Process Planning for Additive Manufacturing of Metallic Functionally Graded Materials
Open Access
- Author:
- Lia, Frederick
- Graduate Program:
- Industrial Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 09, 2022
- Committee Members:
- Zi-Kui Liu, Outside Unit & Field Member
Timothy Simpson, Major & Minor Field Member
Richard Martukanitz, Co-Chair & Dissertation Advisor
Robert Voigt, Major Field Member
Steven Landry, Program Head/Chair
Jay Keist, Outside Field Member
Sanjay Joshi, Co-Chair & Dissertation Advisor - Keywords:
- Additive manufacturing
laser deposition
SS 316L
NAB
analytical model
and melt pool dimensions
Additive manufacturing
laser deposition
SS 316L
NAB
analytical model
and melt pool dimensions and dilutions - Abstract:
- A decision making algorithm for process planning for laser-based directed energy deposition (DED) additive manufacturing (AM) to produce metallic functionally graded materials (FGM) components is proposed in this research. The challenge of processing and modeling the FGM component depends on the local compositions throughout the gradient and directly impact the microstructure development and material properties. The objective in utilizing the algorithm was to minimize the brittle intermetallic phases within the gradient transition regions of the FGM component, which could be caused by dilution effects occurring at the locations of the gradient transition regions during the laser deposition process. Two models were developed for the algorithm: an energy balance model and a dilution model. The energy balance model was a combination of an analytical method and empirical model, which predicted the dimensions of the deposit track, such as: melt pool width, deposit height, and melt pool penetration depth. The dilution model utilized the track dimensions from the energy balance model to predict the chemical compositions of the FGM gradients. Two FGM systems were explored to validate the developed models. A material system based on AISI stainless steel 316L (SS 316L) and nickel aluminum bronze (NAB) system was used to verify the consistency and accuracy of the energy balance model and the dilution model. The stainless steel alloy 316L and Inconel 625® FGM system was also used to demonstrate the capability of the models for producing FGM material with alloys having practical applications. The energy balance model relied on critical laser deposition process parameters, such as laser power, laser scan speed, and laser spot size; as well as material physical properties such as, thermal properties and two empirical variables: powder capture efficiency, Pe, and melt pool aspect ratio, r. This approach for the energy balance model was required to predict the FGM compositions as a function of processing parameters and condition, which would provide predictive capabilities quickly and less expensively as a control algorithm. The energy balance model was utilized to estimate deposit track dimensions and showed strong agreement with the experimentally measured results for the SS 316L and NAB FGM system. The dilution model successfully predicted the gradient compositions and showed correlation with electron diffraction spectroscopy (EDS) data obtained from measured track dimensions and the energy balance model predictions for track dimensions. The dilution model was also used to investigate the gradient transitions along the vertical and horizontal directions for both SS 316L and NAB FGM and SS 316L and Inconel 625® FGM systems, and this analysis indicated that the model was capable of accurately predicting concentrations within these regions.