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In the present study, the PLC characteristic parameters and DSA mechanism of Al-(2.86~9.41) Mg alloy sheets were investigated during tensile testing at room temperature with a tensile rate of 1 × 10−3 s−1. On the basis of the solution Mg concentrations in the α-Al matrix, the initial vacancy concentration, the second-phase particle configuration and the recrystallized grain configuration are almost the same by quenching treatment. The results show that the type of room-temperature tensile stress–strain curves of quenched Al-(2.86~9.41) Mg alloy sheets varied according to the Mg content. The type of stress–strain curve of the Al-2.86 Mg alloy sheet was B + C, while the type of stress–strain curve of the Al-(4.23~9.41) Mg alloy sheets was C. When the quenched Al-(2.86~9.41) Mg alloy sheets were stretched at room temperature, the strain cycle of the rectangular waves corresponding to the high stress flow Δ ε T max and stress drop amplitude Δ σ on the zigzag stress–strain curve of alloy sheets increased with increasing the Mg content. Moreover, the strain cycle of Δ ε T max and Δ σ on the stress–strain curve of alloy sheets increased gradually with increasing tensile deformation. The yield stress of quenched Al-(2.86~9.41) Mg alloy sheets increased gradually with increasing the Mg content. Moreover, the critical strain corresponding to yield stress ε σ and the critical strain corresponding to the occurrence of the PLC shearing band ε c of alloy sheets both increased with increasing the Mg content. However, the difference in flow strain value Δ ε c − σ between ε c and ε σ of alloy sheets decreased gradually with increasing the Mg content. [ABSTRACT FROM AUTHOR]

A parametric pit design in the outer surface of the oil pipeline buried under the soil atmosphere is investigated. This study analyzes the effect of pit size and corrosion contours to evaluate the metal degradation due to various characteristics that impact the corrosion on the oil pipeline. A 3D design of the model has been chosen, and its geometry is modeled in COMSOL MULTIPHYSICS, and appropriate meshing is done before computing to analyze impact of pit size and electron current density in oil pipeline. The behaviour of the pit design was then analysed using various parameters such as electron current density, corrosion rate, the impact of the pit size in localized area. The current findings in the study shows that risk of metal degradation and the depth of the pit size gives a relationship for corrosion in the localized area and the risk for pitting corrosion can be reduced by improving pipeline condition monitoring. [ABSTRACT FROM AUTHOR]

Relaxor ferroelectric Na1/2Bi1/2TiO3-based materials have gained considerable attention as a potential lead-free alternative in recent years and can be tailored to exhibit giant strain or superior high power properties. Quenching (1-x)(Na1/2Bi1/2)TiO3-xBaTiO3 (NBT-BT) ceramics in air from the sintering temperature is beneficial in enhancing the depolarization temperature and the lattice distortion. Here, a comparative study using transmission electron microscopy (TEM) and X-ray diffraction is presented for unpoled, furnace cooled and quenched NBT-BT (3, 6, 9 and 12 ​mol. % BT) ceramics describing the domain structure and phase assemblage. In contrast to the furnace cooled sample, an enhanced lamellar domain contrast is observed for the quenched morphotropic phase boundary composition with 6 ​mol. % BT. The phase fraction obtained using high resolution X-ray diffraction changes from a near pseudocubic structure with small distortions towards a more pronounced rhombohedral and tetragonal phase assemblage. On the NBT-rich side (3 ​mol. % BT), a second rhombohedral phase emerges in addition to the R3c symmetry, exhibiting a long-range lamellar domain structure. Further, quenched and subsequently poled NBT-6BT features an increased tetragonal fraction associated with a highly lamellar domain contrast. The quenching treatment stabilizes the ferroelectric order, evidenced from the development of a long-range ferroelectric domain structure, which rationalizes the enhanced depolarization temperature.

Based on integrated concepts in the aspects of product design, choice of materials and manufacturing technologies, companies in the mechanical engineering as well as oil and gas industries are striving to increase energy efficiency through weight-optimized components and manufacturing processes. With regard to the design of e.g. functional components for hydraulic systems or aircraft structures, customized manufacturing concepts are crucial in order to combine the highest product quality with the economical use of energy and resources. The use of a flexible tooling system for combined internal contouring and mechanical post-processing of boreholes developed within the framework of a ZIM project, founded by the Federal Ministry for Economic Affairs and Energy and in collaboration with BGTB GmbH makes it possible to achieve highest surface qualities of high-performance components. In order to realize a further optimization of the machined surface, the influences of increased operating pressures during roller burnishing on surface smoothing are investigated in analogy tests. In this regard, different steel types are considered as typical application materials. Based on reference tests, the surface integrity as a result of increased working pressures was analyzed as well. Besides the variation of the mechanically applied force, the adjustment of the process strategy is a central issue of the experimental investigations. On the one hand, the influences of varying roll feeds are analyzed with reference to the surface finishing quality and the process efficiency. On the other hand, different strategies for surface improvements increase by varying holding pressures are assessed comparatively. [ABSTRACT FROM AUTHOR]

Abstract We prove CLTs for biased randomly trapped random walks in one dimension. By considering a sequence of regeneration times, we will establish an annealed invariance principle under a second moment condition on the trapping times. In the quenched setting, an environment dependent centring is necessary to achieve a central limit theorem. We determine a suitable expression for this centring. As our main motivation, we apply these results to biased walks on subcritical Galton–Watson trees conditioned to survive for a range of bias values. [ABSTRACT FROM AUTHOR]

The study reported in this paper concerned development of such microstructure of high-chromium (24 % Cr) cast iron which could secure high abrasive wear resistance of die inserts used to fabricate stampings from refractory materials. It was found that by increasing the cast iron cooling rate as a result of thermal interaction with the chill, it is possible to obtain fine carbide precipitates with diversified morphology, rich in Cr and Fe, containing Mo and Si. The matrix in the regions of thermal interaction with the chill was enriched in Cr and Mo, but depleted of Fe and Si. The sub-zero treatment process was developed to secure presence of hardening products in the matrix. The obtained structure of high-chromium cast iron has made the inserts more resistant to abrasive wear compared to tool steels after hear treatment used earlier.

The paper deals with research into dependence of hardness and impact energy of thermal cycle simulated specimens of fine-grained structural steel S960QL on cooling time from 800 to 500 °C and on tested temperature. Results were obtained by measuring hardness of HV 10 and by experimental testing of Charpy notched tubes on instrumented Charpy hammer. Total impact energy, initiation energy and fracture propagation energy needed for occurrence of fracture is also elaborated.

In this paper we prove a quenched functional central limit theorem for a biased random walk on a supercritical Galton–Watson tree with leaves. This extends a result of Peres and Zeitouni (2008) where the case without leaves was considered. A conjecture of Ben Arous and Fribergh (2016) suggests an upper bound on the bias which we observe to be sharp. [ABSTRACT FROM AUTHOR]

As-cast binary copper-tin alloys with over 15% were generally not much in use in antiquity as they get embrittled at higher tin contents due to the increasing presence of the intermetallic delta phase compound. Even so, the unusual and skilled use of a higher tin binary bronze alloy, known as wrought and quenched high-tin beta bronze, is found, especially from some Iron Age or megalithic sites in southern and peninsular India, around the early first millennium BCE. They are closely approximating to the composition of the pure beta phase of 22.9% tin, which is an intermetallic compound. This article presents some of the micro-structural evidence of heavily hot-forged, carinated, and perforated bowls from the site of Adichanallur, Tamil Nadu. They rank amongst the most finely wrought examples of beta bronze known in the world, with continuing traditions into the medieval Chola Tamil region and contemporary period. A process of experimentation with thermomechanical processes in the Peninsular Indian Iron Age is also suggested, since it slightly differed from an example of a vessel with 21% tin that was only cast and quenched, found in Boregaon from the Vidarbha megaliths of Maharashtra in the Central Deccan. [ABSTRACT FROM AUTHOR]

The paper deals with research into dependence of hardness and impact energy of thermal cycle simulated specimens of fine-grained structural steel S960QL on cooling time from 800 to 500 °C and on tested temperature. Results were obtained by measuring hardness of HV 10 and by experimental testing of Charpy notched tubes on instrumented Charpy hammer. Total impact energy, initiation energy and fracture propagation energy needed for occurrence of fracture is also elaborated. [ABSTRACT FROM AUTHOR]

The study reported in this paper concerned development of such microstructure of high-chromium (24% Cr) cast iron which could secure high abrasive wear resistance of die inserts used to fabricate stampings from refractory materials. It was found that by increasing the cast iron cooling rate as a result of thermal interaction with the chill, it is possible to obtain fine carbide precipitates with diversified morphology, rich in Cr and Fe, containing Mo and Si. The matrix in the regions of thermal interaction with the chill was enriched in Cr and Mo, but depleted of Fe and Si. The sub-zero treatment process was developed to secure presence of hardening products in the matrix. The obtained structure of high-chromium cast iron has made the inserts more resistant to abrasive wear compared to tool steels after hear treatment used earlier. [ABSTRACT FROM AUTHOR]

We consider a random walk in a random potential on a square lattice of arbitrary dimension. The potential is a function of an ergodic environment and steps of the walk. The potential is subject to a moment assumption whose strictness is tied to the mixing of the environment, the best case being the i.i.d. environment. We prove that the infinite volume quenched point-to-point free energy exists and has a variational formula in terms of entropy. We establish regularity properties of the point-to-point free energy, and link it to the infinite volume point-to-line free energy and quenched large deviations of the walk. One corollary is a quenched large deviation principle for random walk in an ergodic random environment, with a continuous rate function. [ABSTRACT FROM AUTHOR]

We consider a random walk in random environment on a strip, which is transient to the right. The random environment is stationary and ergodic. By the constructed enlarged random environment which was first introduced by Goldsheid (2008), we obtain the large deviations conditioned on the environment (in the quenched case) for the hitting times of the random walk. [ABSTRACT FROM AUTHOR]

Abstract: Estimating the probability that a species is extinct based on historical sighting records is important when deciding how much effort and money to invest in conservation policies. The framework we offer is more general than others in the literature to date. Our formulation allows for definite and uncertain observations, and thus better accommodates the realities of sighting record quality. Typically, the probability of observing a species given it is extant/extinct is challenging to define, especially when the possibility of a false observation is included. As such, we assume that observation probabilities derive from a representative probability density function. We incorporate this randomness in two different ways (“quenched” versus “annealed”) using a framework that is equivalent to a Bayes formulation. The two methods can lead to significantly different estimates for extinction. In the case of definite sightings only, we provide an explicit deterministic calculation (in which observation probabilities are point estimates). Furthermore, our formulation replicates previous work in certain limiting cases. In the case of uncertain sightings, we allow for the possibility of several independent observational types (specimen, photographs, etc.). The method is applied to the Caribbean monk seal, Monachus tropicalis (which has only definite sightings), and synthetic data, with uncertain sightings. [Copyright &y& Elsevier]

We consider a random walk among i.i.d. obstacles on $\mathbb {Z}$ under the condition that the walk starts from the origin and reaches a remote location y. The obstacles are represented by a killing potential, which takes value M>0 with probability p and value 0 with probability 1− p, 0< p≤1, independently at each site of $\mathbb {Z}$. We consider the walk under both quenched and annealed measures. It is known that under either measure the crossing time from 0 to y of such walk, τ, grows linearly in y. More precisely, the expectation of τ/ y converges to a limit as y→∞. The reciprocal of this limit is called the asymptotic speed of the conditioned walk. We study the behavior of the asymptotic speed in two regimes: (1) as p→0 for M fixed ('sparse'), and (2) as M→∞ for p fixed ('spiky'). We observe and quantify a dramatic difference between the quenched and annealed settings. [ABSTRACT FROM AUTHOR]

A duplex microstructure consisting of allotriomorphic ferrite and austenite at ambient temperature has been produced in a low-alloy steel by a simple heat treatment which involves intercritical annealing followed by quenching. The tensile properties obtained are good, with a total elongation of some 28% at an ultimate tensile strength approaching 900MPa. The form of the stress vs. strain curve is suitable for automotive applications, but it is speculated that the steel could be better exploited in a hot-pressed form. [ABSTRACT FROM AUTHOR]

We consider quenched and annealed Lyapunov exponents for the Green's function of −Δ + γV, where the potentials $${V(x),\ x\in\mathbb {Z}^d}$$, are i.i.d. nonnegative random variables and γ > 0 is a scalar. We present a probabilistic proof that both Lyapunov exponents scale like $${c\sqrt{\gamma}}$$ as γ tends to 0. Here the constant c is the same for the quenched as for the annealed exponent and is computed explicitly. This improves results obtained previously by Wang. We also consider other ways to send the potential to zero than multiplying it by a small number. [ABSTRACT FROM AUTHOR]

Abstract: The tube model for linear and branched architectures is nowadays able to predict in high precision the linear viscoelastic relaxation time spectrum. For linear chains, the involved time scales fit to the commonly accessible dynamic scattering techniques. This makes it possible to microscopically investigate the correlation between structures and relaxation processes. In branched systems, however, the hierarchical nature of relaxations limits direct investigation via these microscopic methods as the dynamic processes are prolongated to much longer relaxation times that are no more accessible to usual dynamic scattering methods. A way to overcome this difficulty is offered by the use of static small angle neutron scattering. Here, the combination of annealing and quenching steps after a step deformation provides unique information of the structure at particular times along the relaxation spectrum. This, however, necessitates the availability of architecturally clean and specifically deuterium labelled model polymers due to the sensitivity of the scattering method. Therefore, we outline in this contribution first the current status on the synthesis and analysis of such compounds with relation to neutron scattering. Secondly, we present exemplary neutron scattering results from in situ stress relaxation studies inside the neutron beam on linear and H-shaped branched polymers which were molecularly designed to highlight specific relaxation processes. We discuss the relevance of the tube model parameters in linear and non-linear studies. [Copyright &y& Elsevier]

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The ordering behavior of quenched Cu-12 at% Mn was investigated by differential scanning calorimetry (DSC) under increasing temperature conditions. The ordering process can be better explained in terms of a homogeneous short-range-order (SRO) rather than a disperse-short-range-order (DSRO) model as for concentrated Cu-γMn solid solutions. At the employed high quench rates ordering is established in one stage here termed stage 1, assisted by excess vacancies. This stage obeys a first order kinetics law, being the effective activation energy consistent with a weighed average sum of the activation energy for migration of free and bound vacancies. An estimated solute-vacancy binding energy of 15 kJ mol-1 seems quite reasonable for this alloy together with the assessed activation energy for complex migration of 92.6 kJ mol-1. By adopting a first SRO order parameter based in quasi-chemical theory in pair approximation and using boundary values calculated from displayed features of DSC traces, the retained degree of quenched-in order at room temperature was calculated. This procedure also enabled to estimate an ordering energy of -2.7 kJ mol-1. The effect of quenching temperature demonstrate that for smaller vacancy sink densities, the retained degree of order at room temperature goes through a minimum. [ABSTRACT FROM AUTHOR]

Abstract: Stress–strain characteristics of Pb–1.5wt% Sb alloy have been studied in the temperature range from 393 to 513K for both quenched and slowly cooled specimens. The coefficient of work hardening, , yield stress, , and fracture stress, , of the quenched specimens were found to be higher than those of the slowly cooled specimens. These parameters of both types of specimens were generally found to decrease with increasing deformation temperature, showing two stages around the transformation temperature (443K). In the first stage the rate of change of these parameters was found to increase with increasing deformation temperature, while it decreases in the second stage. The ductility—fracture strain percent of this alloy exhibited a minimum value at this temperature. The calculated slip distance of the moving dislocations showed a small variation in the temperature range below 443K while a considerable change in slip distance was observed above this temperature for both quenched and slowly cooled specimens. The two observed temperature regions below and above 443K may characterize a point of dislocation intersection mechanisms activated with and 0.6eV for the two regions, respectively. The microstructure of the samples under investigation was examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. [Copyright &y& Elsevier]

In the present work, the role of Mg atoms in the form of either Mg clusters or β phase on the moving dislocations in 5083 aluminum alloy sheet were investigated by comparing the plastic flow behavior and Portevin-Le Chatelier (PLC) character in annealed and quenched conditions. It is found that the tensile strength of quenched sheets at different strain rates is slightly higher than those under annealed condition while the yield strength at both conditions is similar. In annealed sheets, the yield plateau was clearly observed at all tested strain rates with a strain less than 0.012, and its width increased with the increasing strain rate. However, no yield plateau was observed in quenched sheets. On the other hand, the characters of PLC are greatly varied with applied conditions and strain rate. Generally, annealed sheets have a higher waiting time, but lower critical strain/stress at lower strain rate (~1 × 10−4 s−1), but they are similar at a higher strain rate (1 × 10−2 s−1). However, the falling time at both annealed and quenched conditions are almost the same at tested strain rates. [ABSTRACT FROM AUTHOR]