scholarly journals Erratum: “Material Characterization of NiTi Based Memory Alloys Fabricated by the Laser Direct Metal Deposition Process” [Journal of Manufacturing Science and Engineering, 2006, 128(3), pp. 691–696]

2006 ◽  
Vol 128 (4) ◽  
pp. 1030-1030 ◽  
Author(s):  
K. Malukhin ◽  
K. Ehmann
Keyword(s):  
Material Characterization ◽  
Deposition Process ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Science And Engineering ◽  
Manufacturing Science ◽  
Process Journal

Material Characterization of NiTi Based Memory Alloys Fabricated by the Laser Direct Metal Deposition Process

2005 ◽  
Vol 128 (3) ◽  
pp. 691-696 ◽  
Author(s):  
K. Malukhin ◽  
K. Ehmann
Keyword(s):  
Shape Memory ◽  
Secondary Ion Mass Spectrometry ◽  
Profile Analysis ◽  
Deposition Process ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Scanning Calorimetry ◽  
Rp Process ◽  
Monolithic Structures

Shape memory alloys (SMAs) are used in a wide variety of applications including medical stents, couplings, actuators, jointless monolithic structures for actuation and manipulation, etc. Due to the SMA’s poor machinability it is advantageous to use rapid prototyping (RP) techniques for the manufacturing of SMA structures. However, the influence of the RP process on the properties of the SMA is not fully explored yet. A laser based direct metal deposition (DMD) RP process was used in this work to manufacture NiTi SMA samples and to investigate their physical properties using optical microscopy, differential scanning calorimetry (DSC), chemical analysis with secondary ion mass spectrometry (SIMS), and energy dispersive x-ray spectrometry (EDS) with a scanning electron microscope (SEM). DSC analysis has shown that the thermally treated parts possess smooth and pronounced reversible martensite-austenite transformation peaks that are the prerequisite for the shape memory effect (SME) in SMAs. DSC has also shown that quenching affects the peaks. The density of the produced parts was close to the theoretical density of the material as determined by porosity measurements. Finally, SIMS depth profile analysis has shown very low amounts of contamination in the material manufactured by DMD. The major conclusion is that the DMD RP process can be used to manufacture high-quality SMA structures from SMA powders.

Experimental and Numerical Analysis of the Powder Flow in a Multi-Channel Coaxial Nozzle of a Direct Metal Deposition System

2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Piyush Pant ◽  
Dipankar Chatterjee ◽  
Sudip Kumar Samanta ◽  
Aditya Kumar Lohar
Keyword(s):  
Gas Flow ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Deposition Process ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Powder Flow ◽  
Coaxial Nozzle ◽  
Proposed Model ◽  
Blown Powder

Abstract The work explores the powder transport process, using numerical simulation to address the dynamics of the powder flow in an in-house built multi-channel coaxial nozzle of a direct metal deposition (DMD) system. The fluid turbulence is handled by the standard k–ɛ and k–ω turbulence models, and the results are compared in order to predict their suitability. An image-based technique using CMOS camera is adopted to determine the powder flow characteristics. The model is validated with the in-house experimental results and verified available results in the literature. The findings of this work confirms the application of the k–ω model for powder gas flow investigations in blown powder additive manufacturing (AM) processes due to its better predictive capability. The proposed model will assist in simulating the direct metal deposition process.

Surface Finish Issues after Direct Metal Deposition

2012 ◽  
Vol 706-709 ◽  
pp. 228-233 ◽  
Author(s):  
P. Peyre ◽  
M. Gharbi ◽  
C. Gorny ◽  
M. Carin ◽  
S. Morville ◽  
...  
Keyword(s):  
Surface Finish ◽  
Experimental Tests ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Physical Mechanisms ◽  
Melt Pool ◽  
3D Profilometry ◽  
Surface Finishes ◽  
3D Shapes

Derived from laser cladding, the Direct Metal Deposition (DMD) laser process, is based upon a laser beam – projected powder interaction, and allows manufacturing complex 3D shapes much faster than conventional processes. However, the surface finish remains critical, and DMD parts usually necessitate post-machining steps. In this context, the focus of our work was: (1) to understand the physical mechanisms responsible for deleterious surface finishes, (2) to propose different experimental solutions for improving surface finish. Our experimental approach is based upon: (1) adequate modifications of the DMD conditions (gas shielding, laser conditions, coaxial or off-axis nozzles), (2) a characterization of laser-powder-melt-pool interactions using fast camera analysis, (3) a precise check of surface aspects using 3D profilometry, SEM, (4) preliminary thermo-convective simulations to understand melt-pool hydrodynamics. Most of the experimental tests were carried out on a Ti6Al4V titanium alloy, widely investigated already. Results confirm that surface degradation depends on two aspects: the sticking of non-melted or partially melted particles on the free surfaces, and the formation of menisci with more or less pronounced curvature radii. Among other aspects, a reduction of layer thickness and an increase of melt-pool volumes to favor re-melting processes are shown to have a beneficial effect on roughness parameters.

scholarly journals Influence of a pulsed laser regime on surface finish induced by the direct metal deposition process on a Ti64 alloy

2014 ◽  
Vol 214 (2) ◽  
pp. 485-495 ◽  
Author(s):  
Myriam Gharbi ◽  
Patrice Peyre ◽  
Cyril Gorny ◽  
Muriel Carin ◽  
Simon Morville ◽  
...  
Keyword(s):  
Surface Finish ◽  
Pulsed Laser ◽  
Deposition Process ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Ti64 Alloy
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