Laser-based powder bed fusion of 16MnCr5 and resulting material properties

2020 ◽  
Vol 35 ◽  
pp. 101372
Author(s):  
Matthias Schmitt ◽  
Tobias Kamps ◽  
Felix Siglmüller ◽  
Jakob Winkler ◽  
Georg Schlick ◽  
...  
Keyword(s):  
Material Properties ◽  
Powder Bed Fusion ◽  
Powder Bed

scholarly journals Effects of Positioning Conditions on Material Properties In Powder bed Fusion Additive Manufacturing

2021 ◽  
Author(s):  
Mevlüt Yunus Kayacan ◽  
Nihat Yılmaz
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Layer By Layer ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Cooling Rates ◽  
Powder Bed ◽  
Manufacturing Technologies ◽  
Average Size ◽  
Hardness Values

Abstract Among additive manufacturing technologies, Laser Powder Bed Fusion (L-PBF) is considered the most widespread layer-by-layer process. Although the L-PBF, which is also called as SLM method, has many advantages, several challenging problems must be overcome, including part positioning issues. In this study, the effect of part positioning on the microstructure of the part in the L-PBF method was investigated. Five Ti6Al4V samples were printed in different positions on the building platform and investigated with the aid of temperature, porosity, microstructure and hardness evaluations. In this study, martensitic needles were detected within the microstructure of Ti6Al4V samples. Furthermore, some twins were noticed on primary martensitic lines and the agglomeration of β precipitates was observed in vanadium rich areas. The positioning conditions of samples were revealed to have a strong effect on temperature gradients and on the average size of martensitic lines. Besides, different hardness values were attained depending on sample positioning conditions. As a major result, cooling rates were found related to positions of samples and the location of point on the samples. Higher cooling rates and repetitive cooling cycles resulted in microstructures becoming finer and harder.

scholarly journals Position-dependent mechanical characterization of the PBF-EB-manufactured Ti6Al4V alloy

2021 ◽  
Author(s):  
Daniel Kotzem ◽  
Alexandra Höffgen ◽  
Rajevan Raveendran ◽  
Felix Stern ◽  
Kerstin Möhring ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Material Properties ◽  
Mechanical Characterization ◽  
Industrial Applications ◽  
Fatigue Tests ◽  
Ti6al4v Alloy ◽  
Effective Diameter ◽  
Powder Bed Fusion ◽  
Powder Bed

AbstractBy means of additive manufacturing, the production of components with nearly unlimited geometrical design complexity is feasible. Especially, powder bed fusion techniques such as electron beam powder bed fusion (PBF-EB) are currently focused. However, equal material properties are mandatory to be able to transfer this technique to a wide scope of industrial applications. Within the scope of this work, the mechanical properties of the PBF-EB-manufactured Ti6Al4V alloy are investigated as a function of the position on the building platform. It can be stated that as-built surface roughness changes within building platform whereby highest surface roughness detected by computed tomography (Ra = 46.0 ± 5.3 µm) was found for specimens located in the front of the building platform. In contrast, no significant differences in relative density could be determined and specimens can be assumed as nearly fully dense (> 99.9%). Furthermore, all specimens are affected by an undersized effective diameter compared to the CAD data. Fatigue tests revealed that specimens in the front of the building platform show slightly lower performance at higher stress amplitudes as compared to specimens in the back of the building platform. However, process-induced notch-like defects based on the surface roughness were found to be the preferred location for early crack initiation.

Powder Bed Fusion Additive Manufacturing of Ni-Based Superalloys

2020 ◽  
pp. 249-270
Author(s):  
Evren Yasa ◽  
Ozgur Poyraz
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Elevated Temperatures ◽  
Design Criteria ◽  
Complex Geometries ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Volume Production ◽  
Manufacturing Technologies ◽  
Aerospace And Defense

Emerging additive manufacturing technologies have been gaining interest from different industries and widened their fields of application among aerospace and defense. The introduction of powder bed fusion processes was one of the significant developments in terms of direct metal part manufacturing of different materials and complex geometries, presenting good properties, and decreasing the need for tooling to allow fast product development as well as small-volume production. In this respect, nickel-based superalloys are one of the most employed material groups for aerospace and defense applications due to their mechanical strength, creep, wear, and oxidation resistance at both ambient and elevated temperatures. Nevertheless, the use of some materials has not become widespread due to several reasons such as processing difficulties, absence of design criteria or material properties. This chapter presents a comprehensive benchmark for powder bed fusion additive manufacturing of nickel-based superalloys considering applications, characteristics, and limitations.

Evaluation of the Material Properties of the Ti and CoCr Alloys Prepared by Laser Powder Bed Fusion

2020 ◽  
Vol 985 ◽  
pp. 223-228
Author(s):  
Jana Bidulská ◽  
Róbert Bidulský ◽  
Patrik Petrouse ◽  
Tibor Kvačkaj ◽  
Marco Actis Grande ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Image Analysis ◽  
Additive Manufacturing ◽  
Material Properties ◽  
Ti6al4v Alloy ◽  
Homogeneous Distribution ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Quantitative Image

The main aim of the present paper is evaluated the mechanical properties, microstructures and porosity of Ti6Al4V and CoCrW alloys produced by Laser Powder Bed Fusion (L-PBF) as an additive manufacturing (AM) technology. The mechanical properties were follows: For Ti6Al4V alloy the UTS was 1180 MPa; the YS was in the range <600; 745 MPa>. For CoCrW alloys, the UTS were in range <750; 950 MPa> and YS was in range <400; 500>. Evaluation of porosity was realized on non-etched samples using by quantitative image analysis in order to describe the dimensional and morphological porosity characteristics. The pores in the Ti6Al4V alloy showed homogeneous distribution without significant large pores.

scholarly journals Employment of an Extended Double-Integrating-Sphere System to Investigate Thermo-optical Material Properties for Powder Bed Fusion

2021 ◽  
Author(s):  
Thomas Schuffenhauer ◽  
Thomas Stichel ◽  
Michael Schmidt
Keyword(s):  
Optical Properties ◽  
Material Properties ◽  
Integrating Sphere ◽  
Powder Materials ◽  
Powder Bed Fusion ◽  
Empirical Parameter ◽  
Powder Bed ◽  
Heating And Cooling ◽  
Preheating Temperature ◽  
Polyamide Powder

AbstractThe optical energy input during laser-based powder bed fusion of polymers (PBF-LB/P) is influenced by a variety of process parameters (e.g., energy density) and powder material properties (e.g. optical properties, additives). Qualification of newly developed and/or modified powder materials still requires extensive, empirical parameter studies to assess processibility and find suitable process strategies. For powder characterization, a double-integrating-sphere system with an intervening hot stage, which allows accurate sample heating during the measurement of the optical properties, is presented and described. For qualification of the system and the associated characterization method for the PBF-LB/P process, the interaction of a collimated CO2 laser beam with selected polyamide powder materials during heating and cooling is investigated. The obtained results illustrate the suitability of the presented thermo-optical characterization technique, i.e., the temperature-dependent measurement of radiation reflected by and transmitted through the samples, for the systematical investigation of material-related (i.e., additives) and process-related (i.e., preheating temperature, layer height) influences on the beam-matter interaction.

scholarly journals Physics-Based Predictive Model of Lack-of-Fusion Porosity in Laser Powder Bed Fusion Considering Cap Area

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1568
Author(s):  
Wenjia Wang ◽  
Steven Y. Liang
Keyword(s):  
Image Analysis ◽  
Cross Section ◽  
Void Fraction ◽  
Material Properties ◽  
Molten Pool ◽  
Analytical Modeling ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Lack Of Fusion

This work proposed a computationally efficient analytical modeling strategy to calculate the product porosity in laser powder bed fusion (LPBF) induced by a lack-of-fusion defect, with the consideration of cap area in solidified molten pools, influence of powder bed characteristics on material properties, and un-melted powders in the lack-of-fusion portion. The powder packing pattern and powder bed void fraction were estimated by an advancing front method and the technique of image analysis. The effects of powder bed characteristics on the material properties were considered by analytical models with solid properties and powder bed void fraction as inputs. A physics-based thermal model was utilized to calculate the temperature distribution and molten pool size. The molten pool cross section in transvers direction was assumed to be dual half-elliptical. Based on this assumption and molten pool size, the geometry of the molten pool cross section with cap area was determined. The overlapping pattern of molten pools in adjacent scan tracks and layers was then obtained with given hatch space and layer thickness. The lack-of-fusion area fraction was obtained through image analysis of the overlapping pattern. The lack-of-fusion porosity was the multiplication of the lack-of-fusion area fraction and powder bed void fraction. The predictions of porosity under different process conditions were compared with experimental results of 316L stainless steel and showed a better predictive accuracy than the predictions that did not consider cap area. The proposed analytical modeling method has no numerical calculations, which ensures its low computational cost. Thus, the proposed model can be a convenient tool for the fast computation of lack-of-fusion-induced porosity and can help the quality control in LPBF.

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