scholarly journals In situ heat accumulation by geometrical features obstructing heat flux and by reduced inter layer times in laser powder bed fusion of AISI 316L stainless steel

Procedia CIRP ◽  
2020 ◽  
Vol 94 ◽  
pp. 155-160 ◽  
Author(s):  
Gunther Mohr ◽  
Nils Scheuschner ◽  
Kai Hilgenberg
Keyword(s):  
Heat Flux ◽  
316L Stainless Steel ◽  
Powder Bed Fusion ◽  
Aisi 316L ◽  
Laser Powder Bed Fusion ◽  
Heat Accumulation ◽  
Aisi 316L Stainless Steel ◽  
Powder Bed ◽  
Geometrical Features

Influence of processing parameters on the density of 316L stainless steel parts manufactured through laser powder bed fusion

2020 ◽  
Vol 234 (9) ◽  
pp. 1246-1257 ◽  
Author(s):  
João PM Pragana ◽  
Pedro Pombinha ◽  
Valdemar R Duarte ◽  
Tiago A Rodrigues ◽  
João P Oliveira ◽  
...  
Keyword(s):  
Stainless Steel ◽  
316L Stainless Steel ◽  
Processing Parameters ◽  
Powder Bed Fusion ◽  
Aisi 316L ◽  
Laser Powder Bed Fusion ◽  
Optimal Range ◽  
Powder Bed ◽  
Density Measurements ◽  
Part Density

Additive manufacturing technologies are becoming more popular, as they allow the fabrication of specific parts with complex geometries not achievable by conventional manufacturing. In metal additive manufacturing, one of the most widely used technologies is laser powder bed fusion. This work focuses on the influence of different processing parameters on the density of AISI 316L stainless parts obtained through this technology. The article presents a review of published works on the deposition of AISI 316L stainless steel using laser powder bed fusion to define an optimal range of parameters to produce parts with densities above 99%, complemented by density measurements for new sets of laser powder bed fusion processing parameters within the defined optimal range. The investigation provides a further insight on the effect of operating parameters such as vector size and gas atmosphere (Nitrogen and Argon) on the part density. The density measurements were performed using two techniques: micrograph analysis and Archimedes method. Results reveal that an increase in vector size has a negative influence on part density. With the Archimedes method, a maximum relative density of 99.87% was achieved using Nitrogen atmosphere, showing that it is possible to produce near fully dense parts by laser powder bed fusion without post-processing by laser re-melting.

scholarly journals Experimental Determination of the Emissivity of Powder Layers and Bulk Material in Laser Powder Bed Fusion Using Infrared Thermography and Thermocouples

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1546
Author(s):  
Gunther Mohr ◽  
Susanna Nowakowski ◽  
Simon J. Altenburg ◽  
Christiane Maierhofer ◽  
Kai Hilgenberg
Keyword(s):  
In Situ Monitoring ◽  
Powder Layer ◽  
Contact Method ◽  
Powder Bed Fusion ◽  
Aisi 316L ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Powder Surface ◽  
Bulk Surface

Recording the temperature distribution of the layer under construction during laser powder bed fusion (L-PBF) is of utmost interest for a deep process understanding as well as for quality assurance and in situ monitoring means. While having a notable number of thermal monitoring approaches in additive manufacturing (AM), attempts at temperature calibration and emissivity determination are relatively rare. This study aims for the experimental temperature adjustment of an off-axis infrared (IR) thermography setup used for in situ thermal data acquisition in L-PBF processes. The temperature adjustment was conducted by means of the so-called contact method using thermocouples at two different surface conditions and two different materials: AISI 316L L-PBF bulk surface, AISI 316L powder surface, and IN718 powder surface. The apparent emissivity values for the particular setup were determined. For the first time, also corrected, closer to real emissivity values of the bulk or powder surface condition are published. In the temperature region from approximately 150 °C to 580 °C, the corrected emissivity was determined in a range from 0.2 to 0.25 for a 316L L-PBF bulk surface, in a range from 0.37 to 0.45 for 316L powder layer, and in a range from 0.37 to 0.4 for IN718 powder layer.

On the use of spatter signature for in-situ monitoring of Laser Powder Bed Fusion

2017 ◽  
Vol 16 ◽  
pp. 35-48 ◽  
Author(s):  
Giulia Repossini ◽  
Vittorio Laguzza ◽  
Marco Grasso ◽  
Bianca Maria Colosimo
Keyword(s):  
In Situ Monitoring ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed

Titanium Alloys Manufactured by In Situ Alloying During Laser Powder Bed Fusion

JOM ◽  
2017 ◽  
Vol 69 (12) ◽  
pp. 2725-2730 ◽  
Author(s):  
I. Yadroitsev ◽  
P. Krakhmalev ◽  
I. Yadroitsava
Keyword(s):  
Titanium Alloys ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed
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