Selective laser sintering (melting) of stainless and tool steel powders: Experiments and modelling

2005 ◽  
Vol 219 (4) ◽  
pp. 339-357 ◽  
Author(s):  
T H C Childs ◽  
C Hauser ◽  
M Badrossamay
Keyword(s):  
Laser Beam ◽  
Tool Steel ◽  
Selective Laser Sintering ◽  
Element Model ◽  
Powder Bed ◽  
Melt Pool ◽  
H13 Tool Steel ◽  
Complete Melting ◽  
Track Formation ◽  
Elliptic Cross

When a laser beam scans once across the surface of a metallic powder bed, the resulting track may be continuous with a crescent or an elliptic cross-section, irregularly broken, balled or only partially melted. This paper reports what laser powers and scan speeds lead to what types of track, for a CO2 laser beam focused to 0.55 mm and 1.1 mm diameters, scanning over beds made from M2 and H13 tool steel and 314S-HC stainless steel powders. Beds have been made with particle size ranges from 300 μm to 150 μm, from 150 μm to 75 μm, from 75 μm to 38 μm, and less than 38 μm. Measurements are also reported of bed physical properties that are used in a finite element model to predict melt pool dimensions and temperatures. Boundaries between regions of different track formation are explained in terms of melt surface temperature gradients, melt pool length-diameter ratio instabilities, and transitions from partial to complete melting. Implications for building metal parts in powder beds without supports are considered. The modelling is briefly extended to multi-track and multi-layer processing, to conclude that bonding by remelting between layers, while still maintaining control of the melt flow, places severe constraints on the maximum allowable layer thickness.

Improvement of Build Speed and Quality of H13 Tool Steel Processed by Laser-Beam Powder Bed Fusion with a High-Power Laser

2021 ◽  
Vol 68 (10) ◽  
pp. 415-421
Author(s):  
Takashi MIZOGUCHI ◽  
Takaya NAGAHAMA ◽  
Makoto TANO ◽  
Shigeru MATSUNAGA ◽  
Takayuki YOSHIMI ◽  
...  
Keyword(s):  
Laser Beam ◽  
Tool Steel ◽  
High Power ◽  
Powder Bed Fusion ◽  
High Power Laser ◽  
Power Laser ◽  
Powder Bed ◽  
H13 Tool Steel

Melt Pool and Single Track Formation in Selective Laser Sintering/Selective Laser Melting

2014 ◽  
Vol 933 ◽  
pp. 196-201 ◽  
Author(s):  
Mohd Rizal Alkahari ◽  
Tatsuaki Furumoto ◽  
Takashi Ueda ◽  
Akira Hosokawa
Keyword(s):  
Laser Beam ◽  
Layer Thickness ◽  
Laser Power ◽  
Selective Laser Sintering ◽  
Single Track ◽  
Laser Melting ◽  
Consolidation Process ◽  
Melt Pool ◽  
Track Formation ◽  
Scan Speed

Selective Laser Sintering/Selective Laser Melting (SLS/SLM) is one of Additive Manufacturing (AM) processes that utilize layer by layer powder deposition technique and successive laser beam irradiation based on Computer Aided Design (CAD) data. During laser irradiation on metal powders, melt pool was formed, which then solidified to consolidated structure. Therefore, melt pool is an important behavior that affects the final quality of track formation. The study investigates the melt pool behavior through visualization of the consolidation process during the single track formation on the first layer. In order to understand the transformation process of metal powder to consolidated structure and mechanism involved, high speed camera was used to monitor the process. Yb:fiber laser beam was irradiated on metal powder at maximum power of 150W. The laser processing parameters such as laser power, scan speed and layer thickness were varied in order to investigate their influence on the consolidation process. The result shows the size of melt pool increased with laser power and decreasing with increment in scan speed. Furthermore, with the increase of layer thickness, melt pool formation was unstable with chaotic movement. Significant amount of molten powder splattering was recorded from the melt pool. At high layer thickness also, the molten powder formed spherical shaped and the solidified molten powder failed to wet with the substrate.

New Hammerstein Modeling and Analysis for Controlling Melt Pool Width in Powder Bed Fusion Additive Manufacturing

2021 ◽  
pp. 1-7
Author(s):  
Dan Wang ◽  
Xinyu Zhao ◽  
Xu Chen
Keyword(s):  
Finite Element ◽  
Additive Manufacturing ◽  
Process Variations ◽  
Element Model ◽  
Hammerstein Model ◽  
Powder Bed Fusion ◽  
Modeling And Analysis ◽  
Powder Bed ◽  
Melt Pool ◽  
Linearized Model

Abstract Despite the advantages and emerging applications, broader adoption of powder bed fusion (PBF) additive manufacturing is challenged by insufficient reliability and in-process variations. Finite element modeling and control-oriented modeling have been identified fundamental for predicting and engineering part qualities in PBF. This paper first builds a finite element model (FEM) of the thermal fields to look into the convoluted thermal interactions during the PBF process. Using the FEM data, we identify a novel surrogate system model from the laser power to the melt pool width. Linking a linearized model with a memoryless nonlinear submodel, we develop a physics-based Hammerstein model that captures the complex spatiotemporal thermomechanical dynamics. We verify the accuracy of the Hammerstein model using the FEM and prove that the linearized model is only a representation of the Hammerstein model around the equilibrium point. Along the way, we conduct the stability and robustness analyses and formalize the Hammerstein model to facilitate the subsequent control designs.

Influence of overlap between the laser beam tracks on surface quality in laser polishing of AISI H13 tool steel

2012 ◽  
Vol 14 (4) ◽  
pp. 425-434 ◽  
Author(s):  
Abdullah M. Khalid Hafiz ◽  
Evgueni V. Bordatchev ◽  
Remus O. Tutunea-Fatan
Keyword(s):  
Laser Beam ◽  
Surface Quality ◽  
Tool Steel ◽  
Laser Polishing ◽  
H13 Tool Steel ◽  
Aisi H13 ◽  
Aisi H13 Tool Steel

scholarly journals Evaluation of spatter particles, metal vapour jets, and depressions considering influence of laser incident angle on melt pool behaviour

2021 ◽  
Author(s):  
Kotaro Tsubouchi ◽  
Tatsuaki Furumoto ◽  
Mitsugu Yamaguchi ◽  
Atsushi Ezura ◽  
Shinnosuke Yamada ◽  
...  
Keyword(s):  
Laser Beam ◽  
High Speed ◽  
Incident Angle ◽  
Three Dimensional ◽  
Burial Depth ◽  
Metal Vapour ◽  
Building Conditions ◽  
Powder Bed ◽  
Melt Pool ◽  
Pool Formation

Abstract Building of practical parts involves the application of metal-based laser powder bed fusion using a laser beam (PBF-LB/M) owing to its high-precision manufacturing. However, the quality of the built parts obtained via the PBF-LB/M processes varies with the building conditions, and a thorough understanding of the building mechanism has not been achieved owing to the complex and interrelated process parameters involved. The incident angle of the laser beam, which changes on the platform during the laser beam scan owing to the designed three-dimensional data, is among the principal parameters that affects the building aspects. In this study, the melt pool in the singletrack formation during the PBF-LB/M processes was visualised using a high-speed camera, and the influence of the laser incident angle on the ejection characteristics of spatter particles formed around the laser-irradiated area was investigated. Consequently, the spatter particles and metal vapour jet behaviour varied with the laser incident angle. There was a reduction in number of spatter particles owing to the origin of the incident direction being from behind the laser irradiation area. In addition, the laser incident angle also affected the melt pool morphology because of the depression in the melting. Furthermore, the burial depth of the pores varied with the laser incident angle, and is related to the depth of the depression during the melt pool formation.

scholarly journals Part deflection and residual stresses in laser powder bed fusion of H13 tool steel

2021 ◽  
pp. 109659
Author(s):  
Morteza Narvan ◽  
Ali Ghasemi ◽  
Eskandar Fereiduni ◽  
Stephen Kendrish ◽  
Mohamed Elbestawi
Keyword(s):  
Residual Stresses ◽  
Tool Steel ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
H13 Tool Steel

Raster scan selective laser melting of the surface layer of a tool steel powder bed

2005 ◽  
Vol 219 (4) ◽  
pp. 379-384 ◽  
Author(s):  
T H C Childs ◽  
C Hauser
Keyword(s):  
Selective Laser Melting ◽  
Tool Steel ◽  
Laser Energy ◽  
Steel Powder ◽  
Beam Diameter ◽  
Laser Melting ◽  
Powder Bed ◽  
H13 Tool Steel ◽  
Scan Speed ◽  
The Masses

Square areas, 15 mm × 15 mm in size, have been melted in the surface of powder beds made from H13 tool steel, using a raster-scanning CO2 laser focused to a beam diameter of 0.6 mm. Laser powers from approximately 50 to 150 W and scan speeds from 0.5 to 300 mm/s have been used, at two scan spacings, 0.15 mm and 0.45 mm. The appearances of the layers in the different conditions, dense or porous, have been observed by low-magnification scanning electron microscopy. The masses of the layers have been measured and simulations have been carried out to predict the masses. The variation of mass with scan speed, at a constant laser power, has been found to be much less than might be expected from a constant absorptivity of laser energy into the bed. The simulations suggest that absorptivities range from 0.25 to approximately 1.0 and that, during any one scan, heating of the bed by previous scans must be considered in order even partially to explain the observations. The work is relevant to attempts to build metal parts without supports, by selective laser melting.

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