scholarly journals On the Influence of Laser Cladding and Post-processing Strategies on Residual Stresses in Steel Specimens

2014 ◽  
Vol 56 ◽  
pp. 250-261 ◽  
Author(s):  
H. Köhler ◽  
R. Rajput ◽  
P. Khazan ◽  
J. Rebelo Kornmeier
Keyword(s):  
Residual Stresses ◽  
Laser Cladding ◽  
Post Processing ◽  
Processing Strategies

scholarly journals Additive Manufactured 316L Stainless-Steel Samples: Microstructure, Residual Stress and Corrosion Characteristics after Post-Processing

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 182
Author(s):  
Suvi Santa-aho ◽  
Mika Kiviluoma ◽  
Tuomas Jokiaho ◽  
Tejas Gundgire ◽  
Mari Honkanen ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Sample Surface ◽  
Post Processing ◽  
Magnesium Chloride Solution ◽  
Manufacturing Method ◽  
Four Point Bending ◽  
Traditional Manufacturing ◽  
Processing Steps ◽  
Compressive Residual Stresses

Additive manufacturing (AM) is a relatively new manufacturing method that can produce complex geometries and optimized shapes with less process steps. In addition to distinct microstructural features, residual stresses and their formation are also inherent to AM components. AM components require several post-processing steps before they are ready for use. To change the traditional manufacturing method to AM, comprehensive characterization is needed to verify the suitability of AM components. On very demanding corrosion atmospheres, the question is does AM lower or eliminate the risk of stress corrosion cracking (SCC) compared to welded 316L components? This work concentrates on post-processing and its influence on the microstructure and surface and subsurface residual stresses. The shot peening (SP) post-processing levelled out the residual stress differences, producing compressive residual stresses of more than −400 MPa in the AM samples and the effect exceeded an over 100 µm layer below the surface. Post-processing caused grain refinement and low-angle boundary formation on the sample surface layer and silicon carbide (SiC) residue adhesion, which should be taken into account when using the components. Immersion tests with four-point-bending in the heated 80 °C magnesium chloride solution for SCC showed no difference between AM and reference samples even after a 674 h immersion.

Composition and Microstructure of Laser Cladding of 316 Stainless Steel

2011 ◽  
Vol 467-469 ◽  
pp. 2054-2059
Author(s):  
Kai Zhang ◽  
Miao Yan Li ◽  
Xin Min Zhang
Keyword(s):  
Stainless Steel ◽  
Laser Cladding ◽  
Layered Manufacturing ◽  
Rapid Manufacturing ◽  
Cad Model ◽  
Laser Metal Deposition ◽  
Post Processing ◽  
316 Stainless Steel ◽  
3D Cad ◽  
Manufacturing Techniques

Laser Metal Deposition Shaping (LMDS) is a Rapid Manufacturing (RM) process that can be classified under the area of layered manufacturing techniques, where parts are built in layers. Parts of any complexity can be built directly from the 3D CAD model without much human intervention and requires minimum post-processing. In fact, LMDS technique can be recognized as multilayer laser cladding. Accordingly, it is necessary to perform the elementary laser cladding experiments with common metal powder so as to better understand the LMDS process. Then the characteristics of microstructure, composition and phase of as-deposited clads were analyzed through SEM and XRD, as well as relative model. The results prove that the microstructure of 316 stainless steel deposits is composed of the slender dendrites growing epitaxially from the substrate, and the composition is uniform without obvious segregation. Besides, it can be deduced from XRD diagram that the microstructure is composed of mono-phase γ.

Additive manufacturing and post-processing simulation: laser cladding followed by high speed machining

2015 ◽  
Vol 85 (9-12) ◽  
pp. 2401-2411 ◽  
Author(s):  
Konstantinos Salonitis ◽  
Laurent D’Alvise ◽  
Babis Schoinochoritis ◽  
Dimitrios Chantzis
Keyword(s):  
Additive Manufacturing ◽  
Laser Cladding ◽  
High Speed ◽  
High Speed Machining ◽  
Post Processing

scholarly journals Stable, Intelligible Ultrasonic Strain Imaging

Ultrasound ◽  
2008 ◽  
Vol 16 (4) ◽  
pp. 187-192 ◽  
Author(s):  
Andrew Gee ◽  
Joel Lindop ◽  
Graham Treece ◽  
Richard Prager ◽  
Susan Freeman
Keyword(s):  
Breast Biopsy ◽  
Signal To Noise Ratio ◽  
Strain Imaging ◽  
Time Averaging ◽  
Post Processing ◽  
Signal To Noise ◽  
Processing Strategies ◽  
Improved Stability ◽  
Noise Ratio

Background: Freehand quasistatic strain imaging can reveal qualitative information about tissue stiffness with good spatial accuracy. Clinical trials, however, repeatedly cite instability and variable signal-to-noise ratio as significant drawbacks. Methods: This study investigates three post-processing strategies for quasistatic strain imaging. Normalization divides the strain by an estimate of the stress field, the intention being to reduce sensitivity to variable applied stress. Persistence aims to improve the signal-to-noise ratio by time-averaging multiple frames. The persistence scheme presented in this article operates at the pixel level, weighting each frame's contribution by an estimate of the strain precision. Precision-based display presents the clinician with an image in which regions of indeterminate strain are obscured behind a colour wash. This is achieved using estimates of strain precision that are faithfully propagated through the various stages of signal processing. Results and discussion: The post-processing strategy is evaluated qualitatively on scans of a breast biopsy phantom and in vivo head and neck examinations. Strain images processed in this manner are observed to benefit from improved stability and signal-to-noise ratio. There are, however, limitations. In unusual though conceivable circumstances, the normalization procedure might suppress genuine stiffness variations evident in the unprocessed strain images. In different circumstances, the raw strain images might fail to capture significant stiffness variations, a situation that no amount of post-processing can improve. Conclusion: The clinical utility of freehand quasistatic strain imaging can be improved by normalization, precision-weighted pixel-level persistence and precision-based display. The resulting images are stable and generally exhibit a better signal-to-noise ratio than any of the original, unprocessed strain images.

scholarly journals Post-processing strategies in image scanning microscopy

Methods ◽  
2015 ◽  
Vol 88 ◽  
pp. 28-36 ◽  
Author(s):  
J.E. McGregor ◽  
C.A. Mitchell ◽  
N.A. Hartell
Keyword(s):  
Scanning Microscopy ◽  
Post Processing ◽  
Image Scanning ◽  
Processing Strategies
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