scholarly journals Microstructure and Crystallographic Texture of Laser Additive Manufactured Nickel-Based Superalloys with Different Scanning Strategies

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 591
Author(s):  
Xingbo Liu ◽  
Hui Xiao ◽  
Wenjia Xiao ◽  
Lijun Song
Keyword(s):  
Additive Manufacturing ◽  
Epitaxial Growth ◽  
Crystallographic Texture ◽  
Continuous Wave ◽  
Flow Direction ◽  
Fiber Texture ◽  
Laves Phase ◽  
Solidification Structure ◽  
Columnar Grains ◽  
Scanning Strategies

Control of solidification structure and crystallographic texture during metal additive manufacturing is a challenging work which attracts the increasing interest of researchers. In the present work, two kinds of scanning strategies (i.e., single-directional scanning (SDS) and cross-directional scanning (CDS) were used to control the solidification structure and crystallographic texture during quasi-continuous-wave laser additive manufacturing (QCW-LAM) of Inconel 718. The results show that the solidification structure and texture are strongly dependent on scanning strategies. The SDS develops a typical fiber texture with unidirectional columnar grains, whereas the CDS develops a more random texture with a mixture of unidirectional and multidirectional grains. In addition, the SDS promotes the continuously epitaxial growth of columnar dendrites and results in the linearly distributed Laves phase particles, while the CDS leads to the alternately distributed Laves phase particles with chain-like morphology and discrete morphology. The changed stacking features of molten-pool boundary and the switched heat flow direction caused by different scanning strategies plays a crucial role on the epitaxial growth of dendrites and the final solidification structure of the fabricated parts.

Effects of Process Parameters on Morphologies and Microstructures of Laser Melting Deposited V-5Cr-5Ti Alloys

2018 ◽  
Vol 913 ◽  
pp. 227-234
Author(s):  
Lin Rui Bai ◽  
Guo Min Le ◽  
Jin Feng Li ◽  
Xue Liu ◽  
Xiu Yan Li
Keyword(s):  
Deposition Process ◽  
Fiber Texture ◽  
Thin Wall ◽  
Laser Melting ◽  
Thin Walls ◽  
Nuclear Systems ◽  
Columnar Grains ◽  
Deposition Duration ◽  
Scanning Strategies ◽  
Equiaxed Grains

V-Cr-Ti alloys are promising structural materials for future nuclear systems. In this study, a laser melting deposition process has been applied to the fabrications of V-5Cr-5Ti alloys. Laser powers of 1200W, 1400W and 1600W, scanning speeds of 400 mm/min and 600 mm/min, and scanning strategies of single directional scanning and dual directional scanning have been applied to investigate the effects on the morphologies and microstructures of formed individual deposits and thin walls. The dual directional scanning is favored for fabricating thin walls with regular shape, comparing to the single directional scanning. Microstructures of the deposits and walls consist of columnar grains and equiaxed grains. Due to the effects on temperature gradients, both the laser powers and deposition duration show significant effects on the microstructural evolutions of the thin wall samples. As the laser power and deposition duration increase, columnar to equiaxed transitions have been observed. The regions containing columnar grains and equiaxed grains have a <100> fiber texture and a random texture, respectively.

The electron beam freeform fabrication of NiTi shape memory alloys. Part I: Microstructure and physical–chemical behavior

2020 ◽  
pp. 146442072097505
Author(s):  
RPM Guimarães ◽  
F Pixner ◽  
G Trimmel ◽  
J Hobisch ◽  
T Rath ◽  
...  
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Nickel Titanium ◽  
Freeform Fabrication ◽  
Austenitic Transformation ◽  
Columnar Grains ◽  
One Step ◽  
Niti Shape Memory Alloys

Nickel–titanium alloys are the most widely used shape memory alloys due to their outstanding shape memory effect and superelasticity. Additive manufacturing has recently emerged in the fabrication of shape memory alloy but despite substantial advances in powder-based techniques, less attention has been focused on wire-based additive manufacturing. This work reports on the preliminary results for the process-related microstructural and phase transformation changes of Ni-rich nickel–titanium alloy additively manufactured by wire-based electron beam freeform fabrication. To study the feasibility of the process, a simple 10-layer stack structure was successfully built and characterized, exhibiting columnar grains and achieving one-step reversible martensitic–austenitic transformation, thus showing the potential of this additive manufacturing technique for processing shape memory alloys.

The effect of γ-fiber texture intensity of carbon steel substrate on zinc hetero-epitaxial growth

2006 ◽  
Vol 201 (6) ◽  
pp. 3116-3122 ◽  
Author(s):  
K. Raeissi ◽  
M.R. Bateni ◽  
A. Saatchi ◽  
M.A. Golozar ◽  
J.A. Szpunar
Keyword(s):  
Carbon Steel ◽  
Epitaxial Growth ◽  
Steel Substrate ◽  
Fiber Texture ◽  
Texture Intensity

scholarly journals Virtual Development of Process Parameters for Bulk Metallic Glass Formation in Laser-Based Powder Bed Fusion

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 450
Author(s):  
Johan Lindwall ◽  
Andreas Lundbäck ◽  
Jithin James Marattukalam ◽  
Anders Ericsson
Keyword(s):  
Additive Manufacturing ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Process Parameters ◽  
Glass Formation ◽  
Laser Power ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Scanning Strategies ◽  
Hatch Spacing

The development of process parameters and scanning strategies for bulk metallic glass formation during additive manufacturing is time-consuming and costly. It typically involves trials with varying settings and destructive testing to evaluate the final phase structure of the experimental samples. In this study, we present an alternative method by modelling to predict the influence of the process parameters on the crystalline phase evolution during laser-based powder bed fusion (PBF-LB). The methodology is demonstrated by performing simulations, varying the following parameters: laser power, hatch spacing and hatch length. The results are compared in terms of crystalline volume fraction, crystal number density and mean crystal radius after scanning five consecutive layers. The result from the simulation shows an identical trend for the predicted crystalline phase fraction compared to the experimental estimates. It is shown that a low laser power, large hatch spacing and long hatch lengths are beneficial for glass formation during PBF-LB. The absolute values show an offset though, over-predicted by the numerical model. The method can indicate favourable parameter settings and be a complementary tool in the development of scanning strategies and processing parameters for additive manufacturing of bulk metallic glass.

scholarly journals Control of Microstructure and Crystallographic Texture in Intermetallic Silicides by Additive Manufacturing Process

2019 ◽  
Vol 8 (3) ◽  
pp. 84-89
Author(s):  
Koji HAGIHARA ◽  
Takuya ISHIMOTO ◽  
Shi-Hai SUN ◽  
Takayoshi NAKANO
Keyword(s):  
Additive Manufacturing ◽  
Crystallographic Texture ◽  
Manufacturing Process

Magnetostrictive Fe-Ga Wires with Fiber Texture

2008 ◽  
Vol 1129 ◽  
Author(s):  
Shannon Patrick Farrell ◽  
Patti E. Quigley ◽  
Kyle J. Avery ◽  
Tim D. Hatchard ◽  
Stephanie E Flynn ◽  
...  
Keyword(s):  
Crystallographic Texture ◽  
Low Cost ◽  
Annealing Treatment ◽  
Cost Effective ◽  
Fiber Texture ◽  
Saturation Field ◽  
Energy Harvesters ◽  
Cost Effective Approach ◽  
Wire Method ◽  
Deformation Processes

AbstractRecently, low-cost processing approaches that produce textured thin bodies have engendered interest as cost-effective approaches for fabrication of magnetostrictive Fe-Ga alloys. In particular, wire-forming methods that strictly control the solidification direction could lead to some measure of crystallographic texture control. This is critical for development of large magnetostriction in polycrystals and for use of the alloys in actuators, sensors, energy harvesters and other systems. Magnetostrictive Fe-Ga wires have been prepared using an innovative cost-effective approach – based on the Taylor wire method – that combines rapid solidification and deformation processes. The procedure for making magnetostrictive wires is discussed and the wires are evaluated in terms of microstructure, crystallographic texture and magnetostriction. Results show that the Taylor-based approach is an effective and versatile means to draw 1-3 mm diameter textured Fe-Ga wire. Experimentation on the influence of drawing technique and quench conditions on texture development resulted with production of a strong <100> fiber texture in the Fe-Ga wire. Magnetostriction measurements, in the absence of prestress, indicated a maximum magnetostriction of ˜165 ppm in a saturation field of less than 200 mTesla. This is considered a significant strain for bulk polycrystalline Fe-Ga alloys without a pre-stress or a stress-annealing treatment. The unique properties of wires made with the Taylor-based approach coupled with the low intrinsic cost make this an attractive approach for production of textured magnetostrictive wire for a variety of applications.

scholarly journals The Effects of Reduction and Thermal Treatment on the Recrystallization and Crystallographic Texture Evolution of 5182 Aluminum Alloy

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1380
Author(s):  
Sofia Papadopoulou ◽  
Athina Kontopoulou ◽  
Evangelos Gavalas ◽  
Spyros Papaefthymiou
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Thermal Treatment ◽  
Rolled Product ◽  
Crystallographic Texture ◽  
Texture Evolution ◽  
Fiber Texture ◽  
Electron Back Scatter Diffraction ◽  
Cold Rolled ◽  
Hot Rolled

During forming, thickness reduction and thermal treatment affect the recrystallization and evolution of the crystallographic texture of metallic materials. The present study focuses on the consequences of rolling reduction of a widespread aluminum alloy with numerous automotive, marine and general-purpose applications, namely Al 5182. Emphasis is laid on the crystallographic texture and mechanical properties on both hot and cold-rolled semi-final products. In particular, a 2.8 mm-thick hot-rolled product was examined in the as-received condition, while two cold-rolled sheets, one 1.33 mm and the other 0.214 mm thick, both originating from the 2.8 mm material, were examined in both as-received and annealed (350 °C for 1 h) conditions. Electron back-scatter diffraction indicated the presence of a large percentage of random texture as well as a weak recrystallization texture for the hot-rolled product, whereas in the case of cold rolling the evolution of β-fiber texture was noted. In addition, tensile tests showed that both the anisotropy as well as the mechanical properties of the cold-rolled properties improved after annealing, being comparable to hot-rolled ones.

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