High Pressure Pneumatic Forming of Ti-3Al-2.5V Titanium Tubes in a Square Cross-Sectional Die

MATEC Web of Conferences

Yuan

2015

Self Cite

Abstract. Deformation behaviour of laser-welded tube blank of TA15 Ti-alloy at elevated temperature was investigated by both hot tensile tests and high pressure gas forming(HPGF). The hot tensile tests were carried out with four different specimens at 800 • C with an initial strain rate of 1.00×10 −2 s −1 and HPGF test was performed at 800 • C with a constant pressure of 9.5MPa. The tensile results show that base material with equiaxed microstructure exhibited good formability and grain boundary sliding (GBS) accompanied with dynamic recrystallization (DRV) was the main deformation mechanism. However, because the weld bead has coarse columnar grains with fine acicular in the matrix, when the loading direction is parallel with the weld bead, the fine acicular transformed into thicker lamella and the aspect ratio decreased greatly, and voids formed along the initial coarse grain boundaries. When the loading direction is vertical with the weld bead, the welded materials deformed little and the lamella structure thickened obviously after deformation. HPGF tests demonstrate that the laser-welded TA15 tube had a very good formability at 800 • C, and the maximum bulging ratio was as high as 77.4%.

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

“…G. Liu etc. [11] formed Ti-3Al-2.5V parts with seamless tube at temperature around 8000C by high pressure gas forming process (HPGF) successfully. Few reports were found about the deformation behaviour of laser-welded Ti-alloy tube blank within this kind of forming process, especially for Ti-6.5Al-2Zr-1Mo-1V (TA15) alloy.…”

Section: Introductionmentioning

confidence: 99%

Deformation behaviour of laser-welded tube blank of TA15 Ti-alloy for gas forming at elevated temperature

MATEC Web of Conferences

Yuan

2015

Self Cite

“…Drossel developed a measuring instrument to determine the gas temperature curve during pneumatic forming processes and to analyse the influence of gaseous medium with high pressure on the cooling process of work pieces [14]. Liu et al presented a HPPF process based on QPF, HMGF and hydroforming [15]. With the maximum pressure of 30 MPa, they also successfully formed Ti-alloy components with irregular cross-sections and square cross-sections at 850°C [15,16].…”

Section: Introductionmentioning

confidence: 99%

Effects of flow stress behaviour, pressure loading path and temperature variation on high-pressure pneumatic forming of Ti-3Al-2.5V tubes

Int J Adv Manuf Technol

Dang

et al. 2015

Self Cite

High-pressure pneumatic forming (HPPF) is an internal high-pressure forming process at elevated temperatures, which is based on quick plastic forming (QPF), hot metal gas forming (HMGF) and hydroforming. In this study, the HPPF experiments were performed on Ti-3Al-2.5V tubes using a square cross-sectional die at higher pressure levels and lower temperatures. The uniaxial tensile tests were carried out at various temperatures and strain rates before the HPPF experiments. The flow stress of Ti-3Al-2.5V tubes is evidently affected by both temperature and strain rate. Because of this, the corner radii all change linearly over time at the pressurization stage but exponentially over time at the constant pressure stage. The cooling effect of the inflow process on the tubes results in temperature differences between the centre of the straight wall areas and the corner areas of the tubes during the inflow process. Adopting the lower pressurization rate and filling regenerative materials into the tube are effective methods for decreasing or eliminating the temperature difference.

“…G. Liu et al presented high pressure gas forming process based on QPF, HMGF and Hydroforming [9]. With the maximum pressure of 30 MPa, they also successfully formed Ti-alloy components with irregular cross section and square cross section at 850 • C [10]. In this study, the high pressure gas forming process of Ti-alloy hollow part with square cross-section was developed further at higher pressure levels and lower temperatures.…”

Section: Introductionmentioning

confidence: 99%

The effect of pressurization path on high pressure gas forming of Ti-3Al-2.5V at elevated temperature

MATEC Web of Conferences

Dang

et al. 2015

Self Cite

Abstract. High pressure gas forming is a tubular component forming technology with pressurized gas at elevated temperature, based on QPF, HMGF and Hydroforming. This process can be used to form tube blank at lower temperatures with high energy efficiency and also at higher strain rates. With Ti-3Al-2.5V Ti-alloy tube, the potential of HPGF was studied further through experiments at the elevated temperatures of 650 • C and 700 • C. In order to know the formability of the Ti-alloy tube, tensile tests were also carried out. The results show that: at the temperatures of 650 • C and 700 • C, the flow curves exhibit the power-law constitutive relation until peak stress is reached and the deformability is suitable for the HPGF process of Ti-3Al-2.5V alloy tube. The effects of pressurization path on the corner filling process and thickness profile are obvious. The high pressure inflow process can result in temperature difference between the straight wall area and corner area, which makes the thickness profile special. Besides, with the stepped pressurization path, the more constant filling rate and better thickness profile can be obtained.