Quasi-Static Tensile Behaviors, Mechanisms, and Constitutive Descriptions of Commercially Pure Titanium at Diverse Strain Rates in Ambient Air and Liquid Nitrogen

Author(s):  
Xiaohui Shi ◽  
Zhiyuan Fan ◽  
Zuhan Cao ◽  
Ruipeng Guo ◽  
Junwei Qiao

2012 ◽  
Vol 548 ◽  
pp. 174-178 ◽  
Author(s):  
Chong Yang Gao ◽  
Wei Ran Lu

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.



2020 ◽  
Vol 861 ◽  
pp. 23-27
Author(s):  
Wisan Charee ◽  
Viboon Tangwarodomnukun

Underwater laser machining process is a material removal technique that can minimize thermal damage and offer a higher machining rate than the laser ablation in ambient air. This study applied the underwater method associated with a nanosecond pulse laser for turning a commercially pure titanium rod. The effects of laser power, surface speed and number of laser passes on machined depth and surface roughness were investigated in this work. The results revealed that a deeper cut depth and smoother machined surface than those obtained from the laser ablation in ambient air were achievable when the underwater laser turning process was applied. The machined depth and surface roughness were found to significantly increase with the laser power and number of laser passes. The findings of this study can disclose the insight as well as potential of the underwater laser turning process for titanium and other similar metals.



Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 25
Author(s):  
Guilherme Corrêa Soares ◽  
Mikko Hokka

Understanding the mechanical behavior of materials at extreme conditions, such as high temperatures, high strain rates, and very large strains, is fundamental for applications where these conditions are possible. Although tensile testing has been used to investigate material behavior under high strain rates and elevated temperatures, it disregards the occurrence of localized strains and increasing temperatures during deformation. The objective of this work is to combine synchronized full-field techniques and an electrical resistive heating system to investigate the thermomechanical behavior of commercially pure titanium under tensile loading at high temperatures and high strain rates. An electrical resistive heating system was used to heat dog-bone samples up to 1120 °C, which were then tested with a tensile Split Hopkinson Pressure Bar at strain rates up to 1600 s−1. These tests were monitored by two high-speed optical cameras and an infrared camera to acquire synchronized full-field strain and temperature data. The displacement and strain noise floor, and the stereo reconstruction error increased with temperature, while the temperature noise floor decreased at elevated temperatures. A substantial decrease in mechanical strength and an increase in ductility were observed with an increase in testing temperature. The localized strains during necking were much higher at elevated temperatures, while adiabatic heating was much lower or non-existent at elevated temperatures.



2014 ◽  
Vol 611-612 ◽  
pp. 92-98 ◽  
Author(s):  
Irena Eipert ◽  
Giribaskar Sivaswamy ◽  
Rahul Bhattacharya ◽  
Muhammad Amir ◽  
Paul Blackwell

Present work focusses on the effect of stress relaxation on the tensile behaviour of two commercially pure titanium alloys of different strength levels (Grade 1 and Grade 4) subjected to tensile tests at room temperature. The stress relaxation tests were performed by interrupting the tensile tests at regular strain intervals of 5% in the plastic region of the tensile curve and compared to the monotonic tensile tests at different strain rates ranging from 10-4to 10-1s-1. To understand the effect of anisotropy, samples were taken along 0° and 90° to rolling direction (RD) for both the alloys. Improvement in ductility of different levels at all the strain rates was observed in both the alloys when stress relaxation steps were introduced as compared to monotonic tests. However there is not much change in the flow stress as well as in strain hardening behaviour of the alloys. The true stress-true strain curves of Grade 4 samples taken in 90° to RD exhibited discontinuous yielding phenomenon after the yield point, which is termed as a yield-point elongation (YPE). The improvement in ductility of the Cp-Ti alloys can be linked to recovery process occurring during the stress relaxation steps which resulted in the improvement in ductility after repeated interrupted tensile tests. The paper presents and summarise the results based on the stress relaxation for the two different alloys.



Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 155
Author(s):  
Wei Zhang ◽  
Zhikang Zhu ◽  
Changyu Zhou ◽  
Xiaohua He

The aim of the present work is to contribute to the characterization of the biaxial tensile behavior of commercially pure titanium, under various in-plane loading conditions at room temperature, by a non-contact digital image correlation system. Several loading conditions, with load ratio ranging from 4:0 to 0:4 and displacement rate ranging from 0.001 to 0.1 mm/s, are examined. It is found that the yield strength and ultimate tensile strength of biaxial sample are greater than that of uniaxial sample, where the equi-biaxial sample shows the highest strength. It is also observed that increase in strain rate leads to remarkable improvement of tensile strength. Fractographic analysis indicates that the shape and size of dimples are load ratio and strain rate dependent. Additionally, a modified Johnson–Cook constitutive model was proposed to account for the effect of strain rate on biaxial tensile deformation. The experimental results are in good agreement with the simulated results, indicating that the proposed model is reliable to predict biaxial tensile deformation of commercially pure titanium at different strain rates.



2011 ◽  
Vol 59 (9) ◽  
pp. 3431-3446 ◽  
Author(s):  
N.P. Gurao ◽  
Rajeev Kapoor ◽  
Satyam Suwas


Author(s):  
V.V. Skripnyak ◽  
◽  
K.V. Iokhim ◽  
V.A. Skripnyak ◽  
◽  
...  

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.



Alloy Digest ◽  
1979 ◽  
Vol 28 (12) ◽  

Abstract RMI 0.2% Pd is a grade of commercially pure titanium to which up to 0.2% palladium has been added. It has a guaranteed minimum yield strength of 40,000 psi with good ductility and formability. It is recommended for corrosion resistance in the chemical industry and other places where the environment is mildly reducing or varies between oxidizing and reducing. The alloy has improved resistance to crevice corrosion at low pH and elevated temperatures. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and bend strength. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ti-74. Producer or source: RMI Company.



Alloy Digest ◽  
2020 ◽  
Vol 69 (6) ◽  

Abstract UPM CP Titanium Grade 3 (UNS R50550) is an unalloyed commercially pure titanium that exhibits moderate strength (higher strength than that of Titanium Grade 2), along with excellent formability and corrosion resistance. It offers the highest ASME allowable design stress of any commercially pure grade of titanium, and can be used in continuous service up to 425 °C (800 °F) and in intermittent service up to 540 °C (1000 °F). This datasheet provides information on composition, physical properties, and elasticity. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ti-167. Producer or source: United Performance Metals.



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