Fatigue and Strength Studies of Titanium 6Al–4V Fabricated by Direct Metal Laser Sintering

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Casey Holycross ◽  
Tommy George ◽  
Kevin Knapp ◽  
Joseph Beck
Keyword(s):  
Fatigue Behavior ◽  
Laser Sintering ◽  
Direct Metal Laser Sintering ◽  
Turbine Engine ◽  
Powder Bed ◽  
Bending Fatigue ◽  
Microstructure Characteristics ◽  
Sixth Generation ◽  
Cold Rolled ◽  
Process Controls

Vibratory bending fatigue behavior of titanium 6Al–4V plate specimens manufactured via direct metal laser sintering (DMLS), powder bed fusion additive manufacturing (AM), is assessed. Motivation for the work is based on unprecedented performance demands for sixth-generation gas turbine engine technology that requires complex, lightweight components. Due to cost, schedule, and feasibility limitations associated with conventional manufacturing, AM aims to address ubiquitous component concepts. Though AM has promise in the engine community, process controls necessary for consistent material properties remain an enigma. The following manuscript compares variability of DMLS fatigue and strength to cold-rolled data. Results show discrepancies between DMLS and cold-rolled for fatigue and microstructure characteristics.

Fatigue and Strength Studies of Titanium 6Al-4V Fabricated by Direct Metal Laser Sintering

2015 ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Casey Holycross ◽  
Tommy George ◽  
Kevin Knapp ◽  
Jeffery Bruns
Keyword(s):  
Fatigue Life ◽  
Additive Manufacturing ◽  
Manufacturing Process ◽  
Fuel Efficiency ◽  
Engine Performance ◽  
Laser Sintering ◽  
Direct Metal Laser Sintering ◽  
Turbine Engine ◽  
Bending Fatigue ◽  
Cold Rolled

Vibratory bending fatigue life behavior of Titanium (Ti) 6Al-4V plate specimens has been assessed. The plates were manufactured via direct metal laser sintering (DMLS), which is a powder bed, laser deposition additive manufacturing process. Motivation for this work is based on unprecedented performance demands for sixth generation gas turbine engine technology. For example, the inclusion of a third stream flow for improving engine performance may add complexity and weight that could offset anticipated thrust and fuel efficiency gains. Therefore, complex, lightweight components with improved functionalities are desired. Novel component design concepts have been cost, schedule, and feasibility limited when using conventional manufacturing methods. Additive manufacturing, however, can extend the thresholds of component concepts. Though additive manufacturing can be a promising addition to the turbine engine community, the manufacturing process controls required to achieve consistency in material properties have not been fully identified. The work presented in this manuscript investigates variability in vibration-based bending fatigue life of DMLS Ti 6Al-4V compared to cold-rolled Ti 6Al-4V. Results show discrepancies between the fatigue life variation of DMLS and cold-rolled data. Along with the support of fusion and post-fusion process parameters, the fatigue results are also supported by tensile property characterization, fractography, and microscopy.

scholarly journals Bending Fatigue Behavior of 17-4 PH Gears Produced by Additive Manufacturing

2021 ◽  
Vol 11 (7) ◽  
pp. 3019
Author(s):  
Franco Concli ◽  
Luca Bonaiti ◽  
Riccardo Gerosa ◽  
Luca Cortese ◽  
Filippo Nalli ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Specific Resistance ◽  
Fatigue Behavior ◽  
Powder Bed ◽  
Bending Fatigue ◽  
Experimental Campaign ◽  
Single Tooth ◽  
Final Failure ◽  
Effective Design ◽  
Resistance Data

The introduction of Additive Manufacturing (AM) is changing the way in which components and machines can be designed and manufactured. Within this context, designers are taking advantage of the possibilities of producing parts via the addition of material, defining strategies, and exploring alternative design or optimization solutions (i.e., nonviable using subtractive technologies) of critical parts (e.g., gears and shafts). However, a safe and effective design requires specific resistance data that, due to the intrinsic modernity of additive technologies, are not always present in the literature. This paper presents the results of an experimental campaign performed on gear-samples made by 17-4 PH and produced via Laser Powder Bed Fusion (PBF-LB/M). The tests were executed using the Single Tooth Bending Fatigue (STBF) approach on a mechanical pulsator. The fatigue limit was determined using two different statistical approaches according to Dixon and Little. The obtained data were compared to those reported in the ISO standard for steels of similar performance. Additional analyses, i.e., Scanning Electron Microscopy SEM, were carried out to provide a further insight of the behavior 17-4PH AM material and in order to investigate the presence of possible defects in the tested gears, responsible for the final failure.

Investigating Discrepancies in Vibration Bending Fatigue Behavior of Additively Manufactured Titanium 6Al-4V

2018 ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Casey Holycross ◽  
Tommy George ◽  
Luke Sheridan ◽  
Emily Carper ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Stress Amplitude ◽  
Fatigue Behavior ◽  
Sem Analysis ◽  
Concentration Effects ◽  
Bending Fatigue ◽  
Grain Structures ◽  
Life Model ◽  
Microscopic Features ◽  
Cold Rolled

The vibration bending fatigue life uncertainty of additively manufactured Titanium (Ti) 6Al-4V specimens is studied. In this investigation, an analysis of microscopic discrepancies between 10 fatigued specimens paired by stress amplitude is correlated to the bending fatigue life scatter. Through scanning electron microscope (SEM) analysis of fracture surfaces and grain structures, anomalies and distinctions such as voids and grain geometries are identified in each specimen. This data along with previously published results are used to support assessments regarding bending fatigue uncertainty. Corrections on stress and scatter based on microscopic features are implemented to the stress versus fatigue life comparisons. The results of this investigation show that the bending fatigue life uncertainty can be bounded by cold-rolled Ti 6Al-4V data when correcting the tested stress amplitude values with stress concentration effects and variation due to microstructure geometries. The understanding gained from this study is important for future development of a predictive vibration bending fatigue life model that will include the probability of geometry, density, and location of voids as an artifact of LPBF build parameters.

Effect of Build Direction in Direct Metal Laser Sintering (DMLS) of Inconel 718 on Microstructure and Mechanical Behavior

2019 ◽  
Author(s):  
Sachin Alya ◽  
Chaitanya Vundru ◽  
Ramesh Singh ◽  
Khushahal Thool ◽  
Indradev Samajdar ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Mechanical Behavior ◽  
Inconel 718 ◽  
Laser Sintering ◽  
Thermal Gradients ◽  
Layer By Layer ◽  
Direct Metal Laser Sintering ◽  
Powder Bed ◽  
Grain Orientations ◽  
End Use

Abstract Additive manufacturing (AM) technology is gaining enormous popularity in the manufacturing industries. The continuous improvements made in the AM processes features development of 3D metallic prototypes as well as fully functional end-use components. Direct Metal Laser Sintering (DMLS) is a pre-placed powder bed based technique, in which a thin layer of powder is place over the build tray and the areas need to be sintered are exposed to the laser. In the current work the microstructural and mechanical behavior of Inconel 718 parts produced by DMLS are investigated. As the DMLS produces parts in a layer by layer fashion, the orientation of parts with respect to the build direction is an important criterion. Microstructure and mechanical properties of the produce differs depending upon the orientation. This paper emphasize on the variation of grain sizes and grain orientations developed in the components built with different orientations. Another common issue with the additive manufacturing is the development of the residual stresses in the components arising due to the differential thermal gradients experienced during processing. The variation of the residual stress generated in the produced parts has also been characterized and modeled.

Bending fatigue life characterisation of direct metal laser sintering nickel alloy 718

2015 ◽  
Vol 38 (9) ◽  
pp. 1105-1117 ◽  
Author(s):  
O. Scott-Emuakpor ◽  
J. Schwartz ◽  
T. George ◽  
C. Holycross ◽  
C. Cross ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Nickel Alloy ◽  
Laser Sintering ◽  
Alloy 718 ◽  
Direct Metal Laser Sintering ◽  
Bending Fatigue

Influence of the Direct Metal Laser Sintering Process on the Fatigue Behavior of the Ti6Al4V Alloy

2017 ◽  
Vol 891 ◽  
pp. 317-321 ◽  
Author(s):  
Adrián Bača ◽  
Radomila Konečná ◽  
Gianni Nicoletto
Keyword(s):  
Additive Manufacturing ◽  
Process Parameters ◽  
Fatigue Behavior ◽  
Laser Sintering ◽  
Ti6al4v Alloy ◽  
Process Conditions ◽  
Layer By Layer ◽  
Metal Powders ◽  
Direct Metal Laser Sintering ◽  
Post Process

Direct Metal Laser Sintering (DMLS) is additive manufacturing (AM) process that can produce near net shape parts from metal powders such as titanium alloys. DMLS is a layer by layer additive manufacturing technique based on high power fiber laser that creates solid layers from loose powder material and joins them in an additive manner. The specific DMLS process conditions, lead to a specific and complex microstructure and to mechanical properties that show a degree of directionality. It was found that microstructural characteristics are related to the building process parameters. The aim of this work is to evaluate the fatigue performance of the Ti6Al4V alloy depending on the process parameters, building orientations and post-process heat treatment.

High Cycle Fatigue Life of Ti6Al4V Alloy Produced by Direct Metal Laser Sintering

2016 ◽  
Vol 258 ◽  
pp. 522-525 ◽  
Author(s):  
Radomila Konečná ◽  
Gianni Nicoletto ◽  
Adrián Bača ◽  
Ludvík Kunz
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Laser Sintering ◽  
Ti6al4v Alloy ◽  
Cycle Fatigue ◽  
Direct Metal Laser Sintering ◽  
Stress Relieving

High cycle fatigue life of Ti6Al4V alloy specimens manufactured by Direct Metal Laser Sintering (DMLS) was experimentally determined. The DMLS fabrication process was characterized by a 400 W laser power and 50 μm layer melted thickness. Post-fabrication heat treatment consisted in stress relieving for 3 h at 720 °C in vacuum with subsequent cooling in argon atmosphere. Fatigue testing of specimens oriented in three different directions with respect to the material build direction was performed with the aim to examine the influence of the layered microstructure on the fatigue behavior. Results of measurement of surface roughness, metallographic examinations of the layered material and fractographic investigation of the fatigue fracture surfaces were employed in the discussion of fatigue crack initiation in DMLS fabricated Ti6Al4V alloy.

Metallographic Characterization and Fatigue Damage Initiation in Ti6Al4V Alloy Produced by Direct Metal Laser Sintering

2017 ◽  
Vol 891 ◽  
pp. 311-316 ◽  
Author(s):  
Radomila Konečná ◽  
Gianni Nicoletto ◽  
Adrián Bača ◽  
Ludvík Kunz
Keyword(s):  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Structural Heterogeneity ◽  
Cyclic Stress ◽  
Laser Sintering ◽  
Fatigue Tests ◽  
Ti6al4v Alloy ◽  
Direct Metal Laser Sintering ◽  
Damage Initiation ◽  
Complex Process

Direct Metal Laser Sintering (DMLS) is a complex process where a part is build-up by localized melting of gas atomized powder layers by a concentrated laser beam followed rapid solidification. The microstructure of DMLS produced material is substantially different from that of conventionally manufactured materials, although the ultimate strength is similar. However, yield strength and elongation and especially fatigue behavior may vary considerably according to the process parameters and post fabrication heat treatment because they affect structural heterogeneity, porosity content, residual stresses, and surface conditions. Fatigue tests of DMLS Ti6Al4V alloy are interpreted in the light of a thorough metallographic and fractographic investigation. The fatigue crack initiation for three different cyclic stress directions with respect to build direction is determined by fractography.

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