Structure and Mechanical Properties of Laser Powder Bed-Fused and Wrought PH13-8Mo-Type Precipitation Hardening Stainless Steels: Comparative Study

This work focuses on the structure and properties of a laser powder bed-fused (LPBF) precipitation hardening stainless steel and its chemically analogous wrought counterpart, both subjected to an identical combination of solution and aging treatments with the objective of maximizing the material hardness. It was observed that both the LPBF and wrought alloy follows similar evolution of their phase composition, microstructure, and mechanical properties throughout the different stages of the technological workflow. After a solution treatment at 850 °C for 0.5 h and an aging at 525 °C for 2 h, both alloys achieve their highest hardness of ~50 HRC. Notwithstanding this similarity, the LPBF alloy offers a finer microstructure and a lower amount of retained austenite than its wrought counterpart. This microstructure provides comparable strength characteristics to both the LPBF and wrought alloys, while offering a significantly higher ductility to the former as compared to the latter. The elongation at break of the LPBF alloy is, however, strongly build orientation-dependent, with a measured anisotropy of 23%. This anisotropy is caused by the presence of processing-induced pores (average pore size ~23 µm) in the LPBF alloy preferably distributed in planes oriented perpendicular to the build direction.

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Mechanical Properties and Aging Behavior of Ultrafine Grained Al-Ag Alloy Fabricated by Accumulative Roll-Bonding

Materials Science Forum ◽

10.4028/www.scientific.net/msf.794-796.851 ◽

2014 ◽

Vol 794-796 ◽

pp. 851-856

Author(s):

Tadashiege Nagae ◽

Nobuhiro Tsuji ◽

Daisuke Terada

Keyword(s):

Mechanical Properties ◽

Grain Refinement ◽

Accumulative Roll Bonding ◽

Precipitation Hardening ◽

Tensile Elongation ◽

Solution Treatment ◽

High Strength ◽

Subsequent Aging ◽

Roll Bonding ◽

Ultrafine Grained

Accumulative roll-bonding (ARB) process is one of the severe plastic deformation processes for fabricating ultrafine grained materials that exhibit high strength. In aluminum alloys, aging heat treatment has been an important process for hardening materials. In order to achieve good mechanical properties through the combination of grain refinement hardening and precipitation hardening, an Al-4.2wt%Ag binary alloy was used in the present study. After a solution treatment at 550°C for 1.5hr, the alloy was severely deformed by the ARB process at room temperature (RT) up to 6 cycles (equivalent strain of 4.8). The specimens ARB-processed by various cycles (various strains) were subsequently aged at 100, 150, 200, 250°C, and RT. The hardness of the solution treated (ST) specimen increased by aging. On the other hand, hardness of the ARB processed specimen decreased after aging at high temperatures such as 250°C. This was probably due to coarsening of precipitates or/and matrix grains. The specimen aged at lower temperature showed higher hardness. The maximum harnesses achieved by aging for the ST specimen, the specimens ARB processed by 2 cycles, 4 cycles and 6 cycles were 55HV, 71HV, 69HV and 65HV, respectively. By tensile tests it was shown that the strength increased by the ARB process though the elongation decreased significantly. However, it was found that the tensile elongation of the ARB processed specimens was improved by aging without sacrificing the strength. The results suggest that the Al-Ag alloy having large elongation as well as high strength can be realized by the combination of the ARB process for grain refinement and the subsequent aging for precipitation hardening.

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Microstructure and Mechanical Behavior of CaCu3Ti4O12 Ceramics Hollow Fiber Prepared via Dry/Wet Spinning Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1010.239 ◽

2020 ◽

Vol 1010 ◽

pp. 239-243

Author(s):

Mohsen Ahmadipour ◽

Tunmise Ayode Otitoju ◽

Mohammad Arjmand ◽

Zainal Arifin Ahmad ◽

Swee Yong Pung

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Hollow Fiber ◽

Outer Layer ◽

Pore Diameter ◽

Hollow Fibers ◽

Wet Spinning ◽

Outer Diameter ◽

Average Pore ◽

Elongation At Break

Dry/wet method was used to prepare CaCuTi4O12 (CCTO) hollow fibers (HFs) and then the structural and physico-mechanical properties of HFs were characterized by XRD, FESEM, BET and tensile strength, respectively. The outer diameter and thickness of CCTO HFs were found to be 650 μm and 390 μm, respectively. A finger-like macrovoids and sponge-like was observed inside the membrane with a denser structure in the outer layer. It was observed that the crystallite size was increased from 28.5 nm to 37.0 nm while the average pore diameter was decreased from 34.65 nm to 29.16 nm in CCTO hollow fiber with 1.0 wt.% CCTO. In addition, the tensile strength of HFS was significantly improved from 4.84 MPa to 5.54 MPa and elongation at break was decreased from 6.97 % to 5.09 % which is ascribed to the reduction in porosity. All the results indicated the significant effect of CCTO content on properties of CCTO hollow fibers. The finding in this study could lead to a new direction to enhance the properties of HFS with potential application in membranes.

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Physicochemical and Mechanical Properties of Blow Spun Nanofibrous Prostheses Modified with Acrylic Acid and REDV Peptide

Coatings ◽

10.3390/coatings10111110 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1110

Author(s):

Beata A. Butruk-Raszeja ◽

Aleksandra Kuźmińska ◽

Michał Wojasiński ◽

Zuzanna Piotrowska

Keyword(s):

Mechanical Properties ◽

Fiber Diameter ◽

Flow System ◽

Average Pore Size ◽

Internal Diameter ◽

Optimal Parameters ◽

Average Pore ◽

Vascular Prostheses ◽

Modification Process ◽

Inner Surface

The paper presents a method of modifying the inner surface of nanofibrous vascular prostheses. The modification process involves two steps: introducing a hydrophilic linker, followed by a peptide containing the arginine-glutamic acid-aspartic acid-valine (REDV) sequence. The influence of the process parameters (reaction time, temperature, initiator concentration) on morphology and the distribution of fiber diameters were examined. For selected optimal parameters, the prostheses were modified in the flow system. Modifications along the entire length of the prosthesis were confirmed—the inlet and the outlet areas showed no significant (p > 0.05) differences in the value of the contact angle and the analyzed morphological parameters. The basic physicochemical and mechanical properties of modified prostheses were analyzed. The study showed that REDV-modified prosthesis has an average fiber diameter of 318 ± 99 nm, the average pore size of 3.0 ± 1.6 μm, the porosity of 48.4 ± 8.6% and Young’s modulus of 4.0 ± 0.4 MPa. The internal diameter of prostheses remains unchained and amounts to 3 mm. Such modified prostheses can reduce the risk of blood coagulation by increasing the surface’s wettability and, most of all, by introducing endothelial cell-selective peptide. As an effect, the proposed surfaces could recruit endothelial progenitor cells directly from the bloodstream and promote the endothelium formation after implantation.

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Alginate/Gelatin Hydrogels Reinforced with TiO2 and β-TCP Fabricated by Microextrusion-based Printing for Tissue Regeneration

Polymers ◽

10.3390/polym11030457 ◽

2019 ◽

Vol 11 (3) ◽

pp. 457 ◽

Cited By ~ 9

Author(s):

Rodrigo Urruela-Barrios ◽

Erick Ramírez-Cedillo ◽

A. Díaz de León ◽

Alejandro Alvarez ◽

Wendy Ortega-Lara

Keyword(s):

Mechanical Properties ◽

Tissue Engineering ◽

Tissue Regeneration ◽

Average Pore Size ◽

Three Dimensional ◽

Engineering Applications ◽

Average Pore ◽

Viscous Deformation ◽

Freeze Dried ◽

3D Printed

Three-dimensional (3D) printing technologies have become an attractive manufacturing process to fabricate scaffolds in tissue engineering. Recent research has focused on the fabrication of alginate complex shaped structures that closely mimic biological organs or tissues. Alginates can be effectively manufactured into porous three-dimensional networks for tissue engineering applications. However, the structure, mechanical properties, and shape fidelity of 3D-printed alginate hydrogels used for preparing tissue-engineered scaffolds is difficult to control. In this work, the use of alginate/gelatin hydrogels reinforced with TiO2 and β-tricalcium phosphate was studied to tailor the mechanical properties of 3D-printed hydrogels. The hydrogels reinforced with TiO2 and β-TCP showed enhanced mechanical properties up to 20 MPa of elastic modulus. Furthermore, the pores of the crosslinked printed structures were measured with an average pore size of 200 μm. Additionally, it was found that as more layers of the design were printed, there was an increase of the line width of the bottom layers due to its viscous deformation. Shrinkage of the design when the hydrogel is crosslinked and freeze dried was also measured and found to be up to 27% from the printed design. Overall, the proposed approach enabled fabrication of 3D-printed alginate scaffolds with adequate physical properties for tissue engineering applications.

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Mechanical Properties of Micro-Porous Metals Produced by Space-Holding Sintering

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.29-30.75 ◽

2007 ◽

Vol 29-30 ◽

pp. 75-78 ◽

Cited By ~ 3

Author(s):

Takumi Banno ◽

Yun Cang Li ◽

Cui E Wen ◽

Yasuo Yamada

Keyword(s):

Mechanical Properties ◽

Cell Structure ◽

Deformation Behaviour ◽

Average Pore Size ◽

Chemical Vapour ◽

Porous Nickel ◽

Porous Metals ◽

Average Pore ◽

Nickel Foams ◽

Compressive Tests

Micro-porous nickel foams with an open cell structure were fabricated by the space-holding sintering. The average pore size of the micro-porous nickel specimens ranged from 30 μm to 150 μm, and the porosity ranged from 60 % to 80 %. The porous characteristics of the nickel specimens were observed using scanning electron microscopy (SEM). The mechanical properties were studied using compressive tests. For comparison, macro-porous nickel foams prepared by the chemical vapour deposition method with pore sizes of 800 μm and 1300 μm and porosity of 95 % were also presented. Results indicated that the ratio value of 6 and higher for the specimen length to cell size (L/d) is satisfying for obtaining stable compressive properties. The micro-porous nickel specimens exhibited different deformation behaviour and dramatically increased mechanical properties, compared to those of the macro-porous nickel specimens.

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Determination of Local Mechanical Properties of Si3N4 Based Foams

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.606.213 ◽

2014 ◽

Vol 606 ◽

pp. 213-216 ◽

Cited By ~ 1

Author(s):

Zuzana Vilčeková ◽

Monika Kašiarová ◽

Magdaléna Domanická ◽

Miroslav Hnatko ◽

Pavol Šajgalík

Keyword(s):

Mechanical Properties ◽

Silicon Nitride ◽

Resonant Frequency ◽

Volume Fraction ◽

Average Pore Size ◽

Polyurethane Foams ◽

Average Pore ◽

Replication Method ◽

Highly Porous

Local mechanical properties, particularly the hardness and Youngs modulus of highly porous silicon nitride based foams were studied in this work. Silicon nitride foams were prepared using polyurethane foam replication method to obtain appropriate cellular structure suitable for bio-application. Two types of the polyurethane foams were used (with average pore size 0.48 mm and 0.62 mm). Some of these samples were prepared by single or multiple infiltrations. The effects of structures, temperature of calcination, volume fraction of Si3N4 powder and number of the infiltrations on the local mechanical properties were investigated. The Youngs modulus of studied samples range from 12 to 46 GPa at the macroscopic scale measured by resonant frequency technique and from 10 to 28 GPa at the microscopic scale measured by instrumented indentation. Results showed increase of the hardness and Youngs modulus with increasing of the calcination temperature, with increasing of the number of infiltrations and also with increasing of volume fraction of Si3N4 powder in suspension. The results obtained from nanoindentation carry out lower values in comparison with the values measured by resonant frequency technique.

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Optimization of a Solution Treatment in the Al-Cu-Mg-Ag Alloy via a Microstructural Investigation

Metals ◽

10.3390/met12010066 ◽

2021 ◽

Vol 12 (1) ◽

pp. 66

Author(s):

Hyeongsub So ◽

Jae-Hong Shin ◽

Leeseung Kang ◽

Chanuk Jeong ◽

Kyou-Hyun Kim

Keyword(s):

Mechanical Properties ◽

Mechanical Strength ◽

Grain Growth ◽

Microstructural Evolution ◽

Precipitation Hardening ◽

Solution Treatment ◽

Solution Temperature ◽

Al Alloy ◽

Microstructural Investigation ◽

Large Particles

We investigated the effect of solution temperature (Tsol. = 440–530 °C) on the mechanical properties of the Al–3.4Cu–0.34Mg–0.3Mn–0.17Ag alloy, finding that the investigated Al alloy showed the highest mechanical strength of σUTS = ~329 MPa at a Tsol. value of 470 °C. The microstructural investigation demonstrates that the mechanical properties for different Tsol. values stem from grain growth, precipitation hardening, and the formation of large particles at the grain boundaries. On the basis of Tsol. = 470 °C, the effect of each microstructural evolution is significantly different on the mechanical properties. In this study, the relationships between the microstructural evolution and the mechanical properties were investigated with respect to different values of Tsol.

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Short Heat Treatments for the F357 Aluminum Alloy Processed by Laser Powder Bed Fusion

Materials ◽

10.3390/ma14206157 ◽

2021 ◽

Vol 14 (20) ◽

pp. 6157

Author(s):

Matteo Vanzetti ◽

Enrico Virgillito ◽

Alberta Aversa ◽

Diego Manfredi ◽

Federica Bondioli ◽

...

Keyword(s):

Heat Treatment ◽

Precipitation Hardening ◽

Solution Treatment ◽

Heat Treatments ◽

Point Of View ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Heat Treated ◽

Direct Aging

Conventionally processed precipitation hardening aluminum alloys are generally treated with T6 heat treatments which are time-consuming and generally optimized for conventionally processed microstructures. Alternatively, parts produced by laser powder bed fusion (L-PBF) are characterized by unique microstructures made of very fine and metastable phases. These peculiar features require specifically optimized heat treatments. This work evaluates the effects of a short T6 heat treatment on L-PBF AlSi7Mg samples. The samples underwent a solution step of 15 min at 540 °C followed by water quenching and subsequently by an artificial aging at 170 °C for 2–8 h. The heat treated samples were characterized from a microstructural and mechanical point of view and compared with both as-built and direct aging (DA) treated samples. The results show that a 15 min solution treatment at 540 °C allows the dissolution of the very fine phases obtained during the L-PBF process; the subsequent heat treatment at 170 °C for 6 h makes it possible to obtain slightly lower tensile properties compared to those of the standard T6. With respect to the DA samples, higher elongation was achieved. These results show that this heat treatment can be of great benefit for the industry.

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Properties of Hydrophilic Chitosan/Polysulfone Nanofibrous Filtration Membrane

Journal of Engineered Fibers and Fabrics ◽

10.1177/155892501400900109 ◽

2014 ◽

Vol 9 (1) ◽

pp. 155892501400900 ◽

Cited By ~ 2

Author(s):

Leigen Liu ◽

Zhijuan Pan

Keyword(s):

Mechanical Properties ◽

Pore Size ◽

Average Pore Size ◽

High Surface ◽

Chitosan Solution ◽

Water Filtration ◽

Average Pore ◽

Filtration Membrane ◽

Crosslinked Chitosan ◽

Nanofibrous Membranes

Electrospun nanofibrous membranes are useful water filtration materials due to their high interconnected porosity and tunable pore sizes, which cause very high permeability and selectivity. However, poor mechanical properties and easy fouling due to their extremely high surface area limit their applications. Therefore, it is desirable to enhance the mechanical properties and the hydrophilicity of such electrospun nanofibrous membranes. In this paper, electrospun polysulfone (PSF) nanofibrous membranes were treated with plasma. Crosslinked chitosan solution was then employed to pad the membranes. We studied the influence of the chitosan concentration and the volume of glutaraldehyde on the morphology, porosity structure, mechanical properties and hydrophilicity of electrospun polysulfone nanofibrous membranes. The results showed that the average pore size decreased from 4.5 μm to 2.68 μm, the breaking stress increased from 6.01±0.44 MPa to 9.25±0.45 MPa, and the water contact angle decreased from 130.8° to 0° in 30 s when chitosan was applied to the membranes. These changes occurred by padding due to the crosslinked chitosan solution. The results indicate that a significant improvement occurred in the mechanical properties; the highly hydrophobic PSF membrane was changed to a superhydrophilic one and the pore size was reduced. These results encouraged us to propose this material as a water filtration membrane with longer life span, lower fouling and higher rejection efficiency.

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Effects of Aging Parameters on the Mechanical Properties in Corson Alloy System with High Contents of Ni and Si

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.2568 ◽

2010 ◽

Vol 654-656 ◽

pp. 2568-2571 ◽

Cited By ~ 4

Author(s):

Genjiro Hagino ◽

Hayao Eguchi ◽

Yoshimasa Takayama ◽

Hajime Kato

Keyword(s):

Mechanical Properties ◽

Electrical Conductivity ◽

Tensile Strength ◽

Precipitation Hardening ◽

Solution Treatment ◽

Alloy System ◽

Linear Analysis ◽

Matrix Phase ◽

Maximum Hardness ◽

Effects Of Aging

The influences of solution treatments, prior cold drawings and aging treatments on mechanical properties in Corson alloy with high contents more than 8.0 mass% of Ni and Si have been investigated. As a result of the optimization of conditions, the maximum hardness and tensile strength reached 306HV and 968MPa, respectively. Effects of temperatures of solution treatment and aging on the mechanical properties were analyzed based on solid solute concentrations in matrix phase, which were estimated by using the linear analysis and calculated from the electrical conductivity. The solute concentrations were also measured directly by SEM-EDS. Consequently, the precipitation hardening of the alloys was governed mainly by the solute concentrations of Ni and Si in matrix phase in solution treatment. The hardness depended on not only the solute concentrations but also the excess of Ni and Si in the alloys.

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