Influence of microtexture on ultrasonic reflection in Ti-6Al-4V alloy hot-forged in α+β region

Morphological change in regions with microtexture, i.e., macrozones, in Ti-6Al-4V alloy after hot-forging in α+β phase region was analyzed using SEM/EBSD technique, and then the correlation with ultrasonic reflection was investigated. Starting material had colony-type microstructure consisting of lamellar-α with the same crystallographic orientation. Forging (cogging and upsetting) was conducted in α+β phase region to produce a cylindrical material with smaller cross section, followed by air cooling. Thus, resulting microstructure consisted of granular-α. To estimate local change in elastic modulus within the materials, we analyzed crystallographic orientations of α-phase using SEM/EBSD in terms of an inclination angle of c-axis. The regions having the nearly common crystallographic orientations of α-phase were found. Shapes of such regions with microtexture were elongated along the axial direction, which formed quasi-periodic variation of the inclination angle, i.e., elastic modulus, of α-phase along the radial direction of the forged material. Ultrasonic measurement was conducted at a frequency of 5 MHz along the radial direction and the axial direction. Relationship between the morphology of regions having microtexture and the amplitude of backscattered noises was evaluated. It was considered that the quasi-periodicity of the inclination angle correlated with the amplitude of backscattered noises in ultrasonic measurement.

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Crystallographic Peculiarities of β-α Transformation in Brass Induced by Hot Extrusion

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.299.541 ◽

2020 ◽

Vol 299 ◽

pp. 541-545

Author(s):

Mikhail L. Lobanov ◽

S.V. Danilov ◽

Vladimir I. Pastukhov

Keyword(s):

Coincident Site Lattice ◽

Hot Extrusion ◽

Air Cooling ◽

Orientation Microscopy ◽

Β Phase ◽

Α Phase ◽

Orientation Relations ◽

Main Components ◽

Relationship Of ◽

Significant Concentration

Structure-texture states in brass rods after hot extrusion and air-cooling have been investigated with the orientation microscopy (EBSD). In the examined samples, a significant concentration of β-phase with the lattice, close to bcc and fcc α-phase, has been detected. The β-phase texture consisted of the main components: two close to {110}<110> and {001}<110>. The α-phase texture consisted of the main components: close to {001}<100> and two close {110}<111>. The analysis of crystallographic relationship of the texture components of β-and α-phases demonstrates that they may all be obtained, in accordance with the orientation relations, which are intermediate between the Kurdjumov-Sachs and Nishiyama-Wasserman types It is assumed that β-α transformation began in β-phase at coincident site lattice Σ3 and Σ33a boundaries.

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High-Temperature Deformation Behavior and Microstructural Characterization of Ti-35421 Titanium Alloy

Materials ◽

10.3390/ma13163623 ◽

2020 ◽

Vol 13 (16) ◽

pp. 3623 ◽

Cited By ~ 2

Author(s):

Danying Zhou ◽

Hua Gao ◽

Yanhua Guo ◽

Ying Wang ◽

Yuecheng Dong ◽

...

Keyword(s):

Titanium Alloy ◽

Dynamic Recrystallization ◽

Strain Rate ◽

Hot Deformation ◽

Deformation Behavior ◽

Deformation Temperature ◽

Phase Region ◽

Temperature Deformation ◽

Β Phase ◽

Α Phase

A self-designed Ti-35421 (Ti-3Al-5Mo-4Cr-2Zr-1Fe wt%) titanium alloy is a new type of low-cost high strength titanium alloy. In order to understand the hot deformation behavior of Ti-35421 alloy, isothermal compression tests were carried out under a deformation temperature range of 750–930 °C with a strain rate range of 0.01–10 s−1 in this study. Electron backscatter diffraction (EBSD) was used to characterize the microstructure prior to and post hot deformation. The results show that the stress–strain curves have obvious yielding behavior at a high strain rate (>0.1 s−1). As the deformation temperature increases and the strain rate decreases, the α phase content gradually decreases in the α + β phase region. Meanwhile, spheroidization and precipitation of α phase are prone to occur in the α + β phase region. From the EBSD analysis, the volume fraction of recrystallized grains was very low, so dynamic recovery (DRV) is the dominant deformation mechanism of Ti-35421 alloy. In addition to DRV, Ti-35421 alloy is more likely to occur in continuous dynamic recrystallization (CDRX) than discontinuous dynamic recrystallization (DDRX).

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Phase Constitution and Heat Treatment Behavior of Zr-Nb Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.561-565.1435 ◽

2007 ◽

Vol 561-565 ◽

pp. 1435-1440 ◽

Cited By ~ 2

Author(s):

Masahiko Ikeda ◽

Tsuyoshi Miyazaki ◽

Satoshi Doi ◽

Michiharu Ogawa

Keyword(s):

Heat Treatment ◽

Elastic Modulus ◽

Elastic Moduli ◽

X Ray Diffraction ◽

Phase Constitution ◽

X Ray ◽

Β Phase ◽

Ω Phase ◽

Solution Treated ◽

Α Phase

Phase constitution in the solution-treated and quenched state and the heat treatment behavior were investigated by electrical resistivity, hardness, and elastic modulus measurements, X-ray diffraction, and optical microscopy. Hexagonal martensite and the β phase were identified in the Zr-5mass%Nb alloy. β and ω phases were identified in the Zr-10 and 15mass%Nb alloys, and only the β phase was identified in the Ti-20Nb alloy. Resistivity at RT, Vickers hardness and elastic modulus increased up to 10Nb and then decreased dramatically at 15Nb. Above 15Nb, these values slightly decreased. The elastic moduli for 15Nb and 20Nb were 59.5 and 55.5 GPa, respectively. On isochronal heat treatment, the isothermal ω phase precipitated between 473 and 623 K and then the α phase precipitated in the 10Nb, 15Nb and 20Nb alloys.

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Кристаллографические особенности структуры alpha-фазы гафния и сплавов гафний--титан

Журнал технической физики ◽

10.21883/jtf.2019.01.46968.86-18 ◽

2019 ◽

Vol 89 (1) ◽

pp. 86

Author(s):

Ю.В. Хлебникова ◽

Д.П. Родионов ◽

Л.Ю. Егорова ◽

Т.Р. Суаридзе

Keyword(s):

Polymorphic Transformation ◽

Mixed Structure ◽

Cast State ◽

Β Phase ◽

Ti Alloys ◽

Α Phase ◽

Phase Crystal ◽

Lath Crystals ◽

Crystallographic Orientations ◽

Regular Alternation

AbstractThe structure of a hafnium crystal undergoing β → α (bcc → hcp) polymorphic transformation upon gradual cooling and the structure of Hf_55Ti_45 and Hf_30Ti_70 alloys formed under various kinetic conditions of polymorphic transformation are studied. The structure of the α phase in cast hafnium is shown to consist of lath crystals grouped into packets. The misorientations between separate laths in a packet are less than 1°. The Hf–Ti alloys in the cast state exhibit a mixed structure consisting of α-phase crystals of several morphological types. A structure of packet martensite is observed in the Hf–Ti alloys after quenching. Each packet includes laths of several crystallographic orientations. There is no regular alternation of differently orientated laths in the packet. The same set of α-phase orientations within an initial β-phase grain is observed independently of the cooling rate of the Hf–Ti alloys upon β → α polymorphic transformation. The misorientation of substructural elements within an α-phase crystal in the Hf–Ti alloys is ~5° for the cast state and ~2.2° after quenching.

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Effects of Heat Treatment on Microstructures and Mechanical Properties of Ti-38644 Alloy for Aerospace Fasteners

Materials Science Forum ◽

10.4028/www.scientific.net/msf.913.109 ◽

2018 ◽

Vol 913 ◽

pp. 109-117 ◽

Cited By ~ 1

Author(s):

Qing Yun Zhao ◽

Si Rui Cheng ◽

Li Dong Wang ◽

Li Min Dong ◽

Feng Lei Liu

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Grain Size ◽

Tensile Strength ◽

Solution Temperature ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Air Cooling ◽

Β Phase ◽

Α Phase

The effects of heat treatment on microstructure and mechanical properties of Ti-38644 alloy were investigated by scanning electron microscope (SEM) and transmission electron microscopy (TEM) as well as uniaxial tensile test. The results show that when the solution temperature is lower than 845°C, the microstructure of Ti-38644 alloy is equiaxed β phase with the grain size of 20μm, and the tensile strength is about 960MPa. As raising solution temperature to 860°C, the grain size of Ti-38644 alloy increases to 100μm and the tensile strength decreased to 870MPa. There are a large number of secondary α phase precipitated from the grain boundaries and within grain of β phase undergoing aging treatment. Secondary α phase coarsens with increasing the aging temperature, leading to the decrease of tensile strength. After solution treatment at 815°C for 1.5h, water quenching plus aging at 520°C for 10h, air cooling, Ti-38644 alloy shows a better mechanical property with the tensile strength 1330MPa, elongation and reduction of area 10% and 45% respectively.

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Microstructures and Mechanical Properties of Biologically-Inspired Ti-Nb Based Alloys with Ternary Element Additions

Materials Science Forum ◽

10.4028/www.scientific.net/msf.539-543.647 ◽

2007 ◽

Vol 539-543 ◽

pp. 647-652 ◽

Cited By ~ 1

Author(s):

Han Sol Kim ◽

Won Yong Kim

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Martensitic Transformation ◽

Alloy System ◽

Phase Region ◽

Present Alloy ◽

Β Phase ◽

Nb Content ◽

Microstructures And Mechanical Properties ◽

Ternary Alloying

Microstructures and mechanical properties including elastic modulus were investigated in terms of ternary alloying elements Si addition, Nb content variations and tensile test. Martensite structure with α'(hcp) or α"(orthorhombic) was observed in Ti-xNb-1.5at.%Si, where x=10-20at.%. The crystal structure of martensite formed from water quenching process was largely dependent upon Nb content but does not on Si content. On the basis of experimental results obtained, it is suggested that Si has an effective role to suppress the precipitation of ω phase leading to reduction in elastic modulus in the metastable β phase region. Metastable β phase region was superior to reduce the elastic modulus than stable β phase region in the present alloy system. The minimum value of elastic modulus was measured to 48GPa. We have found that stress-induced martensitic transformation takes place during the deformation in the present alloys. Within the alloys having β(bcc) phase studied Nb-poor region appeared to exhibit a dominant behavior for stress-induced martensitic transformation than Nb-rich region. This result suggests that metastable β phase is superior to stable β phase for the occurrence of stress-induced martensitic transformation in the present alloy system.

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Low Elastic Modulus β Ti-Nb-Si Alloys for Biomedical Applications

Materials Science Forum ◽

10.4028/www.scientific.net/msf.510-511.858 ◽

2006 ◽

Vol 510-511 ◽

pp. 858-861 ◽

Cited By ~ 4

Author(s):

Won Yong Kim ◽

Han Sol Kim ◽

In Dong Yeo

Keyword(s):

Elastic Modulus ◽

Alloy System ◽

Phase Region ◽

Β Phase ◽

Low Elastic Modulus ◽

Quenching Process ◽

Nb Content ◽

Effective Role ◽

Si Content ◽

Martensite Structure

We report on advanced β-titanium alloys having excellent biocompatibility without containing V or Al that has been known as a toxic element for human body, and on a low elastic modulus to be used in the fields of artificial joint and dental implant in the replacement of natural human bone. Martensite structure with α’ (hcp) or α”(orthorhombic) was observed in Ti-xNb-1.5at.%Si, where x=10-20at.%. The crystal structure of martensite formed from water quenching process was largely dependent upon Nb content but does not on Si content. On the basis of experimental results obtained, it is suggested that Si has an effective role to suppress the precipitation of ω phase leading to reduction in elastic modulus in the metastable β phase region. Metastable β phase region was superior to reduce the elastic modulus than stable β phase region in the present alloy system. The minimum value of elastic modulus was measured to 48GPa.

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Effect of Sintering Temperature on Microstructure and Mechanical Properties of Ti Mo Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.815.297 ◽

2015 ◽

Vol 815 ◽

pp. 297-300 ◽

Cited By ~ 1

Author(s):

Xing Ping Fan ◽

Ben Ju Wang ◽

Xiao Qing Ren ◽

Fu Chang Peng

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Bending Strength ◽

Sintering Temperature ◽

Test Methods ◽

X Ray Diffraction ◽

X Ray ◽

Β Phase ◽

Sintering Time ◽

Α Phase

The medical Ti-20Mo alloys were fabricated by powder metallurgy. The effects of sintering temperature on the phase, the morphology and the mechanical properties of Ti-Mo alloys were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and mechanical properties test methods. The results showed that after sintering at 1200 °C, the microstructure of Ti-Mo alloys mainly consisted of α phase. The increasing sintering time could promote α→β phase transition, thus the flexural strength and the elastic modulus of Ti-Mo alloys could be controlled. When the sintering temperature was 1300 °C, molybdenum content was 20%, the bending strength and the compressive strength of Ti-20Mo alloy were 1369MPa and 2602MPa respectively, and the elastic modulus was 3.4GPa. It may be concluded that the Ti-20Mo alloys is prospective prostheses materials.

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Effect of Third-Stage Heat Treatments on Microstructure and Properties of Dual-Phase Titanium Alloy

Materials ◽

10.3390/ma14112776 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2776

Author(s):

Xiqin Mao ◽

Meigui Ou ◽

Desong Chen ◽

Ming Yang ◽

Wei Long

Keyword(s):

Tensile Strength ◽

Titanium Alloy ◽

Aging Treatment ◽

Air Cooling ◽

Phase Zone ◽

Two Phase ◽

Β Phase ◽

Solution Treated ◽

Α Phase ◽

Third Stage

Two-phase TC21 titanium alloy samples were solution-treated at 990 °C (β phase zone) and cooled by furnace cooling (FC), air cooling (AC), and water quenching (WQ), respectively. The second solution stage treatment was carried out at 900 °C (α + β phase zone), then aging treatment was performed at 590 °C. The influence of the size and quantity of the α phase on the properties of the sample were studied. The experimental results showed as the cooling rate increased after the first solution stage treatment, wherein the thickness of primary layer α gradually decreased, and the tensile strength and yield strength gradually increased. After the second solution stage treatment, the tensile properties of samples increased due to the quantity of layers α increased. The aging treatment promoted the precipitation of the dispersed α phase and further improved the tensile strength. After the third solution stage treatments, the FC samples with more β-phase had the best comprehensive mechanical properties.

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Fabrication, Structure and Mechanical and Ultrasonic Properties of Medical Ti6Al4V Alloys Part I: Microstructure and Mechanical Properties of Ti6Al4V Alloys Suitable for Ultrasonic Scalpel

Materials ◽

10.3390/ma13020478 ◽

2020 ◽

Vol 13 (2) ◽

pp. 478

Author(s):

Zheyu He ◽

Hao He ◽

Jia Lou ◽

Yimin Li ◽

Dongyang Li ◽

...

Keyword(s):

Mechanical Properties ◽

Solid Solution ◽

Elastic Modulus ◽

Solution Treatment ◽

Phase Content ◽

Ultrasonic Scalpel ◽

Ultrasonic Properties ◽

Β Phase ◽

Α Phase ◽

Microstructure And Mechanical Properties

Ti6Al4V alloy has been considered as a key component used in ultrasonic scalpels. In this series of papers, the fabrication, structure, and mechanical and ultrasonic properties of medical Ti6Al4V alloys suitable for ultrasonic scalpel are studied systemically. These alloys with low elastic modulus and present a typical bimodal microstructure with relatively high β phase content (~40%) and lamellar α thickness of ≤ 0.9 µm. In the first paper, the relationship between the microstructure and mechanical properties of hot-rolled Ti6Al4V alloys treated by heating treatment is discussed. In the second paper, the dependence of the ultrasonic properties on the microstructure of the heat-treated Ti6Al4V alloys is reported. With increasing solid solution temperature, the content and size of the primary α phase decrease. In contrast, the content and size of the lamellar α phase increase. Additionally, the β phase content first increases and then decreases. The microstructure of Ti6Al4V alloys could be slightly changed by aging treatment. When the solid solution treatment temperature increases to 980 °C from 960 °C, the average size of the lamellar α phase in the alloys increases by 1.1 µm. This results in a decrease in the average yield strength (93 MPa). The elastic modulus of alloys is mainly controlled by the β phase content. The microstructure of alloys by solution-treatment at 960 °C shows the highest β phase content and lowest average elastic modulus of 99.69 GPa, resulting in the minimum resonant frequency (55.06 kHz) and the highest average amplitude (21.48 µm) of the alloys at the length of 41.25 mm.

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