scholarly journals Crystallographic Texture Analysis of As-Built and Heat-Treated Ti6Al4V (ELI) Produced by Direct Metal Laser Sintering

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 699
Author(s):  
Amos Muiruri ◽  
Maina Maringa ◽  
Willie du Preez
Keyword(s):  
Heat Treatment ◽  
Crystallographic Texture ◽  
Transformation Temperature ◽  
Electron Backscatter Diffraction ◽  
Laser Sintering ◽  
Reconstruction Method ◽  
Direct Metal Laser Sintering ◽  
Β Phase ◽  
Ebsd Data ◽  
Heat Treated

This paper reports on an investigation of crystallographic texture of as-built and heat-treated Ti6Al4V (ELI) produced by direct metal laser sintering (DMLS). The texture analyses were conducted using electron backscatter diffraction (EBSD). The β-phase texture from the obtained EBSD data was ascertained based on a reconstruction method using the Automatic Reconstruction of Parent Grain for EBSD data (ARPGE) program. A significant improvement of the maximum intensity of the texture from the pole figure was also noted upon heat treatment. The as-built samples and samples heat-treated just below the α→β transformation temperature showed a stronger fibrous texture of the reconstructed β-grains with the ⟨100⟩ directions almost parallel to the build direction. The alignment of the fibrous texture in the build direction disappeared after heat treatment above the α→β-grain transformation temperature.

Influence of post-heat treatment on microstructure, mechanical, and wear properties of maraging steel fabricated using direct metal laser sintering technique

2021 ◽  
pp. 146442072110373
Author(s):  
Anand Kumar Subramaniyan ◽  
Sudarshan Reddy Anigani ◽  
Snehith Mathias ◽  
Akshay Pathania ◽  
Prasad Raghupatruni ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Maraging Steel ◽  
Laser Sintering ◽  
Direct Metal Laser Sintering ◽  
Wear Properties ◽  
Post Heat Treatment ◽  
Heat Treated Sample ◽  
Heat Treated ◽  
Treated Sample

The post-heat treatment of direct metal laser sintered parts is expected to have superior mechanical properties. Therefore, the purpose of the present study is to investigate the post-heat treatment effect on the microstructure, mechanical and wear properties of direct metal laser sintering processed maraging steel. Hence, a systematic methodology for microstructural characterization, mechanical properties, and tribological performance evaluation was performed. The microstructural examinations were performed using optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction technique. The micro-hardness and tensile properties were determined. The unidirectional sliding wear test was performed using a pin on disc wear testing machine for three different sliding velocities (0.8, 1.2, and 1.6 m/s) and three different normal loads (5, 10, and 15 N). The present study’s findings establish that the post-heat treatment techniques significantly altered the microstructural morphology and features. The results showed that the heat-treated sample had finer and non-continuous microstructure and more complex intermetallic precipitate phases, leading to higher hardness (∼64%) and higher tensile strength properties (70–80%) compared to the as-printed sample. The unidirectional sliding wear test results showed that the sliding velocity significantly affected frictional and wear characteristics of direct metal laser sintering processed maraging steel. The wear resistance of the heat-treated sample was three times higher than the as-printed sample, particularly at higher sliding velocities. In addition, the lower coefficient of friction values (∼24%) was observed for heat-treated sample compared to as-printed sample at higher sliding velocities. The post-heat treatment aids as an effective method to enhance mechanical properties of direct metal laser sintered parts and qualify them for tribological applications. The results endorse the suitability of the heat-treated direct metal laser sintered maraging steel in practical tool and die applications involving extreme tribological operating conditions such as higher sliding velocities and contact stresses.

scholarly journals Effect of strain rate on α-lath thickness of TC17 alloy after deformation and subsequent heat treatment

2020 ◽  
Vol 321 ◽  
pp. 13003
Author(s):  
Zimin Lu ◽  
Jiao Luo ◽  
Miaoquan Li
Keyword(s):  
Heat Treatment ◽  
Strain Rate ◽  
Electron Backscatter Diffraction ◽  
Phase Region ◽  
Subsequent Heat Treatment ◽  
Strain Rates ◽  
Optical Micrograph ◽  
Β Phase ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Effect of strain rate on α-lath thickness of TC17 alloy with a basketweave microstructure was studied in the present work. For this purpose, this alloy was deformed in the β phase region and subsequently soluted and aged in α+β phase region. Moreover, optical micrograph (OM) and electron backscatter diffraction (EBSD) were applied to analyze the change of lath thickness at different strain rates. The result showed that α-lath thickness increased with increasing strain rate. This phenomenon was possibly attributed to the higher degree of variant selection (DVS) at higher strain rate (0.1 s-1). The higher DVS was beneficial for the formation of parallel α-lath colonies during cooling after deformation. And, these parallel α-lath colonies would more easily grow up and coarsen during subsequent heat treatment. Therefore, α-lath at higher strain rate is more thick.

The Effect of Oxygen on Heat Treatment Behavior of Titanium-50mass%Tantalum-5mass%Zirconium Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 3613-3618
Author(s):  
Masahiko Ikeda ◽  
Masaaki Mori
Keyword(s):  
Heat Treatment ◽  
Shape Memory ◽  
Shape Recovery ◽  
Liquid Nitrogen Temperature ◽  
X Ray Diffraction ◽  
Resistivity Ratio ◽  
Orthorhombic Martensite ◽  
Β Phase ◽  
Heat Treated ◽  
Effect Of Oxygen

To develop new shape memory and super-elastic alloys for medical applications, titanium alloys using non-toxic metallic elements, such as Ta and Nb, are being actively investigated. In this study, aimed at developing new shape memory Ti alloys, we investigate the effect of oxygen, a powerful alpha stabilizing interstitial element, on the heat treatment behavior of Ti-50mass%Ta-5mass%Zr through electrical resistivity and Vickers hardness measurements and shape-recovery tests. Ti-50Ta-5Zr-0.14Ox and 0.33Ox alloys, and the β and α” bi-phase was confirmed by XRD. Only the β phase was identified in the Ti-50Ta-5Zr-0.62Ox alloy. Upon isochronal heat treatment, the resistivity at LN and resistivity ratio of Zr-0.33 and 0.62Ox alloys decreased up to around 523 K. In the 5Zr-0.62Ox alloy, orthorhombic martensite and the α” and β phases were identified in the specimens heat-treated at 473 and 523 K. The decreases in resistivity at liquid nitrogen temperature and resistivity ratio are due to the formation of α” during isochronal heat treatment. The formation of α” was confirmed by X-ray diffraction in the 5Zr-0.62Ox alloy. The shape memory effect was observed in 5Zr-0.14 and 0.33Ox alloys and the shape recovery ratio of both alloys was about 40% at 673 K.

scholarly journals High Strain Rate Properties of Various Forms of Ti6Al4V(ELI) Produced by Direct Metal Laser Sintering

2021 ◽  
Vol 11 (17) ◽  
pp. 8005
Author(s):  
Amos Muiruri ◽  
Maina Maringa ◽  
Willie du Preez
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Electron Backscatter Diffraction ◽  
Dynamic Strength ◽  
Strain Rates ◽  
Direct Metal Laser Sintering ◽  
Heat Treated ◽  
Electron Backscatter ◽  
Backscatter Diffraction

For analysis of engineering structural materials to withstand harsh environmental conditions, accurate knowledge of properties such as flow stress and failure over conditions of high strain rate and temperature plays an essential role. Such properties of additively manufactured Ti6Al4V(ELI) are not adequately studied. This paper documents an investigation of the high strain rate and temperature properties of different forms of heat-treated Ti6Al4V(ELI) samples produced by the direct metal laser sintering (DMLS). The microstructure and texture of the heat-treated samples were analysed using a scanning electron microscope (SEM) equipped with an electron backscatter diffraction detector for electron backscatter diffraction (EBSD) analysis. The split Hopkinson pressure bar (SHPB) equipment was used to carry out tests at strain rates of 750, 1500 and 2450 s−1, and temperatures of 25, 200 and 500 °C. The heat-treated samples of DMLS Ti6Al4V(ELI) alloys tested here were found to be sensitive to strain rate and temperature. At most strain rates and temperatures, the samples with finer microstructure exhibited higher dynamic strength and lower strain, while the dynamic strength and strain were lower and higher, respectively, for samples with coarse microstructure. The cut surfaces of the samples tested were characterised by a network of well-formed adiabatic shear bands (ASBs) with cracks propagating along them. The thickness of these ASBs varied with the strain rate, temperature, and various alloy forms.

scholarly journals Analysis of direct metal laser sintering ‒ DMLS and heat treatment influence on the Inconel 713C nickel alloy structure

2021 ◽  
Vol 93 (3) ◽  
pp. 49-56
Author(s):  
Jakub Ciftci ◽  
Ryszard Sitek ◽  
Jarosław Mizera
Keyword(s):  
Heat Treatment ◽  
Nickel Superalloy ◽  
Laser Sintering ◽  
Direct Metal Laser Sintering ◽  
Technological Parameters ◽  
Cast Material ◽  
Hardness Tests ◽  
Ni3al Phase ◽  
The Stability ◽  
Inconel 713C

The group of nickel based superalloys produced in the DMLS (Direct Metal Laser Sintering) process is limited to materials, which produced conventionally do not have properties to allow to use them for rotating components of aircraft engines. This work attempts to optimize the technological parameters of the DMLS process for the Inconel 713C nickel superalloy. A heat treatment was performed for selected samples to investigate the effect on the morphology of the Ni3Al phase. The microstructure analysis and hardness tests were carried out. The material after the DMLS process was characterized by the presence of much smaller dendrites than the cast material and exceeded its hardness. For the tested variants of heat treatment, the material was characterized by smaller sizes of the Ni3Al phase. In order to ensure the stability of the microstructure, an optimization of the dedicated heat treatment after the DMLS process is required, as the standard heat treatment for Inconel 713C cast nickel superalloy does not fully recrystallize the material.

Hydrogen-Induced Microstructure Optimization of the Ti-6Al-4V Alloy

2020 ◽  
Vol 986 ◽  
pp. 24-32
Author(s):  
Mohammed Kasim Mohsun
Keyword(s):  
Heat Treatment ◽  
Electron Backscatter Diffraction ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Martensite Phase ◽  
Hydrogen Gas ◽  
Hydrogen Treatment ◽  
Alloying Element ◽  
X Ray ◽  
Β Phase

To obtain advanced materials through the development of traditional materials without the addition of another alloying element, advanced heat treatment can be used. One such innovative process is a thermo-hydrogen treatment (THT); it facilitates a purposeful adjustment of an improved microstructure using hydrogen as a temporary alloying element within heat treatment. In this paper, the five-step process of homogenization, hydrogenation, solution treatment, dehydrogenation, and aging was used in THT. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), backscattered electron (BSE), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) were utilized to analyze the phases and phase transformations in Ti-6Al-4V. Three different homogeneous microstructures were established for the investigation using different homogenization parameters values. The hydrogenation was carried out for these microstructures via hydrogen gas charging leading to hydrogen concentrations for the formation of hydride (δ TiH2). After the solution treatment at a temperature above β transus temperature (Tβ), the metastable phases of a martensitic structure consisting of a mixture of α ́ (hcp) and α ́ ́ (orthorhombic) was found. Steps 4 and 5 of THT were a vacuum annealing (hydrogen degassing) followed by aging treatment. The aging treatment was applied to complete the martensite phase decomposition and the precipitation of two phases. By means of this THT cycle, very fine equiaxed microstructures could be established. These microstructures consist of the αs phase (secondary α) in the β phase matrix and the α2 phase (Ti3Al) in the αp phase. The precipitation of these phases increases the strength of the Ti-6Al-4V alloy and, consequently, enhances the mechanical properties. No evidence of the δ phase was found.

Crystallographic Texture Change of Pilgered Zirconium Alloy Tubes with Heat Treatment

2007 ◽  
Vol 558-559 ◽  
pp. 1379-1382 ◽  
Author(s):  
Y. Choi ◽  
Hirofumi Inoue
Keyword(s):  
Heat Treatment ◽  
Crystallographic Texture ◽  
Zirconium Alloy ◽  
Electron Backscatter Diffraction ◽  
Longitudinal Direction ◽  
X Ray ◽  
Texture Change ◽  
Zirconium Tube ◽  
Backscatter Diffraction ◽  
Tangential Directions

Crystallographic texture of pilgered zirconium alloy tubes was analyzed by neutron diffraction, electron backscatter diffraction (EBSD) and X-ray techniques to study bulk and local texture change with pilgering and heat treatment above re-crystallization temperature. Pilgering resulted in slightly inclining (001) planes to sample normal direction, and aligning effectively (100) planes to the normal of radial direction, respectively. (001) planes of the zirconium tube uniformly exist in radial and tangential directions, however, the (001) planes moved from tangential to radial directions after pilgering followed by heat treatment for 20 hours at 540°C. Some of (001) and (100) planes of pilgered tube were paralleled to longitudinal direction by re-crystallization.

Corrosion Resistance of Mo-Fe-Ti Alloy for Overpack in Simulating Underground Environment

2010 ◽  
Author(s):  
Toshiyasu Nishimura
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Selective Dissolution ◽  
Immersion Test ◽  
Ti Alloy ◽  
Nacl Solution ◽  
Β Phase ◽  
Heat Treated

In order to examine the application of Mo-Fe-Ti alloy for overpak, the corrosion resistance of heat-treated its alloys was investigated by Electrochemical impedance spectroscopy (EIS), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM) and Energy dispersive X-ray analysis (EDAX). Considering the welding, the sample subjected to solution heat treatment (ST) had a single β phase and samples subjected to aging heat treatment at 600–700°C had a-phase precipitation in b-phase. EIS results showed that the corrosion resistance of the aging heat-treated samples was lower than that of the ST sample, but much higher than that of pure Ti in long term immersion test in 10% NaCl solution of pH 0.5 at 97°C which simulating the crevice solution. Laser micrographs of the aging heat-treated samples indicated that a-phase at the grain boundary and in the grain was selectively corroded and caused selective dissolution in NaCl solution. The results of TEM combined with EDAX analyses showed that there were b-phase matrix composed of 2.7 wt% of Mo and 4.8wt% of Fe, and a-phase composed of 0.7 wt% of Mo and 0.1 wt% of Fe in sample aged at 600°C. Thus, Mo-poor a-phase was selectively dissolved in in 10% NaCl solution of pH 0.5 at 97°C. In a result, the ST sample of only b-phase showed the highest resistance, and aging heat-treated samples containing a-phase (0.7 wt% of Mo) showed higher values than pure Ti in the corrosion test. Addition of Fe did not decrease the resistance of alloy in the case of ST condition. Moreover, as Fe was involved in b-phase with Mo which increased remarkably the corrosion resistance, the addition of Fe did not decrease the corrosion resistance of aging heat-treated Mo-Fe-Ti alloy. Finally, it was concluded that Mo-Fe-Ti alloy had excellent resistance for overpack in simulating underground environment.

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