On the advances to obtain excellent and repeatable mechanical properties and build quality of LaserForm~R Ti gr23 (A) across whole build platform

摘要

Direct Metal Printing (DMP) or Laser Based Powder Bed Fusion (L-BPF) enables manufacturing of highly complex geometries which are used in a wide range of applications - healthcare to aerospace. Producing these products with excellent and consistent part quality in terms of density and mechanical properties is key. DMP ProX~R 320 machine has been used for over 10 years for this purpose. In this study, the key improvements made on the process stability for targeting consistent build quality across build platform and repeatability have been evaluated. The quality is assessed by determining the density, mechanical properties and surface roughness of direct metal printed LaserForm~R Ti gr23 (A). The main finding from the study is that the use of the optimized gas flow enables production of LaserForm~R Ti gr23 (A) with consistent and improved mechanical properties across the whole build platform. Moreover, there is no need any more for hot isostatic pressing to ensure good fatigue properties. The elongation strain to failure increased by 15 % to 20 %, which is 4-5 % higher than ASTM F3001 specifications. The axial fatigue limit (5x10~6 loading cycles) was 637 MPa (R=0.1), which is as good as or even better than annealed wrought Ti6Al4V.