scholarly journals Microstructures and Mechanical Properties of Hybrid, Additively Manufactured Ti6Al4V after Thermomechanical Processing

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1039
Author(s):  
Susanne Hemes ◽  
Frank Meiners ◽  
Irina Sizova ◽  
Rebar Hama-Saleh ◽  
Daniel Röhrens ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermomechanical Processing ◽  
Hot Forging ◽  
Tensile Tests ◽  
Beta Phase ◽  
Beta Transus ◽  
Temperature Range ◽  
Fine Grained ◽  
Transus Temperature ◽  
Directed Energy

In the present study, we propose a hybrid manufacturing route to produce high-quality Ti6Al4V parts, combining additive powder laser directed energy deposition (L-DED) for manufacturing of preforms, with subsequent hot forging as a thermomechanical processing (TMP) step. After L-DED, the material was hot formed at two different temperatures (930 °C and 1070 °C) and subsequently heat-treated for stress relief annealing. Tensile tests were performed on small sub-samples, taking into account different sample orientations with respect to the L-DED build direction and resulting in very good tensile strengths and ductility properties, similar or superior to the forged material. The resulting microstructure consists of very fine grained, partially globularized alpha grains, with a mean diameter ~0.8–2.3 µm, within a beta phase matrix, constituting between 2 and 9% of the sample. After forging in the sub-beta transus temperature range, the typical L-DED microstructure was no longer discernible and the anisotropy in tensile properties, common in additive manufacturing (AM), was significantly reduced. However, forging in the super-beta transus temperature range resulted in remaining anisotropies in the mechanical properties as well as an inferior tensile strength and ductility of the material. It was shown, that by combining L-DED with thermomechanical processing in the sub-beta transus temperature range of Ti6Al4V, a suitable microstructure and desirable mechanical properties for many applications can be obtained, with the advantage of reducing the material waste.

Mechanical Properties of Fine-Grained and Ultrafine-Grained Ti-6Al-4V with Equiaxed and Bimodal Microstructures

2016 ◽  
Vol 879 ◽  
pp. 344-349 ◽  
Author(s):  
Yan Chong ◽  
Nobuhiro Tsuji
Keyword(s):  
Mechanical Properties ◽  
Thermomechanical Processing ◽  
Uniform Elongation ◽  
True Strain ◽  
Tensile Tests ◽  
Initial Microstructure ◽  
Equiaxed Microstructure ◽  
Fine Grained ◽  
Ultrafine Grained ◽  
Mean Grain Size

With the purpose of fabricating equiaxed and bimodal Ti-6Al-4V alloy with different grain/primary α (αp) sizes, thermomechanical processing and additional annealing were carried out on samples with martensite initial microstructure. Deformation at 700°C with a strain rate of 0.01s-1 to a true strain of 0.8 could effectively break the martensite initial microstructure into ultrafine-grained (UFG) equiaxed microstructure (mean grain size of 0.51μm) with reasonable uniformity. Subsequent annealing at 930°C with different periods were conducted to change the equiaxed microstructure into bimodal microstructures. The holing time proved to be more critical than heating rate for determining the αp size. An UFG bimodal Ti-6Al-4V with the average αp size of 0.55μm was successfully obtained for the first time by annealing the UFG equiaxed Ti-6Al-4V at 930°C for 2 seconds. The mechanical properties of the equiaxed and bimodal Ti-6Al-4V with different grain/αp sizes were evaluated by tensile tests at room temperature. The bimodal Ti-6Al-4V showed superior balance between strength and uniform elongation than that of the equiaxed Ti-6Al-4V. Moreover, the uniform elongation in the bimodal Ti-6Al-4V was nearly unaffected by reduction of the αp size.

scholarly journals Strength Enhancement of Superduplex Stainless Steel Using Thermomechanical Processing

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1094
Author(s):  
M. A. Lakhdari ◽  
F. Krajcarz ◽  
J. D. Mithieux ◽  
H. P. Van Landeghem ◽  
M. Veron
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Thermomechanical Processing ◽  
Tensile Tests ◽  
Image Correlation ◽  
Strength Enhancement ◽  
Industrial Material ◽  
Superduplex Stainless Steel ◽  
The Impact ◽  
Strength Improvement

The impact of microstructure evolution on mechanical properties in superduplex stainless steel UNS S32750 (EN 1.4410) was investigated. To this end, different thermomechanical treatments were carried out in order to obtain clearly distinct duplex microstructures. Optical microscopy and scanning electron microscopy, together with texture measurements, were used to characterize the morphology and the preferred orientations of ferrite and austenite in all microstructures. Additionally, the mechanical properties were assessed by tensile tests with digital image correlation. Phase morphology was not found to significantly affect the mechanical properties and neither were phase volume fractions within 13% of the 50/50 ratio. Austenite texture was the same combined Goss/Brass texture regardless of thermomechanical processing, while ferrite texture was mainly described by α-fiber orientations. Ferrite texture and average phase spacing were found to have a notable effect on mechanical properties. One of the original microstructures of superduplex stainless steel obtained here shows a strength improvement by the order of 120 MPa over the industrial material.

Formability and Process Conditions of Magnesium Alloy Sheets

2005 ◽  
Vol 488-489 ◽  
pp. 453-456 ◽  
Author(s):  
Shi Hong Zhang ◽  
Yong Chao Xu ◽  
G. Palumbo ◽  
S. Pinto ◽  
Luigi Tricarico ◽  
...  
Keyword(s):  
Deep Drawing ◽  
Tensile Tests ◽  
Process Conditions ◽  
Drawing Ratio ◽  
Temperature Range ◽  
Fine Grained ◽  
Axial Tensile ◽  
Die Surface ◽  
Lower Temperature Range ◽  
Lower Temperature

Comparing the formability with each other, extrusion and various rolling experiments were carried out to make fine-grained AZ31 Mg sheets, and uni-axial tensile tests were carried out at different strain rates and temperatures to investigate the effect of different variables. A warm deep drawing tool setup with heating elements, which were distributed under the die surface and inside the blank holder, was designed and manufactured, and deep drawing was performed. Extruded Mg alloy AZ31 sheets exhibit the best deep drawing ability when working in the temperature range 250-350°C. Extruded and rolled sheets of 0.8 mm thick were also deep drawn in the lower temperature range 105-170°C，showing good formability and reaching a Limit Drawing Ratio up to 2.6 at 170°C for rolled sheets. At last, a sheet cup 0.4 mm thick was deep drawn successfully at 170 °C.

scholarly journals The Influence of Layer Thickness on the Microstructure and Mechanical Properties of M300 Maraging Steel Additively Manufactured by LENS® Technology

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 603
Author(s):  
Natalia Rońda ◽  
Krzysztof Grzelak ◽  
Marek Polański ◽  
Julita Dworecka-Wójcik
Keyword(s):  
Mechanical Properties ◽  
Layer Thickness ◽  
Maraging Steel ◽  
Structural Integrity ◽  
Tensile Tests ◽  
Dendritic Microstructure ◽  
Fine Grained ◽  
Laser Engineered Net Shaping ◽  
Microstructure And Mechanical Properties ◽  
Net Shaping

This work investigates the effect of layer thickness on the microstructure and mechanical properties of M300 maraging steel produced by Laser Engineered Net Shaping (LENS®) technique. The microstructure was characterized using light microscopy (LM) and scanning electron microscopy (SEM). The mechanical properties were characterized by tensile tests and microhardness measurements. The porosity and mechanical properties were found to be highly dependent on the layer thickness. Increasing the layer thickness increased the porosity of the manufactured parts while degrading their mechanical properties. Moreover, etched samples revealed a fine cellular dendritic microstructure; decreasing the layer thickness caused the microstructure to become fine-grained. Tests showed that for samples manufactured with the chosen laser power, a layer thickness of more than 0.75 mm is too high to maintain the structural integrity of the deposited material.

scholarly journals Microstructural Characterization and Mechanical Properties of L-PBF Processed 316 L at Cryogenic Temperature

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5856
Author(s):  
Pragya Mishra ◽  
Pia Åkerfeldt ◽  
Farnoosh Forouzan ◽  
Fredrik Svahn ◽  
Yuan Zhong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cryogenic Temperature ◽  
Room Temperature ◽  
Mechanical Performance ◽  
Microstructural Characterization ◽  
Tensile Tests ◽  
Phase Changes ◽  
X Ray Diffraction ◽  
Temperature Range ◽  
Aerospace Applications

Laser powder bed fusion (L-PBF) has attracted great interest in the aerospace and medical sectors because it can produce complex and lightweight parts with high accuracy. Austenitic stainless steel alloy 316 L is widely used in many applications due to its good mechanical properties and high corrosion resistance over a wide temperature range. In this study, L-PBF-processed 316 L was investigated for its suitability in aerospace applications at cryogenic service temperatures and the behavior at cryogenic temperature was compared with room temperature to understand the properties and microstructural changes within this temperature range. Tensile tests were performed at room temperature and at −196 °C to study the mechanical performance and phase changes. The microstructure and fracture surfaces were characterized using scanning electron microscopy, and the phases were analyzed by X-ray diffraction. The results showed a significant increase in the strength of 316 L at −196 °C, while its ductility remained at an acceptable level. The results indicated the formation of ε and α martensite during cryogenic testing, which explained the increase in strength. Nanoindentation revealed different hardness values, indicating the different mechanical properties of austenite (γ), strained austenite, body-centered cubic martensite (α), and hexagonal close-packed martensite (ε) formed during the tensile tests due to mechanical deformation.

Phase Stability and Mechanical Properties of Ti(Ni, Ru) Alloys

2002 ◽  
Vol 753 ◽  
Author(s):  
Masahiro Tsuji ◽  
Hideki Hosoda ◽  
Kenji Wakashima ◽  
Yoko Yamabe-Mitarai
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
Phase Stability ◽  
Hot Forging ◽  
Tensile Tests ◽  
Lattice Parameter ◽  
Solid Solution Hardening ◽  
Scanning Calorimetry ◽  
Arc Melting ◽  
Transmission Electron

ABSTRACTEffects of ruthenium (Ru) substitution on constituent phases, phase transformation temperatures and mechanical properties were investigated for Ti-Ni shape memory alloys. Ti50Ni50-XRuX alloys with Ru contents (X) from 0mol% (binary TiNi) to 50mol% (binary TiRu) were systematically prepared by Ar arc-melting followed by hot-forging at temperatures from 1173K to 1673K depending on chemical composition. Phase stability was assessed by DSC (differential scanning calorimetry), XRD (X-ray diffractometry) and TEM (transmission electron microscopy). Mechanical properties were investigated using hardness and tensile tests at room temperature. With increasing Ru content, it was found that the lattice parameter of B2 phase increases, the martensitic transformation temperature slightly decreases, and the melting temperature increases monotonously. Besides, R-phase appears for Ti-Ni alloys containing 3mol% and 20mol%Ru but no diffusionless phase transformation is seen in Ti-Ni alloy containing 5mol%Ru. Vickers hardness shows the maximum at an intermediate composition (HV1030 at 30mol%Ru); this suggests that large solid solution hardening is caused by Ru substitution for the Ni-sites in TiNi.

Reduction of Elastic Modulus of Titanium Alloy Ti-6Al-4V by Quenching

2013 ◽  
Vol 586 ◽  
pp. 15-18 ◽  
Author(s):  
Evgeniy Anisimov ◽  
Maxim Puchnin
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Elastic Modulus ◽  
Qualitative Analysis ◽  
Beta Phase ◽  
Beta Transus ◽  
Surface Layers ◽  
Double Phase ◽  
Low Modulus

The use of nanoindentation techniques enhances the capabilities of qualitative analysis of elasto-plastic characteristics, especially, estimating mechanical properties of relatively small specimens in their surface layers. The results are in agreement with macromethods, which gather the information over the higher volume of the material. It was confirmed, that hardening of double phase Ti-6Al-4V alloy by quenching from beta temperatures (above beta-transus), reduces the elastic modulus by about 8 % due to increased ratio of low-modulus beta phase from 8 to 34 %.

Effect of High Strain-Rate Thermomechanical Processing on Microstructure and Mechanical Properties of Ti-10V-2Fe-3Al Alloy

2013 ◽  
Vol 845 ◽  
pp. 96-100 ◽  
Author(s):  
Piotr Skubisz ◽  
Marek Packo ◽  
Katarzyna Mordalska ◽  
Tadeusz Skowronek
Keyword(s):  
Mechanical Properties ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Thermomechanical Processing ◽  
Hot Forging ◽  
High Strength ◽  
Processing Route ◽  
Microstructure And Mechanical Properties ◽  
Processed Material

Results of beta forging of titanium alloy Ti-10V-2Fe-3Al and subsequent thermal treatment are presented, with analysis of the effect of the processing route on the final mechanical properties, correlated with microstructure of thermomechanically processed material. Investigation of response to high strain-rate hot-forging of microstructure and mechanical properties is focused on the effect of the strengthening mechanisms in the material after two common manners of deformation typical of that alloy. The effect of deformation conditions on final microstructure and mechanical properties was analyzed in three crucial stages of thermomechanical processing, e.i. after deformation, quenching and aging. In result, conclusions were formulated as for processing conditions promoting high strength and/or ductility.

Investigation on the Microstructure and Mechanical Properties of Hot Forged Mg−8Gd−2Y−1Nd−0.3Zn−0.6Zr Alloy

2011 ◽  
Vol 284-286 ◽  
pp. 1598-1602 ◽  
Author(s):  
Xiu Li Hou ◽  
Zhan Yi Cao ◽  
Li Dong Wang ◽  
Li Min Wang
Keyword(s):  
Mechanical Properties ◽  
Large Strain ◽  
Hot Forging ◽  
Tensile Tests ◽  
Age Hardening ◽  
Secondary Phases ◽  
Ageing Treatment ◽  
Size Refinement ◽  
Microstructure And Mechanical Properties ◽  
Peak Aged

The influences of hot forging and ageing treatment on the microstructure and mechanical properties of Mg−8Gd−2Y−1Nd−0.3Zn−0.6Zr (wt.%) alloy have been investigated. The results showed that the grains were significantly refined after hot forging. And the secondary phases in this alloy i.e. Mg5(Gd1-x-yNdxYy) and Mg24(Y1-x-yGdxNdy)5phases were fragmented to small particles due to the large strain during hot forging. Tensile tests revealed that mechanical properties were improved due to grain size refinement. Moreover, the as-forged alloy exhibited remarkable age-hardening response and mechanical properties were further improved by ageing treatment. The ultimate tensile strength, yield strength and elongation of the peak-aged (T5) alloy are 286 MPa, 245 MPa and 5.6 % at room temperature, and 211 MPa, 103 MPa and 19.4 % at 300°C, respectively.

Statistical Analysis of Tensile Tests Performed on 316L Specimens Manufactured by Directed Energy Deposition

2020 ◽  
Author(s):  
A. P. Iliopoulos ◽  
J. P. Thomas ◽  
J. C. Steuben ◽  
R. Saunders ◽  
J. G. Michopoulos ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Statistical Analysis ◽  
Energy Deposition ◽  
316L Stainless Steel ◽  
Failure Strain ◽  
Bulk Material ◽  
Tensile Tests ◽  
Tension Tests ◽  
Directed Energy ◽  
Manufacturing Parameters

Abstract The present work reports on the results of tension tests conducted on 316L stainless steel specimens extracted out of thin-walled boxes produced by powder jet additive manufacturing. The specimens were minimally processed to study the potential effects of the manufacturing process on the apparent mechanical properties rather than identifying the properties of the resulting bulk material. Statistical analysis is performed and presented in an attempt to identify correlations between the manufacturing parameters and the apparent mechanical properties. The mechanical properties of interest are Young’s modulus, the yield stress (measured at the 0.2% level), the ultimate stress, and the failure strain.

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