The Effect of Strain Rate on the Plastic Deformation Mode of CP-Ti during Surface Nanocrystallization

2011 ◽  
Vol 675-677 ◽  
pp. 239-242
Author(s):  
Chun Huan Chen ◽  
Cheng Jin ◽  
Rui Ming Ren
Keyword(s):  
Plastic Deformation ◽  
Surface Layer ◽  
Strain Rate ◽  
Shot Peening ◽  
Pure Titanium ◽  
Deformation Mode ◽  
Rate Variation ◽  
Commercially Pure Titanium ◽  
Surface Nanocrystallization ◽  
Cp Ti

The effect of the strain rate on the surface nanocrystallization of titanium is investigated both theoretically and experimentally in this paper. The strain rate variation and stress distribution from surface to the interior of titanium during shot peening are estimated firstly using finite element method. Then shot peening experiment is carried out on a commercially pure titanium (CP-Ti) plate, and the obtained surface microstructures is characterized by transmission electron microscopy (TEM). Combining theoretical simulations and experimental observations, the effect of strain rate on the strain accommodation mechanism and plastic deformation mode are discussed. It is concluded that the strain rate and stress achieve the highest at the top surface layer of CP-Ti, and the strain rate decrease dramatically from the surface to the interior. The strain rate at the top surface layer is up to 104 s-1, which leads to superplastic deformation of Ti. There is no mechanical twin in the surface layer, instead, deformation lamella and adiabatic shear bands are the dominating microstructures. By means of rotation recrystallization, those deformation bands evolve to nanocrystallines.

High Energy Shot Peening of Commercially Pure Titanium TIG Weld Joint

2010 ◽  
Vol 148-149 ◽  
pp. 659-663
Author(s):  
Chun Huan Chen ◽  
Rui Ming Ren
Keyword(s):  
Surface Layer ◽  
Weld Joint ◽  
Shot Peening ◽  
Welded Joint ◽  
Pure Titanium ◽  
High Energy ◽  
Commercially Pure Titanium ◽  
Nanostructured Surface ◽  
Commercially Pure ◽  
Cp Ti

Commercially pure Titanium (CP-Ti) TIG weld joint was treated by means of high energy shot peening (HESP) using a shot peening equipment commonly used in industry. The nanostructured surface layer was characterized by XRD, TEM, SEM and Microhardometer. The results showed that surface nanocrystallization of CP-Ti TIG weld joint were realized by high energy shot peening treatment. The finest grain size in the top surface layer is about 40nm. The hardness of the surface layer is enhanced significantly after shot peening compared with that of the as-welded joint, which resulted in a remarkable surface hardening effect. Surface welded defects such as air pores are eliminated successfully so that relative uniform surface layer was obtained.

Wear Assessment of Ti/SiC Surface Nano-Composite Layer and its Associated CP-Ti Substrate

2012 ◽  
Vol 445 ◽  
pp. 595-600 ◽  
Author(s):  
Ali Shamsipur ◽  
Seyed Farshid Kashani-Bozorg ◽  
Abbas Zarei Hanzaki
Keyword(s):  
Surface Layer ◽  
Wear Behavior ◽  
Composite Layer ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Micro Hardness ◽  
Wear Properties ◽  
Friction Stir ◽  
Pin On Disc ◽  
Cp Ti

In the present investigation, the surface of a commercially pure titanium (CP-Ti) substrate was modified to Ti/SiC nanocomposite layer employing friction stir processing technique; nanosized SiC powder was introduced into the stir zone provided by a rotating and advancing tool. The fabricated nanocomposite surface layer exhibited a micro hardness value of ~535HV which is much greater than 160HV of the substrate material using Vickers micro hardness testing. In addition, the un-treated CP-Ti substrate showed sever wear regime in the pin-on-disc test against the hardened AISI 52100 steel. It suffers extensive typical adhesive wear dominated by plastic deformation as evidenced by scanning electron microscopy. Also, deep grooves were formed, i.e. evidence of abrasive wear. Contrary to this, enhanced wear properties were detected for the Ti/SiC nanocomposite surface layer, i.e. lower coefficient of friction and weight loss. The nanocomposite surface layer was found to be adherent to the underlying substrate during the pin-on-disc test. The superior wear behavior of the nanocomposite surface layer is attributed to its improved micro hardness value due to the presence of hard nanosize SiC particles in a refined titanium matrix.

The Influence of Strain Rate on the Springback of Commercially Pure Titanium in a Stretch Forming Operation

2015 ◽  
Vol 639 ◽  
pp. 107-114 ◽  
Author(s):  
Alan G. Leacock ◽  
Shane Quinn ◽  
Gregor Volk ◽  
David McCracken ◽  
Desmond Brown
Keyword(s):  
Stress State ◽  
Strain Rate ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Stretch Forming ◽  
Commercially Pure ◽  
Strain And Strain Rate ◽  
Strain Magnitude ◽  
Cp Ti ◽  
Processing Stress

A common processing stress state used in the construction of sheet metal components is that of uniaxial tension/stretching. This work examines the stretching of CP-Ti over a rigid form tool using varying degrees of strain and strain rate. The degree of springback is shown to be influenced by the interaction of strain rate, strain magnitude and time following forming.

scholarly journals Effect of oxygen contents on strain rate sensitivity of commercially pure titanium

2020 ◽  
Vol 321 ◽  
pp. 04009
Author(s):  
Min-Su Lee ◽  
Yong-Taek Hyun ◽  
Tea-Sung Jun
Keyword(s):  
Strain Rate ◽  
Grain Orientation ◽  
Pure Titanium ◽  
Constant Strain Rate ◽  
Nanoindentation Test ◽  
Commercially Pure Titanium ◽  
Commercially Pure ◽  
Effect Of Oxygen ◽  
Cp Ti ◽  
The Impact

In this study, we have investigated the effect of oxygen contents on strain rate senstivitiy (SRS) within Gr. 1 and 4 commercially pure titanium (CP-Ti). The SRS was evaluated in multi-scales using macro-scopic tensile test with constant strain rate (CSR) method and strain rate jump (SRJ) method, and nanoindentation test with SRJ method. Electron backscatter diffraction (EBSD) has been used to characterise crystallographic texture and individual grain orientation of samples. Slip and twin activities of each CP-Ti were compared by EBSD measurements and the associated Schmid factor (SF) analysis. The active slip system is anticipated to be different in each relation between loading directions and textures, but twin activity is much similar. The texture dependent global SRS is thus thought to be resulted from the different slip activity. Local SRS was dependent not only on the grain orientation but also on the oxygen contents, leading to the fact that the impact of oxygen contents is closely correlated in macro- and micro-scopic level.

scholarly journals LOCALIZATION OF PLASTIC DEFORMATION IN COMMERCIALLY PURE TITANIUM IN A COMPLEX STRESS STATE UNDER HIGH-SPEED TENSION

2021 ◽  
pp. 89-102
Author(s):  
V.V. Skripnyak ◽  
◽  
K.V. Iokhim ◽  
V.A. Skripnyak ◽  
◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Stress State ◽  
Strain Rate ◽  
High Speed ◽  
Pure Titanium ◽  
Complex Stress ◽  
Complex Stress State ◽  
Strain Rates ◽  
Commercially Pure Titanium ◽  
Commercially Pure

In this work, the effect of a triaxiality stress state on the mechanical behavior and fracture of commercially pure titanium VT1-0 (Grade 2) in the range of strain rates from 0.1 to 1000 s−1 is studied. Tensile tests are carried out using a servo-hydraulic testing machine Instron VHS 40 / 50-20 on flat specimens with a constant cross-sectional area and on flat specimens with a notch. To study the effect of the complex stress state on the ultimate deformation before fracture, the samples with the notch of various radii (10, 5, 2.5 mm) are used in the experiments. Phantom V711 is employed for high-speed video registration of specimen’s deformation. Deformation fields in a working part of the sample are investigated by the digital image correlation method. It is shown that the effect of the strain rate on the ultimate deformations before fracture has a nonmonotonic behavior. An analysis of strain fields in the working part of the samples shows that the degree of uniform deformation of the working part decreases with an increase in the strain rate. At strain rates above 1000 s−1, the shear bands occur at the onset of a plastic flow. Commercially pure titanium undergoes fracture due to the nucleation, growth, and coalescence of damages in the bands of localized plastic deformation oriented along the maximum shear stresses. The results confirm that the fracture of commercially pure titanium exhibits ductile behavior at strain rates varying from 0.1 to 1000 s−1, at a triaxiality stress parameter in the range of 0.333 ≤ η <0.467, and at a temperature close to 295 K.

scholarly journals Comparison of Biocompatible Coatings Produced by Plasma Electrolytic Oxidation on cp-Ti and Ti-Zr-Nb Superelastic Alloy

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 401
Author(s):  
Ruzil Farrakhov ◽  
Olga Melnichuk ◽  
Evgeny Parfenov ◽  
Veta Mukaeva ◽  
Arseniy Raab ◽  
...  
Keyword(s):  
Plasma Electrolytic Oxidation ◽  
Electrochemical Impedance ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
X Ray ◽  
Kinetic Coefficients ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
Cp Ti ◽  
Peo Coatings

The paper compares the coatings produced by plasma electrolytic oxidation (PEO) on commercially pure titanium and a novel superelastic alloy Ti-18Zr-15Nb (at. %) for implant applications. The PEO coatings were produced on both alloys in the identical pulsed bipolar regime. The properties of the coatings were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The PEO process kinetics was modeled based on the Avrami theorem and Cottrell equation using a relaxation method. The resultant coatings contain TiO2, for both alloys, and NbO2, Nb2O5, ZrO2 for Ti-18Zr-15Nb alloy. The coating on the Ti-18Zr-15Nb alloy has a higher thickness, porosity, and roughness compared to that on cp-Ti. The values of the kinetic coefficients of the PEO process—higher diffusion coefficient and lower time constant for the processing of Ti-18Zr-15Nb—explain this effect. According to the electrochemical studies, PEO coatings on Ti-18Zr-15Nb alloy provide better corrosion protection. Higher corrosion resistance, porosity, and roughness contribute to better biocompatibility of the PEO coating on Ti-18Zr-15Nb alloy compared to cp-Ti.

Thermomechanical Response of Commercially Pure Titanium under Large Plastic Deformation at High Strain Rates

2012 ◽  
Vol 548 ◽  
pp. 174-178 ◽  
Author(s):  
Chong Yang Gao ◽  
Wei Ran Lu
Keyword(s):  
Pure Titanium ◽  
Optimal Solution ◽  
Optimization Method ◽  
Strain Rates ◽  
Commercially Pure Titanium ◽  
Thermomechanical Response ◽  
Commercially Pure ◽  
Different Temperatures ◽  
Cp Ti ◽  
Constitutive Parameters

By using a dislocation-based plastic constitutive model for hcp metals developed by us recently, the dynamic thermomechanical response of an important industrial material, commercially pure titanium (CP-Ti), was described at different temperatures and strain rates. The constitutive parameters of the material are determined by an efficient optimization method for a globally optimal solution. The model can well predict the dynamic response of CP-Ti by the comparison with experimental data and the Nemat-Nasser-Guo model.

scholarly journals Deformation Resistance and Recrystallization of Commercially Pure Titanium in the High Strain Rate Hot Deformation

1986 ◽  
Vol 72 (2) ◽  
pp. 321-328 ◽  
Author(s):  
Takehide SENUMA ◽  
Hiroshi YADA ◽  
Hirobumi YOSHIMURA ◽  
Hisaaki HARADA ◽  
Takuji SHINDO ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Hot Deformation ◽  
High Strain ◽  
Pure Titanium ◽  
Deformation Resistance ◽  
Commercially Pure Titanium ◽  
Commercially Pure

scholarly journals Transformations of the Microstructure and Phase Compositions of Titanium Alloys during Ultrasonic Impact Treatment. Part I. Commercially Pure Titanium

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 562
Author(s):  
Alexey Panin ◽  
Andrey Dmitriev ◽  
Anton Nikonov ◽  
Marina Kazachenok ◽  
Olga Perevalova ◽  
...  
Keyword(s):  
Surface Layer ◽  
Phase Transformations ◽  
Pure Titanium ◽  
Surface Plastic ◽  
Commercially Pure Titanium ◽  
Ultrasonic Impact Treatment ◽  
Coordination Numbers ◽  
Microscopy Technique ◽  
Transmission Electron ◽  
Treated Sample

Experimental and theoretical studies helped to reveal patterns of surface roughening and the microstructure refinement in the surface layer of commercial pure titanium during ultrasonic impact treatment. Applying transmission electron microscopy technique, a gradient microstructure in the surface layer of the ultrasonically treated sample, where the grain size is varied from nano- to micrometers was revealed. It was shown that the surface plastic strains of the titanium sample proceeded according to the plastic ploughing mechanism, which was accompanied by dislocation sliding, twinning, and the transformations of the microstructure and phase composition. The molecular dynamics method was applied to demonstrate the mechanism of the phase transformations associated with the formation of stacking faults, as well as the reversible displacement of atoms from their sites in the hcp lattice, causing a change in coordination numbers. The role of the electronic subsystem in the development of the strain-induced phase transformations during ultrasonic impact treatment was discussed.

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