliable and repeatable properties.
