Microstructural evolution, mechanical properties and fracture toughness of near β titanium alloy during different solution plus aging heat treatments

Wu, Chaohua; Zhan, Mei

doi:10.1016/j.jallcom.2019.07.134

Cited by 90 publications

(32 citation statements)

References 35 publications

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“…All solution-treated samples were oil-quenched (OQ), to induce the formation of secondary phases (i.e., α -Ti/α"-Ti phases). In order to obtain an adequate combination of mechanical properties, high strength properties and increased ductility, one must complete the TM processing route with a final heat treatment (ageing), aimed to reduce the weight-fraction of secondary phases, i.e., α -Ti and α"-Ti phases, by applying an ageing treatment [32][33][34][35][36]. The ageing treatment must be performed to a temperature high enough to allow α -Ti → α-Ti and/or α"-Ti → β-Ti transformations, stress relieving and reordering/restructuring phenomena in parent α-Ti/β-Ti phases.…”

Section: Methodsmentioning

confidence: 99%

Microstructure and Mechanical Properties Evolution during Solution and Ageing Treatment for a Hot Deformed, above β-transus, Ti-6246 Alloy

Alluaibi

Cojocaru

Rusea³

et al. 2020

Metals

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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 (σUTS = 1279 ± 15 MPa, σ0.2 = 1161 ± 14 MPa, εf = 10.1 ± 1.3%).

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Section: Methodsmentioning

confidence: 99%

Microstructure and Mechanical Properties Evolution during Solution and Ageing Treatment for a Hot Deformed, above β-transus, Ti-6246 Alloy

Alluaibi

Cojocaru

Rusea³

et al. 2020

Metals

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“…Sample 80% CR+ aging exhibits the highest ultimate tensile strength of 1480 MPa among all the samples, which is approximately 16% higher than that of the sample with the normal lamellar microstructure (sample 0% CR + aging). It was reported that, as the strength higher than 1200 MPa, the elongation is usually lower than 10% (even lower than 5%) in the lamellar near β-Ti alloy without α + β filed deformation [ 3 , 42 , 43 , 44 ]. However, the highest elongation of 10.1% was achieved in the sample with the highest ultimate tensile strength as well.…”

Section: Resultsmentioning

confidence: 99%

Strengthening of a Near β-Ti Alloy through β Grain Refinement and Stress-Induced α Precipitation

Chen

Feng³

et al. 2020

Materials

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Near β-Ti alloys with high strength and good ductility are desirable for application in aviation and aerospace industries. Nevertheless, strength and ductility are usually mutually exclusive in structural materials. Here we report a new thermo-mechanical process, that is, the alloy was cross-rolled in β field then aged at 600 °C for 1 h. By such a process, a high strength (ultimate tensile strength: 1480 MPa) and acceptable ductility (elongation: 10%) can be simultaneously achieved in the near β-Ti alloy, based on the microscale β matrix and nanoscale α phase. The microstructure evolution, mechanical properties and strengthening mechanisms have been clarified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the grain size of the β phase progressively decreased with the increasing of rolling reduction. Moreover, dense dislocation structures and martensite phases distributed in the cross-rolled β matrix can effectively promote the precipitation of nanoscale α particles. TEM analyses confirmed that a heat-treatment twin was generated in the newly formed α lath during aging. These findings provide insights towards developing Ti alloys with optimized mechanical properties.

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“…Therefore, the crack propagates in β matrix more easily, and namely, the α phase can effectively inhibit the crack propagation. On the other hand, the grain size has an obvious influence on the crack propagation resistance, and the increasing grain size can extend the crack length [ 14 , 15 ], and finally improves the ductility [ 18 ].…”

Section: Resultsmentioning

confidence: 99%

Study on Grain Refinement Mechanisms and Mechanical Properties of bi-Modal Ti-55511 Titanium Alloy during Hot Rolling

et al. 2020

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Multi-pass hot rolling was performed on bi-modal Ti-55511 alloy with 50% rolling reduction at 700 °C. Mechanical properties were evaluated by tensile test, and microstructure evolution was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the Ti-55511 alloy with bi-modal microstructure exhibits good strength and high ductility (1102 MPa, 21.7%). Comparatively, after 50% hot rolling, an enhanced strength and decreased ductility were obtained. The refinement of α phases leads to the increased tensile strength, while the fragmentation of the equiaxed α phase results in a decreased ductility. The fragmentation process of equiaxed α phases followed the sequence of: elongation of α phases → formation of grooves and localized shear bands → the final fragmentation accomplished via deepening grooves.

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Microstructural evolution, mechanical properties and fracture toughness of near β titanium alloy during different solution plus aging heat treatments

Cited by 90 publications

References 35 publications

Microstructure and Mechanical Properties Evolution during Solution and Ageing Treatment for a Hot Deformed, above β-transus, Ti-6246 Alloy

Microstructure and Mechanical Properties Evolution during Solution and Ageing Treatment for a Hot Deformed, above β-transus, Ti-6246 Alloy

Strengthening of a Near β-Ti Alloy through β Grain Refinement and Stress-Induced α Precipitation

Study on Grain Refinement Mechanisms and Mechanical Properties of bi-Modal Ti-55511 Titanium Alloy during Hot Rolling

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