MICROSTRUCTURE PROPERTIES OF (Α+Β) TITANIUM ALLOYS: A REVIEW

Journal of Physics: Conference Series, 2010

Different morphologies of α+β microstructures were obtained in a commercial Ti-6Al-4V alloy by cooling at different rates from the single β-phase region into the two phase region. The effect of such morphologies on mechanical properties was studied using hot compression tests in a Gleeble thermomechanical simulator. A variety of complex morphologies could be obtained since the cooling rate has a significant influence on the β to α phase transformation and the resulting morphological development. While most of the β phase transformed to colonies of α at high cooling rates, it was possible to obtain a complex mixture of α colonies, grain boundary α and lamellar structure by decreasing the cooling rate. These complex morphologies each exhibited distinctive mechanical properties and characteristic dynamic phase transformation behaviour during deformation as a function of strain rate.

Journal of Materials Processing Technology, 2003

This paper presents the results of investigations of the microstructure and mechanical properties of two-phase a þ b titanium alloys after different heat treatment. The influence of the morphology of lamellar microstructure and phase composition on the tensile properties and fracture toughness of the alloys was studied. Static tensile, hardness and fracture toughness tests and microstructure investigations were performed. It was noticed that the cooling rate from the b-phase range and ageing conditions had an effect on the microstructure parameters, volume fraction and chemical composition of the b-phase, and has a significant effect on the mechanical properties of the alloys tested. #

Procedia structural integrity, 2019

Ti-6Al-4V is a dual phase (α+β) titanium alloy widely used in aerospace industry. Mechanical properties of a component strongly depend upon its microstructure and morphology. Desired mechanical properties can be achieved by the development of appropriate microstructure with the help of different heat treatments and deformation. In the present work, different microstructures obtained through different heat treatment processes are studied and presented. A variety of morphologies of α+β microstructure are obtained by heating above and below β transus temperature and cooling at different rates i.e. water quench, air cool and furnace cool. Heating above β transus and cooling with different rates results into lamellar structure whereas a duplex microstructure is obtained after heating below β transus and cooling with different rates. A lamellar structure with blocky acicular α is obtained after heating above β transus followed by furnace cool up to temperature below β transus and cooling with different rates. It is observed that cooling rate has a significant effect on hardness of heat treated sample. Faster cooling results in higher hardness.

Journal of Materials Engineering and Performance, 2005

The mechanical behavior and microstructure evolution of a stable ␤, metastable ␤, and ␤-rich titanium alloys during hot deformation in both ␤ and ␣/␤ phase fields were studied. The effects of thermomechanical processing and alloy content on final grain size and microstructure homogeneity in the alloys are given. The processing windows in both ␤ and ␣/␤ phase fields for the formation of homogeneous microstructures with grain sizes down to submicron values are discussed. Isothermal multiple-step forging was used to produce the billets of a ␤-rich alloy with homogeneous fine-grained microstructure and low ultrasonic noise.

2018

The effect of heat treatment conditions on the microstructure, phase transformation and mechanical properties of Bi-modal  titanium alloy was investigated. The heat treatment process comprises of solution treated at various temperatures of 640, 680, 720 and 760 C for 30 min followed by water quenching and aged at 500 C for 30 min then air cooling. This study was carried out using X-ray diffraction analysis (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), differential thermal analysis (DTA), compression universal testing machine and Vickers hardness tester. The results show that the microstructure of investigated alloys consists of  phase, as a matrix, primary  phase, small precipitates of secondary  phase in addition to orthorhombic martensite ( ") phase found only in the solutionized samples at 720 and 760 C. Transus temperature for the  phase found to be around 865 C at heating rate of 10 C/min. The / phase zone is ranging from 650 to 865 C at the same heating rate for all samples. The formation temperature of nanometer α phase and/or disappearing of iso phase are almost constant at 385 °C. The formation of primary α phase was detected at a temperature more than 400 C. Hardness measurements increased as the solution temperature increase. The highest ultimate compression strength, 2680 MPa, achieved with solution temperature of 680 °C. However the maximum yield stress, 1725 MPa, obtained with 760 C solution temperature. The highest contraction was attained with the solutionized sample at 640 C for 30 min.

Journal of Materials Engineering and Performance - J MATER ENG PERFORM, 1994

Metastable 13-titanium alloys have improved formability and ductility compared to high-strength ix-and ct+[~ titanium alloys; this can be attributed to their body-centered cubic structure in the solution-treated condition. In addition, a high strength level can be achieved by a simple aging treatment. During manufacturing, components are subjected to a variety of thermal cycles at temperatures ranging from 650 to 925 ~ as well as to cooling rates that vary from air cooling to furnace cooling. Consequently, various microstructures are produced that influence the mechanical properties of the products. Th~ study was undertaken to characterize the precipitation behavior of Timetal 21S at various heat treatment conditions by employing x-ray diffraction techniques combined with optical and scanning electron microscopy. It was observed that ct precipitated preferentially on the grain boundaries during high-temperature aging (650 ~ and within the grains during low-temperature aging (400 ~ High-temperature solutioning produced a coarse grain size, and at the same time enhanced finer ct precipitation during aging. The amount of ct precipitate attained after the standard aging treatment was about 33%. Resolution treatment followed by slow cooling, such as that which occurred during brazing of the alloy, resulted in ct precipitation during cooling; however, an aging treatment was necessary to precipitate an ct content greater than 20%.

Sadhana, 2008

In this technical paper, the microstructure, hardness, tensile deformation and final fracture behaviour of an emerging titanium alloy for performancecritical applications are presented and discussed. Both longitudinal and transverse test specimens were prepared from the as-provided sheet stock of the alloy and deformed in uniaxial tension. The yield strength and tensile strength of the alloy sheet in the transverse orientation was higher than the longitudinal orientation. The ductility of the test specimens, quantified in terms of reduction-in-cross-sectional area, was higher for the transverse specimen when compared to the longitudinal counterpart. The elongation-to-failure of the test specimens was identical in the two orientations of the sheet stock. The tensile fracture behaviour of the alloy was quantified by careful examination of the fracture surfaces in a scanning electron microscope. The intrinsic fracture features on the tensile fracture surface were discussed taking into consideration the nature of loading and contribution from intrinsic microstructural features.

Materials Science and Engineering: A, 2009

A set of stereological procedures has been developed for the rigorous quantification of microstructural features resolvable using scanning electron microscopy in ␣ + ␤-processed ␣/␤ titanium alloys. This paper identifies the four microstructural features that most likely influence the mechanical properties in ␣ + ␤processed titanium alloy, including: the size of the equiaxed alpha, the volume fraction of the equiaxed alpha, the volume fraction of total alpha, and the thickness of the Widmanstätten alpha laths. The details regarding the quantification methodologies are provided, as are the origins of the associated uncertainties.

International Journal of Engineering Research and Technology (IJERT), 2021

https://www.ijert.org/microstructure-and-mechanical-properties-of-heat-treated-ti8al1mo1v-alloy https://www.ijert.org/research/microstructure-and-mechanical-properties-of-heat-treated-ti8al1mo1v-alloy-IJERTV10IS040248.pdf Titanium and its alloys exhibit several unique properties and have been widely used in the field of chemical industry, aviation, aerospace, marine and medical devices since 1950.Titanium and titanium alloys are widely used in aerospace field due to property of high strength to weight ratio as it saves lot of cost spent on fuel due to weight and non reactivity to adverse environmental conditions. The applications of Ti8Al1Mo1V include compressor blades, turbine discs, housing inner skin and frame for nozzle assembly of Jet engines. Literature review indicates that published information not available regarding systematic reporting of structure and properties of this alloy. Hence in this study systematically studies have been carried out on structure and properties of Ti-8Al-1Mo-1V alloy when subjected to solutionising and ageing followed by air cooling and thermal oxidation heat treatments. In this study Titanium alloy Ti8Al1Mo1V (TA8DV) is subjected to solutionising and ageing followed by air cooling and further subjected to thermal oxidation at 600°C, 750°C and 900°C for 6 hours, 15 hours and 24 Hours time duration in each combination in a resistance furnace in presence of Air. The thermal oxidized samples are subjected to Tensile test, Micro hardness test and the cross sectioned samples are tested for microstructure in an optical microscope. Micro hardness (knoop hardness number) is more at the surface and reduces gradually to core. The maximum number achieved is 548.8 for sample To-24-900; it is revealed that the hardness increases with temperature and time duration. From Microstructure studies the effect of thermal oxidation varies from15 microns at 6 hrs duration 600°C and 150 microns at 24 hours duration 900°C temperature and it is known that the effect of oxidation varies proportional to temperature and time duration. From tensile test the yield strength and ultimate tensile strength decreases from 8% to 15 % as compared to the value of the sample in ASR condition. 1. INTRODUCTION: Titanium is the 4 th abundant structural metal available on earth crust after aluminum, iron and magnesium. Titanium element was discovered in 1791. There are two allotropic forms of titanium: α-Ti at 882.5°C or lower, with a closely packed hexagonal (hcp) lattice structure and β-Ti at 882.5°C or higher with a body centered cubic (bcc) lattice structure. Depending on the phase structure and the content of β stable element, titanium alloy is classified in to three categories: α, α+β and β. There are varieties of Titanium alloys available depending on the composition some of the alloys are Ti6Al4V, Ti8Al1Mo1V, Ti6Al2Sn4Zr2Mo, Ti10V3Fe3Al etc. Depending on the phases formed the alloys are classified as α, α+β, β titanium alloy. Titanium and its alloys exhibit several unique properties and have been widely used in the field of chemical industry, aviation, aerospace, marine and medical devices since 1950. [1]. Main physical properties of titanium and titanium alloys include: Low density and high specific strength: the density of Ti is 4.51 g/cm3 with tensile strength up to 1300MPa. The specific strength is much higher than that of aluminum and alloying steel. Good heat resistance: some new types of titanium alloys can be used for a long time at 600°C or higher, and are suitable for the aviation and aerospace heat-resistance components; Good low temperature resistance: at temperature of-196 to-253°C, titanium maintains relatively good ductility and toughness. These make Ti to be an ideal material for cryogenic vessels and tank equipments; Good corrosion resistance: Ti is very stable among many media. For example, Ti is corrosion resistant in the medium of oxidation, neutral and weak reduction. However titanium also has some drawbacks along with aforementioned advantages which are Low wear resistance: the low surface hardness of titanium makes the adhesive wear easy to occur. Low oxidation resistance at high temperature: titanium shows a strong tendency of oxidation at a temperature of 350°C or higher. High cost: the price of titanium is 5-10 times higher than that of steel. [1]. Ti8Al1Mo1V is considered which comes under near α alloy, which was initially developed as super alloy for engine use principally as forgings. Ti8Al1Mo1V alloy contains a relatively large amount of alpha stabilizer, aluminum and Fairley small amounts of beta stabilizers, molybdenum and vanadium (plus iron as impurity). Although this alloy is metallurgically an alpha-beta alloy, the small amount of beta stabilizer in this grade(1Mo+1V) permits only small amounts of the beta phase to be stabilized, thus the alloy is also known as near alpha alloy. Although this is a near alpha alloy, an increase in tensile strength by almost 25% over that of mill annealed material can be obtained by appropriate choice of heat treatment sequence consisting of quenching followed by an ageing treatment.[9]. The yield strength, the ultimate tensile strength and the elongation depend strongly on the solutionising temperature [10]. Many non metallic elements are used to enhance the titanium alloy surface to improve its Tribological properties, which can form a hardened, interstitially enriched alpha-case layer with or without an outer surface layer of hard compound. [7]. The thermal oxidation process is one of the most important advances in the field of surface engineering of Ti-based materials due to its capability of enhancing the Tribological properties of Ti alloys [1]. Ti-6Al-4V alloy treated using thermal oxidation exhibited low coefficient of friction and low wear rate, which is attributed to both the formation of a useful oxide and hardened diffusion layer. Many non metallic elements are used to enhance the titanium alloy surface to improve its