More Like this

1. Characterization of Additively Manufactured Metals from ADDERE Printing

   Foster, J. ; Kumpaty, S. ; Coen, L. ; Perkins, A. ; Gengler, M. ; Woida, S. ( November 2022 , ASME International Mechanical Engineering Congress and Exposition)

   IMECE2022-88299 Midwest Engineered Systems Inc. has created a novel laser wire metal deposition process, ADDere manufacturing. ADDere has a much higher deposition rate than powder bed fusion, making it ideal for large components. In this project, the mechanical properties of ADDere printed materials were tested and compared to typical values found in ASM publications to show the quality of materials manufactured by the ADDere printing process. A detailed material analysis was performed on samples made from Ti-6Al-4V and 17-4 PH stainless steel. This work builds upon an earlier study of samples made from 17-4 PH that were produced using a single direction pattern. In this project, the 17-4 PH samples were printed in a cross hatched pattern, and testing results were compared to existing data from single direction samples of the previous research. The Ti-6Al-4V samples were created in two builds. One using the uni-directional method and the other with the crossed pattern. Testing specimens were removed from the samples using a water jet cutter and further machined into ASTM tensile bars and metallurgic mounts to perform a thorough material evaluation. The Ti-6Al-4V sample met the expected values in the ASM literature, and the cross hatched 17-4 PH exhibited amore »higher hardness and better microstructure than the single direction samples from the previous work. It was also observed that when the Ti64 samples were manufactured in the cross hatched pattern, the properties indicated slight improvement and more homogeneity than those printed in single layer direction. The obtained results indicate that ADDere’s printing process can produce highly refined materials that are customizable with their expected uses. This work showcases an excellent industry collaboration of an undergraduate research experience.« less
2. Effect of Specimen Surface Area Size on Fatigue Strength of Additively Manufactured Ti-Al-4V Parts

   Pegues, Jonathan ; Roach, Michael ; Williamson, R. Scott ; Shamsaei, Nima ( August 2017 , 28th International Solid Freeform Fabrication Symposium - An Additive Manufacturing Conference)

   As additive manufacturing becomes an increasingly popular method for advanced manufacturing of components, there are many questions that need to be answered before these parts can be implemented for structural purposes. One of the most common concerns with additively manufactured parts is the reliability when subjected to cyclic loadings which has been shown to be highly sensitive to defects such as pores and lack of fusion between layers. It stands to reason that larger parts will inherently have more defects than smaller parts which may result in some sensitivity to surface area differences between these parts. In this research, Ti-6Al-4V specimens with various sizes were produced via a laser-based powder bed fusion method. Uniaxial fatigue tests based on ASTM standards were conducted to generate fatigue-life curves for comparison. Fractography on the fractured specimens was performed to distinguish failure mechanisms between specimen sets with different sizes.
3. Effects of Inter-Layer Time Interval on Temperature Gradients in Direct Laser Deposited Ti-6Al-4V

   Masoomi, M. ; Thompson, S.M. ; Shamsaei, N. ; Bian, L. ( August 2016 , Annual International Solid Freeform Fabrication Symposium)

   Parts fabricated via additive manufacturing (AM) methods are prone to experiencing high temperature gradients during manufacture resulting in internal residual stress formation. In the current study, a numerical model for predicting the temperature distribution and residual stress in Directed Energy Deposited (DED) Ti–6Al–4V parts is utilized for determining a relationship between local part temperature gradients with generated residual stress. Effects of time interval between successive layer deposits, as well as layer deposition itself, on the temperature gradient vector for the first and each layer is investigated. The numerical model is validated using thermographic measurements of Ti-6Al-4V specimens fabricated via Laser Engineered Net Shaping® (LENS), a blown-powder/laser-based DED method. Results demonstrate the heterogeneity in the part’s spatiotemporal temperature field, and support the fact that as the part number, or single part size or geometry, vary, the resultant residual stress due to temperature gradients will be impacted. As the time inter-layer time interval increases from 0 to 10 second, the temperature gradient magnitude in vicinity of the melt pool will increase slightly.
4. Contrasting the Role of Pores on the Stress State Dependent Fracture Behavior of Additively Manufactured Low and High Ductility Metals

   https://doi.org/10.3390/ma14133657  

   Wilson-Heid, Alexander E. ; Furton, Erik T. ; Beese, Allison M. ( July 2021 , Materials)

   This study investigates the disparate impact of internal pores on the fracture behavior of two metal alloys fabricated via laser powder bed fusion (L-PBF) additive manufacturing (AM)—316L stainless steel and Ti-6Al-4V. Data from mechanical tests over a range of stress states for dense samples and those with intentionally introduced penny-shaped pores of various diameters were used to contrast the combined impact of pore size and stress state on the fracture behavior of these two materials. The fracture data were used to calibrate and compare multiple fracture models (Mohr-Coulomb, Hosford-Coulomb, and maximum stress criteria), with results compared in equivalent stress (versus stress triaxiality and Lode angle) space, as well as in their conversions to equivalent strain space. For L-PBF 316L, the strain-based fracture models captured the stress state dependent failure behavior up to the largest pore size studied (2400 µm diameter, 16% cross-sectional area of gauge region), while for L-PBF Ti-6Al-4V, the stress-based fracture models better captured the change in failure behavior with pore size up to the largest pore size studied. This difference can be attributed to the relatively high ductility of 316L stainless steel, for which all samples underwent significant plastic deformation prior to failure, contrasted with the relativelymore »low ductility of Ti-6Al-4V, for which, with increasing pore size, the displacement to failure was dominated by elastic deformation.« less
5. Effects of Printing Layer Orientation on the High-Frequency Bending-Fatigue Life and Tensile Strength of Additively Manufactured 17-4 PH Stainless Steel

   https://doi.org/10.3390/ma16020469  

   Ghadimi, Hamed ; Jirandehi, Arash P. ; Nemati, Saber ; Ding, Huan ; Garbie, Abdelrahman ; Raush, Jonathan ; Zeng, Congyuan ; Guo, Shengmin ( January 2023 , Materials)

   In this paper, small blocks of 17-4 PH stainless steel were manufactured via extrusion-based bound powder extrusion (BPE)/atomic diffusion additive manufacturing (ADAM) technology in two different orientations. Ultrasonic bending-fatigue and uniaxial tensile tests were carried out on the test specimens prepared from the AM blocks. Specifically, a recently-introduced small-size specimen design is employed to carry out time-efficient fatigue tests. Based on the results of the testing, the stress–life (S-N) curves were created in the very high-cycle fatigue (VHCF) regime. The effects of the printing orientation on the fatigue life and tensile strength were discussed, supported by fractography taken from the specimens’ fracture surfaces. The findings of the tensile test and the fatigue test revealed that vertically-oriented test specimens had lower ductility and a shorter fatigue life than their horizontally-oriented counterparts. The resulting S-N curves were also compared against existing data in the open literature. It is concluded that the large-sized pores (which originated from the extrusion process) along the track boundaries strongly affect the fatigue life and elongation of the AM parts.