Effect of scan length on the thermal and structural revolution of pure tantalum during selective laser melting: a simulation study

Abstract As a refractory metal with excellent biocompatibility and high temperature resistance, the conventional fabrication of pure tantalum (Ta) is challenging, and selective laser melting (SLM) has emerged as a promising alternative. In this study, the effect of scan length (2–10 mm) on Ta thin-walled components is investigated by means of a three-dimensional thermal-structural coupled finite element model incorporating a simplified Gaussian heat source and temperature-dependent material properties. The results validated with existing literature indicate that, owing to its high thermal conductivity, tantalum exhibits a near-circular molten pool with an aspect ratio of only approximately 1.29 during the SLM process, which is unlike other alloys such as Ti6Al4V which form teardrop-shaped molten pools. As the scan length increases, the secondary peak temperatures at various positions decrease monotonically while remaining below the melting point (3290 K). Short scan lengths (2–6 mm) effectively alleviate compressive stress in the Y and Z directions, whereas long scan lengths (>6 mm) reduce tensile stress. As the scan length decreases from 6 mm to 2 mm, the compressive stresses at Node 2 in the Y- and Z-directions decrease from 350 MPa to 284 MPa and from 885 MPa to 209 MPa, respectively. Compared with the case of a 2 mm scan length, the tensile stresses at Node 2 in all three directions each decrease with the longer scan lengths of 6–10 mm by more than 40 MPa. Overall, an optimal scan length of 6 mm was found. This study provides data support for optimizing the SLM process parameters of pure tantalum thin-walled components. It is recommended that a segmented scanning strategy be adopted in practical production to control the scan length.