Eliminating the crack of laser 3D printed functionally graded material from TA15 to Inconel718 by base preheating

High quality manufacturing the functionally graded material (FGM) from TA15 to Inconel718 (IN718) has wide application prospects in the aerospace field. However, the crack always can be found in linear gradient structure of the FGM manufactured by laser 3D printing. In the present study, the crack-free FGM was fabricated by laser 3D printing via base preheating. The microstructure and mechanical properties were analyzed in detail to evaluate the mechanism that the preheating process prevented the formation of the crack. The microstructure of the unpreheated FGM presented that the crack mainly formed in the region between 60% and 80% IN718. Obviously, no cracks formed in the preheated sample because base preheating process made the level of internal stress to be below the yield strength. The tensile strength of the FGM with the preheating was 207 MPa. This is a noticeable improvement compared with that fabricated without the preheating, which could not be measured due to the formation of the crack. These research results indicate that the base preheating process can effectively prevent the formation of the crack during laser 3D printing FGMs from Ti- to Ni-based alloys.