scholarly journals Microstructure and Fracture Behavior of Special Multilayered Steel

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 789
Author(s):  
Xin Zhou ◽  
XiaoKang Zhao ◽  
Rui Cao ◽  
RuiHua Zhang ◽  
Yun Ding ◽  
...  
Keyword(s):  
Bending Strength ◽  
Tensile Tests ◽  
Tensile Fracture ◽  
Outer Side ◽  
Interfacial Delamination ◽  
Weakest Link ◽  
Initiation And Propagation ◽  
Martensite Layer ◽  
Bonding Method ◽  
Carbon Martensite

In this research, multilayered steel (MLS), which is composed of middle-carbon martensite steel, high-carbon martensite steel, and a pure Ni thin layer was obtained by the accumulative roll-bonding method. The microstructure and mechanical properties of the MLS were investigated by scanning electron microscopy (SEM), Vickers microhardness, tensile, and bending tests. In-situ SEM tensile tests were used to observe the crack initiation and propagation processes during the tensile loading. The results show that the ultimate tensile strength and bending strength of the MLS can reach 946 MPa and 3153 MPa, and the maximum elongation can reach 18%, which is related to the better combined quality of the interface. The middle and larger martensite layer (ML) becomes the weakest link of tensile fracture and interfacial delamination of the MLS during the tensile processes, because there are lots of large hard blocks Cr23C6 phases distributed in the middle thicker ML layer. Besides, the MLS can withstand larger bending deformation. When the MLS was bent to 180 degrees, neither macro-cracks in the outer side of the bending parts nor interfacial delamination can be found.

Elastic Waves Created During Tensile Fracture: The Phenomenon of a Second Fracture

1953 ◽  
Vol 20 (1) ◽  
pp. 122-130
Author(s):  
Julius Miklowitz
Keyword(s):  
Cross Sections ◽  
Tensile Tests ◽  
Analog Computer ◽  
Tensile Fracture ◽  
Strain Waves ◽  
Unloading Wave ◽  
Second Fracture ◽  
Wave Compression ◽  
Initial Fracture ◽  
The Moment

Abstract In some tensile tests with brittle materials, it was noted that fractures were produced at two different cross sections of the specimen when the rupture load was reached. The phenomenon of the second fracture prompted the present investigation. It is believed that the second fracture is caused by the destructive action of the elastic strain waves created during the first of the two fractures. The analytical and experimental work carried out was focused on describing the character of these waves. Consideration of the mechanics involved reduces the problem to that of a vibrating cantilever beam with time-dependent boundary conditions. Two types of waves are shown to exist. The first is a longitudinal unloading wave (compression). The other is a group of flexural strain waves caused by the moment that develops at the initial fracture section. The methods of operational mathematics and the electric-analog computer have been employed in the analytical study.

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.

High Dynamic Mechanical Strength of Zirconium-Based Bulk Amorphous Alloys

1998 ◽  
Vol 554 ◽  
Author(s):  
Tao Zhang ◽  
Akihisa Inoue
Keyword(s):  
Residual Stress ◽  
Mechanical Strength ◽  
Amorphous Alloys ◽  
Compressive Residual Stress ◽  
Bending Strength ◽  
Tensile Fracture ◽  
Uniaxial Tensile ◽  
Cast Sample ◽  
Bulk Amorphous Alloys ◽  
Squeeze Cast

AbstractA bulk amorphous Zr55Al10Ni5Cu30 alloy prepared by squeeze casting was found to exhibit high mechanical strength values, i.e., uniaxial tensile fracture strength (σt) of 1850 MPa, three-point bending strength (σb) of 3200 MPa, bending fatigue strength (σf) of 1100 MPa, Charpy impact fracture energy (Ef) of 135 kJ/m2 and fracture toughness of 68 MPa√m. The σb, σf and Ef are about two times higher than those for the corresponding bulk amorphous alloys prepared by unidirectional solidification and powder consolidation techniques, though the σt of the squeeze cast sample is higher by about 15 % than those for the other samples. The remarkable increases in the σb, σf and EF are presumably due to the introduction of high compressive residual stress of about 1240 MPa in the outer surface region only for the squeeze cast sample. The finding of the effectiveness of the compressive residual stress on the increase in the mechanical strength under the bending stress mode is important and expected to be widely used as a new strengthening mechanism for bulk amorphous alloys, as is the case for reinforced oxide glasses subjected to strengthening treatment.

Tensile and Creep Properties of the Refractory Nb Base In-Situ Composite

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1608-1614
Author(s):  
Jin Hak Kim ◽  
Tatsuo Tabaru ◽  
Hisatoshi Hirai
Keyword(s):  
Fracture Surface ◽  
Tensile Tests ◽  
Constant Load ◽  
Tensile Creep ◽  
Tensile Fracture ◽  
Creep Tests ◽  
Tensile Fracture Surface ◽  
In Situ Composite ◽  
Temperature Ranges

Niobium-base in-situ composite Nb-18Si-5Mo-5Hf-2C (in mol%) was prepared and heat-treated at 2070 K for 20 hour. The uni-axile tensile tests at high temperature ranges and the constant load tensile creep tests at 1570 K were performed. The specimen tensile-tested at 1470 K exhibited the excellent UTS of 450 MPa, and the brittle to ductile transition temperature is between 1470 and 1670 K. The specimens creep tested showed good creep strength; the stress exponent is about 5. The tensile fracture surface of the in-situ composite is complex and attributed to cleavage of the Nb 5 Si 3, Nb ss / Nb 5 Si 3 interface separation, ductile rupture of the Nb ss and correlations of these. On the otherhand, the fracture surface of creep tested consists of intergranular above 150 MPa and transgranular below 120 MPa with severely deformed Nb ss .

Notched Tensile Fracture of Ti-6Al-6V-2Sn Welds at Elevated Temperature

2009 ◽  
Vol 79-82 ◽  
pp. 1137-1140 ◽  
Author(s):  
Lv Wen Tsay ◽  
C.L. Hsu
Keyword(s):  
Elevated Temperature ◽  
Grain Boundary ◽  
Tensile Tests ◽  
Tensile Fracture ◽  
Boundary Shear ◽  
Dimple Fracture ◽  
Laser Welds ◽  
Fracture Appearance ◽  
Notched Tensile Strength ◽  
Increasing Temperature

The notched tensile tests of Ti-6Al-6V-2Sn laser welds with distinct post-weld heat treatments (PWHTs) were carried out at 150, 300, and 450oC and the results were also compared with the mill-annealed base metal (BM). The BM specimen had the highest notched tensile strength (NTS) among the specimens being tested at room temperature but became the lowest at 450oC. At/above 150oC, all welds showed a decrease in NTS with increasing temperature. The cracks tended to grow along the α / β interface in the BM specimen. The formation of premature fine pores at the grain boundary in the weld with PWHT at 704oC accounted for the intergranular dimple fracture of the specimen. The fracture appearance of the as-welded (AW) and the 482oC-aged (W-482) welds comprised of mainly transgranular dimple and increased the extent of grain boundary shear at elevated temperature.

Influence of Deformation Speed on Fatigue and Tensile Properties of a Ti-Ni-Cu Shape Memory Alloy

1999 ◽  
Vol 604 ◽  
Author(s):  
Y Kishi ◽  
Z. Yajima ◽  
K Shimizu ◽  
M. Asai
Keyword(s):  
Fatigue Life ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Tensile Properties ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Tensile Fracture ◽  
Scanning Calorimetry ◽  
Sinusoidal Waveform ◽  
Deformation Speed

AbstractThe mechanical fatigue life and tensile property of a Ti-41at.%Ni-8.5at.%Cu alloy, which was solution-treated after some thermo-mechanical treatments, were investigated at 370±1 K as a function of deformation speed. The tensile properties were also investigated at 295±1 K as a function of deformation speed. The B2→B19 martensitic transformation start temperature, Ms, of the alloy was determined to be 338 K by a differential scanning calorimetry, while that of the as-rolled alloy could not be determined. Two types of fatigue tests were carried out by using plate-shaped specimens of 3.5 mm width and 1.5 mm thickness with sinusoidal waveform stresses of 20 Hz and 0.5 Hz frequencies being applied respectively. The fatigue life obtained from the 20 Hz tests was superior to that from the 0.5 Hz tests, the former being about 2 times longer than the latter at the same stress level. Tensile tests were performed at three tensilem speeds of 8.3 × 106, 8.3 × 10−5 and 8.3 × 10−3 m/s. In all the stress - strain curves obtained, an apparent yielding was observed after the liner elastic deformation. The apparent yielding is due to the occurrence of martensitic transformation. The critical stress for inducing martensite and tensile fracture stress increased with increasing tensile speed. Therefore, it is clear that fatigue and tensile properties of Ti-Ni-Cu shape memory alloys are strongly affected by not only test temperature but also deformation speed.

scholarly journals Influence of Oxygen on the Fatigue Behaviour of Ti-6Al-7Nb Alloy

2016 ◽  
Vol 704 ◽  
pp. 44-52 ◽  
Author(s):  
Alexandra Amherd Hidalgo ◽  
Thomas Ebel ◽  
Wolfgang Limberg ◽  
Florian Pyczak
Keyword(s):  
Mechanical Properties ◽  
Oxygen Content ◽  
Treatment Time ◽  
Light And Electron Microscopy ◽  
Tensile Tests ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Four Point Bending ◽  
Initiation And Propagation ◽  
Effect Of Oxygen

One of the challenges in PM Ti alloys is to control the impurities level. Oxygen affects the microstructure and the mechanical properties of titanium alloys. Ti-6Al-7Nb is a promising alloy to use in PM due to its outstanding biocompatibility and mechanical properties required for load bearing medical implants. In this work, the influence of the impurities content on the ductility, fatigue resistance and microstructure of Ti-6Al-7Nb alloy processed by metal injection moulding was examined. Tensile and fatigue specimens were manufactured using Ti-6Al-7Nb gas atomized powder. Depending on the thermal treatment time, various oxygen contents were introduced into the specimens. The resulting oxygen content was determined by melt extraction technique. Tensile tests and high cycle four-point bending fatigue tests at room temperature were performed. First studies about the effect of oxygen content on crack initiation and propagation were done by the observation of microstructures and fractured surfaces using light and electron microscopy (SEM).

Microstructure and strength of Al-sapphire interface by means of the surface activated bonding method

1997 ◽  
Vol 12 (3) ◽  
pp. 852-856 ◽  
Author(s):  
T. Akatsu ◽  
G. Sasaki ◽  
N. Hosoda ◽  
T. Suga
Keyword(s):  
Room Temperature ◽  
Dissimilar Materials ◽  
Tensile Tests ◽  
Beam Irradiation ◽  
Atom Beam ◽  
Sapphire Surface ◽  
Transmission Electron ◽  
Partially Observed ◽  
Fast Atom Beam ◽  
Bonding Method

Sapphire (α–Al2O3) and Al were joined by means of the surface activated bonding (SAB) method in an ultrahigh vacuum at room temperature. Tensile tests have shown that failure occurred not along the interface but inside the Al bulk near the interface. High resolution transmission electron microscopy has revealed the formation of a direct interface between Al and sapphire, indicating the possibility to artificially fabricate an atomically direct interface of dissimilar materials at room temperature. However, an intermediate layer was partially observed, which might be attributed to the effect of fast atom beam irradiation of the sapphire surface.

Mechanical Properties and Fracture Study of Alumina Dispersion Hardened Copper-Based Nano-Composite at Elevated Temperatures

2013 ◽  
Vol 829 ◽  
pp. 583-588 ◽  
Author(s):  
Ali Dalirbod ◽  
Yahya A. Sorkhe ◽  
Hossein Aghajani
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Fracture Surface ◽  
Yield Strength ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Testing Temperature ◽  
Optical Microscope ◽  
Tensile Fracture ◽  
Different Temperatures

Alumina dispersion hardened copper-base composite was fabricated by internal oxidation method. The high temperature tensile fracture of Cu-Al2O3 composite was studied and tensile strengths were determined at different temperatures of 600, 680 and 780 °C. Microstructure was investigated by means of optical microscope and field emission scanning electron microscope (FESEM) with energy dispersive spectroscopy (EDS). Results show that, ultimate tensile strength and yield strength of copper alumina nanocomposite decrease slowly with increasing temperature. The yield strength reaches 119 MPa and ultimate tensile strength reaches 132 MPa at 780 °C. Surface fractography shows a dimple-type fracture on the fracture surface of the tensile tests where dimple size increases with increasing testing temperature and in some regions brittle fracture characteristics could be observed in the fracture surface.

Numerical Simulation on Propagation Mechanism of Hydraulic Fracture in Fractured Rockmass

2014 ◽  
Vol 488-489 ◽  
pp. 417-420 ◽  
Author(s):  
Xiao Xi Men ◽  
C.A. Tang ◽  
Zhi Hui Han
Keyword(s):  
Hydraulic Fracturing ◽  
Fracture Initiation ◽  
Coupling Model ◽  
Natural Fracture ◽  
Tensile Fracture ◽  
Propagation Mechanism ◽  
Initiation And Propagation ◽  
Fracturing Process ◽  
Two Factors ◽  
Seepage Characteristics

Hydraulic fracturing process in fractured rockmass which with an existing single natural fracture at its various conditions: its different angles and different lengths was simulated by using RFPA2D(2.0)-Flow version which adopts the finite element method and considers the heterogeneous characteristics of rock in meso-scale, creates seepage-stress-failure coupling model. The effect tendency of natural fractures angle and length on the seepage characteristics of fractured rockmass was given through the description of tensile fracture initiation and propagation in the rock specimens. The simulation results show that the effect of these two factors on fractures initiation, propagation and rockmass stability under the hydraulic fracturing could be remarkable.

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