scholarly journals Influence of hydrogen on mechanical properties of pure titanium T40 (grade 2) and TA6V ELI (grade 23): a local approach of fracture

2020 ◽  
Vol 321 ◽  
pp. 09004
Author(s):  
Alexandre POLONI ◽  
Abdelali OUDRISS ◽  
Juan CREUS ◽  
Stéphane COHENDOZ ◽  
Jamaa Bouhattate ◽  
...  
Keyword(s):  
Cathodic Polarization ◽  
Hydrostatic Stress ◽  
Equivalent Plastic Strain ◽  
Pure Titanium ◽  
Tensile Tests ◽  
Solubility Limit ◽  
Local Approach ◽  
Hydrogen Charging ◽  
Β Phase ◽  
The Impact

The effect of hydrogen charging by cathodic polarization on T40 (grade 2) and TA6V ELI (grade 23) in artificial seawater appeared to be dependent on the metallurgical structure of the alloys. Mechanical tensile tests were performed on smooth samples and with different notches without and with hydrogen charging. Evolution of the fracture mode has been studied and the impact of hydrides was questioned. FEM calculation offers the opportunity to associate the local hydrostatic stress σm and equivalent plastic strain εpeq leading to the fracture and to illustrate the evolution of these conditions with hydrogen absorption and hydrides formation. Hydrogen charged by cathodic polarization appeared to have a small impact on grade 2 reducing its A%, whereas it leads to a strong embrittlement of grade 23 when the solubility limit of β-phase is exceeded and hydrides formed.

scholarly journals Hydrogen absorption and hydride formation in pure titanium T40 (grade 2) and TA6V ELI (grade 23) under cathodic polarization in artificial seawater

2020 ◽  
Vol 321 ◽  
pp. 09002
Author(s):  
Alexandre POLONI ◽  
Abdelali OUDRISS ◽  
Juan CREUS ◽  
Cyril BERZIOU ◽  
Egle CONFORTO ◽  
...  
Keyword(s):  
Hydrogen Absorption ◽  
Cathodic Polarization ◽  
Pure Titanium ◽  
Solubility Limit ◽  
Artificial Seawater ◽  
Nacl Solution ◽  
Hydride Formation ◽  
Calcareous Deposit ◽  
Β Phase ◽  
Kinetics Of

Different kinetics of hydrogen absorption in T40 (grade 2) and TA6V ELI (grade 23) under cathodic polarization in artificial seawater have been highlighted. These polarizations were made by applying potentials from -0.8 to -1.8V/SCE in artificial seawater and NaCl solution. Four stages were identified and related in term of hydrogen ingress, hydrides formation and calcareous deposit growth. The formation of γ and δ-hydrides have been observed, localized and characterized using several techniques. On T40, hydrides form as a layer that increases the surface roughness and clusters form in the bulk after first moments of hydrogen absorption. Whereas in TA6V ELI, hydrogen is absorbed by β-phase leading to a volume expansion of this phase. Then after reaching the hydrogen solubility limit of β-phase, hydrides form on interfaces α/β or α/α and in α grains. For long durations, the hydrogen ingress is limited by the subsurface hydrides and the stabilized calcareous deposit. These different steps are time depend on processes which need to be tacked into account to improve knowledge of hydrogen embrittlement in titanium alloys.

scholarly journals Numerical and Experimental Results on Charpy Tests for Blends Polypropylene + Polyamide + Ethylene Propylene Diene Monomer (PP+PA+EDPM)

2020 ◽  
Author(s):  
Catalin Pirvu ◽  
Andreea Elena Musteata ◽  
George Ghiocel Ojoc ◽  
Lorena Deleanu
Keyword(s):  
Equivalent Plastic Strain ◽  
Material Model ◽  
Element Model ◽  
Tensile Tests ◽  
Experimental Results ◽  
Low Velocity ◽  
Sem Images ◽  
Charpy Test ◽  
Simulation Results ◽  
The Impact

This paper presents results from numerical and experimental investigation on Charpy tests in order to point out failure mechanisms and to evaluate new polymeric blends PP+PA6+EPDM. Charpy tests were done for initial velocity of the impactor of 0.96 m/s and its mass of 3.219 kg and these data were also introduced in the finite element model. The proposed model take into account the system of four balls, including support and the ring of fixing the three balls and it has a finer discretization of the impact area to highlight the mechanisms of failure and their development in time. The constitutive models for four materials (polypropylene with 1% Kritilen, two blends PP+PA6+EPDM and a blend PA6+EPDM) were derived from tensile tests. Running simulations for each constitutive model of material makes possible to differentiate the destruction mechanisms according to the material introduced in the simulation, including the initiation and the development of the crack(s), based on equivalent plastic strain at break (EPS) for each material. The validation of the model and the simulation results was done qualitatively, analysing the shape of broken surfaces and comparing them to SEM images and quantitatively by comparing the impact duration, energy absorbed by the sample, the value of maximum force during impact. The duration of the destruction of the specimen is longer than the actual one, explainable by the fact that the material model does not take into account the influence of the material deformation speed in Charpy test, the model being designed with the help of tests done at 0.016 m/s (1000 mm/min) (maximum strain rate for the tensile tests). Experimental results are encouraging for recommending the blends 20% PP+42% PA6+28% EPDM and 60% PA6+ 40%EPDM as materials for impact protection at low velocity (1m/s). Simulation results are closer to the experimental ones for the more brittle tested materials (with less content of PA6 and EPDM) and more distanced for the more ductile materials (with higher content of PA6 and EPDM).

scholarly journals Numerical and Experimental Results on Charpy Tests for Blends Polypropylene + Polyamide + Ethylene Propylene Diene Monomer (PP + PA + EPDM)

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5837
Author(s):  
Cătălin Pîrvu ◽  
Andreea Elena Musteată ◽  
George Ghiocel Ojoc ◽  
Lorena Deleanu
Keyword(s):  
Equivalent Plastic Strain ◽  
Material Model ◽  
Element Model ◽  
Tensile Tests ◽  
Experimental Results ◽  
Low Velocity ◽  
Sem Images ◽  
Charpy Test ◽  
Simulation Results ◽  
The Impact

This paper presents results from numerical and experimental investigation on Charpy tests in order to point out failure mechanisms and to evaluate new polymeric blends PP + PA6 + EPDM. Charpy tests were done for initial velocity of the impactor of 0.96 m/s and its mass of 3.219 kg and these data were also introduced in the finite element model. The proposed model takes into account the system of four balls, including support and the ring of fixing the three balls and it has a finer discretization of the impact area to highlight the mechanisms of failure and their development in time. The constitutive models for four materials (polypropylene with 1% Kritilen, two blends PP + PA6 + EPDM and a blend PA6 + EPDM) were derived from tensile tests. Running simulations for each constitutive model of material makes possible to differentiate the destruction mechanisms according to the material introduced in the simulation, including the initiation and the development of the crack(s), based on equivalent plastic strain at break (EPS) for each material. The validation of the model and the simulation results were done qualitatively, analyzing the shape of broken surfaces and comparing them to SEM images and quantitatively by comparing the impact duration, energy absorbed by the sample, the value of maximum force during impact. The duration of the destruction of the specimen is longer than the actual one, explainable by the fact that the material model does not take into account the influence of the material deformation speed in Charpy test, the model being designed with the help of tests done at 0.016 m/s (1000 mm/min) (maximum strain rate for the tensile tests). Experimental results are encouraging for recommending the blends 20% PP + 42% PA6 + 28% EPDM and 60% PA6 + 40% EPDM as materials for impact protection at low velocity (1 m/s). Simulation results are closer to the experimental ones for the more brittle tested materials (with less content of PA6 and EPDM) and more distanced for the more ductile materials (with higher content of PA6 and EPDM).

scholarly journals Low-carbon cast microalloyed steel intercritically heat-treated at different temperatures: microstructure and mechanical properties

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Hadi Torkamani ◽  
Shahram Raygan ◽  
Carlos Garcia Mateo ◽  
Yahya Palizdar ◽  
Jafar Rassizadehghani ◽  
...  
Keyword(s):  
Carbon Content ◽  
Volume Fraction ◽  
Block Size ◽  
Tensile Tests ◽  
Total Elongation ◽  
Martensite Phase ◽  
Low Carbon ◽  
Steel Increase ◽  
Different Temperatures ◽  
The Impact

AbstractIn this study, dual-phase (DP, ferrite + martensite) microstructures were obtained by performing intercritical heat treatments (IHT) at 750 and 800 °C followed by quenching. Decreasing the IHT temperature from 800 to 750 °C leads to: (i) a decrease in the volume fraction of austenite (martensite after quenching) from 0.68 to 0.36; (ii) ~ 100 °C decrease in martensite start temperature (Ms), mainly due to the higher carbon content of austenite and its smaller grains at 750 °C; (iii) a reduction in the block size of martensite from 1.9 to 1.2 μm as measured by EBSD. Having a higher carbon content and a finer block size, the localized microhardness of martensite islands increases from 380 HV (800 °C) to 504 HV (750 °C). Moreover, despite the different volume fractions of martensite obtained in DP microstructures, the hardness of the steels remained unchanged by changing the IHT temperature (~ 234 to 238 HV). Applying lower IHT temperature (lower fraction of martensite), the impact energy even decreased from 12 to 9 J due to the brittleness of the martensite phase. The results of the tensile tests indicate that by increasing the IHT temperature, the yield and ultimate tensile strengths of the DP steel increase from 493 to 770 MPa, and from 908 to 1080 MPa, respectively, while the total elongation decreases from 9.8 to 4.5%. In contrast to the normalized sample, formation of martensite in the DP steels could eliminate the yield point phenomenon in the tensile curves, as it generates free dislocations in adjacent ferrite.

scholarly journals Strength Enhancement of Superduplex Stainless Steel Using Thermomechanical Processing

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1094
Author(s):  
M. A. Lakhdari ◽  
F. Krajcarz ◽  
J. D. Mithieux ◽  
H. P. Van Landeghem ◽  
M. Veron
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Thermomechanical Processing ◽  
Tensile Tests ◽  
Image Correlation ◽  
Strength Enhancement ◽  
Industrial Material ◽  
Superduplex Stainless Steel ◽  
The Impact ◽  
Strength Improvement

The impact of microstructure evolution on mechanical properties in superduplex stainless steel UNS S32750 (EN 1.4410) was investigated. To this end, different thermomechanical treatments were carried out in order to obtain clearly distinct duplex microstructures. Optical microscopy and scanning electron microscopy, together with texture measurements, were used to characterize the morphology and the preferred orientations of ferrite and austenite in all microstructures. Additionally, the mechanical properties were assessed by tensile tests with digital image correlation. Phase morphology was not found to significantly affect the mechanical properties and neither were phase volume fractions within 13% of the 50/50 ratio. Austenite texture was the same combined Goss/Brass texture regardless of thermomechanical processing, while ferrite texture was mainly described by α-fiber orientations. Ferrite texture and average phase spacing were found to have a notable effect on mechanical properties. One of the original microstructures of superduplex stainless steel obtained here shows a strength improvement by the order of 120 MPa over the industrial material.

scholarly journals Mechanical Properties of Spruce Wood Extracted from GLT Beams Loaded by Fire

2021 ◽  
Vol 13 (10) ◽  
pp. 5494
Author(s):  
Lucie Kucíková ◽  
Michal Šejnoha ◽  
Tomáš Janda ◽  
Jan Sýkora ◽  
Pavel Padevět ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Cross Section ◽  
Negative Impact ◽  
Tensile Tests ◽  
Thermal Recovery ◽  
Bending Test ◽  
Small Scale ◽  
Spruce Wood ◽  
The Impact

Heating wood to high temperature changes either temporarily or permanently its physical properties. This issue is addressed in the present contribution by examining the effect of high temperature on residual mechanical properties of spruce wood, grounding on the results of full-scale fire tests performed on GLT beams. Given these tests, a computational model was developed to provide through-thickness temperature profiles allowing for the estimation of a charring depth on the one hand and on the other hand assigning a particular temperature to each specimen used subsequently in small-scale tensile tests. The measured Young’s moduli and tensile strengths were accompanied by the results from three-point bending test carried out on two groups of beams exposed to fire of a variable duration and differing in the width of the cross-section, b=100 mm (Group 1) and b=160 mm (Group 2). As expected, increasing the fire duration and reducing the initial beam cross-section reduces the residual bending strength. A negative impact of high temperature on residual strength has also been observed from simple tensile tests, although limited to a very narrow layer adjacent to the charring front not even exceeding a typically adopted value of the zero-strength layer d0=7 mm. On the contrary, the impact on stiffness is relatively mild supporting the thermal recovery property of wood.

scholarly journals Mechanical, Thermal and Rheological Properties of Polyethylene-Based Composites Filled with Micrometric Aluminum Powder

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1242
Author(s):  
Olga Mysiukiewicz ◽  
Paulina Kosmela ◽  
Mateusz Barczewski ◽  
Aleksander Hejna
Keyword(s):  
Mechanical Properties ◽  
Melt Flow Index ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Flow Index ◽  
Scanning Calorimetry ◽  
Metal Composites ◽  
Pre Treatment ◽  
The Impact ◽  
Properties Of Composites

Investigations related to polymer/metal composites are often limited to the analysis of the electrical and thermal conductivity of the materials. The presented study aims to analyze the impact of aluminum (Al) filler content (from 1 to 20 wt%) on the rarely investigated properties of composites based on the high-density polyethylene (HDPE) matrix. The crystalline structure, rheological (melt flow index and oscillatory rheometry), thermal (differential scanning calorimetry), as well as static (tensile tests, hardness, rebound resilience) and dynamic (dynamical mechanical analysis) mechanical properties of composites were investigated. The incorporation of 1 and 2 wt% of aluminum filler resulted in small enhancements of mechanical properties, while loadings of 5 and 10 wt% provided materials with a similar performance to neat HDPE. Such results were supported by the lack of disturbances in the rheological behavior of composites. The presented results indicate that a significant content of aluminum filler may be introduced into the HDPE matrix without additional pre-treatment and does not cause the deterioration of composites’ performance, which should be considered beneficial when engineering PE/metal composites.

The impact of graphene nanoparticle additives on the strength of simple and hybrid adhesively bonded joints

2018 ◽  
Vol 53 (23) ◽  
pp. 3335-3346 ◽  
Author(s):  
Hamid Reza Borghei ◽  
Bashir Behjat ◽  
Mojtaba Yazdani
Keyword(s):  
Joint Strength ◽  
Tensile Tests ◽  
Lap Joints ◽  
Homogeneous Distribution ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Single Lap Joints ◽  
Hybrid Joints ◽  
Graphene Nanoparticles ◽  
The Impact

In this paper, the effect of graphene nanoparticle additive on the strength of simple and hybrid (rivet-bonded) single-lap joints is studied using the experimental method. Two different types of graphene with different number of layer and thicknesses are used in adhesive-graphene nanoparticle composite construction. At first, tensile tests are done on bulk specimens of adhesive with different additives. It is found that adding 0.5 wt% of graphene to the neat adhesive leads to an increase in the ultimate tensile strength of bulk specimens almost 24% and 12% for two graphene types compared to the neat adhesive. Also, the shear strength of adhesive and hybrid lap joints incorporating two types of graphene nanoparticles (types I and II) is compared to that of adhesive and hybrid joints without graphene nanoparticles. SEM results of fracture surfaces show that the inclusion of graphene nanoparticle to the adhesive increases the roughness of surfaces. Experimental results reveal that graphene nanoparticle increases the strength of bonded and hybrid joints. It is observed that, graphene with a lower thickness and number of layers has a better influence on joint strength. In fact, graphene nanoparticle type II makes a homogeneous distribution in adhesive-graphene nanoparticle composite and causes a significant increase on joint strength.

scholarly journals Adhesion Strength of BNT Films Hydrothermally Deposited on Titanium Substrates

2010 ◽  
Vol 123-125 ◽  
pp. 399-402
Author(s):  
Fang Chao Xu ◽  
Kazuhiro Kusukawa
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Adhesion Strength ◽  
Pure Titanium ◽  
Tensile Tests ◽  
Film Deposition ◽  
Lead Free ◽  
Element Analysis ◽  
Substrate Strain ◽  
Titanium Substrates

Lead-free piezoelectric (Bi1/2Na1/2)TiO3 (BNT) films were deposited on 1 mm thick pure titanium(Ti) substrates by a hydrothermal method. Tensile tests were performed to quantitatively assess the adhesion strength between BNT films and Ti substrates. Ti substrates were pretreated by chemical polish and mechanical polish respectively prior to BNT film deposition. In the tensile test, the behavior of BNT film exfoliation was investigated by the replica method. The critical Ti substrate strain inducing BNT film exfoliation was determined by the aid of finite element analysis (FEM). In this study, the results revealed that BNT film exfoliations were caused by the strain of Ti substrate, and the mechanical polish pretreatment improved the adhesion of BNT film to Ti substrate.

scholarly journals 3D characterization of the fracture mechanisms of a Fe-rich Al-Si-Cu alloy

2018 ◽  
Vol 165 ◽  
pp. 04006
Author(s):  
Angelika Brueckner-Foit ◽  
Inigo Bacaicoa ◽  
Martin Luetje ◽  
Marcel Wicke ◽  
Andreas Geisert ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Fracture Mechanisms ◽  
Crack Advance ◽  
Micro Computed Tomography ◽  
Initiation Mechanism ◽  
Initiation Phase ◽  
Β Phase ◽  
Cu Alloy

The effect of the defect size and morphology on the fatigue damage evolution was analysed in a recycled Al-Si-Cu alloy by micro-computed tomography and scanning electron microscopy. Fatigue tests were performed and the different crack initiation scenarios were characterized and classified. The interaction between shrinkage and gas pores was the key crack initiation mechanism and the ß-Al5FeSi particles did not play any role in the crack initiation phase. However, crack path analysis indicated that there is a certain amount of crack advance by brittle fracture of the β-phase particles. This is in accordance with the findings of tensile tests in which the ductility depended strongly on the iron content.

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