scholarly journals Effect of Hydrogen on the Tensile Behavior of Austenitic Stainless Steels 316L Produced by Laser-Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 586
Author(s):  
Farzaneh Khaleghifar ◽  
Khashayar Razeghi ◽  
Akbar Heidarzadeh ◽  
Reza Taherzadeh Mousavian
Keyword(s):  
Strain Rate ◽  
Tensile Deformation ◽  
High Current Density ◽  
Uniform Elongation ◽  
Austenitic Stainless Steels ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Elongation To Failure ◽  
A Minor

Hydrogen was doped in austenitic stainless steel (ASS) 316L tensile samples produced by the laser-powder bed fusion (L-PBF) technique. For this aim, an electrochemical method was conducted under a high current density of 100 mA/cm2 for three days to examine its sustainability under extreme hydrogen environments at ambient temperatures. The chemical composition of the starting powders contained a high amount of Ni, approximately 12.9 wt.%, as a strong austenite stabilizer. The tensile tests disclosed that hydrogen charging caused a minor reduction in the elongation to failure (approximately 3.5% on average) and ultimate tensile strength (UTS; approximately 2.1% on average) of the samples, using a low strain rate of 1.2 × 10−4 s−1. It was also found that an increase in the strain rate from 1.2 × 10−4 s−1 to 4.8 × 10−4 s−1 led to a reduction of approximately 3.6% on average for the elongation to failure and 1.7% on average for UTS in the pre-charged samples. No trace of martensite was detected in the X-ray diffraction (XRD) analysis of the fractured samples thanks to the high Ni content, which caused a minor reduction in UTS × uniform elongation (UE) (GPa%) after the H charging. Considerable surface tearing was observed for the pre-charged sample after the tensile deformation. Additionally, some cracks were observed to be independent of the melt pool boundaries, indicating that such boundaries cannot necessarily act as a suitable area for the crack propagation.

scholarly journals Strengthening control in laser powder bed fusion of austenitic stainless steels via grain boundary engineering

2021 ◽  
pp. 110246
Author(s):  
Hossein Eskandari Sabzi ◽  
Everth Hernandez-Nava ◽  
Xiao-Hui Li ◽  
Hanwei Fu ◽  
David San-Martín ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Powder Bed Fusion ◽  
Grain Boundary Engineering ◽  
Laser Powder Bed Fusion ◽  
Powder Bed

scholarly journals Compressive Properties of Al-Si Alloy Lattice Structures with Three Different Unit Cells Fabricated via Laser Powder Bed Fusion

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2902 ◽  
Author(s):  
Xiaoyang Liu ◽  
Keito Sekizawa ◽  
Asuka Suzuki ◽  
Naoki Takata ◽  
Makoto Kobashi ◽  
...  
Keyword(s):  
Strain Rate ◽  
Lattice Structure ◽  
Unit Cell ◽  
Lattice Structures ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Compressive Properties ◽  
Powder Bed ◽  
Unit Cells ◽  
Indentation Tests

In the present study, in order to elucidate geometrical features dominating deformation behaviors and their associated compressive properties of lattice structures, AlSi10Mg lattice structures with three different unit cells were fabricated by laser powder bed fusion. Compressive properties were examined by compression and indentation tests, micro X-ray computed tomography (CT), together with finite element analysis. The truncated octahedron- unit cell (TO) lattice structures exhibited highest stiffness and plateau stress among the studied lattice structures. The body centered cubic-unit cell (BCC) and TO lattice structures experienced the formation of shear bands with stress drops, while the hexagon-unit cell (Hexa) lattice structure behaved in a continuous deformation and flat plateau region. The Hexa lattice structure densified at a smaller strain than the BCC and TO lattice structures, due to high density of the struts in the compressive direction. Static and high-speed indentation tests revealed that the TO and Hexa exhibited slight strain rate dependence of the compressive strength, whereas the BCC lattice structure showed a large strain rate dependence. Among the lattice structures in the present study, the TO lattice exhibited the highest energy absorption capacity comparable to previously reported titanium alloy lattice structures.

scholarly journals The origin and formation of oxygen inclusions in austenitic stainless steels manufactured by laser powder bed fusion

2020 ◽  
Vol 35 ◽  
pp. 101334 ◽  
Author(s):  
Pu Deng ◽  
Mallikarjun Karadge ◽  
Raul B. Rebak ◽  
Vipul K. Gupta ◽  
Barton C. Prorok ◽  
...  
Keyword(s):  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed

scholarly journals Laser Powder Bed Fusion of Precipitation-Hardened Martensitic Stainless Steels: A Review

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 255 ◽  
Author(s):  
Le Zai ◽  
Chaoqun Zhang ◽  
Yiqiang Wang ◽  
Wei Guo ◽  
Daniel Wellmann ◽  
...  
Keyword(s):  
Process Parameters ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Machining Process ◽  
Future Research ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Martensitic Stainless Steels

Martensitic stainless steels are widely used in industries due to their high strength and good corrosion resistance performance. Precipitation-hardened (PH) martensitic stainless steels feature very high strength compared with other stainless steels, around 3-4 times the strength of austenitic stainless steels such as 304 and 316. However, the poor workability due to the high strength and hardness induced by precipitation hardening limits the extensive utilization of PH stainless steels as structural components of complex shapes. Laser powder bed fusion (L-PBF) is an attractive additive manufacturing technology, which not only exhibits the advantages of producing complex and precise parts with a short lead time, but also avoids or reduces the subsequent machining process. In this review, the microstructures of martensitic stainless steels in the as-built state, as well as the effects of process parameters, building atmosphere, and heat treatments on the microstructures, are reviewed. Then, the characteristics of defects in the as-built state and the causes are specifically analyzed. Afterward, the effect of process parameters and heat treatment conditions on mechanical properties are summarized and reviewed. Finally, the remaining issues and suggestions on future research on L-PBF of martensitic precipitation-hardened stainless steels are put forward.

scholarly journals AUSTENITIC STAINLESS STEELS MANUFACTURING BY LASER POWDER BED FUSION TECHNIQUE

2020 ◽  
Vol 26 (1) ◽  
pp. 24-26
Author(s):  
Andrea Di Schino ◽  
Paolo Fogarait ◽  
Domenico Corapi ◽  
Orlando Di Pietro ◽  
Chiara Zitelli
Keyword(s):  
Surface Roughness ◽  
Mechanical Behaviour ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Fusion Technique ◽  
Powder Bed ◽  
Dynamic Conditions ◽  
Mechanical Performances

In this paper we report about the possibility to process stainless steels by laser powder bed fusion (L-PBF) systems. Austenitic stainless steels are analysed showing the possibility to successfully process them, targeting different applications. In particular, it is shown that stainless steels can be successfully processed and their mechanical behaviour allow them to be put in service. Porosities inside manufactured components are extremely low and comparable to conventionally processed materials. Mechanical performances are even higher than standard requirements. Micro surface roughness typical of the as-built material can act as crack initiator, reducing the strength in both quasi-static and dynamic conditions.

scholarly journals Strain rate dependent micromechanical properties of NiTi shape memory alloys: laser powder bed fusion versus casting

2021 ◽  
pp. 100055
Author(s):  
Md. Minhazul Islam ◽  
Parisa Bayati ◽  
Mohammadreza Nematollahi ◽  
Ahmadreza Jahadakbar ◽  
Mohammad Elahinia ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Strain Rate ◽  
Shape Memory ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Micromechanical Properties ◽  
Rate Dependent ◽  
Niti Shape Memory Alloys

scholarly journals Temperature- and Time-Dependent Mechanical Behavior of Post-Treated IN625 Alloy Processed by Laser Powder Bed Fusion

2019 ◽  
Vol 3 (3) ◽  
pp. 75
Author(s):  
Alena Kreitcberg ◽  
Karine Inaekyan ◽  
Sylvain Turenne ◽  
Vladimir Brailovski
Keyword(s):  
Hot Isostatic Pressing ◽  
Solution Treatment ◽  
Mechanical Resistance ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Annealed Alloy ◽  
Creep Properties ◽  
Powder Bed ◽  
Elongation To Failure ◽  
Temperature Solution

The microstructure and mechanical properties of IN625 alloy processed by laser powder bed fusion (LPBF) and then subjected to stress relief annealing, high temperature solution treatment, and hot isostatic pressing were studied. Tensile testing to failure was carried out in the 25–871 °C temperature range. Creep testing was conducted at 760 °C under 0.5–0.9 yield stress conditions. The results of the present study provided valuable insights into the static and creep properties of LPBF IN625 alloy, as compared to a wrought annealed alloy of similar composition. It was shown that at temperatures below 538 °C, the mechanical resistance and elongation to failure of the LPBF alloy were similar to those of its wrought counterpart, whereas at higher temperatures, the elongation to failure of the LPBF alloy became significantly lower than that of the wrought alloy. The solution-treated LPBF alloy exhibited significantly improved creep properties at 760 °C as compared to the wrought annealed alloy, especially under intermediate and low levels of stress.

scholarly journals Analysis of As-Built Microstructures and Recrystallization Phenomena on Inconel 625 Alloy Obtained via Laser Powder Bed Fusion (L-PBF)

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 619
Author(s):  
Thibaut De Terris ◽  
Olivier Castelnau ◽  
Zehoua Hadjem-Hamouche ◽  
Halim Haddadi ◽  
Vincent Michel ◽  
...  
Keyword(s):  
Tensile Properties ◽  
Austenitic Stainless Steels ◽  
High Energy ◽  
Energy Conditions ◽  
Inconel 625 ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Dislocation Densities ◽  
Inconel 625 Alloy

The microstructures induced by the laser-powder bed fusion (L-PBF) process have been widely investigated over the last decade, especially on austenitic stainless steels (AISI 316L) and nickel-based superalloys (Inconel 718, Inconel 625). However, the conditions required to initiate recrystallization of L-PBF samples at high temperatures require further investigation, especially regarding the physical origins of substructures (dislocation densities) induced by the L-PBF process. Indeed, the recrystallization widely depends on the specimen substructure, and in the case of the L-PBF process, the substructure is obtained during rapid solidification. In this paper, a comparison is presented between Inconel 625 specimens obtained with different laser-powder bed fusion (L-PBF) conditions. The effects of the energy density (VED) values on as-built and heat-under microstructures are also investigated. It is first shown that L-PBF specimens created with high-energy conditions recrystallize earlier due to a larger density of geometrically necessary dislocations. Moreover, it is shown that lower energy densities offers better tensile properties for as-built specimens. However, an appropriate heat treatment makes it possible to homogenize the tensile properties.

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