Unsafe Domains Research Articles

Hot Deformation Behavior and Microstructural Evolution Based on the Processing Map of Dual-Phase Mg-Li Based Alloy.

The deformation behavior of the as-extruded Mg-Li-Al-Zn-Si alloy was studied by conducting a hot compression test, with a temperature range of 180–330 °C and a strain rate range of 0.01–10 s−1. The constitutive relationship of flow stress, temperature, and strain rate was expressed by the Zener–Hollomon parameter and included the Arrhenius term. By considering the effect of strain on the material constants, the flow stress at 240–330 °C could be precisely predicted with the constitutive equation (incorporating the influence of strain). A processing map was established at the strain of 0.7. The unsafe domains that are characterized by uneven microstructures were detected at low temperatures (<230 °C) or high temperatures (>280 °C), with high strain rates (>1 s−1). The optimum hot deformation region was obtained at a medium temperature (270–300 °C), with a peak power dissipation efficiency of 0.44. The microstructural evolution in different domains is investigated. The unstable domains are characterized by a non-uniform flow behavior and uneven microstructure. The observation showed that the dynamic recrystallization (DRX) process could easily occur at the safe domain with high power dissipation efficiency. For the α-phase, some features of continuous dynamic recrystallization can be found. The triple points serve as prominent nucleation sites for the β-phase DRX grains and the growth in the grains was carried out by subgrain boundary migration. The microstructure exhibits characteristics of discontinuous dynamic recrystallization.

Hot working behaviour and processing maps of duplex cast steel

Abstract In this paper the hot working behaviour of medium carbon duplex cast steel is studied using uniaxial hot compression tests over a temperature range varying from 700 ˚C to 1 000 °C and at different strain rates ranging from 10–4 to 10–1 s–1. A model based on a variant of a dynamic materials model was employed to construct processing maps. These maps delineate the safe and unsafe domains. The safe domains, associated with dynamic recrystallization and dynamic recovery, can be chosen to optimize the hot workability of the studied material. Whereas, the unsafe domain is to be avoided because it is associated with plastic deformation instabilities. The domain associated with dynamic recrystallization is centred at 1000 °C and 10–4 s–1 with a peak energy dissipation efficiency of about 40%, while the domain associated with dynamic recovery is centred at 700 °C and 10–4 s–1 with a peak energy dissipation efficiency of about 27%. The unsafe hot working domain, spread over the entire temperature range and moderate to high strain rates, predicts the appearance of flow instabilities, in the form of shear bands and intergranular cracks. To validate the obtained results, microstructural observations corresponding to different processing conditions are presented.

Prediction of thermo-mechanical behavior and microstructural evolution of copper considering initial grain size at elevated temperature

To characterize and evaluate the workability of pure copper, the hot compression test at temperature range of 673–1073 K, strain rate range of 0.001–0.1s−1 and two initial grain sizes (IGS) of 20 and 50μm with 60% deformation were performed. The results of the true stress-strain curve showed that the processing parameters including IGS, temperature, strain rate, and strain have a significant effect on the elevated temperature behavior of pure copper. As the flow curve of finer grain size at lower temperatures has higher flow stress than the larger grain size which is reversed by increasing the temperature due to changes in the deformations mechanism. A hyperbolic-sine Arrhenius model and strain-compensated Arrhenius constitutive equation with good accuracy were developed to describe and predict the hot flow behavior of this material. The activation energy was determined in different processing conditions for two different IGS and the results showed that this energy increases with increasing strain, and its values are greater for finer grain sizes. The investigation of the deformation mechanism showed that the mechanism of cross-slip and dislocation climb controlled the deformation process are dominant mechanisms for IGS of 20μm whereas self-diffusion is the dominant mechanism for IGS of 50μm. To determine the safe and optimal conditions for hot deformation, the processing maps were drawn based on DMM theory at different strains. Finally, by examining and evaluating the microstructure under different processing conditions, the dominant mechanisms were identified for the two investigated IGS at different temperature ranges and strain rates, and the safe and unsafe domains were specified for the hot deformation of copper.

Construction of hot deformation processing maps for 9Cr-1Mo steel through conventional and ANN approach

The behavior of hot deformed flow curves in a 9Cr-1Mo steel have been analysed using constitutive and artificial neural network (ANN) approaches. At each temperature (850 ° C-1100 ° C) various strain rates (0.001 s−1–10 s−1) of deformation behavior has been analysed. The corrections of flow stress due to the adiabatic temperature rise during hot deformation have been made through artificial neural network (ANN) method and compared it with the linear interpolation (conventional) method. The temperature corrected (conventional) flow stress has been compared and analyzed with the predicted flow stress data obtained by established constitutive equation. Additionally, the experimental flow stresses obtained by thermomechanical simulator have also been compared and analyzed with predicted flow stresses obtained by ANN method. Further, the predicted and corrected flow stress curves obtained by ANN method have been compared and analyzed. The processing maps at 0.6 true strain based on flow stress data corrected through both ANN and conventional methods have been compared. Upon analyzing the safe and unsafe domains of the maps with the corresponding microstructures, the ANN approach depicted the best precise results over that of the conventional method. Variation in strain hardening rate and correlated it with EBSD analysis have also been carried out to analyze the variation in hardness for some of the deformed specimens.

A Fault Detection and Diagnosis System for Autonomous Vehicles Based on Hybrid Approaches

An accurate fault detection and diagnosis system is of great importance for autonomous vehicles to prevent the potential hazardous situations. In this paper, we propose a fault detection and diagnosis system based on hybrid approaches. First, to detect the state faults of the autonomous vehicle, One-Class Support Vector Machine (SVM) method is adopted to train the boundary curve which separates the safe domain and unsafe domain. Meanwhile, a Kalman filter observer is designed based on the linear kinematic vehicle bicycle model to predict the current position of the vehicle, and after obtaining the residuals between prediction and measurement, Jarque-Bera test is applied to check the normality of the residuals probability distribution to monitor whether the trajectory deviates. Furthermore, we design a fuzzy system to distinguish the types of the detected faults based on a modified neutral network, in which a membership function layer is added after the input layer. With the strong self-learning ability of neutral network, the initial membership function of the fuzzy system is updated through black box test and can indicate the probability of each fault type. Experiments on the real autonomous vehicle platform ‘Xinda’ and performance comparison with other fault detectors validate the effectiveness of these methods and the usability of the fault detection and diagnosis system.

Hot deformation behavior of a heat-resistant alloy without γ′-phase

The hot compression behavior of the nickel-based heat-resistant alloy C-HRA-2® was investigated by a Gleeble-1500 thermo-mechanical simulator with the deformation temperature range of 950–1150 °C and the strain rate of 0.001–10 s−1. The constitutive equation of the alloy was established by using a hyperbolic sine function, and the peak stress followed a power law relationship with the Zener–Hollomon parameter (Z). The activation energy was about 446 kJ mol−1 for the whole hot deformation domain in this alloy. The optimum hot deformation condition was obtained in the temperature range of 1050–1150 °C and the strain rate range of 0.005–0.1 s−1. Unsafe domains during the hot deformation would occur in the strain rate range of 0.1–10 s−1 with inhomogeneous microstructure and high-density twins in the alloy. The dominant nucleation mechanism of dynamic recrystallization (DRX) was continuous dynamic recrystallization with sub-grain rotation at high strain rate, while DRX at low strain rate was discontinuous dynamic recrystallization with original grain boundaries bulging.

Securing Ethernet-based Optical Fronthaul for 5G Network

In 5G networks, an optical fronthaul transports massive user data from remote radio heads (RRH) to the core network (CO) with high throughput and low latency. eCPRI is a new standard interface for the Ethernet-based optical fronthaul network to enhance the efficiency and performance. However, if fronthaul networks are deployed in an unsafe domain, an end-to-end security system should be implemented over the data flow, which requires additional overhead and processing time. This redundancy may cause unexpected latency and performance degradation in the data transport for 5G networks. According to the specification of eCPRI, vendors may optionally implement either IPsec or MACsec for the secure transmission. In this paper, we investigate security solutions suitable for the Ethernet-based optical fronthaul network. We analyse the standard security protocols such as IPsec and MACsec. Alternatively, we propose WireGuard as an replacement of IPsec for secure fronthaul networks. According to our analysis, the extended overhead for three security protocols has negligible impact on the latency. However, the encryption and decryption of transmission packets may cause additional latency on the eCPRI processing time and eventually reduce the maximum transmission distance between RRH and CO. To verify our analysis, we simulated an eCPRI traffic on our test platform with the WireGuard protocol enabled. Our test results showed that the latency caused by encryption and decryption process could be significant. We also point out that a re-key interval should be carefully selected not to compromise the security of the high capacity transmission link such as 5G fronthaul networks. Our analysis is further extended with quantum-resistant cryptographic solutions for the long-term security of fronthaul networks.

Constitutive Equation and Processing Maps of Al-7Si-0.3 Mg Hybrid Composites: a Novel Approach to Reduce Cost of Material by Using Agro-Industrial Wastes

The waste materials are not only found abundantly but also a threat to the environment. However, it can be used as a good additive for composite materials which turns industrial-waste into industrial-wealth. The hypothesis of present study is the utilization of the waste materials not only reduces the production cost but also beneficial for the environment. Aluminium with waste particles (agro and industrial) is prepared by using double stir-casting process. The hot deformation behaviour of aluminium alloy and aluminium hybrid composites was studied over deformation temperature range of 300–500 °C and strain rate of 0.1–10 s−1. The processing maps were developed for addition of different weight fractions (0, 7.5, 10 and 12.5%) of waste particles with A356 alloy to identify the safe and unsafe domains during hot processing. The A356/10%RHA-10%Fly ash hybrid composite achieved higher efficiency and high activation energy compare to base alloy and other hybrid composites.

Process Resilience Analysis Framework (PRAF): A systems approach for improved risk and safety management

Risk management challenges and continuous increase of global public aversion to hazards and risks associated with the process industry have been observed in the recent years. In order to manage process industry risk, several studies and methods have been developed and are currently used. The authors believe that two types of interacting factors: 1) technical (equipment malfunction, process parameter variation), and 2) social (regulations/policy, human and organizational factors) are important in assessment of risk for a process system. However, current methods are based on analysis of either technical factors, often quantitatively, or social factors, usually qualitatively. Apart from failure to establish all critical scenarios due to either factors, their combined and interactive effects are seldom considered. This research need calls for the development of a holistic and integrated systems framework for effective risk management, although full coverage of possible mishaps will be utopian. The application of the resilience engineering perspective is gradually being explored as an approach for considering the dynamics of socio-technical aspects based on systems theory to provide a safety net. This paper presents a novel framework - Process Resilience Analysis Framework (PRAF) for incorporating both technical and social factors in an integrated approach. This is based on four aspects: Early Detection (ED), Error Tolerant Design (ETD), Plasticity (P) and Recoverability (R). The resilience methodology emphasizes dynamics, unforeseen and even unknown types of threats, uncertainty, systems degradation and complex interactions. With resilience metrics a combined framework for predictability, survivability and recoverability, all via dynamic analysis, is introduced. PRAF primarily focuses on early detection of unsafe domains of operation, assessment of aggregate risks and prioritization of safety barriers during process upset situations and reduction in response time resulting in a reduced frequency of loss of containment events (LoC), reduced consequences and enhanced recovery. The paper describes the concepts and principles of the PRAF as a first step.

Influence of a Sub-Seismic Blind Faults on the Safety Assessment of CO2 Geological Storage in Deep Saline Aquifer

Within the European context, CO2 storage operations shall address the potential impacts of largescale CO2 storage through risk assessment. The key risks identified for this onshore CO2 storage site were the migration through sub-seismic blind faults.To quantify the CO2 migration along such sub-seismic blind fault, the impact of the fault is investigated both for its mechanical and flow contribution.In this study, a blind sub-seismic fault was assumed near a CO2 injection well. The study area is in the eastern part of the Paris Basin and targeting the Lower Triassic Sandstone formation which is deemed adequate for CO2 injection. The arbitrary geometry of the fault (with limited throw c.a. 1 m), was assumed across the expected migration pathway of the injected CO2. The fault is assumed to extend vertically between the storage aquifer and a control aquifer.The flow-geomechanics model coupled with an uncertainties management computes the failure probability, i.e. the probability of mechanical failure in the fault vicinity. Such probability of failure is characterized by low to very low probability of occurrence which requires a large number of simulations to enable its evaluation. Each failure scenario models the CO2 migration from a storage horizon to a control aquifer when altering the mechanical parameters of the fault damage zones and fault core. To limit CPU requirements associated with the flow-geomechanics model, it is replaced by a fast surrogate model in order to evaluate the numerous simulations needed to evaluate the probability of failure. They show that limited CO2 migration is occurring within the fault but no breakthrough in the control aquifer. The injection induces limited pressure disturbance resulting in small ground level heave in the order of a millimeter at the end of the 30-year injection period at an average rate of about 0.8 Mtpa.For each geological layer, several uncertain mechanical parameters were considered to illustrate the approach: the permeability, the young modulus and Poisson ratio of the core and damaged zones of the fault, the shale content within the fault core, the critical gas saturation and capillary entry pressure of the fault damaged zones. The key response of interest was the safety factor based upon the Mohr-Coulomb failure criteria.An initial local sensitivity analysis identified that only four of the 18 uncertain input variables have a significant influence on the response of the model. A Sobol design of experiments was then launched with the four remaining parameters in order to construct a surrogate model. Gaussian process surrogates were chosen because of their capability of giving an approximation of the prediction error, which is useful to assess the quality of the surrogate along the domain of interest. Furthermore, the error of prediction can also be taken into account when computing probabilities. From this surrogate, it was concluded that there is a strong influence of the mechanical integrity of the base of the sub-seismic blind fault (Sobol Sensitivity Indices). Based on the surrogate model of the mechanical safety factor (elastic behavior i.e. no loss of integrity), a Monte-Carlo experiment was used to evaluate the probability of mechanical failure of the fault at the base of the storage cap rock.The most influential parameter on the mechanical safety factor is the anisotropy ratio between horizontal stresses. Within the considered domain of variations of the parameter, the unsafe domain (mechanical failure) may be reached at the upper bound of the uncertain domain and the failure probability was estimated to be lower than 10-3 for this case. A confirmation run with the detail numerical model at the upper bound of the uncertain domain confirmed that the mean behavior is inside the safe domain. Consequently, the uncertainty of the surrogate model was further reduced and showed no failure within the uncertain domain (failure probability below 10-6 for this case): the mechanical failure of the base of the sub-seismic blind fault is very unlikely.

Hot deformation behavior of GH4945 superalloy using constitutive equation and processing map

The hot deformation behavior of GH4945 superalloy was investigated by isothermal compression test in the temperature range of 1000–1200 °C with strain rates of 0.001–10.000 s−1 to a total strain of 0.7. Dynamic recrystallization is the primary softening mechanism for GH4945 superalloy during hot deformation. The constitutive equation is established, and the calculated apparent activation energy is 458.446 kJ/mol. The processing maps at true strains of 0.2, 0.4 and 0.6 are generally similar, demonstrating that strain has little influence on processing map. The power dissipation efficiency and instability factors are remarkably influenced by deformation temperature and strain rate. The optimal hot working conditions are determined in temperature range of 1082–1131 °C with strain rates of 0.004–0.018 s−1. Another domain of 1134–1150 °C and 0.018–0.213 s−1 can also be selected as the optimal hot working conditions. The initial grains are replaced by dynamically recrystallized ones in optimal domains. The unsafe domains locate in the zone with strain rates above 0.274 s−1, mainly characterized by uneven microstructure. Hot working is not recommended in the unsafe domains.

Processing map-microstructure evolution correlation of hot compressed near alpha titanium alloy (TiHy 600)

Hot compression tests on TiHy 600 alloy (equivalent to IMI 834) is performed using Gleeble-3800® thermo-mechanical simulator. The hot deformation behavior of TiHy 600 alloy is characterized on the basis of flow stress variation with true stress-true strain curves at different strain rates ranging from 10−3 s−1 to 10 s−1 and hot deformation temperatures ranging from 900 °C to 1050 °C, with maximum engineering strain up to 50%. The flow stress is found to be strongly dependent on deformation temperature, strain rate and strain, and it decreases with increasing temperature and decreasing strain rate. The flow curves at various temperatures and strain rates also showed dynamic recrystallization process at temperature range (900 °C–975 °C) in all strain rates and dynamic recovery process at high temperature range (1000 °C and above) in all the strain rates. Using flow stress values from the true stress-true strain curves and by applying dynamic material modeling approach, processing maps are developed at various true strains of 0.3, 0.4, 0.5 and 0.6. Processing maps exhibited safe and unsafe domains with varying efficiency of power dissipation values. Safe and unsafe domains at 0.6 strain are derived from their flow curves are correlated with its related microstructures and misorientation distribution profiles. Hot compression at 900 °C (α-rich region) mostly resulted into new fine dynamic recrystallized equiaxed α grains along grain boundaries of large deformed α grains. Higher temperature (950 °C–975 °C) compression in the (α+β) region generated mixture of deformed large alpha grains containing subgrain boundaries and secondary α laths generates from deformed β. Further compression at higher temperature (1000 °C -β-rich region and 1050 °C -single β region) resulted in the formation of secondary α laths from deformed β with few equiaxed α grains at 1000 °C sample only. The misorientation profile of α phase corroborates with the deformation mechanism in α region through its equiaxed α grains and in β region through its secondary α variant laths misorientations.

Hot deformation behavior of 2060 alloy

The hot deformation behavior of 2060 alloy has been studied using thermal simulation test, EBSD technique and transmission electron microscopy. The flow stress could be described by a Zener-Hollomon parameter in hyperbolic sine function with the hot deformation activation energy of 205 kJ/mol. Dynamic recovery is the main dynamic soften mechanism of 2060 alloy. The relative volume fraction of subgrains increases from about 30% to 90% as the temperature rises from 350 °C to 400 °C. When the temperature is higher than 400 °C, both the relative volume fraction of the deformed grains and subgrains remain steady. The processing maps are similar in the strain ranging from 0.1 to 0.5, and the unsafe domains increase with the increase of strain. The optimum hot-working condition for 2060 alloy is 380–500 °C and 0.01–3 s−1.

Hot deformation characteristics of Alloy 617B nickel-based superalloy: A study using processing map

The deformation behavior of Alloy 617B was investigated by the isothermal compression test at temperature range of 1120–1210 °C with strain rates of 0.01–20 s−1 on a Gleeble-1500 thermo-mechanical simulator. The approach of processing map was used to reveal the hot workability and microstructural evolution during hot deformation. The temperature correction was invited here for high strain rate condition to get more accurate processing map. The results show that the processing parameters have significant effects on power dissipation efficiency and instability factors. The unsafe domains are detected at the high strain rate (>10 s−1) condition and is characterized by uneven microstructure and high density twins, which should be avoided in hot working process. The optimum hot working condition are obtained in the temperature range of 1120–1165 °C and strain rate scope of 0.01–0.1 s−1 with the peak power dissipation efficiency of 48%. Another domain of 1170–1210 °C and 0.1–4.5 s−1 can also be chosen as the optimal working condition at large strains (>0.8). In these two optimum domains, the original grains are substituted by fine dynamic recrystallization (DRX) grains and DRX is the main power dissipation mechanism. The dominant nucleation mechanism of DRX in the safe domain is the bulging of original grain boundaries accompanied with twining, which is the feature of discontinuous dynamic recrystallization (DDRX). Some characteristics of continuous dynamic recrystallization (CDRX) can also be found when deformed at strain rate of 1 s−1, although it can only be considered as an assistant nucleation mechanism.

Constitutive analysis and processing map of an extruded Mg–3Gd–1Zn alloy under hot shear deformation

Hot shear deformation behavior of the as-extruded Mg–3Gd–1Zn (GZ31) alloy was investigated by constructing processing-maps and developing constitutive equations. Hot shear punch tests (SPT) were conducted on the specimens taken perpendicular to the extrusion direction, and processing maps were developed from shear punch data within the temperature range of 573–773K and shear strain rate range of 3.3×10−3–1.3×10−1s−1. Based on the processing maps, the optimum processing condition was identified as 713–773K and 0.009–0.020s−1 in the safe region with a maximum efficiency parameter, while the flow instability region was found to occur in the temperature range 580–650K and shear strain rate range of 0.07–0.13s−1. The characteristic microstructures of the safe and unsafe domains were dynamically recrystallized and partially recrystallized grains, respectively. Constitutive equations were formulated using the sine hyperbolic function. Dislocation creep was found to be the dominant deformation mechanism based on the activation energy of 197kJmol−1 and the power-law stress exponents of 4.5–5.5, obtained from the sine hyperbolic function.

Study on Hot-Working Behavior of High Carbon Steel / Low Carbon Steel Composite Material Using Processing Map

The high carbon steel (HCS)/low carbon steel (LCS) laminated composite made by centrifugal casting technology was subjected to hot compression tests on Gleeble 3500 thermomechanical simulator in a range of temperatures (800-1100 oC) and strain rates (0.02-10 s-1). The hot-working behavior of the laminate was characterised by analysing the flow stress-strain curves and constructing the processing map based on dynamic materials model via superimposing efficiency of power dissipation and flow instability maps. The safe and unsafe processing conditions were identified in the processing map which was validated by microstructural examinations. Banded microstructure and micro-shear cracks occurred in the unsafe domains were responsible for the flow instability, while dynamic recrystallisation in stable domains with high efficiency of power dissipation imparted a good workability to the laminate. The optimum hot-working parameters were determined to be: (i) 800-1050 oC and 0.02-0.04 s-1, (ii) 800-1045 oC and 2.5-10 s-1 and (iii) 1050-1100 oC and 0.02-2.5 s-1.

Multimode Analysis of the Dynamics and Integrity of Electrically Actuated MEMS Resonators

We present a theoretical investigation of the dynamic behavior of a microelectromechanical system (in brief, MEMS) device modelled as a clamped-clamped microbeam subjected to electrostatic and electrodynamic actuation. We use the Galerkin projection technique to reduce the partial integro-differential equation governing the dynamics of the microbeam to a system of coupled ordinary differential equations which describe the interactions of the linear mode shapes of the microbeam. Analytical solutions are derived and their stability is studied for the simplest reduced-order model which takes into account only the first linear mode in the Galerkin procedure. We further investigate the influence of the first few higher modes on the Galerkin procedure, and hence its convergence, by analysing the boundaries between pull-in and pull-in-free vibrations domains in the space of actuation parameters. These are determined for the various multimode combinations using direct numerical time integration. Our results show that unsafe domains form V-like shapes for actuation frequencies close to the superharmonic, fundamental, and subharmonic resonances. They also reveal that the single first-mode reduced model usually considered underestimates the left branches and overestimates the right branches of these boundaries.

The Climate Adaptation Frontier

Climate adaptation has emerged as a mainstream risk management strategy for assisting in maintaining socio-ecological systems within the boundaries of a safe operating space. Yet, there are limits to the ability of systems to adapt. Here, we introduce the concept of an ―adaptation frontier‖, which is defined as a socio-ecological system's transitional adaptive operating space between safe and unsafe domains. A number of driving forces are responsible for determining the sustainability of systems on the frontier. These include path dependence, adaptation/development deficits, values conflicts and discounting of future loss and damage. The cumulative implications of these driving forces are highly uncertain. Nevertheless, the fact that a broad range of systems already persist at the edge of their frontiers suggests a high likelihood that some limits will eventually be exceeded. The resulting system transformation is likely to manifest as anticipatory modification of management objectives or loss and damage. These outcomes vary significantly with respect to their ethical implications. Successful navigation of the adaptation frontier will necessitate new paradigms of risk governance to elicit knowledge that encourages reflexive reevaluation of societal values that enable or constrain sustainability.

Reliability analysis of uncertain structures using earthquake response spectra

This paper develops a probabilistic methodology for the seismic reliability analysis of structures with random properties. The earthquake loading is assumed to be described in terms of response spectra. The proposed methodology takes advantage of the response spectra and thus does not require explicit dynamic analysis of the actual structure. Uncertainties in the structural properties (e.g. member cross-sections, modulus of elasticity, member strengths, mass and damping) as well as in the seismic load (due to uncertainty associated with the earthquake load specification) are considered. The structural reliability is estimated by determining the failure probability or the reliability index associated with a performance function that defines safe and unsafe domains. The structural failure is estimated using a performance function that evaluates whether the maximum displacement has been exceeded. Numerical illustrations of reliability analysis of elastic and elastic-plastic single-story frame structures are presented first. The extension of the proposed method to elastic multi-degree-of-freedom uncertain structures is also studied and a solved example is provided.

Hot working of Ti-17 titanium alloy with lamellar starting structure using 3-D processing maps

Isothermal compression of Ti-17 titanium alloy with lamellar starting structure at the deformation temperatures ranging from 780 °C to 860 °C, the strain rates ranging from 0.001 to 10 s−1, and the height reductions ranging from 15% to 75% with an interval 15% were carried out. Based on experimental results, 3-D processing maps including strain were developed and used to identify various microstructural mechanisms and distinguish the safe and unsafe domains. The processing maps exhibit two maximum power dissipation efficiency domains and dynamic globularization takes place in this two domains. The first domain occurs at 800–860 °C and at strain rates lower than 0.01 s−1, and the second occurs at 780–800 °C and at strain rates lower than 0.01 s−1. With the increasing of the strains, the values of maximum power dissipation efficiency in this two domains increase. One flow instability domain due to adiabatic shear bands and lamellar kinking occurs at strain rates higher than 0.487 s−1, lower temperature, and higher strain above 0.2. The instability deformation region increases with increasing strain, strain rate, and decreasing temperature.