Tensile and Fatigue Properties of Ti-6Al-4V Alloy Fabricated by Laser Powder-Bed Fusion Process

2020 ◽  
Author(s):  
M. Shafiqur Rahman ◽  
Uttam K. Chakravarty
Keyword(s):  
Fatigue Life ◽  
Fatigue Limit ◽  
Fatigue Behavior ◽  
Functional Materials ◽  
Fatigue Properties ◽  
Small Scale ◽  
Powder Bed Fusion ◽  
Cycle Fatigue ◽  
Laser Powder Bed Fusion ◽  
Powder Bed

Abstract The tensile and fatigue properties of laser-powder-bed-fusion (L-PBF) processed Ti-6Al-4V specimens are investigated at different loading conditions. Two types of as-built and post-machined L-PBF processed dogbone specimens are considered for the study, one is an ASTME8M round specimen and the other one is a customized small-scale flat structure. The tensile and fatigue behavior of the specimens are investigated numerically using the finite element (FE) method. The FE modeling considers both low cycle fatigue (LCF) and high cycle fatigue (HCF) test conditions by applying cyclic loads in fully-reversed and stress ratio R = 0.1 conditions. The FE results for the von Mises stress, strain, total deformation, fatigue life, factor of safety, and fatigue limit of the Ti-6Al-4V specimens are obtained at room temperature (295 K). Results obtained from the model show that the fatigue life decreases as the load increases. It is also found that fatigue life does not vary with the change of the test frequency under a specific fatigue load. The comparison of mechanical properties of the L-PBF processed specimens with conventionally manufactured Ti-6Al-4V parts is also shown to understand the differences in the tensile and fatigue behavior. The validation of the FE model is performed by comparing the numerical results for the yield stress and fatigue limit with the experimental results found from the literature. The overall study contains a detailed analysis of the tensile and fatigue behavior of additively manufactured Ti-6Al-4V parts and provides a guide to investigating the similar properties for other functional materials used in the L-PBF process.

scholarly journals High cycle fatigue life estimation of AlSi10Mg processed by laser powder bed fusion

2018 ◽  
Vol 188 ◽  
pp. 03015 ◽  
Author(s):  
Even W. Hovig ◽  
Amin S. Azar ◽  
Martin F. Sunding ◽  
Knut Sørby ◽  
Mohammed M'hamdi ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Surface Properties ◽  
High Cycle Fatigue ◽  
Material Surface ◽  
Powder Bed Fusion ◽  
Cycle Fatigue ◽  
Laser Powder Bed Fusion ◽  
Element Analysis ◽  
Powder Bed

Fatigue life is known to be dependent on the surface properties of the material. Surface roughness provokes local stress concentration and cause crack initiation even at minute cyclic loads. In laser powder bed fusion, the as-built surfaces show variable roughness depending on the orientation of the specimens with respect to the build plate. In order to analyse the effect of build angle on surface properties, flat tensile specimens were produced from an AlSi10Mg alloy in a Concept Laser M2 Cusing machine. Seven specimens were arranged from flat to perpendicular with respect to the build plate at 15° intervals. The as-built surface topography of each specimen was characterised by white light interferometry. Two methods for calculating the stress concentration factor for high cycle fatigue simulation were developed. The presence of subsurface porosity was a crucial factor in expanding the stress concentration as demonstrated by finite element analysis.

scholarly journals High cycle fatigue life estimation of materials processed by laser powder bed fusion

2019 ◽  
Vol 42 (7) ◽  
pp. 1454-1466 ◽  
Author(s):  
Even W. Hovig ◽  
Amin S. Azar ◽  
Martin F. Sunding ◽  
Erik Andreassen ◽  
Knut Sørby
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Powder Bed Fusion ◽  
Cycle Fatigue ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Life Estimation ◽  
Fatigue Life Estimation

Mechanisms driving high-cycle fatigue life of as-built Inconel 718 processed by laser powder bed fusion

2019 ◽  
Vol 761 ◽  
pp. 137993 ◽  
Author(s):  
Dillon S. Watring ◽  
Kristen C. Carter ◽  
Dustin Crouse ◽  
Bart Raeymaekers ◽  
Ashley D. Spear
Keyword(s):  
Fatigue Life ◽  
Inconel 718 ◽  
High Cycle Fatigue ◽  
Powder Bed Fusion ◽  
Cycle Fatigue ◽  
Laser Powder Bed Fusion ◽  
Powder Bed

scholarly journals Corrosion Fatigue Characteristics of 316L Stainless Steel Fabricated by Laser Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1046
Author(s):  
Balachander Gnanasekaran ◽  
Jie Song ◽  
Vijay Vasudevan ◽  
Yao Fu
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Corrosion Fatigue ◽  
Fatigue Properties ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Corrosion Properties ◽  
Powder Bed ◽  
Fatigue Characteristics

Laser powder bed fusion (LPBF) has been increasingly used in the fabrication of dense metallic structures. However, the corrosion related properties of LPBF alloys, in particular environment-assisted cracking, such as corrosion fatigue properties, are not well understood. In this study, the corrosion and corrosion fatigue characteristics of LPBF 316L stainless steels (SS) in 3.5 wt.% NaCl solution have been investigated using an electrochemical method, high cycle fatigue, and fatigue crack propagation testing. The LPBF 316L SSs demonstrated significantly improved corrosion properties compared to conventionally manufactured 316L, as reflected by the increased pitting and repassivation potentials, as well as retarded crack initiation. However, the printing parameters did not strongly affect the pitting potentials. LPBF samples also demonstrated enhanced capabilities of repassivation during the fatigue crack propagation. The unique microstructural features introduced during the printing process are discussed. The improved corrosion and corrosion fatigue properties are attributed to the presence of columnar/cellular subgrains formed by dislocation networks that serve as high diffusion paths to transport anti-corrosion elements.

scholarly journals Effect of Surface and Subsurface Defects on Fatigue Behavior of AlSi10Mg Alloy Processed by Laser Powder Bed Fusion (L-PBF)

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1063 ◽  
Author(s):  
Milad Hamidi Nasab ◽  
Alessandro Giussani ◽  
Dario Gastaldi ◽  
Valeria Tirelli ◽  
Maurizio Vedani
Keyword(s):  
Crack Nucleation ◽  
Fatigue Behavior ◽  
Fatigue Behaviour ◽  
Surface Finishing ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Finishing Processes ◽  
Effect Of Surface ◽  
Subsurface Defects

The fatigue behaviour of an AlSi10Mg alloy processed by laser powder bed fusion (L-PBF) and subjected to different surface finishing processes was investigated paying special attention to the residual defects on the surface and the dominant fatigue failure mechanisms. Roughness measurements and qualitative surface morphology analysis showed smooth surfaces in the case of vibro-finishing and machining followed by polishing. The fatigue performance did not reveal to be directly related to surface roughness, but residual intrusions left on the finished surfaces. Post-mortem analysis showed single- or multiple-crack nucleation from pores opened on the surface, un-melted powders, or spatters considered as typical L-PBF defects. A fatigue limit of 195 MPa for machined and polished samples was obtained by substantial removal of surface and subsurface defects.

scholarly journals Fatigue Improvement of AlSi10Mg Fabricated by Laser-Based Powder Bed Fusion through Heat-Treatment.

2021 ◽  
Author(s):  
Felix Sajadi ◽  
Jan-Marc Tiemann ◽  
Nooshin Bandari ◽  
Ali Cheloee Darabi ◽  
Javad Mola ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fatigue Behavior ◽  
Fatigue Properties ◽  
Powder Bed Fusion ◽  
Microstructural Characteristics ◽  
Powder Bed ◽  
Treated Condition ◽  
Heat Treated ◽  
Treatment Parameter ◽  
Heat Treated Condition

This study aims to identify an optimal heat-treatment parameter set for an additively manufactured AlSi10Mg alloy in terms of increasing the hardness and eliminating the anisotropic microstructural characteristics of the alloy in as-built condition. Furthermore, the influence of these optimized parameters on the fatigue properties of the alloy investigated. In this respect, microstructural characteristics of an AlSi10Mg alloy manufactured by Laser-Based Powder Bed Fusion in non-heat-treated and heat-treated conditions were investigated. Their static and dynamic mechanical properties were evaluated, and fatigue behavior was explained by a detailed examination of fracture surfaces. Much of the microstructure in the non-heat-treated condition was composed of columnar grains oriented parallel to the build direction. Further analysis revealed a high fraction of pro-eutectic α-Al. Through heat-treatment, the alloy was successfully brought to its peak-hardened condition, while eliminating the anisotropic microstructural features. Yield strength and ductility increased simultaneously after heat-treatment, which is due to the relief of residual stresses, preservation of refined grains, and introduction of precipitation strengthening. The fatigue strength, calculated at 10^7 cycles, improved as well after heat-treatment and finally detailed fractography reviled that a more ductile fracture mechanism has happened in the heat-treated condition compared to the non-heat-treated condition.

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