The new additive manufacturing techniques, such as 3D printing, allow you to create metal parts with varied shapes facilitating the prototyping of different components. However, do not exists many knowledge about the microstructure of printed pieces and on its mechanical properties. In this paper, steel parts obtained by the traditional process of casting and machining were compared with obtained by 3D printing pieces, both of the same chemical composition. For this, we used x-ray microtomography, this technology that allows non-destructive analysis, and optical microscopy to characterize the microstructure. Mechanical tests such as tensile test and hardness were employed for the analysis of mechanical properties of materials due to different manufacturing process. Through these analyzes it was concluded that the printed part has a higher tensile strength compared with the melt, this difference is due to a manufacturing process explained by formation of different parts of the microstructure.