Distortion prediction and geometry compensation using modified inherent strain method for additively manufactured Ti-6Al-4V

Abstract

A laser powder bed fusion (LPBF) process enables the production of intricate geometries for specialized applications demanding high precision in various industries such as medical, aerospace, and automotive. However, substantial thermal gradients in the LPBF process often led to residual stress, resulting in noticeable distortion and potential part failure of fabricated parts. Therefore, the present work investigates distortion prediction and geometry compensation for additively manufactured Ti-6Al-4V components employing a modified inherent strain method. Unlike previous studies, both relaxed distortions from substrate removal and as-built distortion are considered, incorporating specimens with varying geometrical features such as height and thickness. The study aims to comprehensively evaluate the efficacy of the modified inherent strain approach in capturing distortion under different build scenarios and assess the effectiveness of geometrical compensation in minimizing as-built distortion. Overall, we found that numerical models effectively capture relaxed deflection for samples with varied geometrical features, showing reasonable agreement with experimental results. Additionally, the as-built distortion of samples with thicknesses of 5 mm and above is well-predicted, with an average deviation between numerical and experimental results of approximately 0.125 mm. Nonetheless, we noted the challenge in capturing out-of-plane distortion for thin wedges, suggesting avenues for future investigation. Furthermore, geometry compensation reduces maximum distortion from 0.68 to 0.28 mm and average distortion from 0.15 to 0.05 mm. Multiple iterations of compensation yield insignificant differences in distortion reduction, which suggests sufficient distortion alleviation from single compensation for geometries explored in the present work. Overall, the study provides valuable insights into distortion prediction and compensation strategies for additively manufactured Ti-6Al-4V components.