Compressive deformation and forging behavior of Ti14 alloy in semi-solid state

Advances in Mechanical Engineering

Yazhou

et al. 2015

The semi-solid compressive deformation behavior of Ti-Cu alloys was investigated by Gleeble-3500 hot simulator at the deformation temperatures ranging from 1273 to 1473 K with strain rates ranging from 5 3 10 23 to 5 3 10 21 s 21. The relationship between Cu concentration and flow stress was analyzed, and the deformation apparent activation energy was also calculated. The results show that Cu concentration has significant influence on the flows' behavior of Ti-Cu alloys, especially at high semi-solid deformation temperatures. The Ti-14Cu exhibits the highest flow stress at 1273 and 1373 K, Ti-2.5Cu alloy exhibits the highest flow stress at 1473 K, and Ti-7Cu alloy shows the lowest flow stress at all tested temperatures, which corresponds to liquid fraction caused by varied Cu concentration and the deformation temperature. The difference in microstructure suggests that the shape and distribution of Ti 2 Cu precipitates are significantly affected by Cu concentration. The increase in Cu concentration leads to the growth and precipitation of acicular Ti 2 Cu along grain boundaries at high semi-solid deformation temperatures. The deformation apparent activation energy of Ti-14Cu alloy significantly decreases from solid deformation to semi-solid deformation owing to the change in main deformation mechanism from plastic deformation of solid particles to solid particles' slippage and rotation of grain boundaries.

Section: Introductionmentioning

confidence: 83%

Effect of Cu concentration on the semi-solid deformation behavior and microstructure of Ti–Cu alloy

Advances in Mechanical Engineering

Yazhou

et al. 2015

“…In the initial compression, yield stress is rapidly increased to the limit with the increase of strain. The phenomenon is also provided in the semisolid deformation of the Ti14 alloy (Chen et al 2009(Chen et al , 2012(Chen et al , 2014. However, at the temperature of 1273 K, the stress-strain curves show steady-state characteristic without any obvious peak stress, and the flow stress of the alloy increases markedly and decreases very slowly with the increasing strain in the whole true strain scope of 0-0.75.…”

Section: Flow Behavior At Different Temperaturesmentioning

confidence: 90%

Characterization of semisolid deformation behavior and constitutive analysis of Ti230 alloy

Wei

et al. 2015

Mech Time-Depend Mater

The semisolid compressive deformation behavior of Ti230 titanium alloy at the temperature range of 1273 K to 1573 K and strain rate range of 0.005 to 5 s −1 has been investigated by hot compressive testing. The relationship between flow stress and deformation parameters and microstructure were discussed. The results show that the alloy expresses obvious yield point in semisolid state. The maximum decreased with decreasing solid phase fraction and/or decreasing strain rate, and a transition in stress occurred at a solid phase fraction close to 0.95, which is considered to be associated with the decrease in amount of solid bridges between grains and the decomposing effects of the liquid on α-Ti matrix. A deformation constitutive equation for Ti230 alloy in semisolid state was established considering high-temperature deformation activation energy Q. Furthermore, microstructural analysis confirmed that increasing temperature could reduce the deformation-resistant stress and lead to the transformation of softening mechanism from plastic deformation of solid particles (PDS) to sliding between the solid particles (SS).

“…The slope of the fitted line is reduced with the decrease of strain rate. The early investigation into deformation behavior of Ti14 in semisolid state shows that the slope of the linear part of the forcedisplacement curve ( / ) is decreased with decreasing strain rate [14][15][16]. Consequently the pressure gradient on liquid phase ( liq / ) drops since it is proportional to ( / ) [9].…”

Section: Liquid Segregation Behavior With Different Deformationmentioning

confidence: 99%

Liquid Segregation Phenomenological Behaviors of Ti14 Alloy during Semisolid Deformation

Advances in Mechanical Engineering

Wei

et al. 2014

The liquid segregation phenomenon and its effect on deformation mechanism of Ti14 alloy in semisolid metal processing were investigated by thermal simulation test. Microstructure of depth profile was determined by cross-section quantitative metallography, and liquid segregation phenomenon was described by Darcy's law. The results show that segregation phenomenon was affected by solid fraction, strain rate, and deformation rate. More liquid segregated from center to edge portion with high strain rate and/or deformation ratio as well as low solid fraction, which caused different distribution of dominating deformation mechanism. The relationship between liquid segregation and main deformation mechanism was also discussed by phenomenological model.