Numerical and Experimental Investigations of Laser Metal Deposition (LMD) Using STS 316L

Park, Jaewoong; Kim, Jin-young; Ji, Inseo; Lee, S. H.

doi:10.3390/app10144874

Cited by 14 publications

(6 citation statements)

References 29 publications

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“…Microstructural tuning in order to tailor mechanical properties has great importance. It is evident from the extensive literature in metal AM [4][5][6][7][8][9][10][11][12][13][14]. Studies on grain morphology, melt pool solidification, solidification texture, the temperature gradient in the melt pool, the affect of cooling rate on morphology, and size of the microstructure are reported for AM [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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Base Plate Preheating Effect on Microstructure of 316L Stainless Steel Single Track Deposition by Directed Energy Deposition

et al. 2021

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The microstructural morphology in additive manufacturing (AM) has a significant influence on the building structure. High-energy concentric heat source scanning leads to rapid heating and cooling during material deposition. This results in a unique microstructure. The size and morphology of the microstructure have a strong directionality, which depends on laser power, scanning rate, melt pool fluid dynamics, and material thermal properties, etc. The grain structure significantly affects its resistance to solidification cracking and mechanical properties. Microstructure control is challenging for AM considering multiple process parameters. A preheating base plate has a significant influence on residual stress, defect-free AM structure, and it also minimizes thermal mismatch during the deposition. In the present work, a simple single track deposition experiment was designed to analyze base plate preheating on microstructure. The microstructural evolution at different preheating temperatures was studied in detail, keeping process parameters constant. The base plate was heated uniformly from an external heating source and set the stable desired temperature on the surface of the base plate before deposition. A single track was deposited on the base plate at room temperature and preheating temperatures of 200 °C, 300 °C, 400 °C, and 500 °C. Subsequently, the resulting microstructural morphologies were analyzed and compared. The microstructure was evaluated using electron backscattered diffraction (EBSD) imaging in the transverse and longitudinal sections. An increase in grain size area fraction was observed as the preheating temperature increased. Base plate preheating did not show influence on grain boundary misorientation. An increase in the deposition depth was noticed for higher base plate preheating temperatures. The results were convincing that grain morphology and columnar grain orientation can be tailored by base plate preheating.

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Section: Introductionmentioning

confidence: 99%

“…The cooling rate (G*R) while depositing a 3D solid structure varies over building direction [ 14 ]. A higher cooling rate was evident in the layers near the base plate.…”

Section: Introductionmentioning

confidence: 99%

Base Plate Preheating Effect on Microstructure of 316L Stainless Steel Single Track Deposition by Directed Energy Deposition

et al. 2021

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“…Large temperature gradients, with the base plate at room temperature and elastic compression, imposed by the material around the melt pool results in the development of large thermal stress. Supporting these results, Park et al, reported a decrease in a thermal gradient from the bottom to the top layers at three positions [ 47 ]. Higher temperature at the upper layers results in a lower degree of restriction by surrounding material (beneath layer).…”

Section: Resultsmentioning

confidence: 58%

Heat Source Modeling and Residual Stress Analysis for Metal Directed Energy Deposition Additive Manufacturing

et al. 2022

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The advancement in additive manufacturing encourages the development of simplified tools for deep and swift research of the technology. Several approaches were developed to reduce the complexity of multi-track modeling for additive manufacturing. In the present work, a simple heat source model called concentrated heat source was evaluated for single- and multi-track deposition for directed energy deposition. The concentrated heat source model was compared with the widely accepted Goldak heat source model. The concentrated heat source does not require melt pool dimension measurement for thermal model simulation. Thus, it reduces the considerable time for preprocessing. The shape of the melt pool and temperature contour around the heat source was analyzed for single-track deposition. A good agreement was noticed for the concentrated heat source model melt pool, with an experimentally determined melt pool, using an optical microscope. Two heat source models were applied to multi-track 3D solid structure thermo-mechanical simulation. The results of the two models, for thermal history and residual stress, were compared with experimentally determined data. A good agreement was found for both models. The concentrated heat source model reported less than the half the computational time required for the Goldak model. The validated model, for 3D solid structure thermo-mechanical simulation, was used to analyze thermal stress evolution during the deposition process. The material deposition on the base plate at room temperature results in lower peak temperatures in the layers near the base plate. Consequently, the higher thermal stress in the layers near the base plate was found, compared to the upper layers during the deposition process.

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“…The reason for the shape of this graph in Figure 6f results from the different increments between G and R in increasing the layers of the deposit, as shown in Figure 5. In other words, the decreasing rate of R is less than that of G. According to the previous study, the boundary of the G/R in which the columnar dendrite develops is 10-10 2 • C•s/mm 2 [25,26], and the boundary of the equiaxed is at less than ~10 • C•s/mm 2 [27]. In this study, the G/R values in each layer ranged from 18 to 33 • C•s/mm 2 , thereby distributed in the columnar dendritic region, as shown in Figure 6f.…”

Section: Additive Manufacturing Guideline Using Solidification Mapmentioning

confidence: 85%

CMT-Based Wire Arc Additive Manufacturing Using 316L Stainless Steel (2): Solidification Map of the Multilayer Deposit

Park

Lee

2021

Metals

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This study aimed to suggest a solidification map based on the solidification parameters G and R of each layer in the multilayer deposition for the investigation of heat accumulation on the deposit. Through the solidification map, the appropriate solidification conditions of the microstructure were determined. In order to investigate the solidification parameters, the temperature profile of the deposit was experimentally acquired during deposition. A simulation model reflecting the characteristics of the deposition process was developed and verified. The solidification parameters from the simulation model and the microstructure from experiments were correlated. Based on the analysis, a solidification map of 316L SS processed with CMT-WAAM process was derived, which is suggested as a guide for controlling and predicting the morphology of the microstructure in the deposit.

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Numerical and Experimental Investigations of Laser Metal Deposition (LMD) Using STS 316L

Cited by 14 publications

References 29 publications

Base Plate Preheating Effect on Microstructure of 316L Stainless Steel Single Track Deposition by Directed Energy Deposition

Base Plate Preheating Effect on Microstructure of 316L Stainless Steel Single Track Deposition by Directed Energy Deposition

Heat Source Modeling and Residual Stress Analysis for Metal Directed Energy Deposition Additive Manufacturing

CMT-Based Wire Arc Additive Manufacturing Using 316L Stainless Steel (2): Solidification Map of the Multilayer Deposit

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