A comparative study on the hot deformation behavior of Ti 5Al 5Mo 5V 3Cr and newly developed Ti 4Al 7Mo 3V 3Cr alloys

The deformation mechanisms and dynamic softening behavior of a Ti–6Al–4V alloy with thick lamellar microstructures are studied by uniaxial hot tensile tests. The true stress first rapidly reaches a peak value because of the rapid dislocations proliferation and tangle, and then gradually decreases due to the dynamic softening with raising the deformation amount. The dynamic softening behavior is mainly induced by the severe dynamic globularization of lamellar α phases. The globularization of α phase is always accompanied by the formation of high‐angle grain boundaries (HAGBs). The fraction of globularized α phases increases with the increasing deformation temperature. The fracture mechanism is microvoid coalescence, i.e., in the initial stage of tensile deformation, the microvoids begin to emerge. With the increasing deformation amount, the number of microvoids increases, and the microvoids accumulate and accelerate to propagate until the final fracture. According to the experimental flow stress curves, a modified Arrhenius‐type equation and a Hensel–Spittel (HS) model are developed to forecast the flow stresses. The average absolute relative error of the established strain‐compensated Arrhenius‐type (SCAT) and HS models are 6.108% and 3.385%, respectively. Both models can be well used to describe the hot tensile flow characteristics of the Ti–6Al–4V alloy with thick lamellar microstructures.

Section: Introductionmentioning

confidence: 99%

Hot Tensile Deformation Mechanism and Dynamic Softening Behavior of Ti–6Al–4V Alloy with Thick Lamellar Microstructures

Lin

Pang

et al. 2019

“…Lots of metastable β and β Ti alloys with favorable properties have been developed via the assistance of the Mo equivalent. [102][103][104][105][106] Some reports indicated that Ti alloys with a [Mo] eq value between 8 and 12 should be metastable β Ti alloys. [107,108] Other publications proved that the metastable β Ti alloys would have low elastic modulus.…”

Section: Design Methods For Low-modulus Ti Alloysmentioning

confidence: 99%

“…Some Ti alloys with low elastic modulus designed through [Mo] eq are shown in Table 2. [19,31,33,34,36,102,103,[107][108][109][110][111] Results show that the elastic modulus of Ti alloys is not only related to the [Mo] eq value but also concerned with the category of alloying elements. Therefore, the [Mo] eq models are efficient in the screening composition of certain Ti alloy systems.…”

Section: Design Methods For Low-modulus Ti Alloysmentioning

confidence: 99%

Review of the Design of Titanium Alloys with Low Elastic Modulus as Implant Materials

Liang

2020

“…By now, considerable investigations have intensively focused on the descriptions of hot deformation behaviors for diverse metals. Phenomenological constitutive models, such as Field–Backofen (F–B) model, [ 4 ] Johnson–Cook (JC) model, [ 5–7 ] Arrhenius hyperbolic‐sine equations, [ 8–12 ] and Cingara–Queen (C–Q) equations, [ 13,14 ] are developed to precisely characterize the flow characteristics of hot deformed alloys. [ 15,16 ] Considering the specific deformation mechanisms such as dislocation motion, work hardening (WH), dynamic recrystallization (DRX), and dynamic recovery (DRV), a series of physically based constitutive models, including Voyiadjis–Abed (VA) model, [ 17–19 ] Zerilli–Armstrong (Z–A) model, [ 20–22 ] unified dislocation density‐based model, [ 23–27 ] and two‐stage physically based constitutive equations, [ 28–33 ] are used to model the flow behaviors of alloys.…”

Section: Introductionmentioning

confidence: 99%

An Enhanced Johnson–Cook Model for Hot Compressed A356 Aluminum Alloy

Chen

Lin

et al. 2020

The isothermal compression experiments with the strain rates of 0.01–10 s−1 and deformation temperature range of 300–420 °C are performed to investigate the hot deformation behavior of A356 aluminum alloy. Also, the complex deformation mechanisms are analyzed. It is found that, as the strain is gradually increased, the flow stress first rises, and then the stable stress appears without a tangible peak. The microstructures exhibit large elongated grains, and only a few small new grains appear under most deformation conditions. It is because the dynamic recovery (DRV) is the dominant softening mechanism. Based on the measured data, both the original Johnson–Cook (O–JC) model and modified Johnson–Cook model (M–JC) are built for the tested aluminum alloy. However, there are different deviations between the experimental and the predicted true stresses by O–JC model and M–JC model. Considering the obvious DRV features, an enhanced Johnson–Cook (EH–JC) model is proposed by introducing the stress–dislocation relation. The accuracy of the EH–JC model is validated because the correlation coefficient between the experimental and predicted results is as high as 0.997, whereas the average absolute relative error is merely 2.84%.