Additive manufacturing is a groundbreaking manufacturing method that enables nearly lossless processing of high-value materials and produces complex components with a level of flexibility that traditional methods cannot achieve. Wire arc additive manufacturing (WAAM), utilizing a conventional welding process such as gas metal arc welding, is one of the most efficient additive manufacturing technologies. The WAAM process is fully automated and guided by CAD/CAM systems on robotic or CNC welding platforms. This paper explores the fundamental concepts and metallurgical characteristics of WAAM. It focuses primarily on the mechanical properties of printed sample structures made from P91, X20, and alloys 625 and 718 wire feedstock. The study particularly addresses the anisotropy of mechanical properties through both short-term and long-term testing, comparing these results to materials processed using conventional methods.