Internal Friction Study Research Articles

Evaluation of hydrogen interactions with defects induced by deformation in the duplex stainless steel microstructure: An internal friction study

Despite their good corrosion resistance and optimal mechanical properties, duplex stainless steels are affected by hydrogen embrittlement. Therefore, understanding the hydrogen-defect interactions in these steels is crucial. This study uses internal friction to evaluate the interactions of hydrogen with microstructural defects. Analysis of the internal friction spectra of the steels subjected to straining and hydrogen charging, together with thorough microstructural characterization, gives new insights in hydrogen interactions with defects present in the different phases, i.e. ferrite (body centered cubic) and austenite (face centered cubic).While no significant effect of tensile deformation can be observed by thermal desorption spectroscopy, the internal friction spectra show a clear influence of the presence of defects. Detailed analysis of these spectra reveals the interactions in the austenite as dominant, while no indications for hydrogen-dislocation interactions in ferrite are observed. This can be related to limited trapping in ferrite due to the austenite sink action or to limited dislocation formation in ferrite. Indications for hydrogen interactions with dislocations in the austenite are found, possibly suggesting enhanced dislocation mobility when surrounded by hydrogen. Moreover, a pronounced influence of hydrogen charging on the vacancy cluster related peaks is observed, indicating strong interactions between hydrogen and vacancy clusters in austenite. This can be put in contrast to behavior of pure ferritic steels, where dislocations provided the strongest hydrogen interactions. As these specific defects are of primary interest in the hydrogen embrittlement mechanisms, internal friction is concluded to provide important unique insights in hydrogen-defect interactions, even for complicated multiphase microstructures.

Structure, microstructure and magneto-elastic property study on Co40Ni29Al31 ferromagnetic shapememory alloy ribbon

Ferromagnetic shapememory Alloys having huge magnetic field and stress-induced strain are suitable materials for sensors and actuators. Ni2MnGa being the prototype of these materials and because of its brittleness alternative systems CoNiAl/Ga were recently developed. CoNiAl being a ductile material because of its two-phase microstructure and the large range of transformation temperatures. In this line, a ribbon with nominal composition Co40Ni29Al31 was prepared using melt-spun technique. The structure and microstructure of the sample was determined using XRD and SEM. The transformation temperatures were determined using four probe method using a cryocooler within the temperature range of 4 K to 350 K. The elastic and magneto-elastic properties were studied using a Vibrating reed method within the temperature 80 K to 300 K. A constant magnetic field of 300 Oe is applied with a coil wound on the cryostat of the vibrating reed setup. As was expected the sample has two phases of microstructure, from the XRD data, a high amount of β phase with a few amount of γ phase was found and it was also replicated in SEM photographs. The phase fractions were found by fitting the XRD data with Reitveld refinement. The transformation temperatures of the sample were obtained from the four probe resistivity measurements, and they are TMs = 133 K, TMf = 83 K, TAs = 130 K and TAf = 179 K. From the sound velocity and internal friction study without and with the magnetic field interesting results were found. The martensitic and inter martensitic transformations were suppressed with the application of magnetic field. It was clearly seen in the sound velocity change plots as a function of temperature and the same was replicated in the internal friction plots. Such studies through light on the magneto-elastic coupling-related issues and are quite useful for the application of these materials for the Micro Electro Mechanical Systems at different operating conditions.

A combined thermal desorption spectroscopy and internal friction study on the interaction of hydrogen with microstructural defects and the influence of carbon distribution

Hydrogen interactions with different microstructural defects were analysed in ultra-low carbon steel, with specific focus on the influence of carbon distribution. For this purpose, the steel was cold rolled and subjected to various annealing treatments, obtaining microstructures ranging from as cold rolled, over recovered up to fully recrystallized. Optical microscopy, transmission electron microscopy and hardness measurements were used to obtain information on the grain boundary structure and dislocation density. Positron annihilation spectroscopy measurements revealed metastable open volume defects related to both dislocations and vacancy clusters. The carbon distribution was characterized by internal friction experiments. Hydrogen interactions were studied by thermal desorption spectroscopy and internal friction measurements of samples electrochemically pre-charged with hydrogen.The most dominant contribution in hydrogen trapping in the cold rolled material is provided by dislocations. However, their contribution is strongly reduced after annealing at temperatures in the range between 300 K and 600 K due to dissolution of metastable kink-pairs and small carbon-vacancy clusters. Dissolution of such clusters provides fresh supply of carbon to dislocations, which reduces the dislocation trapping capacity for hydrogen due to carbon-hydrogen repulsion. The presence of carbon also reduces the vacancy mobility, allowing clustering and growth during cold rolling resulting in strong hydrogen trapping sites. Binding energies at dislocations were obtained from thermal desorption spectroscopy and internal friction measurements and compared to various models. The small discrepancy in the activation energy is argued to originate from the quantum effect. Hydrogen release from vacancy clusters is determined by the energy required for complete cluster dissolution.

Preparation and Study of Composite Materials of the NiAl-Cr-Mo-Nanoparticles (ZrO2, MgAl2O4) System.

Materials based on the NiAl-Cr-Mo system with zirconium oxide or aluminum-magnesium spinel nanoparticle small additions were obtained by spark plasma sintering. Thermodynamic modeling was carried out to predict the phase formation in the NiAl-Cr-Mo system and its change depending on temperature, considering the presence of a small amount of carbon in the system. The phase composition and microstructure of materials were studied. NiAl (B2) and CrMo phases were found in the sintered samples. Bending strength measurements at different temperatures shows that nanoparticles of insoluble additives lead to an increase in bending strength, especially at high temperatures. A fractographic analysis of the sample’s fractures shows their hybrid nature and intercrystalline fracture, which is confirmed by the clearly visible matrix grains similar to cleavage. The maximum strength at 700 °C (475 MPa) was found for material with the addition of 0.1 wt.% zirconium oxide nanoparticles. In the study of internal friction, typical peaks of a nickel-aluminum alloy were found in the temperature ranges of 150–200 °C and 350–400 °C.

The interaction of hydrogen with microstructural defects studied by internal friction

In order to evaluate the hydrogen-defect interactions, an internal friction study is performed on hydrogen-charged cold rolled ultra-low carbon steel. For this purpose, the steel is subjected to various thermo-mechanical treatments and information on the hydrogen-dislocation interactions are obtained via thorough analysis of the so-called hydrogen cold work peak obtained by internal friction. Using existing theoretical models, the peak could be decomposed into two contributions from hydrogen segregation at screw and non-screw dislocations.

Experimental Study of Classical and Quantum Internal Friction in Solid 4He

Experimental Study of Classical and Quantum Internal Friction in Solid 4He

Internal Friction Study of the Bake-Hardening Properties on Low Carbon Steel Influenced by the Degree of Pre-Deformation

This paper selected cold-rolled low carbon steel as the object of experimentation to better understand that the annealed sample was baked in different degree of pre-deformation span to measure its baking hardening property. The main results of the experiments are as follows: The sample was set in different pre-deformation. Firstly, the baking temperature was set as 170°C and the time span was 20 minutes. The results released that when the degree of pre-deformation was set between 2% and 5%, the BH value increased with the increasing degree of pre-deformation. Secondly, the degree of pre-deformation was set between 5% and 10%, the BH value decreased with the increasing degree of pre-deformation. Thirdly, when the degree of pre-deformation was set at 5%, the BH value reached the maximum. It is illustrated that the BH value increased along with the rising of SKK peak while decreased with the falling of SKK peak. It indicated that the increase of the BH value was mainly due to the intensification of the Cottrell Atmosphere. As the pre-deformation increased, the sum of hSnoek+hSKK decreased. It is worth noting that while under the same circumstances, the sum of hSnoek+hSKK increased after baking.

Preparation and Study of Ni–Al–O System Cermet Composites with a Small Addition of MgAl2O4 Nanoparticles

This paper presents the results of obtaining and studying the structure and properties of cermets based on powders of aluminum oxide and nickel–aluminum alloy doped with 0.1 wt % of aluminum–magnesium spinel nanoparticles sintered by the electrospark method on a FCT-HP D 25 unit in argon at t = 1470°C for 30 min. The results of the NiAl–65Al2O3 charge TG and DSC analysis at up to 1300°C are presented. It is found that the MgAl2O4 spinel in the form of individual nanoparticles (60 nm) or aggregates (less than 700 nm) are present along the grain boundaries of the composite. Internal friction studies at t = 20–900°C and high-temperature X-ray phase analysis at t = 700, 800, and 900°C were carried out to describe the degradation mechanisms of the strength properties of the materials. The effect of nanoparticles on the internal friction of the composite within Δt = 20–900°C in the NiAl–65Al2O3–0.1MgAl2O4 system is shown. Potential mechanisms for cermet strength-property degradation with increasing temperature are discussed. It is suggested that the appearance of extrema on internal friction curves at high temperatures can be caused by shifted phase boundaries of intermetallic compounds and the oxide component due to different coefficients of thermal expansion (CTE). A positive effect of doping with spinel nanoparticles on the short-term heat resistance of cermets at t = 750°C is found. The study of short-term heat resistance at t = 750°C shows that the sample with nanoparticles is more stable than the unmodified sample, which can be associated with the influence of interfacial hardening zones formed around nanoparticles according to the Obraztsov–Lurie–Belov theory and a number of studies carried out on metal matrices.

Internal friction study on precipitation/dissolution of Mn-Ni-Si phase in aged RPV model steel

The precipitation/re-dissolution of Mn-Ni-Si-based phase (MNPs) in Fe-1.6%Mn-1.0%Ni-0.2%Si (wt.%) RPV model steel under different aging temperatures was systematically studied using internal friction (IF) technique. It is clearly observed that the pinning/depinning effect of GB sliding results from the precipitation/re-dissolution of MNPs, which is also in favor of the corresponding variations in tensile strength and nanoindentation results.

Preparation and study of Ni–Al–O system cermet composites with a small addition of MgAl<sub>2</sub>O<sub>4</sub> nanoparticles

The paper presents the results of obtaining and studying the structure and properties of cermets based on powders of aluminum oxide and nickel-aluminum alloy doped with 0.1 wt.% of aluminum-magnesium spinel nanoparticles sintered by the electrospark method on the FCT-HP D 25 unit in argon at t = 1470°C for 30 min. The results of the NiAl–65Al 2 O 3 charge TG and DSC analysis at up to 1300°C are presented. It is found that MgAl 2 O 4 spinel in the form of individual nanoparticles (60 nm) or aggregates (less than 700 nm) are present along the grain boundaries of the composite. Internal friction studies at t = 20÷900°C and high-temperature X-ray phase analysis at t = 700, 800 and 900°C were carried out to describe strength properties degradation mechanisms of the developed materials. The effect of nanoparticles on the internal friction of the composite within Δ t = 20÷900°C in the NiAl–65Al 2 O 3 –0.1MgAl 2 O 4 system is shown. Potential mechanisms for cermet strength properties degradation with increasing temperature are discussed. It is suggested that the appearance of extrema on internal friction curves at high temperatures can be caused by shifted phase boundaries of intermetallic compounds and the oxide component due to different coefficients of thermal expansion (CTE). A positive effect of doping with spinel nanoparticles on the short-term heat resistance of cermets at t = 750°C is found. The study of short-term heat resistance at t = 750°C showed that the sample with nanoparticles is more stable than the unmodified sample, which can be associated with the influence of interfacial hardening zones formed around nanoparticles according to the Obraztsov– Lurie–Belov theory and a number of studies carried out on metal matrices.

In situ X-ray diffraction and the internal friction study of the binary yellow 18-carat gold alloy

Phase transitions in AuCu alloy are investigated using in situ temperature XRD and mechanical spectroscopy. The measurements are carried out from room temperature up to 973 K starting from the ordered phase AuCuI. Using a temperature ramp rate of 1 K/min, the following phase transition sequence was recorded on heating: AuCuI - > AuCuI + AuCuII- > AuCuI + AuCuII + A1 - > AuCuII + A1 - > A1. The mechanical (elastic and anelastic) properties are determined by this phase transition sequence. The mechanical spectroscopy, using a forced torsion pendulum, shows a peak due to antiphase boundary movement in the orthorhombic phase AuCuII according to the temperature dependent internal friction tests. The isothermal frequency measurements show several thermally activated peaks in the phase transitions intervals.

Impulse Excitation Internal Friction Study of Retained Austenite in Ferrous Martensite

Internal friction (IF) measurements were conducted using ferrous lath martensite specimens with different retained austenite fractions. While a distinctive Snoek-Ke-Koster (SKK) peak was detected in the IF spectra, the peak shape did not conform to the peak shape observed for fully martensitic steel. Peak analysis suggests that the peak shape is related to the overlap of the SKK peak with a Finkelstein–Rosin peak, additional Debye-type peak related to the retained austenite.

Anelasticity of iron-aluminide Fe3Al type single and polycrystals

Mechanical spectroscopy and in situ neutron diffraction techniques were employed to study and interpret anelasticity in Fe-27 at.%Al single crystal (SC) and polycrystal (PC) alloys from room temperature to 600 °C. Thermally activated Zener relaxation was recorded in the temperature dependent internal friction (IF) curves for both SC and PC alloys upon heating and cooling. The reversible second-order D03 ↔ B2 phase transition studied by in situ neutron diffraction leads to a transient anelastic effect at ∼550 °C both upon heating and cooling. The transient peak temperature does not depend on measurement frequency, whereas the peak height is roughly proportional to the inverse frequency of measurements according to Landau's theory for the second order transitions. Calorimetry and magnetometry techniques recorded the same temperature range for the D03 ↔ B2 phase transition as mechanical spectroscopy and in situ neutron diffraction. The study of amplitude dependent internal friction (ADIF) revealed that the absolute value of maximum damping Qm−1 in the SC sample is about five times higher than that of in the PC sample at room temperature. The calculated value of internal stresses opposing magnetic domain wall motions for the PC sample is ∼1.5 times larger than that of for the SC sample, which corresponds to the detrimental influence of grain boundaries to magnetomechanical damping. By increasing the tightening force of torque wrench, a higher level of localized stress is induced to the sample, and the damping capacity (Qm−1) in single cantilever configuration of forced bending vibrations reduces monotonously.

Microstructure Analyses and Multiscale Stochastic Modeling of Steel Structures Operated in Extreme Environment

The article primarily is concerned with the problem of damage accumulation and fracture modeling for steel structures operated at low temperature conditions. The inhomogeneity of the weld joints is other issue associated with the need to examining the microstructure and defects in steel at different scale levels. The next problem is that, extreme environment contains not only the extreme temperature conditions but phase transitions also, fluctuations in temperature, inappropriate in service and repair. Last factors have stochastic behavior and are even uncertain in nature. So these problems are observed and discussed in this paper as theoretical and experimental for building the multiscale model of structural damage accumulation, taking into account the following: the inhomogeneity of the weld, the low-temperature brittle-ductile transition for bcc steels, and the uncertainty factors estimation concept. The applications describe the locomotive tire lifetime estimation at low temperature conditions. The modeling approach is based on Kachanov-Rabotnov structural damage accumulation theory and stochastic crack growth modeling. Bayesian probability approach has been used for uncertainty factor estimation. The experimental part includes the internal friction study of low temperature transition mechanism for bcc steel, the mechanical tension and impact toughness tests for locomotive tire steel, and the low-cycling testing and microhardness estimation of mechanical properties for welded steel probes. The experimental testing shows the impact toughness drop at low temperature. The microstructural study for weld joints reveals the small cracks in heat affected zone, so the size and distance between such defects are used for stochastic modeling visualization of crack propagation and crack velocity estimation. The revealing mechanisms and proposed relationships could be used for theoretical and numerical modelling of damage accumulation and fracture in welded steel structures.

Dynamic magnetic characteristics during martensitic transformations in NiMnInCo metamagnetic shape memory alloy

We present here the results of experimental study of magnetic permeability, electrical resistance and magnetomechanical internal friction during magnetostructural martensitic transformation in metamagnetic NiMnInCo shape memory alloy. We show that dynamical characteristics (permeability, linear and non-linear magnetomechanical damping components) related to the mobility of ferromagnetic domain walls are not proportional to the volume fraction of ferromagnetic austenite, in contrast to resistivity or magnetization, and decline very rapidly at the onset of the martensitic transformation. Immobilization of domain walls by non-magnetic nuclei of martensite or by high internal stresses induced during the martensitic transformation is considered as possible origin of this effect.

Internal Friction Study of Aging Hardening and Kinetics in Low Carbon Steel

Abstract The low carbon steel with 2% pre-strained had the strain aging treatment in different baking time at 170°C. The stress-strain curves, bake hardening (BH) value and internal friction-temperature spectrum of tested steels were studied by tensile test and internal friction. The Harper aging kinetic equation respectively using the parameters of BH value, yield point elongation (YPE) or Snoek-Ke-Koster (SKK) peak height was established. The results show that with the increase of aging time, the yield point elongation and BH value of tested steel increases, and then the stress-strain curve of the steel become from continuous yield to discontinuous yield. In the internal friction-temperature curve, the Snoek peak height decreases, the SKK peak height continuously increases, and peak temperature changes slightly. It indicates that the primary mechanism of age hardening is Cottrell atmosphere hardening. The time index n in the Harper aging kinetic equation fitted by the BH value, YPE and SKK peak height were 0.53, 0.59 and 0.59, respectively. The linear relationship of BH value and SKK peak is BH=17119•h SKK -33.

Brittle Fracture Modeling for Steel Structures operated in the Extreme

The Extreme here is an environment that contains conditions that are hard to survive even for steel structures due to extreme temperature, corrosion, inappropriate service and repair. So not only the mechanical properties and behavior of steel structures are important for structural integrity but also the phase transition processes, inhomogeneity and uncertainty factors. These problems are observed and discussed in the paper consisting of three main theoretical parts: the multiscale modeling approach for structural damage accumulation, the theory of low-temperature brittle-ductile transition for bcc steels, and uncertainty factors estimation concept. The applications describe the locomotive tire lifetime estimation at low temperature conditions, weld inhomogeneity calculation and bridge service life prediction. The modeling approach based on Kachanov-Rabotnov structural damage accumulation theory and stochastic crack growth modeling. Bayesian probability approach has been used for uncertainty factor estimation. The experimental research included the internal friction study of bcc steel, the mechanical tension and impact toughness testing for probes prepared from used in climatic condition of Central Yakutia locomotive tire steel, the low-cycling testing for welded steel probes, and microhardness estimation. The inhomogeneity of probes used for stress and strain state modeling. The microstructural study reveals the small cracks in heat affected zone so the size and distance between such defects used for stochastic modeling visualization of crack propagation and crack velocity estimation. The concept of service life estimation for welded steel bearing for bridges has been presented.

Parametric evaluation of shear strength parameters on the stability of cut slope: a case study from Mahabaleshwar road section, India

Stability of rock cut slopes depends upon the type of material, discontinuity attributes and geometry present in any location. Although, gravity remains the constant important factor in dictating the slope failure but other parameters like shear strength and available shear stress along the slope also decides the stability of the slopes to great extent. The strength of the material comes from the internal bonding between the mineral grains, contact between the particles and the ability of the material to respond to the stress conditions. Variation of these material attributes fluctuate the cohesion and angle of internal friction that constitutes the most important properties in defining the strength of any material. Rock resists shear stress by these two internal mechanisms. Numerical simulation by Finite Element Method technique is attempted for assessing the stability cut slope. An attempt has been made in this study to document the behavior of strength of the material in terms of stability of slopes by parametric study of cohesion and internal friction. This study carried to understand how the factor of safety changes with reference to change in cut slope height, cohesion and internal friction of the discontinuities that attributes the shear strength of discontinuities. The study is based on Finite Element Modeling (FEM). From the study it is found that factor of safety has strongly proportional relation with cohesion and internal friction but shown inversely proportional relation with height of cut slope.

Thermally-activated anelastic relaxation in a high-manganese Cu-Mn alloy studied by isothermal low-frequency internal friction

Low-frequency internal friction study has been conducted for a copper-manganese-rich alloy (Cu-60at%, γ Mn). The study used a forced torsion pendulum working in low-frequency scans at constant temperatures, damping experiments ranging between 40Hz and 10−4Hz. The dependence on temperature was extended from room temperature to the spinodal curve frontier at 923K. Phenomenological stages in anelastic relaxations of (Cu, γ Mn) were evidenced. Three thermally activated relaxation peaks were assigned respectively to point defects (Zener relaxation), dislocation segments and dislocation walls.

Control of Degradation of Construction Materials in the Course of Use for the Case of String Elements

Features in metrological assurance of the parameters of construction materials used in machine-building components in the course of service are considered. An analysis of existing approaches to testing of samples, including studies of internal friction, is conducted. A phase chronometer method of measurement of the properties of construction materials over time using a harmonic oscillator as an example is proposed. An alternative approach to estimation of the residual life is proposed.