scholarly journals Tensile Deformation Behavior of Medium Manganese Steels with High Carbon Concentrations and Austenitic Microstructures

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 902
Author(s):  
Guoqing Luan ◽  
Olena Volkova ◽  
Javad Mola
Keyword(s):  
Tensile Deformation ◽  
Tensile Tests ◽  
Detailed Examination ◽  
Rapid Quenching ◽  
Transgranular Fracture ◽  
Surface Cracks ◽  
Tensile Direction ◽  
Gauge Section ◽  
Grain Boundary Decohesion ◽  
Stress Drops

: Tensile properties of the Fe–1.44C–8Mn–1.9Al (mass %) steel with a fully austenitic microstructure, obtained by rapid quenching from the austenite range, was determined at room temperature. Tensile tests were performed using specimens prepared in two different routes involving an exchanged sequence of machining and heat treatment as the last processing steps prior to tensile tests. In spite of the occurrence of deformation twinning, total tensile elongations in both processing routes remained below 18%. Abrupt stress drops during tensile tests suggested the occurrence of discontinuities in tensile specimens. Detailed examination of the fracture surface indicated a mixed intergranular–transgranular fracture mode. Furthermore, a high density of surface cracks was observed near the outer surface in the gauge section of fractured tensile specimens. The origin of surface cracks could not be identified. The coincidence of surface cracks with the grain boundaries, especially those nearly perpendicular to the tensile direction, is thought to be responsible for the accelerated grain boundary decohesion and the premature fracture of tensile specimens.

scholarly journals Deformation Behavior and Precipitation Features in a Stretched Al–Cu Alloy at Intermediate Temperatures

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2495 ◽  
Author(s):  
Y.C. Lin ◽  
Wen-Yong Dong ◽  
Xu-Hao Zhu ◽  
Qiao Wu ◽  
Ying-Jie He
Keyword(s):  
Strain Rate ◽  
Deformation Behavior ◽  
Tensile Deformation ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Precipitation Process ◽  
Heating Process ◽  
Cu Alloy ◽  
Hot Tensile Deformation ◽  
Stress Drops

Deformation behavior and precipitation features of an Al–Cu alloy are investigated using uniaxial tensile tests at intermediate temperatures. It is found that the true stress drops with the decreased strain rate or the increased deformation temperature. The number of substructures and the degree of grain elongation decrease with the raised temperature or the decreased strain rate. At high temperatures or low strain rates, some dynamic recrystallized grains can be found. The type of precipitates is influenced by the heating process before hot tensile deformation. The content and size of precipitates increase during tensile deformation at intermediate temperatures. As the temperature increases over 200 °C, the precipitation process (Guinier Preston zone (G.P. zones)→θ′′ phase→θ′ phase) is enhanced, resulting in increased contents of θ′′ and θ′ phases. However, θ′′ and θ′ phases prefer to precipitate along the {020}Al direction, resulting in an uneven distribution of phases. Considering the flow softening degree and the excessive heterogeneous precipitation of θ′′ and θ′ phases during hot deformation, the reasonable strain rate and temperature are about 0.0003 s−1 and 150 °C, respectively.

scholarly journals Tensile Deformation Behavior of Typical Porous Laminate Structure at Different Temperatures

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5369
Author(s):  
Ping Wang ◽  
Ye-Da Lian ◽  
Zhi-Xun Wen
Keyword(s):  
High Temperature ◽  
Tensile Deformation ◽  
Tensile Tests ◽  
Image Correlation ◽  
Test Material ◽  
Transgranular Fracture ◽  
Laminate Structure ◽  
Actual Structure ◽  
High Temperature Tensile ◽  
The Impact

In this study, the Ni-Cr-W superalloy GH3230 is used as the test material. According to the actual structure of the flame tube, a porous laminate structure specimen is designed. The structure consists of impact holes, overflow holes and pin fins. High-temperature tensile tests at 650 °C, 750 °C and 850 °C were carried out to study the high-temperature mechanical properties and fracture mechanism of the specimens of porous laminate structure, and the strain nephogram of the specimens were obtained by digital image correlation (DIC) technique. Due to the large number and dense arrangement of overflow holes, an obvious hole interference effect can be found from the strain nephogram. The stress concentration around the pore and the interference between the pores provide priority places and paths for the initiation and propagation of microcracks. The test found that the microcracks of the porous laminate structure first occurred around the hole, the overflow surface fractured first, after which the impact surface fractured. The strength of the alloy exhibits a significant temperature sensitivity to temperature. From 650 °C to 750 °C, the ultimate strength (σb) and yield strength (σ0.2) decrease slightly, but they decrease significantly at 850 °C. The microstructure of the fracture surface shows that all microcracks occur at the interface between the matrix and the carbides but that the fracture mode of the specimens gradually changes from intergranular fracture to transgranular fracture as the temperature increases. Due to the pinning effect of the intracrystalline diffusive solute atoms on the dislocations, the stress-strain curves of the high-temperature tensile tests at 650 °C and 750 °C showed zigzag characteristic fluctuations during the strengthening stage.

scholarly journals A Flow Stress Model of 300M Steel for Isothermal Tension

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 252
Author(s):  
Rongchuang Chen ◽  
Shiyang Zhang ◽  
Xianlong Liu ◽  
Fei Feng
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Tensile Deformation ◽  
Flow Behavior ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Model Parameters ◽  
Average Deviation ◽  
Cross Sectional ◽  
300M Steel

To investigate the effect of hot working parameters on the flow behavior of 300M steel under tension, hot uniaxial tensile tests were implemented under different temperatures (950 °C, 1000 °C, 1050 °C, 1100 °C, 1150 °C) and strain rates (0.01 s−1, 0.1 s−1, 1 s−1, 10 s−1). Compared with uniaxial compression, the tensile flow stress was 29.1% higher because dynamic recrystallization softening was less sufficient in the tensile stress state. The ultimate elongation of 300M steel increased with the decrease of temperature and the increase of strain rate. To eliminate the influence of sample necking on stress-strain relationship, both the stress and the strain were calibrated using the cross-sectional area of the neck zone. A constitutive model for tensile deformation was established based on the modified Arrhenius model, in which the model parameters (n, α, Q, ln(A)) were described as a function of strain. The average deviation was 6.81 MPa (6.23%), showing good accuracy of the constitutive model.

Superplastic Behavior of a Cu-Cr-Zr Alloy Subjected to ECAP

2016 ◽  
Vol 838-839 ◽  
pp. 404-409
Author(s):  
Roman Mishnev ◽  
Iaroslava Shakhova ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev
Keyword(s):  
Grain Size ◽  
Dislocation Density ◽  
Strain Rate ◽  
Temperature Interval ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Superplastic Behavior ◽  
Average Grain Size ◽  
Gauge Section ◽  
Zr Alloy

A Cu-0.87%Cr-0.06%Zr alloy was subjected to equal channel angular pressing (ECAP) at a temperature of 400 °C up to a total strain of ~ 12. This processing produced ultra-fine grained (UFG) structure with an average grain size of 0.6 μm and an average dislocation density of ~4×1014 m-2. Tensile tests were carried out in the temperature interval 450 – 650 °C at strain rates ranging from 2.8´10-4 to 0.55 s-1. The alloy exhibits superplastic behavior in the temperature interval 550 – 600 °C at strain rate over 5.5´10-3 s-1. The highest elongation-to-failure of ~300% was obtained at a temperature of 575 °C and a strain rate of 2.8´10-3 s-1 with the corresponding strain rate sensitivity of 0.32. It was shown the superplastic flow at the optimum conditions leads to limited grain growth in the gauge section. The grain size increases from 0.6 μm to 0.87 μm after testing, while dislocation density decreases insignificantly to ~1014 m-2.

scholarly journals An Experimental Study of the Tension-Compression Asymmetry of Extruded Ti-6.5Al-2Zr-1Mo-1V under Quasi-Static Conditions at High Temperature

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1299
Author(s):  
Chen Zhang ◽  
Dongsheng Li ◽  
Xiaoqiang Li ◽  
Yong Li
Keyword(s):  
High Temperature ◽  
Strain Hardening ◽  
Yield Stress ◽  
Mechanical Response ◽  
Tensile Deformation ◽  
Uniaxial Tensile ◽  
Tensile Direction ◽  
Stress Asymmetry ◽  
Static Conditions ◽  
Tension Compression Asymmetry

The tension-compression asymmetry (TCA) behavior of an extruded titanium alloy at high temperatures has been investigated experimentally in this study. Uniaxial tensile and compressive tests were conducted from 923 to 1023 K with various strain rates under quasi-static conditions. The corresponding yield stress and asymmetric strain hardening behavior were obtained and analyzed. In addition, the microstructure at different temperatures and stress states indicates that the extruded TA15 profile exhibits a significant yield stress asymmetry at different testing temperatures. The flow stress and yield stress during tension are greater than compression. The yield stress asymmetry decreases with the increase in temperature. The alloy also exhibits TCA behavior on the strain hardening rate. Its mechanical response during compression is more sensitive than tension. A dynamic recrystallization phenomenon is observed instead of twin generated in tension and compression under high-temperature quasi-static conditions. The grains are elongated along the tensile direction and deformed by about 45° along the compressive load axis. Finally, the TCA of Ti-6.5Al-2Zr-1Mo-1V (TA15) alloy is due to slip displacement. The tensile deformation activates basal <a>, prismatic <a> and pyramidal <c + a> slip modes, while the compressive deformation activates only prismatic <a> and pyramidal <c + a> slip modes.

Tensile Deformation and Fracture in a Bulk Nanostructured Al-5083/SiCp Composite at Elevated Temperatures

2007 ◽  
Vol 29-30 ◽  
pp. 245-248
Author(s):  
F. Tang ◽  
B.Q. Han ◽  
Masuo Hagiwara ◽  
Julie M. Schoenung
Keyword(s):  
Elevated Temperatures ◽  
Tensile Deformation ◽  
Tensile Tests ◽  
Nanostructured Composite ◽  
Sic Particles ◽  
Deformation And Fracture ◽  
Ultrafine Grained ◽  
Al 5083 Alloy

An ultrafine-grained Al-5083 alloy reinforced with 5 vol.% nano-sized β-SiC particles was fabricated with a powder cryomilling and consolidation technique. Tensile tests were conducted at temperatures from 298 to 773 K for this composite. The mechanisms for deformation and fracture of this nanostructured composite at various temperatures are discussed.

Microstructure and Tensile Behavior of Ti-Rich Ti-Ni-Cu Melt-Spun Ribbon

2014 ◽  
Vol 936 ◽  
pp. 1163-1167
Author(s):  
Wen Jun He ◽  
Guang Hui Min ◽  
Oleg Tolochko
Keyword(s):  
Melt Spinning ◽  
Tensile Deformation ◽  
Amorphous Ribbon ◽  
Fracture Morphology ◽  
Tensile Tests ◽  
Tensile Fracture ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Annealed Ribbon ◽  
Martensitic State

Microstructure and mechanical properties of Ti51.5Ni25Cu23.5 ribbon fabricated by melt spinning were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and tensile tests. Some B19 martensite crystalline with (011) compound twin was embedded in the mainly amorphous ribbon, while the ribbon annealed at 450°C for 1 h is at fully martensitic state. Annealing process alter the preferential orientation from (022)-B19 to (111)-B19. Tensile fracture stresses of as-spun ribbon and the annealed ribbon are 1257 MPa and 250 MPa, respectively. The tensile fracture morphology of as-spun ribbon shows typical vein fringe while that of the annealed ribbon reveals fine but depth-inhomogeneous dimples. After tensile deformation, the annealed ribbon exhibits typical martensitic detwinning behavior accompanying with the strain contrast.

Tensile Deformation of Si Single Crystals at High Temperatures

2021 ◽  
Vol 1016 ◽  
pp. 1443-1447
Author(s):  
Tubasa Suzuki ◽  
Masaki Tanaka ◽  
Tatsuya Morikawa ◽  
Yelm Okuyama ◽  
Jun Fujise ◽  
...  
Keyword(s):  
Slip System ◽  
Single Crystals ◽  
Tensile Deformation ◽  
Tensile Tests ◽  
Stage Ii ◽  
Electron Backscattered Diffraction ◽  
Kink Bands ◽  
Schmid Factor ◽  
Primary Slip System ◽  
Yield Point Phenomenon

Czochralski silicon single crystals were deformed in tensile tests along the direction at between 1173 K and 1373. Yield point phenomenon were observed in the specimens deformed at below 1273 K while continues yield was observed in the specimens deformed at above 1323 K. It is due to the effect of dislocation starvation in the used crystals. Work-hardening rates in stage II were consistent with those reported in fcc crystals such as copper. The onset of stage II was found to be active before the Schmid factor of the second slip system becomes larger than that of the primary slip system. Electron backscattered diffraction images indicated clear kink bands near grips and in the parallel portion. The kink bands were formed at the middle of stage I, which suggest that the formation of kink bands is a trigger of stage II.

Effect of Loading Rate and Pipe Wall Thickness on the Strength and Toughness of Welded and Unwelded Polyethylene Pipes

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Tarek M. A. A. EL-Bagory ◽  
Hossam E. M. Sallam ◽  
Maher Y. A. Younan
Keyword(s):  
Mechanical Behavior ◽  
Mechanical Characteristics ◽  
Tensile Tests ◽  
Primary Objective ◽  
Design Data ◽  
Practical Applications ◽  
Polyethylene Pipes ◽  
Gauge Section ◽  
Reliable Design ◽  
Hdpe Pipes

Abstract The primary objective of this paper is to depict the mechanical behavior of welded and unwelded high-density polyethylene (HDPE), pipes to provide the designer with reliable design data relevant to practical applications. Therefore, it is necessary to study the effect of strain rate and specimen configuration on the mechanical behavior of welded and unwelded pipes made from HDPE. Tensile tests are conducted on specimens longitudinally cut from the pipe with thickness (10 and 30 mm), at different crosshead speeds (5–500 mm/min), and different gauge lengths (20, 25, and 50 mm) to investigate the mechanical properties of welded and unwelded specimens. All tests are performed at room temperature (Ta = 23 °C). Butt fusion, BF, welding method is used to join the different parts of HDPE pipes. The present results showed that the mechanical characteristics of welded specimens are lower than those of unwelded specimens. In the case of test specimens taken from unwelded pipe, the results of mechanical characteristics revealed that a necking phenomenon before failure appears at different locations along the gauge section. On the other hand, the fracture of welded specimens almost occurs at the fusion zone. It is found that the crosshead speed and specimen configurations have a significant effect on the mechanical behavior of both welded and unwelded specimens.

450°C Stress Rupture Properties of a Non-Quenched and Tempered Steel MFT8

2014 ◽  
Vol 997 ◽  
pp. 507-511
Author(s):  
Jue Wang ◽  
Zhang Zhong Wang ◽  
Meng Jiao Zhang ◽  
Sui Chun Zhao ◽  
Xiao Juan Shang
Keyword(s):  
Rupture Life ◽  
Stress Rupture ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Strength Properties ◽  
Transgranular Fracture ◽  
Accelerated Creep ◽  
Quenched And Tempered Steel ◽  
High Temperature Tensile ◽  
Tempered Steel

The thermal strength properties of a non-quenched and tempered steel, MFT8 were investigated by stress rupture tests at 450°C. High-temperature tensile tests were also carried out to determine the stress range for the accelerated creep experiments. Optical microscope (OM) and scanning electron microscope (SEM) were used to analyze the fractography and microstructure evolution. The results showed that MFT8 steels exhibited transgranular fracture and high ductility in the stress rupture tests. Although the creep cavities were observed, the critical reason of creep rupture was the wedge cracks caused by stress concentration in the area of carbide fragments. The rupture life of MFT8 at 450°C/ 100000 hours was calculated to be 184.4MPa by linear extrapolation. The data of this study inferred that MFT8 had the potential to substitute for the quenched and tempered steels of the same class in power industry.

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