Mohammed Hayder Ismail Alluaibi - Academia.edu (original) (raw)

Papers by Mohammed Hayder Ismail Alluaibi

MDPI, 2024

This study aims to investigate the effect of hot deformation on commercially available Ti-6246 al... more 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.

MDPI, 2020

The present study investigates the influence of hot-deformation, above β-transus and different th... more 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 (T...

UPB Scientific Bulletin, Series B: Chemistry and Materials Science, 2021

This study highlights the evolution of microstructure and associated mechanical properties induce... more 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.

METAL 2020 - 29th International Conference on Metallurgy and Materials, 2020

The Ti-6Al-2Sn-4Zr-6Mo (Ti-6246) titanium alloy is categorized as one of α + β titanium alloys gr... more The Ti-6Al-2Sn-4Zr-6Mo (Ti-6246) titanium alloy is categorized as one of α + β titanium alloys group, which plays an important role in the aerospace applications. This study aims to find out the optimal thermomechanical processing route to obtain a good balance of strength, ductility and fracture toughness. The Ti-6246 alloy was hot-deformed at a temperature of 900°C, with a total deformation degree of approximately 60%, and heattreated by a solution treating at temperatures between 800°C-1000°C for 18 minutes. The microstructural evolution, mechanical properties and fractography analysis were investigated. Results revealed that the volume fraction of the primary α (αp) phase decreases progressively until it is completely dissolved with increasing solution temperature; the secondary α (αs) phase increases whereas its width decrease with increasing solution temperature, and also the yield stress and ultimate tensile strength decrease with increasing solution temperature. A good balance of ultimate tensile strength and ductility was obtained in the case of a solution temperature of 900°C, which showed a tensile strength close to 812±4 MPa and an elongation close to 11.1±2.4 %. The fine αs phase facilitates the paths of crack propagation, meaning decrease the crack propagation resistance and decrease the ductility and fracture toughness.

MDPI, 2020

The present study investigates the influence of hot-deformation, above β-transus and different th... more 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%).

UPB Scientific Bulletin, Series B: Chemistry and Materials Science, 2019

The paper aims to study the effects induced by thermomechanical processing on the microstructural... more The paper aims to study the effects induced by thermomechanical processing on the microstructural evolution of the Super Duplex Stainless Steel F55 (SDSS F55). The experimental investigations involved five samples, of identical dimensions, hot deformed at temperatures between (800°C - 1100°C). All samples were deformed by the dead-weight drop method at the same potential energy. The microstructural features of SDSS F55 alloy induced by hot deformation were analyzed using scanning electron microscopy (SEM). The results showed that initial sample presented two stable phases (ferrite () and austenite ()), while hot deformation at a temperature between (800°C - 1000°C) induces the appearance of the deleterious sigma () and chi () phases. It was observed that the sigma () and chi () phases are disappearing at hot deformation temperatures above 1000°C.

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 ... more 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.

IOP Conference Series: Materials Science and Engineering, 2018

In the present study, the microstructures of five samples of the Ti-6246 alloy were investigated ... more In the present study, the microstructures of five samples of the Ti-6246 alloy were investigated using SEM and OM devices. Four samples had been examined during different thermo-mechanical processing and heat treatment (hot plastic deformation and normalizing heat treatment) in α + β and β field domain respectively. The results demonstrate that the phase transformations and compositional modifications induced by thermo-mechanical processing and heat treatment have a dramatic influence on the microstructural characteristics. It was concluded that all samples present many morphologies textures and orientations. The microstructures features had improved in the normalizing heat process in comparison with the parent material and the hot deformation process.

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 ... more 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, 2024

This study aims to investigate the effect of hot deformation on commercially available Ti-6246 al... more 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.

MDPI, 2020

The present study investigates the influence of hot-deformation, above β-transus and different th... more 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 (T...

UPB Scientific Bulletin, Series B: Chemistry and Materials Science, 2021

This study highlights the evolution of microstructure and associated mechanical properties induce... more 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.

METAL 2020 - 29th International Conference on Metallurgy and Materials, 2020

The Ti-6Al-2Sn-4Zr-6Mo (Ti-6246) titanium alloy is categorized as one of α + β titanium alloys gr... more The Ti-6Al-2Sn-4Zr-6Mo (Ti-6246) titanium alloy is categorized as one of α + β titanium alloys group, which plays an important role in the aerospace applications. This study aims to find out the optimal thermomechanical processing route to obtain a good balance of strength, ductility and fracture toughness. The Ti-6246 alloy was hot-deformed at a temperature of 900°C, with a total deformation degree of approximately 60%, and heattreated by a solution treating at temperatures between 800°C-1000°C for 18 minutes. The microstructural evolution, mechanical properties and fractography analysis were investigated. Results revealed that the volume fraction of the primary α (αp) phase decreases progressively until it is completely dissolved with increasing solution temperature; the secondary α (αs) phase increases whereas its width decrease with increasing solution temperature, and also the yield stress and ultimate tensile strength decrease with increasing solution temperature. A good balance of ultimate tensile strength and ductility was obtained in the case of a solution temperature of 900°C, which showed a tensile strength close to 812±4 MPa and an elongation close to 11.1±2.4 %. The fine αs phase facilitates the paths of crack propagation, meaning decrease the crack propagation resistance and decrease the ductility and fracture toughness.

MDPI, 2020

The present study investigates the influence of hot-deformation, above β-transus and different th... more 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%).

UPB Scientific Bulletin, Series B: Chemistry and Materials Science, 2019

The paper aims to study the effects induced by thermomechanical processing on the microstructural... more The paper aims to study the effects induced by thermomechanical processing on the microstructural evolution of the Super Duplex Stainless Steel F55 (SDSS F55). The experimental investigations involved five samples, of identical dimensions, hot deformed at temperatures between (800°C - 1100°C). All samples were deformed by the dead-weight drop method at the same potential energy. The microstructural features of SDSS F55 alloy induced by hot deformation were analyzed using scanning electron microscopy (SEM). The results showed that initial sample presented two stable phases (ferrite () and austenite ()), while hot deformation at a temperature between (800°C - 1000°C) induces the appearance of the deleterious sigma () and chi () phases. It was observed that the sigma () and chi () phases are disappearing at hot deformation temperatures above 1000°C.

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 ... more 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.

IOP Conference Series: Materials Science and Engineering, 2018

In the present study, the microstructures of five samples of the Ti-6246 alloy were investigated ... more In the present study, the microstructures of five samples of the Ti-6246 alloy were investigated using SEM and OM devices. Four samples had been examined during different thermo-mechanical processing and heat treatment (hot plastic deformation and normalizing heat treatment) in α + β and β field domain respectively. The results demonstrate that the phase transformations and compositional modifications induced by thermo-mechanical processing and heat treatment have a dramatic influence on the microstructural characteristics. It was concluded that all samples present many morphologies textures and orientations. The microstructures features had improved in the normalizing heat process in comparison with the parent material and the hot deformation process.

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 ... more 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.