BRITTLENESS PROBLEM OF PUDDLED STEEL RESULTING FROM MICROSTRUCTURAL DEGRADATION PROCESSES IN TERMS OF STATIC, CYCLIC AND DYNAMIC TESTS

2011 ◽  
Vol 162 (4) ◽  
pp. 254-269
Author(s):  
Grzegorz LESIUK ◽  
Józef RABIEGA ◽  
Mieczysław SZATA
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Tests ◽  
Critical Value ◽  
J Integral ◽  
Dynamic Tests ◽  
Initial State ◽  
Operating Period ◽  
Degradation Processes ◽  
Static Tensile

In the paper the investigation results of puddled steel from nineteenth-century constructions are presented. The results of static tensile tests after more than 130-year operating period: fracture toughness, the critical value of the J integral and the fatigue crack growth, and dynamic tests – toughness results are presented in this article. The results show a significant effect of degradation processes. The abovementioned processes caused the brittleness of puddled steel. All the tests were performed for the material in two states, i.e. post-operated and normalised ones. In accordance with the guidelines developed in the framework of the degradation theory [4] and its material aspects [8], normalising is designed to reproduce the microstructure of steel in the initial state. The results presented allow us to draw the conclusions about trends related to the nature and future negative changes in mechanical properties.

scholarly journals Strain-rate-dependent mechanical properties of the equine hoof wall.

1996 ◽  
Vol 199 (5) ◽  
pp. 1133-1146 ◽  
Author(s):  
M A Kasapi ◽  
J M Gosline
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Strain Rate ◽  
Tensile Tests ◽  
Bending Test ◽  
Strain Rates ◽  
Dynamic Tests ◽  
Electron Microscopic ◽  
Initial Modulus ◽  
Equine Hoof

The mechanical properties of fully hydrated equine hoof wall were examined at various loading rates in compact tension (CT) fracture, tensile and three-point bending dynamic tests to determine possible effects of hoof wall viscoelasticity on fracture toughness and tensile parameters. Four cross-head rates were used in CT tests: 1.7 x 10(-5), 1.7 x 10 (-3), 1.7 x 10(-2) and 2.5ms-1; four strain rates were used in tensile tests: 1.6 x 10(-3), 3.2 x 10(-2), 0.33 and 70s(-1). Speeds for the highest test rates were achieved using a large, custom-built impact pendulum. Bending test frequencies ranged from 0.04 to 200 Hz. In CT tests, both the initial modulus Ei and the stress intensity factor K rose with increasing strain rate (from 0.38 to 0.76 GPa for Ei and from 0.71 to 1.4 MN m-3/2 for K), whereas the fracture toughness parameter J remained constant at 12kJm-2. All tensile parameters except ultimate strain were sensitive to strain rate. Ei, total energy to breakage and maximum stress rose with increasing strain rate from 0.28 to 0.85 GPa, from 5.4 to 9.7 MJm-3 and from 17 to 31 MPa, respectively. Data from low-amplitude dynamic tests agreed well with Ei trends from CT and tensile tests. Direction of crack growth differed through the thickness of the wall, the pattern of which resembled a trilaminar ply. Although scanning electron microscopic examination of fracture surfaces revealed a decreasing pseudo-ductile behaviour with increasing strain rate, and ultimate tensile parameters are positively affected, equine hoof wall viscoelasticity does not appear to compromise fracture toughness at high strain rates.

scholarly journals Influence of Hydrostatic Extrusion on the Mechanical Properties of the Model Al-Mg Alloys

2021 ◽  
Author(s):  
Aleksandra Towarek ◽  
Wojciech Jurczak ◽  
Joanna Zdunek ◽  
Mariusz Kulczyk ◽  
Jarosław Mizera
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Tensile Strength ◽  
Microstructural Analysis ◽  
Tensile Tests ◽  
Hydrostatic Extrusion ◽  
Microstructure Formation ◽  
Initial State ◽  
Degree Of Deformation ◽  
Al Mg Alloys

AbstractTwo model aluminium-magnesium alloys, containing 3 and 7.5 wt.% of Mg, were subjected to plastic deformation by means of hydrostatic extrusion (HE). Two degrees of deformation were imposed by two subsequent reductions of the diameter. Microstructural analysis and tensile tests of the materials in the initial state and after deformation were performed. For both materials, HE extrusion resulted in the deformation of the microstructure—formation of the un-equilibrium grain boundaries and partition of the grains. What is more, HE resulted in a significant increase of tensile strength and decrease of the elongation, mostly after the first degree of deformation.

Effect of Loading Rate on Tensile Properties of Automotive Steel Sheet

2013 ◽  
Vol 690-693 ◽  
pp. 211-217
Author(s):  
Jin Gui Qin ◽  
Fang Yun Lu ◽  
Yu Liang Lin ◽  
Xue Jun Wen
Keyword(s):  
Strain Rate ◽  
Testing Machine ◽  
Structural Response ◽  
Tensile Tests ◽  
Dynamic Tests ◽  
Static Tests ◽  
Split Hopkinson Tensile Bar ◽  
Axial Tensile ◽  
Static Tensile ◽  
Cook Model

Results of uni-axial tensile loading of three automotive steels at different strain rates (0.0011–3200s-1) are reported here. Quasi-static tensile tests were performed under the strain rate of 1.1×10-3 s-1 using an electromechanical universal testing machine, whereas dynamic tests were carried out under the strain rate in the range of 1100 to 3200 s-1 using a Split Hopkinson Tensile Bar apparatus. Based on the experimental results, the material parameters of widely used Johnson–Cook model which described the strain rate and temperature-dependent of mechanical behaviour were determined. The experiments show that strain-rate hardening is superior to thermal softening: yield stresses, tensile strength, deformation, and energy dissipation increase with the strain rate from quasi-static tests to dynamic tests. The Johnson–Cook model can describe the behaviour of these steels and provides the opportunity to study the material and structural response.

Mechanical Properties of Flat Braided Composites With a Circular Hole

1999 ◽  
Author(s):  
Takeru Ohki ◽  
Shinya Ikegaki ◽  
Ken Kurasiki ◽  
Hiroyuki Hamada ◽  
Masaharu Iwamoto
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Circular Hole ◽  
Fracture Behavior ◽  
Fatigue Property ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Braided Composites ◽  
Static Tensile ◽  
The One

Abstract In this study, fracture behavior and strength in the flat braided bar with a circular hole were investigated by static and fatigue test. Two type of specimens were prepared. They are a braided flat bar with an integrally-formed braided hole and a braided flat bar with a machined hole. Moreover, we also examined a specimen that had a metal pin inserted at the circular hole. This specimen was subjected to a static tensile test. The results of the tensile tests indicate that the strength of the flat bar with a braided hole was larger than that of the one with the machined hole. Furthermore, from the results of the fatigue tests, the flat bar with the braided hole showed higher fatigue property than that of the one with the machined hole.

Mechanical Properties of Flat Braided Composites With a Circular Hole

2000 ◽  
Vol 122 (4) ◽  
pp. 420-424 ◽  
Author(s):  
Takeru Ohki ◽  
Shinya Ikegaki ◽  
Ken Kurasiki ◽  
Hiroyuki Hamada ◽  
Masaharu Iwamoto
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Circular Hole ◽  
Fracture Behavior ◽  
Fatigue Property ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Braided Composites ◽  
Static Tensile ◽  
The One

In this study, fracture behavior and strength in the flat braided bar with a circular hole were investigated by static and fatigue test. Two types of specimen were prepared. They are a braided flat bar with an integrally formed braided hole and a braided flat bar with a machined hole. Moreover, we also examined a specimen that had a metal pin inserted at the circular hole. This specimen was subjected to a static tensile test. The results of the tensile tests indicate that the strength of the flat bar with a braided hole was larger than that of the one with the machined hole. Furthermore, from the results of the fatigue tests, the flat bar with the braided hole showed higher fatigue property than that of the one with the machined hole. [S0094-4289(00)02604-9]

Preparation and Properties of Nano-Calcium Carbonate Modified PVC Using Ultrasonic Irradiation

2007 ◽  
Author(s):  
Shengfei Hu ◽  
Wen Chen ◽  
Huaxing Li
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Polymer Nanocomposites ◽  
Ultrasonic Irradiation ◽  
Integral Method ◽  
J Integral ◽  
Optimum Time ◽  
Mechanical Performances ◽  
Dispersion Of Nanoparticles ◽  
Better Than

PVC/nano-CaCO3 composites were prepared through ultrasonic irradiation. The optimum time of ultrasonic irradiation is 30 min. The fracture toughness of the nanocomposites was investigated by J-integral method based on the mechanical properties and morphology. Compared with corresponding nanocomposites and unfilled PVC, the prepared nanocomposites exhibit outstanding mechanical performances. The mechanical properties of spindly shaped CaCO3 filled PVC are better than these of the cubic nano-CaCO3, which are likely attributed to high aspect ratio of spindly shaped nano-CaCO3. In addition, the mechanical properties of PVC/nano-CaCO3 composites can be improved considerably when the content of nano-CaCO3 is 5–15 phr. Ultrasonic irradiation realizes the excellent dispersion of nanoparticles in the PVC, and offers a new way to deal with the challenges encountered in preparing polymer/nanocomposites materials.

scholarly journals Characterization of Nanobainitic Structure Obtained in 100Crmnsi6-4 Steel after Industrial Heat Treatment/ Charakteryzacja Struktury Nanobainitycznej Wytworzonej W Handlowej Stali Łożyskowej – 100Crmnsi6-4 W Przemysłowej Obróbce Cieplnej

2014 ◽  
Vol 59 (4) ◽  
pp. 1637-1640 ◽  
Author(s):  
J. Dworecka ◽  
E. Jezierska ◽  
K. Rozniatowski ◽  
W. Swiatnicki
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Treatment Process ◽  
Tensile Tests ◽  
Bearing Steel ◽  
Transformation Kinetics ◽  
Transmission Electron ◽  
Microstructure Parameters ◽  
Static Tensile

Abstract The aim of the work was to produce a nanobainitic structure in the commercial bearing steel - 100CrMnSi6-4 and to characterize its structure and mechanical properties. In order to produce this structure the austempering heat treatment was performed, with parameters that have been selected on the basis of dilatometric measurements of phase transformation kinetics in steel. The heat treatment process was performed in laboratory as well as in industrial furnaces. The obtained structure was characterized using transmission electron microscopy. In order to investigate the effect of the microstructure parameters on the material’s mechanical properties, the hardness, impact strength and static tensile tests have been conducted.

Notch Effects on Room Temperature Tensile and Bend Properties of Ni3Al and Ni3Al+B

1988 ◽  
Vol 133 ◽  
Author(s):  
P. S. Khadkikar ◽  
J. D. Rigney ◽  
J. J. Lewandowski ◽  
K. Vedula
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fracture Stress ◽  
Room Temperature ◽  
Tensile Tests ◽  
Boron Addition ◽  
Notched Specimens ◽  
Grain Boundary Fracture ◽  
Bend Tests ◽  
Boundary Fracture

ABSTRACTThe notched mechanical properties of Ni3AI and Ni3Al+B prepared by powder metallurgy techniques have been determined in both tension and bending at room temperature. Ten- sile tests performed using double notched specimens containing relatively blunt notches produced intergranular fracture in both Ni3Al and Ni3AI+B, with evidence of fracture initiating in an intergranular manner ahead of the blunt notch in both cases. Estimates of notched fracture toughness from bend tests and of local grain boundary fracture stress from the notched tensile tests suggest an increase in these values with boron addition.

Experimental Study on Mechanical Properties of Epoxy/MWCNT Nanocomposites—Effects of Acid Treatment, Pressured Curing, and Liquid Rubber

2012 ◽  
Vol 3 (1) ◽  
Author(s):  
Yuan Li ◽  
Ning Hu ◽  
Takashi Kojima ◽  
Takaomi Itoi ◽  
Tomonori Watanabe ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Carbon Nanotube ◽  
Acid Treatment ◽  
Tensile Tests ◽  
Type I ◽  
Multiwalled Carbon ◽  
Liquid Rubber ◽  
Type Iv ◽  
Positive Effect

The unique properties of carbon nanotube (CNT) have made it very attractive as reinforcement in polymer nanocomposites in the hope of effectively improving the mechanical properties. In order to explore the effects of three appealing influencing factors, i.e., acid treatment, pressured curing, and liquid rubber (LR) on mechanical properties of nanocomposites, tensile tests, and single-edge notched bending (SENB) tests are carried out for four types of CNT-reinforced nanocomposites. Compared with type I of nanocomposites using pristine multiwalled carbon nanotube (MWCNT) as reinforcement for epoxy, which are termed as Epoxy/MWCNT, type II of Epoxy/MWCNT-COOH nanocomposites with acid-treated MWCNTs as reinforcement, show obvious improvement on tensile properties and fracture toughness. This positive effect of acid treatment can be attributed to better dispersion of CNTs and stronger interface based on the corresponding fracture surfaces. For type III of P-Epoxy/MWCNT-COOH nanocomposites under pressured curing, although the voids in samples are decreased effectively and the interface is strengthened, there is no expected positive results because of severe CNTs agglomeration. For type IV of P-Epoxy/LR/MWCNT-COOH nanocomposites, addition of LR results in at least around a threefold increase in fracture toughness compared with that of P-Epoxy/MWCNT-COOH, indicating the amazing effect of LR. The present work provides much more choices for fabricating specific CNT-reinforced nanocomposites with desired properties by reasonably combining proper fabrication conditions including acid treatment, pressured curing, liquid rubber with polymer matrix, and reinforcement loading.

Impact of Initial State during Calibre Rolling: Investigating Microstructure and Mechanical Properties of AZ80 Magnesium Alloy

2018 ◽  
Vol 941 ◽  
pp. 857-862
Author(s):  
Marie Moses ◽  
Johannes Luft ◽  
Madlen Ullmann ◽  
Ulrich Prahl ◽  
Rudolf Kawalla
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Microstructural Characterization ◽  
Tensile Tests ◽  
Strengthening Effect ◽  
Grain Refining ◽  
Initial State ◽  
Cast Material ◽  
Microstructure And Mechanical Properties ◽  
Initial States

In order to investigate the effect of rolling on microstructure and mechanical properties of different initial states, cast and extruded magnesium alloy AZ80 bars were rolled in calibre. The microstructural characterization was done by light microscopy. As a result, the initial grain size of the cast AZ80 (66 μm) clearly differs from the extruded bar (13 μm). After 14 passes of hot rolling in calibre, a significant grain refining effect was achieved resulting in grain sizes of 5 μm for the cast and 3 μm for the extruded material. To investigate the mechanical properties in the initial and rolled state, tensile tests of both conditions were conducted at room temperature. Due to grain refining, the tensile strength (162 MPa) and the elongation (3 %) of cast AZ80 increased remarkably during 14 passes of calibre rolling (360 MPa and 19 %). The strengthening effect was also evident for the rolled extruded AZ80. However, the cast material exhibited cracks during calibre rolling due to its inexpedient microstructure for a high deformation calibre. On the contrary, the extruded AZ80 was easily deformable. This shows the clear impact of initial states on aspired end properties of processed materials. Future investigations will deal with developing a suitable calibration for cast AZ80.

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