X-ray Peak-Shift Determination of Deformation Fault Probability in Fe-Mn-Si Alloys

The X-ray diffraction peak-shift method was introduced into the determination of deformation fault probability (a) of Fe-Mn-Si alloys with various Mn contents and thermomechanical cycling numbers. The precise lattice constants required were obtained by numerical calculation instead of using standard sample without any fault. The influence of internal stress on the determined a has been evaluated, and the caused relative error was determined as about 4% and thus negligible. The results show that the deformation fault probability increases with decreasing Mn-content and increasing cycle number, which are qualitatively consistent with those results of Psf determined by peak-broadening method.

Stacking fault probability and stacking fault energy in CoNi alloys

The stacking fault probability of CoNi alloys with different contents of Ni was measured by X ray diffraction methods. The results show that the stacking fault decreases with increasing Ni content and with increasing temperature. The thermodynamical calculation has found an equation that can express the stacking fault energy γ of CoNi at temperature T . The phase equilibrium temperature depends on the composition of the certain alloy. The relationship between stacking fault energy γ and stacking fault probability P sf is determined.

Edge Device Fault Probability Based Intelligent Calculations for Fault Probability of Smart Systems

In a smart system, the faults of edge devices directly impact the system’s overall fault. Further, complexity arises when different edge devices provide varying fault data. To study the Smart System Fault Evolution Process (SSFEP) under different fault data conditions, an intelligent method for determining the Smart System Fault Probability (SSFP) is proposed. The data types provided by edge devices include the following: (1) only known edge device fault probability;(2) known Edge Device Fault Probability Distribution (EDFPD);(3) known edge device fault number and EDFPD;(4) known factor state of the edge device fault and EDFPD. Moreover, decision methods are proposed for each data case. Transfer Probability (TP) is divided into Continuity Transfer Probability (CTP) and Filterability Transfer Probability (FTP). CTP asserts that a Cause Event (CE) must lead to a Result Event (RE), while FTP requires CF probability to exceed a threshold before RF occurs. These probabilities are used to calculate SSFP. This paper introduces a decision method using the information diffusion principle for low-data SSFP determination, along with an improved method. The method is based on space fault network theory, abstracting SSFEP into a System Fault Evolution Process (SFEP) for research purposes.

A Cascading Fault Path Prediction Method for Integrated Energy Distribution Networks Based on the Improved OPA Model under Typhoon Disasters

In recent times,the impact of typhoon disasters on integrated energy active distribution networks(IEADNs)has received increasing attention,particularly,in terms of effective cascading fault path prediction and enhanced fault recovery performance.In this study,we propose a modified ORNL-PSerc-Alaska(OPA)model based on optimal power flow(OPF)calculation to forecast IEADN cascading fault paths.We first established the topology and operational model of the IEADNs,and the typical fault scenario was chosen according to the component fault probability and information entropy.The modified OPA model consisted of two layers:An upper-layer model to determine the cascading fault location and a lower-layer model to calculate the OPF by using Yalmip and CPLEX and provide the data to update the upper-layer model.The approach was validated via the modified IEEE 33-node distribution system and two real IEADNs.Simulation results showed that the fault trend forecasted by the novel OPA model corresponded well with the development and movement of the typhoon above the IEADN.The proposed model also increased the load recovery rate by>24%compared to the traditional OPA model.

Risk Assessment Based on Fault Tree Analysis for Damaged Pipe Repair During Operation in Petrochemical Plant

In petrochemical plant, the in-operation repairing is usually a repairing strategy with pressured inoperation repairing for avoiding huge economic losses caused by unplanned shutdown when some slight local leakage happens in pipes. This paper studies the effects of repairing strategies on the failure probability of the pipe systems in process industries based on the time-average fault tree approach, especially the in-operation repairing strategies including pressured in-operation repairing activities. The fault tree model can predict the effect of different repairing plans on the pipe failure probability, which is significant to the optimization of the repairing plans. At first pipes are distinguished into four states in this model, i.e., successive state, flaw state, leakage state and failure state. Then the fault tree approach, which is usually applied in the studies of dynamic equipment, is adopted to model the pipe failure. Moreover, the effect of pressured in-operation repairing is also considered in the model. In addition, this paper proposes a series of time-average parameters of the fault tree model, all of which are used to calculate node parameters of the fault tree model. At last, a practical case is calculated based on the fault tree model in a repairing activity of pipe thinning.

Estimating the Degree of Earthquake Risk from Fault Characteristics

A theoretical model considering the relationship between fault characteristics and tectonic stress is proposed to quantify earthquake risk degree. The model is applied in practice to the fault along the southern margin of Weihe basin in Shaanxi Province, Northwestern China and fitted well with reality.

X-ray Diffractions of Deformation Structurein Polycrystalline Fe-32Mn-5Si Alloy

The change of microstructure with strain was investigated in a Fe-32Mn-5Si austenitic alloy at room temperature by X-raydiffraction profile analysis.The experimental results show that the Fe-32Mn-5Si alloy is deformed by the strain—induced γ→εtransformation and the twinning except dislocation slip at room temperature.The amount of strain-induced ε-martensite,thestacking fault probability and the twinning probability all exhibit parabolic relationship with increasing strain.The stackingfault probability is higher than the twinning probability.

Fault mode probability factor based fault-tolerant control for dissimilar redundant actuation system

This paper presents a Fault Mode Probability Factor（FMPF） based Fault-Tolerant Control（FTC） strategy for multiple faults of Dissimilar Redundant Actuation System（DRAS）composed of Hydraulic Actuator（HA） and Electro-Hydrostatic Actuator（EHA）. The long-term service and severe working conditions can result in multiple gradual faults which can ultimately degrade the system performance, resulting in the system model drift into the fault state characterized with parameter uncertainty. The paper proposes to address this problem by using the historical statistics of the multiple gradual faults and the proposed FMPF to amend the system model with parameter uncertainty. To balance the system model precision and computation time, a Moving Window（MW） method is used to determine the applied historical statistics. The FMPF based FTC strategy is developed for the amended system model where the system estimation and Linear Quadratic Regulator（LQR） are updated at the end of system sampling period. The simulations of DRAS system subjected to multiple faults have been performed and the results indicate the effectiveness of the proposed approach.

On the stacking fault forming probability and stacking fault energy in carbon-doped 17 at%Mn steels via transmission electron microscopy and atom probe tomography

Assessing the stacking fault forming probability(P_(sf)) and stacking fault energy(SFE)in medium-or highMn base structural materials can anticipate and elucidate the microstructural evolution before and after deformation.Typically,these two parameters have been determined from theoretical calculations and empirical results.However,the estimation of SFE values in Fe–Mn–C ternary systems is a longstanding debate due to the complicated nature of carbon:that is,whether the carbon doping indeed plays an important role in the formation of stacking faults;and how the amount of carbon atoms exist at grain boundaries or at internal grains with respect to the nominal carbon doping contents.Herein,the use of atom probe tomography and transmission electron microscopy(TEM)unveils the influence of carbondoping contents on the structural properties of dual-phase Fe–17 Mn–x C(x=0–1.56 at%)steels,such as carbon segregation free energy at grain boundaries,carbon concentration in grain interior,interplanar D-spacings,and mean width of intrinsic stacking faults,which are essential for SFE estimation.We next determined the Psfvalues by two different methods,viz.,reciprocal-space electron diffraction measurements and stacking fault width measurements in real-space TEM images.Then,SFEs in the Fe–17 Mn–x C systems were calculated on the basis of the generally-known SFE equations.We found that the high amount of carbon doping gives rise to the increased SFE from 8.6 to 13.5 m J/m^(2)with non-linear variation.This SFE trend varies inversely with the mean width of localized stacking faults,which pass through both other stacking faults and pre-existingε-martensite plates without much difficulty at their intersecting zones.The high amount of carbon doping acts twofold,through increasing the segregation free energy(due to more carbon at grain boundaries)and large lattice expansion(due to increased soluble carbon at internal grains).The experimental data obtained here strengthens the composition-dependent SFE maps for predicting the deformation structure and mechanical response of other carbon-doped high-Mn alloy compositions.

Microstructural Development and Deformation Mechanisms during Cold Rolling of a Medium Stacking Fault Energy TWIP Steel

The magnetic response, microstructural and texture changes occurring during cold rolling of a Fe-14Mn-0.64C-2.4AI-0.25Si medium stacking fault energy TWlP （twinning induced plasticity） steel have been studied by X-ray diffraction and magnetic techniques. The changes in the sub-grain size （Ds）, probability of stacking fault formation （Psf） and microstrain in the material as cold rolling progressed were determined by using a modified version of the Williamson and Hall equation. A strong development of the crystallographic texture with increasing deformation was observed. Deformation-induced formation of a small fraction α＇-martensite was observed, indicating that the steel also exhibits γ→α＇-martensite transformation during cold rolling, which is discussed via the changes of the stacking-fault probability and the texture development during cold rolling.

Stacking fault energy in some single crystals

The stacking fault energy of single crystals has been reported using the peak shift method.Presently studied all single crystals are grown by using a direct vapor transport（DVT） technique in the laboratory.The structural characterizations of these crystals are made by XRD.Considerable variations are shown in deformation （α） and growth（β） probabilities in single crystals due to off-stoichiometry,which possesses the stacking fault in the single crystal.

Grain Size Effect on the Martensite Formation in a High-Manganese TWIP Steel by the Rietveld Method

The aim of the present work was to study the effect of austenite grain size （AGS） on the martensite formation in a high-manganese twinning-induced plasticity （TWIP） steel. The results of a quantitative microstructural characterization of the steel by the whole X-ray pattern fitting Rietveld software, materials analysis using diffraction （MAUD）, indicated that the volume fraction of αbcc-martensite increases with increasing AGS. However, the value of the stacking fault probability （Psf） does not show a large variation for samples with different values of AGS under water-quenching conditions.

Damping performance and martensitic transformation of rapidly solidified Fe-17%Mn alloy

The rapid solidification of Fe-17%Mn alloy was performed to investigate the influence of cooling rate on its damping performance and martensitic transformation mechanism. A proper heat treatment was also carried out to clarify its coupled effects with rapid solidification. The stacking fault probability and martensitic transformation temperature were determined to demonstrate their relationship with the cooling rate and the heat treatment process. With the increase of cooling rate, the volume fraction of ε-martensite increased and the stacking fault probability of ε-martensite was enhanced. The formation ofε-martensite phase was remarkable for the increase of damping capacity and microhardness. It was found that rapid solidification was beneficial for the formation of ε-martensite and the improvement of damping capacity. This effect can be facilitated by the incorporation of the heat treatment process.