Microstructure and tensile properties of additive manufactured Ti-6Al-4V with refined prior-β grain structure obtained by rapid heat treatment

Zou, Zhiyi; Simonelli, Marco; Katrib, Juliano; Dimitrakis, Georgios; Hague, Richard

doi:10.1016/j.msea.2021.141271

Cited by 71 publications

(24 citation statements)

References 48 publications

(55 reference statements)

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“…Many researchers have reported that above 882 °C (β-transus), prior-β grains will be transformed into α′ martensite as seen in figures 3(c), (f), (i) and above 500 °C temperature α 2 precipitates (Titanium aluminides) will be formed within the α-grains. The presence of martensite and α 2 precipitates in the microstructure will enhance the strength of the alloy [26,29,30]. In SRA and STA process, an increase in strength has resulted than the WHT, which could be ascribed by the above said reason since their processing temperatures are above 500 °C.…”

Section: Discussionmentioning

confidence: 99%

Effect of thermal cycling on mechanical and microstructural properties of heat-treated Ti-6Al-4V alloy

Teja

Manikandan

Ayyagari³

2022

Mater. Res. Express

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Titanium (Ti-6Al-4V) is an α+β phase-field alloy utilized in many industries due to its high strength-to-weight ratio and near-net shaping capability. Solution treated & aging, and stress relief annealing processes were performed on the samples to increase the strength and % of elongation. The heat-treated samples then thermally cycled for 500 cycles, 1000 cycles, and 1500 cycles to evaluate the microhardness and tensile properties. The presence of martensite and α2 precipitates in the thermally cycled samples was confirmed by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). In this investigation, at 1000 thermal cycles, all specimens show improvement in both hardness and strength when compared within the cycles. Solution-treated and aging (STA), stress relief annealing (SRA), and without any heat-treatment (WHT) processes have their highest hardness values recorded for 1000 thermal cycles, and the values are 471 HV0.5, 381 HV0.5, and 374.6HV0.5, respectively. For the SRA process, ultimate tensile strength (UTS) of 925 MPa and yield strength (YS) of 896 MPa have resulted in 1000 cycles. Similarly, at 1000 thermal cycle WHT processed samples yielded UTS of 920 MPa and YS of 885 MPa. STA process samples that are heat-treated for 1000 thermal cycles have better strength properties than SRA and WHT and had a UTS of 1530MPa and YS of 1420MPa. From a ductility point of view, a maximum elongation of 29% for the STA process has resulted. Compared to forged titanium alloy (base metal), an increase of 31% elongation and 41% ultimate tensile strength for solution treated and aging process at 1000 cycles has resulted in this investigation.

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Section: Discussionmentioning

confidence: 99%

Effect of thermal cycling on mechanical and microstructural properties of heat-treated Ti-6Al-4V alloy

Teja

Manikandan

Ayyagari³

2022

Mater. Res. Express

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“…Meanwhile, as shown in Figures11d, 12d, 13d and 14d, the high angle grain boundaries (HAGBs) of the reconstructed β grains accounted for about 80% of the residual deformed billet. Such a boundary angle distribution suggests that recrystallization occurred during the plastic deformation [35] since the dislocation accumulation and rearrangement formed subgrains in the deformation process. With increasing strain, these subgrains trapped more dislocations in the LAGBs which finally transformed into HAGBs, and thus new continuous dynamic recrystallization (CDRX) grains formed [36].…”

Section: Discussionmentioning

confidence: 99%

“…In the present study, the β grain size increased while the grain boundary decreased according to the increase in the holding time. According to the studies [34,35], grain boundary sliding was a substantial contribution to high-temperature deformation of alloy, which was ascribed to the weaker strength of the grain boundary than the grain at high temperatures. Thus, the extrusion force increased with the extension of the holding time.…”

Section: The Effect Of β Grains On the Extrusion Forcementioning

confidence: 99%

Effect of Holding Time on the Extrusion Force and Microstructure Evolution during the Plastic Forming of Ti-6Al-4V Micro-Gears

Yan

Zhang²,

Huang

et al. 2022

Materials

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The application of titanium alloy micro-gears in microelectromechanical systems has been severely restricted, as the graphite mold is prone to abrasion or even to crack at high temperatures, mainly due to the forming load. We aimed to manufacture Ti-6Al-4V alloy micro-gears through hot extrusion under an electric field and to clarify the influence of holding time on the extrusion force. The results suggest that the formed gears had a complete filling and clear tooth profile. Moreover, the contact resistance and current density caused a gradient temperature distribution inside the billet, resulting in a carburized layer and inhomogeneous β grains. The extrusion force increased with an increased holding time, which can be ascribed to the increase in the thickness of the carburized layer and the β grain size. Among these two factors, β grain size played a leading role in the extrusion force. Continuous dynamic recrystallization dominated the deformation in a single β phase, and the misorientation of the transformed α laths from β grains followed the Burgers orientation relationship. This study may pave the way for the extrusion forming of other titanium alloy micro-components.

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“…A sharp acicular α′ structure was observed inside these prior β grains and were randomly embedded as laths as shown in Figure 2(b). Since Ti6Al4V is a dual-phase α + β alloy, the formation of martensite α′ phase followed a diffusionless transformation from βphase into α′ (β → α′) due to high cooling rates (~10 4 -10 5 K/s) experienced by the sample during SLM processing [1,6,11,24]. According to Bai et al [12], the cooling rate of SLM process is much higher than the critical transformation rate of martensite α′ phase, which explains the existence of martensite α′ phase on the microstructure of SLM manufactured Ti6Al4V samples.…”

Section: Microstructurementioning

confidence: 99%

“…Zou et al [24] investigated the influence of heat treatment on microstructure and tensile properties of SLM produced Ti6Al4V by conducting heat treatment on cylindrical Ti6Al4V samples that were produced using proprietary optimised process parameters. The samples were heat treated at temperatures in the range 925-1030 °C for a period of 2 h before they were cooled at a cooling rate of 7 °C/min.…”

Section: Introductionmentioning

confidence: 99%

Effect of heat treatment on microstructure, hardness and tensile properties of high-speed selective laser melted Ti6Al4V

et al. 2022

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This study presents the investigation of the influence of heat treatment on microstructure, hardness and tensile properties of high-speed selective laser melted Ti6Al4V components. Heat treatment was performed to obtain an improved microstructure with enhanced hardness and tensile properties. It was found that the acicular martensitic α′ structure on the as-built sample lead to high hardness, yield strength and ultimate tensile strengths of 389±10 HV0.3, 949 ± 10 MPa and 1045 ± 3 MPa, respectively,with a low ductility of 5%. Heat treatment transformed the martensitic α′ structure into lamella α + β phases, with heat treatment at 1000 °C resultingin the most improved hardness and ductility from 389 ± 10 HV0.3 and 5% to 325 ± 20 HV0.3 and 13%, and a decrease in yield and ultimate tensile strength from 949 ± 10 MPa and 1045 ± 13MPa to 835 ± 11 MPa and 911 ± 5 MPa, respectively.

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Microstructure and tensile properties of additive manufactured Ti-6Al-4V with refined prior-β grain structure obtained by rapid heat treatment

Cited by 71 publications

References 48 publications

Effect of thermal cycling on mechanical and microstructural properties of heat-treated Ti-6Al-4V alloy

Effect of thermal cycling on mechanical and microstructural properties of heat-treated Ti-6Al-4V alloy

Effect of Holding Time on the Extrusion Force and Microstructure Evolution during the Plastic Forming of Ti-6Al-4V Micro-Gears

Effect of heat treatment on microstructure, hardness and tensile properties of high-speed selective laser melted Ti6Al4V

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