Effect of thermomechanical processing and heat treatment on the microstructure evolution of the Ti-6246 alloy (original) (raw)
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UPB Scientific Bulletin, Series B: Chemistry and Materials Science, 2021
This study highlights the evolution of microstructure and associated mechanical properties induced by different thermomechanical (TM) processing conditions in the case of Ti-6246 alloy. The as-cast alloy was hot-rolled at 1000ºC, with a total deformation degree close to 65%, in 4 rolling passes. The TM processing route continued with solution treatments (ST's) performed at different temperatures of 800°C (ST1), 900°C (ST2) and 1000°C (ST3), with a treatment duration of 18 minutes and quenching in oil. A final ageing treatment (AT) was also applied, with a treatment temperature of 600°C, a treatment duration of 6 hours, and cooling in air. The evolution of Ti-6246 alloy's microstructure showed different morphologies and volumetric fractions depending on TM processing step. The microstructure of the as-cast alloy showed a Widmanstätten/basket-weave type, while the hot-deformation state showed large deformation of the initial grains, along rolling-direction. The α-Ti and β-Ti phases regenerated after application of ST's and the formation of the α′-Ti and α′′-Ti secondary phases resulting from rapid quenching in the oil. The α′-Ti and α′′-Ti secondary phases are reverted in the initial phases due to AT. The evolution of mechanical properties showed the extent to which the strength (ultimate tensile strength, yield strength, microhardness) and ductility (elongation to fracture) properties are influenced by the change in microstructure evolution as a result of the applied TM processing conditions. A good combination of strength and ductility was observed in the state of ST2 + AT.
Microstructural evolution during thermomechanical processing of Ti-6246 titanium alloy
UPB Scientific Bulletin, Series B: Chemistry and Materials Science, 2019
A Ti-6Al-2Sn-4Zr-6Mo (wt. %) alloy has extensively used in the aerospace applications due to its high mechanical properties. The present paper aimed at examining the changes in the microstructure of Ti-6246 titanium alloy during thermomechanical processes (TMPs). The alloy was subjected to a combination of TMPs comprising in the following stages: hot plastic deformation in the α + β field and normalizing heat treatment in the β field. The results showed that the effects generated by TMPs have a strong influence on the microstructural characteristics. All the samples were exhibiting various microstructural morphologies in different orientations. The microstructures features were highly improved by the normalizing heat process as compared to the initial material and the processed material by hot plastic deformation.
UPB Scientific Bulletin, Series B: Chemistry and Materials Science, 2018
The microstructure evolution and tensile strength test of The Ti-6246 alloy were investigated in the present study. Ten samples have been modified by using different thermo-mechanical processes (heat homogenization process, hot plastic deformation, and solution heat treatment) in the β-field range. The tensile test parameters were also investigated for all samples. The results revealed that the phase transformations and compositional changes induced by thermo-mechanical processes have a significant influence on the microstructural and mechanical characteristics. It was concluded that all samples present different crystallographic structure/lattice and morphologies. The mechanical properties have improved in the solution heat treatment in comparison with hot deformation processes.
MDPI, 2020
The present study investigates the influence of hot-deformation, above β-transus and different thermal treatments on the microstructural and mechanical behaviour of a commercially available Ti-6246 titanium-based alloy, by SEM (scanning electron microscopy), tensile and microhardness testing techniques. The as-received Ti-6246 alloy was hot-deformed-HR by rolling, at 1000 • C, with a total thickness reduction (total deformation degree) of 65%, in 4 rolling passes. After HR, different thermal (solution-ST and ageing-A) treatments were applied in order to induce changes in the alloy's microstructure and mechanical behaviour. The applied solution treatments (ST) were performed at temperatures below and above β-transus (α → β transition temperature; approx. 935 • C), to 800 • C, 900 • C and 1000 • C respectively, while ageing treatment at a fixed temperature of 600 • C. The STs duration was fixed at 27 min while A duration at 6 h. Microstructural characteristics of all thermomechanical (TM) processed samples and obtained mechanical properties were analysed and correlated with the TM processing conditions. The microstructure analysis shows that the applied TM processing route influences the morphology of the alloy's constituent phases. The initial AR microstructure shows typical Widmanstätten/basket-weave-type grains which, after HR, are heavily deformed along the rolling direction. The STs induced the regeneration of α-Ti and β-Ti phases, as thin alternate lamellae/plate-like structures, showing preferred spatial orientation. Also, the STs induced the formation of α-Ti/α"-Ti martensite phases within parent α-Ti/β-Ti phases. The ageing treatment (A) induces reversion of α-Ti/α"-Ti martensite phases in parent α-Ti/β-Ti phases. Mechanical behaviour showed that both strength and ductility properties are influenced, also, by applied TM processing route, optimum properties being obtained for a ST temperature of 900 • C followed by ageing (ST2 + A state), when both strength and ductility properties are at their maximum (σ UTS = 1279 ± 15 MPa, σ 0.2 = 1161 ± 14 MPa, ε f = 10.1 ± 1.3%).
MDPI, 2024
This study aims to investigate the effect of hot deformation on commercially available Ti-6246 alloy below its β-transus transition temperature at 900 °C, knowing that the α → β transition temperature of Ti-6246 alloy is about 935 °C. The study systematically applies a thermomechanical processing cycle, including hot rolling at 900 °C and solution and ageing treatments at various temperatures, to investigate microstructural and mechanical alterations. The solution treatments are performed at temperatures of 800 °C, 900 °C and 1000 °C, i.e., below and above the β-transus transition temperature, for 9 min, followed by oil quenching. The ageing treatment is performed at 600 °C for 6 h, followed by air quenching. Employing various techniques, such as X-ray diffraction, scanning electron microscopy, optical microscopy, tensile strength and microhardness testing, the research identifies crucial changes in the alloy’s constituent phases and morphology during thermomechanical processing. In solution treatment conditions, it was found that at temperatures of 800 °C and 900 °C, the α′-Ti martensite phase was generated in the primary α-Ti phase according to Burger’s relation, but the recrystallization process was preferred at a temperature of 900 °C, while at a temperature of 1000 °C, the α″-Ti martensite phase was generated in the primary β-Ti phase according to Burger’s relation. The ageing treatment conditions cause the α′-Ti/α″-Ti martensite phases to revert to their α-Ti/β-Ti primary phases. The mechanical properties, in terms of strength and ductility, underwent an important beneficial evolution when applying solution treatment, followed by ageing treatment, which provided an optimal mixture of strength and ductility. This paper provides engineers with the opportunity to understand the mechanical performance of Ti-6246 alloy under applied stresses and to improve its applications by designing highly efficient components, particularly military engine components, ultimately contributing to advances in technology and materials science.
Structural and mechanical evolution of the thermo-mechanical processed Ti-46Al-6.5Nb alloy
2014
The formation of a high quality as-cast structure for the Ti-46Al-6.5Nb-0.5Ta-1Cr-0.3Ni-0.2Si (at.%) alloy, with a new alloying concept, and also the application of a thermomechanical (TM) processing scheme was the subject of present investigation. The investigations consisted of structural and mechanical characterizations of the alloy in 6 different structural conditions: S1 – in cast state, S2 – after a heat treatment of homogenization, S3–S6 – after a TM processing scheme. The micro-structural investigations were performed using a SEM analyzing system, and an X-ray diffractometer. The investigations of mechanical properties have been based on tensile strength, modulus of elasticity, elongation to fracture measurements and fracture surface analysis for the as-cast sample, and on micro-hardness measurements for the TM processed samples. The alloy in cast condition, with specific nearlamellar morphology, has a homogeneous, fine-grained structure (d ∼ 30 μm), and no axial texture. Th...
Purpose: Hot deformation behaviour of two-phase titanium alloys is determined depending on microstructure developed in heat treatment and plastic deformation processes. In the paper stereological parameters of microstructure obtained in initial heat treatment and plastic working in the α+β↔β phase transformation range with various forging reduction (ε ≈ 20 and 50%) were determined. Evaluation of the effect of thermomechanical process parameters on hot plasticity of Ti-6Al-4V and Ti-6Al-2Mo-2Cr titanium alloys was performed.
Effect of the thermomechanical treatment on the structure of titanium alloy Ti6Al4V
J Mater Process Technol, 2004
This paper deals with the actual problem connected with preparing of titanium alloy well known as Ti64. We are solving physical-metallurgical process of the preparing Ti64 alloy with good useful properties namely with very good notch toughness and tensile strength in our laboratory on the Slovak University of Technology in Bratislava. Aim of our research task was obtain a very good biocompatible material. The research material was prepared through the plasma metallurgy, vacuum metallurgy, HIP produces in hot camera and heat treatment. Through the using phase analysis and microanalysis were established some very hard particles, of which chemical substances are titanium carbonitrides.
Effect of microstructural morphology on the mechanical properties of titanium alloys
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.