Stress-Strain Behavior of an Aluminum Alloy under Transient Strain Rates

The objective of the study is to investigate the material behavior of aluminum alloy under varying (non-constant) strain rate loading and predict their behavior.Approved for public release; distribution is unlimited

Stress-Strain Behavior of an Aluminum Alloy under Transient Strain Rates

Research ProjectThe objective of the study is to investigate the material behavior of aluminum alloy under varying (non-constant) strain rate loading and predict their behavior

Corrosion of femtosecond laser surface textured aluminium alloy

The article of record may be found at https://doi.org/10.1080/1478422X.2017.1348090With superhydrophobic properties being extended to a variety of metallic substrates through the process of ablation due to femtosecond laser surface processing (FLSP), it is important to understand corrosion behaviour of such a processed material. The material was tested through the use of an accelerated corrosion fog chamber using both treated and untreated aluminium alloy samples. During the accelerated corrosion testing, the FLSP-treated sample suffered from pitting corrosion at a rate faster than the untreated sample, effectively removing the surface treatment. While there are significant hydrodynamic benefits to this material, the elevated corrosion rates raise concerns about the resiliency of this surface treatment

Corrosion of femtosecond laser surface textured aluminium alloy

The article of record may be found at http://dx.doi.org/10.1080/1478422X.2017.1348090With superhydrophobic properties being extended to a variety of metallic substrates through the process of ablation due to femtosecond laser surface processing (FLSP), it is important to understand corrosion behaviour of such a processed material. The material was tested through the use of an accelerated corrosion fog chamber using both treated and untreated aluminium alloy samples. During the accelerated corrosion testing, the FLSP-treated sample suffered from pitting corrosion at a rate faster than the untreated sample, effectively removing the surface treatment. While there are significant hydrodynamic benefits to this material, the elevated corrosion rates raise concerns about the resiliency of this surface treatment.This research was sponsored by Office of Naval Researc

Direct manufacturing of CubeSat using 3-D digital printer and determination of its mechanical properties

Contract number: 11-F836.Approved for public release; distribution is unlimited

Effect of high energy ball milling on spherical metallic powder particulates for additive manufacturing

The article of record as published may be found at https://doi.org/10.1080/02726351.2021.1876192Properties, such as morphology, particle size, and hardness affect the ability of a powder to flow and bond to a surface in additive manufacturing (AM) applications. The effects of high energy ball milling on spherical copper and stainless steel powders were evaluated. Morphology of both stainless steel and copper powders, quantifiable by aspect ratio, showed larger changes due to ball-to-powder ratio (BPR, 2:1–1:10) compared to the total milling time (2–60min). Hardness of copper increased from 53 HV0.01 in the as-received condition to 96 HV0.01 after milling for 60min with a BPR of 1:1 or 2:1. Hardness of steel increased from 336 HV0.01 in the as-received condition to 523 HV0.01 after milling for 60min with a BPR of 2:1. Hardness of both powders was insensitive to milling times at low BPR (1:10). At high BPR (2:1), hardness of steel increases after just 2min of milling, while Cu changed significantly only after 60min. Hardness was influenced more by BPR than by milling time. It is shown that a broad range of milling parameters exist where metallic powders can be processed with minimal changes to their morphology, while controlling for hardness.The Hartnell College and California State University at Monterey Bay for supporting and organizing the Hartnell Community College Catalyst (3C) programs which enabled T. Hanneman and A. Gonzalez-Perez to conduct research at NPS during the summer of 2019.NPS Foundation SEED programNPS Research Initiation Progra

Effects of Environmental Factors on Additive Manufactured Materials

N4 - Materials Readiness and LogisticsNPS-19-N180-ANSETTI Project ID N-0094-1

Mechanical Properties of 3D-Printed Maraging Steel Induced by Environmental Exposure

The article of record as published may be found at https://doi.org/doi:10.3390/met10020218Changes in the mechanical properties of selective laser melted maraging steel 300 induced by exposure to a simulated marine environment were investigated. Maraging steel samples were printed in three orientations: vertical (V), 45◦ (45), and horizontal (H) relative to the print bed. These were tested as-printed or after heat-treatment (490 ◦C, 600 ◦C, or 900 ◦C). One set of specimens were exposed in a salt spray chamber for 500 h and then compared to unexposed samples. Environmental attack induced changes in the microstructural features and composition were analyzed by scanning electron microscopy and energy dispersive spectroscopy respectively. Samples printed in the H and 45◦ directions exhibited higher tensile strength than those printed in the V direction. Corrosion induced reduction in strength and hardness was more severe in specimens heat-treated between 480 ◦C and 600 ◦C versus as-printed samples. The greatest decrease in tensile strength was observed for the 45◦-printed heat-treated samples after exposure. A comparison between additive and subtractive manufactured maraging steel is presented.This research was funded by the Naval Postgraduate School through the Naval Research Program, grants NPS-19-M283-A and NPS-19-N180-A.This research was funded by the Naval Postgraduate School through the Naval Research Program, grants NPS-19-M283-A and NPS-19-N180-A

Evaluation of Mechanical Properties of 3-D Printed Maraging Steel

Marine Corps Logistics CommandNPS-19-M283

Mechanical Properties of 3D-Printed Maraging Steel Induced by Environmental Exposure

Changes in the mechanical properties of selective laser melted maraging steel 300 induced by exposure to a simulated marine environment were investigated. Maraging steel samples were printed in three orientations: vertical (V), 45° (45), and horizontal (H) relative to the print bed. These were tested as-printed or after heat-treatment (490 °C, 600 °C, or 900 °C). One set of specimens were exposed in a salt spray chamber for 500 h and then compared to unexposed samples. Environmental attack induced changes in the microstructural features and composition were analyzed by scanning electron microscopy and energy dispersive spectroscopy respectively. Samples printed in the H and 45° directions exhibited higher tensile strength than those printed in the V direction. Corrosion induced reduction in strength and hardness was more severe in specimens heat-treated between 480 °C and 600 °C versus as-printed samples. The greatest decrease in tensile strength was observed for the 45°-printed heat-treated samples after exposure. A comparison between additive and subtractive manufactured maraging steel is presented