Estimation method of Interpass time for the control of temperature during a directed energy deposition process of a Ti–6Al–4V planar layer

• Main Authors: Chua, Bih Lii, Ahn, Dong-Gyu
• Format: Article
• Language: English
• Published: MDPI 2020
• Subjects: HD9720-9975 Manufacturing industries; T55.4-60.8 Industrial engineering. Management engineering
• Online Access: https://eprints.ums.edu.my/id/eprint/42460/1/FULL%20TEXT.pdf; https://eprints.ums.edu.my/id/eprint/42460/; http://dx.doi.org/10.3390/ma13214935
• Institution: Universiti Malaysia Sabah

Directed energy deposition (DED) provides a promising additive manufacturing method to fabricate and repair large metallic parts. However, it may suffer from excessive heat accumulation due to a high build rate, particularly during a wire feeding-type DED process. The implementation of interpass time in between two depositions of beads plays an important process role to passively control the interpass temperature. In this study, a method to estimate the proper interpass time using regression analysis from heat transfer finite element analysis is proposed for maintaining the interpass temperature during a wire feeding-type DED deposition of a planar layer. The overlapping beads of a planar layer are estimated using a polygonal-shaped bead profile in the finite element model. From the estimated proper interpass time, a selected proper interpass time scheme (PITS) is suggested for practical implementation. The selected PITS is applied in a thermo-mechanical finite element model to evaluate the temperature distribution and its effects on the depth of the melt pool, the depth of the heat-affected zone (HAZ), displacement, and residual stresses. By comparing the predicted results with those using a constant interpass time scheme (CITS), the selected PITS shows better control in reducing the depths of the melt pool and HAZ without severely inducing large displacement and residual stresses.