Cyclic Stress-Strain Response of Superelastic Polycrystalline Cu-12wt%Al-0.5wt%Be Alloy

2010 ◽  
Vol 643 ◽  
pp. 91-97
Author(s):  
Fabio José Carvalho França ◽  
Nilmário Galdino Guedes ◽  
Severino Jackson Guedes de Lima ◽  
Tadeu Antônio de Avezedo Melo ◽  
Rodinei Medeiros Gomes
Keyword(s):  
Residual Strain ◽  
Room Temperature ◽  
Volume Fraction ◽  
Tensile Tests ◽  
Cyclic Stress ◽  
Applied Strain ◽  
Strain Response ◽  
Loading And Unloading ◽  
Total Volume Fraction ◽  
The Stability

The effect of cyclic deformation on the stability of superelasticity was investigated for the Cu-12wt%Al-0.5wy%Be alloy. The loading and unloading cyclic tensile tests were performed at room temperature and at 57oC with the maximum constant strain of 4%. The effect of holding the applied strain for a period of time on the superelastic properties was also investigated. It was confirmed that the total volume fraction of the retained martensite changes with time after unloading cycle, leading to the reduction of the residual strain. Additionally, the residual strain increases as the loading cycle of the applied strain is kept constant for a period of time.

Spark Plasma Sintering of Ti-4.5Al-3V-2Fe-2Mo (SP-700)

2010 ◽  
Vol 654-656 ◽  
pp. 819-822
Author(s):  
Genki Kikuchi ◽  
Hiroshi Izui ◽  
Yuya Takahashi ◽  
Shota Fujino
Keyword(s):  
Spark Plasma Sintering ◽  
Room Temperature ◽  
Volume Fraction ◽  
Titanium Boride ◽  
Tensile Tests ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Tib2 Particles

In this study, we focused on the sintering performance of Ti-4.5Al-3V-2Mo-2Fe (SP-700) and mechanical properties of SP-700 reinforced with titanium boride (TiB/SP-700) fabricated by spark plasma sintering (SPS). TiB whiskers formed in titanium by a solid-state reaction of titanium and TiB2 particles were analyzed with scanning electron microscopy and X-ray diffraction. The TiB/SP-700 was sintered at temperatures of 1073, 1173, and 1273 K and a pressure of 70 MPa for 10, 30, and 50 min. The volume fraction of TiB ranged from 1.7 vol.% to 19.9 vol.%. Tensile tests of TiB/SP-700 were conducted at room temperature, and the effect of TiB volume fraction on the tensile properties was investigated.

Plasticity-Induced Martensitic Phase Transformation in Fatigue of Unnotched SUS304 Plates

2005 ◽  
Vol 297-300 ◽  
pp. 1152-1157
Author(s):  
Yoshifumi Iwasaki ◽  
Yuji Nakasone
Keyword(s):  
Phase Transformation ◽  
Fatigue Life ◽  
Room Temperature ◽  
Volume Fraction ◽  
Tensile Tests ◽  
Martensitic Phase ◽  
Martensitic Phase Transformation ◽  
Air Volume ◽  
Maximum Value ◽  
Residual Fatigue

The present study has investigated plasticity-induced martensitic phase transformation in fatigue of unnotched SUS304 plates. Martensitic phase transformation occurred in uunotched SUS304 plate specimens fatigued at room temperature in air. Volume fraction Va’ of a’ martensite in the uunotched portion of fatigued specimens was measured by ferrite scope. The relations between the maximum value of Va’, Va’max, and the number of load cycles N were represented by reverse sigmoidal curves for all the applied stress range Ds levels tested in this study. For the most portion of fatigue life, the value of Va’max remained almost constant. This value was increased with increase in the value of Ds. The spatial distribution of Va’ in the specimens varied with N: i.e., continued cycling of stress made a’ transformation localized near the central portion of specimens where the Va’ value reached as high as 35-40%. This value is more than doubled compared to the highest Va’ value found in the tensile tests of SUS304 at room temperature in air. Invisible cracks of 200µm in length were found in the high Va’ value region. These results imply that the measurement of Va’ in fatigued SUS304 components may detect crack initiation sites and may predict residual fatigue life.

Mechanical Behavior After Stress Relaxation in PVDF

2018 ◽  
Author(s):  
Rafael Luis Menezes Freitas ◽  
Celio Costa ◽  
Erica Gervasoni Chaves ◽  
Sylvia Teixeira
Keyword(s):  
Stress Relaxation ◽  
Tensile Properties ◽  
Room Temperature ◽  
Volume Fraction ◽  
Tensile Tests ◽  
Yield Strain ◽  
Cooling Temperature ◽  
Cooling Conditions ◽  
C 23 ◽  
Processing Stress

This study presents the mechanical properties evaluation of two commercial grades of PVDFs, which were extruded with the same parameters but with different cooling temperatures. After processing, stress relaxation with 7% strain was imposed and tensile properties were measured. The cooling temperature after extrusion were 4°C, 23°C and 80°C. Then, the PVDFs were submitted to stress relaxation at 23°C and 7% strain. The as processed and after relaxation samples were characterized by FTIR, XRD, DSC and tensile tests at 23°C. The stress relaxation at 23 °C resulted in no change in volume fraction of crystallinity for PVDF A and B. The XRD and FTIR, for both PVDFs, showed that the crystalline phases were the same, for all cooling conditions and did not change after the stress relaxation. The tensile properties at room temperature showed that the yield stress was a little affect by the cooling temperature, while Young’s Modulus and yield strain were insensible to the cooling temperature. After the stress relaxation, these three tensile properties were slightly affected for both grades.

Temperature Development during Step-Wise Tensile Tests on a TRIP Steel

2010 ◽  
Vol 638-642 ◽  
pp. 3579-3584
Author(s):  
Lie Zhao ◽  
Corinna Thomser ◽  
Kirsten Schneider ◽  
Wolfgang Bleck ◽  
Jilt Sietsma
Keyword(s):  
Trip Steel ◽  
Retained Austenite ◽  
Room Temperature ◽  
Longitudinal Direction ◽  
Tensile Tests ◽  
Transformation Induced Plasticity ◽  
Trip Steels ◽  
Loading Process ◽  
Temperature Development ◽  
The Stability

Temperature development during plastic deformation affects the stability of retained austenite and thus the mechanical properties in transformation-induced plasticity (TRIP) steels. In this work, we used a thermo-camera to monitor the temperature development during a step-wise tensile test of an Al-containing multiphase TRIP steel. The tensile tests were performed by loading the specimen at six straining rates ranging from 5 to 30 s-1 to a stress of 700 MPa and then holding for 15 min, followed by further loading at 50 s-1 until fracture. It is found that temperature increases about 13 – 18 °C during the first loading process and drops back to room temperature with a time-constant of around 2 min. The increment of temperature increases with increasing straining rate. The temperature increases around 30 °C during the second loading process. The distribution of temperature over the specimen surface is found to be rather homogeneous along the longitudinal direction in most cases, except for the ending points of two loading processes. The measurement of temperature development is found to be consistent with previous numerical simulation on the temperature development under constant stress in TRIP steels.

scholarly journals Effect of Pre-Quenching Process on Microstructure and Mechanical Properties in a Nb-Microalloyed Low Carbon Q-P Steel

2015 ◽  
Vol 816 ◽  
pp. 729-735 ◽  
Author(s):  
Jun Zhang ◽  
Hua Ding ◽  
Jing Wei Zhao
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Room Temperature ◽  
Volume Fraction ◽  
Total Elongation ◽  
Trip Effect ◽  
Low Carbon ◽  
Quenching And Partitioning ◽  
The Stability ◽  
Critical Annealing

A refined microstructure consisting of martensite and retained austenite at room temperature has been produced in a Nb-microalloyed low carbon Si-Mn steel by a novel heat-treatment, pre-quenching prior to quenching and partitioning processes (Q&Q-P). The results showed that compared with the conventional quenching and partitioning steel the mechanical properties of steel obtained by the novel treatment have been significantly improved, with a good combination of ultimate tensile strength (1000MPa) and total elongation (above 30%). Meanwhile, the volume fraction of retained austenite has been increased. It was found that the improvement of mechanical properties was mainly attributed to the enhanced TRIP effect due to the relatively high fraction of metastable retained austenite at room temperature. The increased stability of austenite results from the C and Mn partitioning during inter-critical annealing, which increased the chemical stability of austenite. The formation of refined austenite at inter-critical annealing also had a positive effect on the stability of the austenite. As a consequence, the volume fraction of retained austenite at room temperature was significantly increased. Compared with the Q-P steel, the Q&Q-P steel exhibited higher work hardening exponents during the stage of TRIP effect and had the higher ductility.

SHAPE MEMORY EFFECT AND CYCLIC DEFORMATION BEHAVIOR OF Ti–Nb–N ALLOYS

2009 ◽  
Vol 02 (02) ◽  
pp. 79-82 ◽  
Author(s):  
MASAKI TAHARA ◽  
HEE YOUNG KIM ◽  
HIDEKI HOSODA ◽  
SHUICHI MIYAZAKI
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Cyclic Deformation ◽  
Tensile Tests ◽  
Ternary Alloys ◽  
Loading And Unloading ◽  
Perfect Recovery ◽  
The Stability ◽  
Stress Hysteresis

The effect of 1 at.% N addition on the shape memory effect of Ti – Nb alloys was investigated. The shape memory effect and superelasticity were observed in Ti –(18–20) Nb –1.0 N and Ti –(21–25) Nb –1.0 N alloys, respectively. The Ti –23 Nb –1.0 N alloy exhibits the best superelastic properties with almost perfect recovery and small stress hysteresis among N added ternary alloys. The effect of cyclic deformation on the stability of superelasticity was investigated for the Ti –23 Nb –1.0 N alloy by loading and unloading cyclic tensile tests up to 500 cycles with a constant maximum applied strain of 2.5%. It was confirmed that the stability of superelasticity was improved by the addition of N due to the increase of the critical stress for slip.

Multi length scale characterization of austenite in TRIP steels using high-energy X-ray diffraction

2013 ◽  
Vol 28 (2) ◽  
pp. 77-80 ◽  
Author(s):  
R. Blondé ◽  
E. Jimenez-Melero ◽  
L. Zhao ◽  
J.P. Wright ◽  
E. Brück ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Tensile Tests ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Trip Steels ◽  
Stable Austenite ◽  
Scale Characterization ◽  
The Stability

The martensitic transformation behavior of the meta-stable austenite phase in low alloyed TRIP steels has been studied in situ using high-energy X-ray diffraction during deformation. The stability of austenite has been studied at different length scales during tensile tests and at variable temperatures down to 153 K. A powder diffraction analysis has been performed to correlate the macroscopic behavior of the material to the observed changes in the volume fraction of the phases. Our results show that at lower temperatures the deformation induced austenite transformation is significantly enhanced and extends over a wider deformation range, resulting in a higher elongation at fracture. To monitor the austenite behavior at the level of an individual grain a high-resolution far-field detector was used. Sub-grains have been observed in austenite prior to transformation.

Influence of Duplex Annealing on the Microstructure and Mechanical Properties of Ti62421S Titanium Alloy Plate

2015 ◽  
Vol 816 ◽  
pp. 804-809 ◽  
Author(s):  
Xiao Yun Song ◽  
Yong Ling Wang ◽  
Wen Jing Zhang ◽  
Song Xiao Hui ◽  
Wen Jun Ye
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Volume Fraction ◽  
Annealing Treatment ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Alloy Plate ◽  
Β Phase ◽  
Α Phase ◽  
Microstructure And Mechanical Properties

The effects of different duplex annealing treatments on the microstructure and mechanical properties of Ti62421S alloy plate were studied by optical microscope (OM), scanning electron microscope (SEM), electron probe microanalysis (EPMA) and tensile tests, The experimental results indicated that the original microstructure of Ti62421S was composed of primary α phase (αp) and intergranular β phase. With the increase of first-stage annealing temperature, the volume fraction of equiaxed αp phase decreased. In contrast, the content of transformed β structure (βt) increased, and the width of lamellar secondary α phase (αs) in βt increased. Consequently, the yield strength (σ0.2) and ultimate tensile strength (σb) at room temperature and 600°C increased, while the elongation (δ5) declined. After 1000°C/2h/AC+ 600°C/2h/AC duplex annealing treatment, Ti62421S alloy plate showed superior tensile properties. The values of σb and δ5 at room temperature reached 1133MPa and 6%, as well as the value of σb at 600°C exceeded 710MPa.

Room Temperature Ductility of B2-Type CoZr Intermetallic Compounds

2006 ◽  
Vol 980 ◽  
Author(s):  
Yasuyuki Kaneno ◽  
Takayuki Takasugi ◽  
Mitsuhiko Yoshida ◽  
Hiroshi Tsuda
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Volume Fraction ◽  
Tensile Ductility ◽  
Tensile Tests ◽  
Ductile Deformation ◽  
Chemical Compositions ◽  
Second Phase ◽  
Intermetallic Alloys ◽  
Hot Rolled

AbstractB2 (CsCl) CoZr intermetallic alloys with different chemical compositions were hot-rolled and subsequently recrystallized to evaluate tensile properties and rolling workability. Co-49.0Zr, -49.5Zr and -50.0Zr alloys showed the B2-matrixed microstructure containing C15 Co2Zr dispersions, while Co-50.5Zr and -51.0Zr alloys showed the B2-matrixed microstructure containing C16 CoZr2 dispersions. These homogenized ingots were successfully hot-rolled without edge cracks, except for the Co-51.0Zr alloy. The tensile tests revealed that the Co-49.5Zr, -50.0Zr and -50.5Zr alloys exhibited a notable tensile ductility at room temperature as well as at elevated temperatures. Moreover, the recrystallized CoZr alloys were cold-rolled up to 70% reduction without intermediate annealing. It was also found that tensile ductility was most prominent in the Co-50.0Zr alloy with the least volume fraction of second phase dispersions in the investigated alloys, suggesting that the B2 phase of CoZr was inherently ductile. Deformation microstructures were characterized by means of XRD and TEM observations. Mechanisms responsible for the observed large tensile ductility of the CoZr alloys were discussed, on the basis of the observed deformation microstructures.

Fatigue and Cyclic Plasticity Properties of a Super-Austenitic Stainless Steel

2007 ◽  
Author(s):  
Sergiy Kalnaus ◽  
Feifei Fan ◽  
Yanyao Jiang
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Cyclic Stress ◽  
Applied Strain ◽  
Cyclic Plasticity ◽  
Strain Response ◽  
Cracking Behavior ◽  
Lower Strain ◽  
Cyclic Plasticity Model ◽  
Super Austenitic Stainless Steel

Tension-compression, torsion and axial-torsion experiments were conducted on AL-6XN® alloy. The main goal was to investigate experimentally, in detail, the cyclic plasticity behavior as well as fatigue life of AL-6XN® steel. Details of cyclic stress-strain response were collected during the experiments, which can serve as a baseline for development of cyclic plasticity model for this material. Microscopic observations of cracking behavior conducted in the present study allow connecting the fracture mechanism with fatigue life prediction. It was observed, that fatigue life of this material is a function of the fracture mode (mixed or tensile). The mixed cracking was observed in the specimens tested under higher applied strain levels, while the tensile cracking was revealed in the tests under lower strain amplitudes. Strain-life curves of the specimens failed in mixed mode and of those failed in tensile mode run parallel to each other, but the specimens that exhibit mixed failure mode show lower fatigue life as compared to the tensile mode specimens. Transition between mixed and tensile cracking orientations was studied in detail. The results of the experimental work presented in this study can serve for design of fatigue models for this material in the future.

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