Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore
doi:10.3850/978-981-18-6021-8_OR-01-0241
A Study on the Effects of the Deposition Path on Thermo-mechanical Characteristics for the Case of Gridur6 Deposited on a Thin AISI4140 Substrate Using an LMD Process
1Department of Mechanical Engineering, CHOSUN University, 309 Pilmunde-Ro, Dong-gu, Gwangju, 61452, South Korea
2DN Solutions Inc., T Tower, 30 Sowol-Ro 2 Gil, Jung-gu, Seoul, 04637, South Korea
ABSTRACT
The laser metal deposition (LMD) process is one of directed energy deposition (DED) processes. The deposited region is formed by repetition of melting and solidification of the feeding powder on the substrate and the previous layer for the case of the DED process. A typical cooling rate of the DED process lies in the range of 103-105/s. The rapid temperature change causes an excessive residual stress in the vicinity of the deposited region and a large deformation of the fabricated part. The distribution and the history of the temperature are greatly dependent on the deposition path, dwell time, interlayer time, etc. The objective of this paper is to investigate the effects of the deposition path on thermo-mechanical characteristics for the case of Gridur6 (G6) deposited on a thin AISI4140 substrate using the LMD process. In order to estimate temperature and residual stress distribution for different times, a three-dimensional non-linear finite element analysis (FEA) model is developed. The substrate is designed to be a cantilever beam structure. The deposited region with a rectangular cross-section is fabricated from the deposition of G6 powders on AISI4140 substrate. Characteristic dimensions of the deposited bead are obtained from the results of the experiments. The dwell time between successive paths and the inter-layer time between successive layers are estimated from the investigation of the movement of the deposition head. The laser is assumed to be a three-dimensional heat flux with the penetration depth. The distribution of the laser intensity in a plane is assumed as a Gaussian distribution. An equivalent heat loss model, including the forced convection by shielding gas and the radiation, and the heat sink model are applied to top surface of the specimen and the clamped region of the specimen by the fixture, respectively. The natural convection, the forced convection by the fume and the radiation are assigned to bottom and side surfaces. The clamped condition is applied to one end region of the specimen. Temperature dependent thermo-mechanical properties considering phase changes are estimated from JmatPro V12. The FEA was carried out by a commercial software SYSWELD V16. Through comparison of the results of experiments and those of FEAs from viewpoints of HAZ formation and temperature history, a proper FE model is obtained. Using the results of the FEAs, the influence of the deposition path on temperature, residual stress and displacement distributions for different times are investigated. In addition, the effects of the deposition path on the deformation and the warpage characteristics are examined. Finally, a suitable deposition path is proposed.
Keywords: Laser Metal Deposition, Deposition Path, Thermo-mechanical Characteristics, Finite Element Analysis
1Department of Mechanical Engineering, CHOSUN University, 309 Pilmunde-Ro, Dong-gu, Gwangju, 61452, South Korea
2DN Solutions Inc., T Tower, 30 Sowol-Ro 2 Gil, Jung-gu, Seoul, 04637, South Korea
ABSTRACT
The laser metal deposition (LMD) process is one of directed energy deposition (DED) processes. The deposited region is formed by repetition of melting and solidification of the feeding powder on the substrate and the previous layer for the case of the DED process. A typical cooling rate of the DED process lies in the range of 103-105/s. The rapid temperature change causes an excessive residual stress in the vicinity of the deposited region and a large deformation of the fabricated part. The distribution and the history of the temperature are greatly dependent on the deposition path, dwell time, interlayer time, etc. The objective of this paper is to investigate the effects of the deposition path on thermo-mechanical characteristics for the case of Gridur6 (G6) deposited on a thin AISI4140 substrate using the LMD process. In order to estimate temperature and residual stress distribution for different times, a three-dimensional non-linear finite element analysis (FEA) model is developed. The substrate is designed to be a cantilever beam structure. The deposited region with a rectangular cross-section is fabricated from the deposition of G6 powders on AISI4140 substrate. Characteristic dimensions of the deposited bead are obtained from the results of the experiments. The dwell time between successive paths and the inter-layer time between successive layers are estimated from the investigation of the movement of the deposition head. The laser is assumed to be a three-dimensional heat flux with the penetration depth. The distribution of the laser intensity in a plane is assumed as a Gaussian distribution. An equivalent heat loss model, including the forced convection by shielding gas and the radiation, and the heat sink model are applied to top surface of the specimen and the clamped region of the specimen by the fixture, respectively. The natural convection, the forced convection by the fume and the radiation are assigned to bottom and side surfaces. The clamped condition is applied to one end region of the specimen. Temperature dependent thermo-mechanical properties considering phase changes are estimated from JmatPro V12. The FEA was carried out by a commercial software SYSWELD V16. Through comparison of the results of experiments and those of FEAs from viewpoints of HAZ formation and temperature history, a proper FE model is obtained. Using the results of the FEAs, the influence of the deposition path on temperature, residual stress and displacement distributions for different times are investigated. In addition, the effects of the deposition path on the deformation and the warpage characteristics are examined. Finally, a suitable deposition path is proposed.
Keywords: Laser Metal Deposition, Deposition Path, Thermo-mechanical Characteristics, Finite Element Analysis
