Real Process Conditions Research Articles

Effects of carbon-based conductive materials on semi-continuous anaerobic co-digestion of organic fraction of municipal solid waste and waste activated sludge

Organic fraction of municipal solid waste (OFMSW) and waste activated sludge (WAS) are the most produced organic waste streams in urban centres. Their anaerobic co-digestion (AcoD) allows to generate methane (CH4) and digestate employable as renewable energy source and soil amendment, respectively, fully in accordance with circular bioeconomy principles. However, the widespread adoption of such technology is limited by relatively low CH4 yields that fail to bridge the gap between benefits and costs. Among strategies to boost AcoD of OFMSW and WAS, use of conductive materials (CMs) to promote interspecies electron transfer has gained increasing attention. This paper presents one of the few experimental attempts of investigating the effects of four different carbon(C)-based CMs (i.e., granular activated carbon – GAC, graphite – GR, graphene oxide – GO, and carbon nanotubes – CNTs) separately added in semi-continuous AcoD of OFMSW and thickened WAS. The presence of C-based CMs has been observed to improve CH4 yield of the control process. Specifically, after 63 days of operation (concentrations of GAC and GR of 10.0 g/L and of GO and CNTs of 0.2 g/L), 0.186 NL/gVS, 0.191 NL/gVS, 0.203 NL/gVS, and 0.195 NL/gVS of CH4 were produced in reactors supplemented with GAC, GR, GO, and CNTs, respectively, compared to 0.177 NL/gVS produced in the control process. Likewise, at the end of the test (i.e., after 105 days at concentrations of C-based CMs half of the initial ones), CH4 yields were 0.193 NL/gVS, 0.201 NL/gVS, 0.211 NL/gVS, and 0.206 NL/gVS in reactors supplemented with GAC, GR, GO, and CNTs, respectively, compared to 0.186 NL/gVS of the control process. Especially with regard to GR, GO, and CNTs, results obtained in the present study represent a significant advance of the knowledge on the effects of such C-based CMs to realistic and scalable AD process conditions respect to previous literature.

CO-PROX on MnO2 catalysts: DFT-based microkinetic and experimental macrokinetic approaches

A microkinetic analysis in terms of DFT-calculated temperature-dependent Gibbs free energies was performed for the oxidation reactions of CO and H2 on a model Mn4O8 cluster. Apparent activation energies data predict a peculiar CO preferential oxidation pattern of Mn(IV) sites in presence of hydrogen (PROX) substantiated by the unprecedented PROX behavior of a nanocomposite MnCeOx catalyst in the range of 353–423 K under both ideal and real process conditions. Micro- and macrokinetic data on the “model” cluster and “real” catalyst are discussed.

Pixelwise high-temperature calibration for in-situ temperature measuring in powder bed fusion of metal with laser beam

High-temperature calibration methods in additive manufacturing involve the use of advanced techniques to accurately measure and control the temperature of the build material during the additive manufacturing process. Infrared cameras, blackbody radiation sources and non-linear optimization algorithms are used to correlate the temperature of the material with its emitted thermal radiation. This is essential for ensuring the quality and repeatability of the final product. This paper presents the calibration procedure of an imaging system for in-situ measurement of absolute temperatures and temperature gradients during powder bed fusion of metal with laser beam (PBF-LB/M) in the temperature range of 500 K–1500 K. It describes the design of the optical setup to meet specific requirements in this application area as well as the procedure for accounting the various factors influencing the temperature measurement. These include camera-specific effects such as varying spectral sensitivities of the individual pixels of the sensor as well as influences of the exposure time and the exposed sensor area. Furthermore, influences caused by the complex optical path, such as inhomogeneous transmission properties of the galvanometer scanner as well as angle-dependent transmission properties of the f-theta lens were considered. A two-step fitting algorithm based on Planck's law of radiation was applied to best represent the correlation. With the presented procedure the calibrated thermography system provides the ability to measure absolute temperatures under real process conditions with high accuracy.

A Novel In-Line Measurement and Analysis Method of Bubble Growth-Dependent Strain and Deformation Rates during Foaming.

Bubble growth processes are highly influenced by the elongational viscosity of the blowing agent-loaded polymer melt. Therefore, the elongational viscosity is an important parameter for the development of new polymers for foaming applications, as well as for the prediction of bubble growth processes. Thus, knowledge of the initial expansion and deformation behavior in dependency on the polymer, the blowing agent concentration, and the process conditions is necessary. This study presents a novel method for the in-line observation and analysis of the initial expansion and deformation behavior within the bead foam extrusion process. For this purpose, nitrogen as the blowing agent was injected into the polymer melt (PS and PLA) during the extrusion process. The in-line observation system consists of a borescope equipped with a camera, which was integrated into the water box of an underwater pelletizer. The camera is controlled by a developed trigger by means of angular step signal analysis of a rotary encoder on the cutter shaft of the underwater pelletizer. Thus, images can be taken at any time during the foaming process depending on the cutter position to the die outlet. It is shown that the developed method provides reliable results and that the differences of the initial expansion and deformation behavior during bubble growth can be analyzed in-line in dependency on real foaming process conditions and the type of polymer used.

Prediction of grain size and dislocation density in the cold spraying process using a dislocation-based model

The cold spray particle deposition process was simulated by modeling the high-velocity impacts of spherical particles onto a flat substrate at different velocities. In addition to simulating the single particle, this study also employed a unique simulation technique to predict the evolution of the material's microstructure under real process conditions. A dislocation-based model was implemented as a VUMAT subroutine to model the microstructure. Additionally, Python scripting was also utilized in the multi-particle impact simulation to create particles and assign velocity and interaction randomly. The relationships between stress-strain values and material microstructure are linked together. By using this model, calculations were done for the equivalent plastic strain, dislocation density, and grain size in the particle, substrate, and interface. At the interface, there were high levels of plastic strain and strain rates reaching up to, which formed a bond between the particles and the substrate. It was found that a minimum plastic strain of approximately 1 is needed to create this bond. At velocities exceeding a critical velocity, a jet was produced. The particle grain size in regions distant from the interface measured between 200 and 500 nm, which is in good agreement with the experimental results. The smallest grain size was observed at the interface, measuring 140 nm. The validation outcomes demonstrated that the suggested model effectively replicates the cold spraying process. As a result, the suggested model has the capability to predict and evaluate the changes in the material's microstructure during the cold spraying process using various factors.

Theoretical and experimental validation of critical thermal properties of advanced vacuum bagging for composite manufacturing

The vacuum bagging is a common but critical step of various manufacturing process chains for Carbon/Glass Fibre reinforced polymers (C/GFRP). Whilst developing a new generation of vacuum bagging, significant efforts have been made to deeply understand the relevant physics fields, process variables involved and to provide predictive approaches to support dimensioning and scaling exercises prior to implementation into real production process. Main features of the new bagging system are, (1) the reduction of material diversity through merging of various properties within one single layer and, (2) the suppression of critical folding steps by using thermoforming for pre-shaping purposes. This paper will mainly focus on considerations of heat transfer during the pre-shaping of the film, directly on the CFRP part short before the curing step. For the better risk assessment of the short time exposition of an uncured composite part to the heat flow, a problem of transient coupled field analysis involving heat transfer via conduction, convection and radiation is formulated and solved by using Finite Element Analysis in COMSOL under consideration of realistic process conditions. Further a section dedicated to the comparison of the obtained results with measurements performed on a system including an IR-emitter, the bagging material, a ground plate and in some studies as well a CFRP sample is included. During the study the influence of time, power output of the emitter, distance between emitter and surface as well as irradiation angle has been assessed including a comparison of simulated results and performed measurements.

Laboratory and field validation of a new Coriolis metering concept for better measurement uncertainty, reliability and process insight

Coriolis mass flowmeters are widely accepted in various industries for their high performance measurement of density and mass flow rate. Not only do they play a critical role in O&G custody transfer applications, they are also increasingly important in addressing the new challenges and applications related to the energy transition where the highest accuracy and reliability is also required. Analogous to multi-beam Ultrasonic flowmeters, a new measuring concept based on the Coriolis principle has been developed with a metering system consisting of two individual Coriolis meters arranged in parallel to measure the incoming flow into the overall system. There are numerous advantages of this arrangement, among which reducing measurement uncertainty, increasing reliability and gaining greater process insights are the most significant addressed in this paper. Statistic theory suggests that for a total measurement equally divided by two sub-measurements of two independent measuring devices, the measurement uncertainty caused by random errors is reduced by a factor of the square root of 2 for the combined total measurement if the two sub-measurements are not correlated. This advantage applies to the zero-point and repeatability performance of the metering system. Taking advantage of independently measuring the same or similar fluid parameters twice, the measurement reliability is enhanced by cross-checking the two sets of measured parameters. For certain special cases, such as the transient disturbance caused by entrained gas that often exists under real process conditions, the corresponding negative impact can even be mitigated or eliminated by utilizing the undisturbed measured parameter set from the two. The spacial arrangement of the two Coriolis meters makes it useful to monitor the measured fluid parameters such as two sets of density, flow and temperature values to obtain additional knowledge of the spacial distribution of these fluid parameters, which can provide greater process insights.A critical step has been the validation of the theoretical advantages in third-party laboratories and in the field. A test was done for the zero-point stability of the metering system under various temperatures, pressures and viscosities at NEL using the EPAT facility. The measurement results suggested that the zero-point deviations of the two Coriolis meters followed a random probability and tended to cancel each other to certain degree, leading to a reduced zero-point deviation for the complete metering system. Repeatability and reproducibility tests conducted both at NEL EPAT and at Euroloop oil rigs with provers, showed good and consistent results. Recognizing most hydrocarbon markets trade on a volumetric basis rather than mass, the advantages the design brings towards density measurement are discussed and measurement data is presented across varying fluid densities and viscosities. In step with the growing importance of gaseous fluids associated with the evolving energy markets, the influence the novel design has on performance in gas applications is described and measurement data in gases is also presented. Furthermore, an interesting phenomenon has been captured during the flow stabilization phase before proving at Euroloop that transient disturbance of gas bubbles could be present, and very often disturbed only one of the two measuring systems at the same time, which enables the possibility to remediate the effect of transient disturbances. The same phenomenon was observed in field tests of this novel metering system, indicating the high probability of the occurrence. In this paper, the laboratories data from the NEL EPAT rig, Euroloop rig, pigsar rig, and H&D Fitzgerald as well as the data from field applications are presented and analysed to validate the theoretical analysis.

On the Use of Advanced Friction Models for the Simulation of an Industrial Stamping Process including the Analysis of Material and Lubricant Fluctuations

The use of numerical simulations for tool tryout and process control is becoming increasingly prevalent. In this work, the deep drawing process of a car inner door panel of DC06 mild steel is numerically analyzed and compared with industrial process results. Five batches of DC06 material were analyzed mechanically and tribologically. Diverse tribological models were developed based on experimental strip drawing tests, where a Coefficient of Friction (CoF) was obtained as a function of contact pressure, sliding velocity, and amount of lubricant. A topography analysis was defined to compare material batches and to replicate industrial tool conditions. The simulation was fed with three tribological models: constant (CoF 0.15), Filzek pressure and velocity dependent, and TriboForm with lubrication zones. Thinning, Forming Limit Diagram (FLD) and draw-in were used as indicators for the comparison. Using the industrial tool, both FLD and draw-in were measured and compared with the numerical models. The constant model predicted the most conservative strain state and also differed most from the experimental results. The P-v-dependent and TriboForm models more accurately predicted the experimental results. This work highlights the importance of considering more complex tribological models to feed numerical simulations to yield results closer to real process conditions.

Synergistic removal of pharmaceuticals and antibiotic resistance from ultrafiltered WWTP effluent: Free-floating ARGs exceptionally susceptible to degradation

To protect the environment and human health, antibiotic resistance genes (ARGs) and persistent pharmaceuticals need to be removed from WWTP effluent prior to its reuse. However, an efficient process for removing free-floating extracellular DNA (exDNA) in combination with a wide range of pharmaceuticals is yet to be reported for real process conditions. As a possible solution, we treated real ultrafiltered WWTP effluent with UV/H2O2 and combined GAC and zeolite sorption. In terms of exDNA, sequencing and high-throughput quantitative PCR (HT-qPCR) showed that exDNA is a potent carrier of numerous ARGs in ultrafiltered WWTP effluent (123 ARGs), including multi-drug efflux pump mexF that became the dominant exARG in GAC effluent over time. Due to the exposure to degradation agents, exDNA was reduced more efficiently than intracellular DNA, and overall levels of ARGs were substantially lowered. Moreover, GAC sorption was particularly effective in the removal of almost all the 85 detected pharmaceutical residues, with fresh GAC demonstrating an efficiency of up to 100%. However, zeolite (Si/Al 0.8) addition was needed to enhance the removal of persistent pollutants such as gabapentin and diclofenac to 57% and up to 100%, respectively. Our combined approach eminently decreases the hazardous effects of pharmaceuticals and antibiotic resistance in the ultrafiltered WWTP effluent, producing effluent suitable for multiple reuse options according to the latest legislation. In addition, we provided similarly promising but less extensive data for surface water and treated greywater.

Solar-driven calcium looping in fluidized beds for thermochemical energy storage

Integration between Concentrated Solar Power (CSP) and Calcium Looping (CaL) is gaining consideration in the perspective of large shares of renewable energy sources, to smooth the variability of non-dispatchable energy input. The scope of this study is to investigate the CaL process for ThermoChemical Energy Storage (TCES), by performing a dedicated experimental campaign in fluidized bed under realistic process conditions suitable for CaL-CSP integration. Chemical deactivation of the limestone-based sorbent has been assessed by measuring the extent of Ca carbonation along iterated calcination/carbonation cycles, correlated with physico-chemical characterization of the sorbent at selected stages of the conversion. Properties that have been scrutinized were particle size distribution, bulk density, and particle size, density, and porosity of bed solids. The attainable values of energy storage density were evaluated as well.A remarkable finding of the experimental campaign is the pronounced synergistic deactivation of limestone when it is co-processed with silica sand. Chemical interaction of CaO with the silica sand constituents at the process temperatures has been scrutinized as possible responsible for the loss of reactive CaO toward CO2 uptake. Post-process of particle density data, together with N2-intrusion porosimetric analysis, and quantitative and qualitative XRD analyses, suggests that the sand/lime interaction induces a strong reduction of the total and reactive sorbent porosity and, in turn, of reactivity.Density-based classification to separate converted and unconverted limestone particles after the carbonation step has been evaluated with the goal of increasing process efficiency, by avoiding the circulation of streams with unreacted particles through the plant. For this purpose, the minimum fluidization velocity of calcined and carbonated particles has been measured after each reaction step at the relevant process temperature.

The Modelling of SiC Gate Oxide Thickness based on Thermal Oxidation Temperatures and Durations for High-Voltage Applications

This research has shown that the oxide thickness for silicon carbide (SiC) based wide materials can be predicted using regression techniques in wet/dry nitrided or wet/dry non-nitrided thermal oxidation process conditions for high voltage applications by employing 2 different regression techniques: Polynomial and linear regression. The R-squared (R2) and Mean Absolute Percentage Error (MAPE) techniques are used to evaluate the regression models. Furthermore, this work investigates and presents a calculation of gate oxide thickness that is correlated to gate voltage ranges for high voltage applications. In this work, the thermal oxidation process environment is classified into 3 different processing conditions: conventional (dry and wet), dry nitrided (NO,N2O), and wet nitrided (HNO3 vapour). The findings from this study showed that wet oxidation combined with nitrided elements can produce thicker and better-quality gate oxide as compared to conventional dry and wet oxidation techniques. The outcome of this work clearly shows that gate oxide thickness may be derived from silicon carbide-based wide-bandgap materials utilizing linear and polynomial approaches using thermal oxidation durations at different temperatures for high-power applications. The regression models and formulations produced in this work are expected to aid the researchers in determining appropriate oxide thickness under practicable process conditions, with the exception of real thermal oxidation process conditions. Hence, the outcome of this work is expected to save the processing time, material, and cost of the power semiconductor device fabrication technology, mainly for high voltage applications. HIGHLIGHTS Regression approaches are being used to determine the oxide thickness (Tox) for SiC-based broad materials in nitrided and non-nitrided thermal oxidation process conditions for high-voltage applications The regression models are assessed using the R-squared (R2) and Mean Absolute Percentage Error (MAPE) approaches The results of this work are anticipated to reduce processing time, material requirements, and manufacturing costs for power semiconductor devices used in high-voltage applications GRAPHICAL ABSTRACT

Absorbance measurement for in situ process regime identification in laser processing

Laser melting can be conducted in two different process regimes, the conduction and the keyhole mode, which exhibit significantly different characteristics, dynamics, and stability and are highly sensitive to a magnitude of process parameters. Despite these differences and the resulting high relevance of the prevailing process regime for process development, the regime is commonly deduced after specimen testing. An identification of the regime parallel to the process could speed up the process development of, for example, laser beam welding or laser-based powder bed fusion of metals. Therefore, the possibility of an in situ regime identification under process-near conditions is the aim of these investigations. For this, the absorbance is measured in situ by using an integrating sphere on an in-house-developed test rig. This test rig can mimic real production process conditions to detect the characteristic change in the degree of absorption when switching between the process regimes. These measurements were conducted during experiments in which only the laser power was varied. A significant change in absorption was detected at a threshold laser power of 100 W, which correlates with the transition between the process regimes’ conduction and keyhole regime. This threshold was proven by subsequent identification analysis of micrographic cross sections. This correlation promises the possibility of fast in situ process regime identification under near-real production process conditions with the potential of accelerating process development.

New‐Generation Anion‐Pillared Metal–Organic Frameworks with Customized Cages for Highly Efficient CO2 Capture

AbstractThe rational design of porous materials for CO2 capture under realistic process conditions is highly desirable. However, trade‐offs exist among a nanopore's capacity, selectivity, adsorption heat, and stability. In this study, a new generation of anion‐pillared metal‐organic frameworks (MOFs) are reported with customizable cages for benchmark CO2 capture from flue gas. The optimally designed TIFSIX‐Cu‐TPA exhibits a high CO2 capacity, excellent CO2/N2 selectivity, high thermal stability, and chemical stability in acid solution and acidic atmosphere, as well as modest adsorption heat for facile regeneration. Additionally, the practical separation performance of the synthesized MOFs is demonstrated by breakthrough experiments under various process conditions. A highly selective separation is achieved at 298–348 K with the impressive CO2 capacity of 2.1–1.4 mmol g−1. Importantly, the outstanding performance is sustained under high humidity and over ten repeat process cycles. The molecular mechanism of MOF's CO2 adsorption is further investigated in situ by CO2 dosed single crystal structure and theoretical calculations, highlighting two separate binding sites for CO2 in small and large cages featured with high CO2 selectivity and loading, respectively. The simultaneous adsorption of CO2 inside these two types of interconnected cages accounts for the high performance of these newly designed anionic pillar‐caged MOFs.

Swelling phenomenon in rubber weatherstrip manufacturing under real process conditions imposed in a commercial extrusion line

Swelling phenomenon in rubber weatherstrip manufacturing under real process conditions imposed in a commercial extrusion line

An investigation of the effect of powder flowability on the powder spreading in additive manufacturing

Identification of the most reliable method to characterise powder flow behaviour in correlation with the conditions of powder spreading in additive manufacturing (AM) is still challenging. In this study, a number of standard and advanced flowability techniques were used to characterise the flowability of two grades of Ti6Al4V powder (gas atomized, GA, and hydride-dehydride, HDH) used for the powder bed fusion (PBF) based AM. In parallel, the powder spreading behaviour was characterised using an in-house spreading rig. It is found that GA powder has better spreading behaviour than HDH, owing to its better flowability due to the regular particle shapes. However, none of the flow test techniques investigated in this paper can offer a correlation between the dynamic powder flow and powder spreadability at varying speeds. The study in this work has revealed the shortcomings in correlating the flowability of powder and their spreadability under real process conditions. • Flowability of two grades of Ti6Al4V powder was characterised using a range of techniques. • The powder spreading behaviour was characterised using an in-house spreading rig. • Caution is needed when correlating powder flow behaviour with the spreadability. • The powder flow behaviour obtained in current study cannot predict the dynamic behaviour of spreading.

Características termoreologicas e aptidão de extrudabilidade de um novo amido de mandioca sem amilose

ABSTRACT Cassava crops have always been fundamental in human nutrition and industry. Nowadays, the development of new cultivars with specific properties has become a major research area. In this research, amylose-free cassava starch (WXCS) extracted from clone AM206-5 was evaluated with respect to its physicochemical, morphological, and thermorheological properties. The waxy nature of cassava starch was verified (0.54 ± 0.09% w/w amylose), showing a 16.92±0.20 µm average granule size and elliptical or spherical truncated shapes without granule aggregation. There were significant differences in the pasting profiles evaluated, with WXCS being thermally less stable (Breakdown = 698±2 cP) generating less viscous final pastes (731±16 cP) compared to a commercial amylose-free corn starch. The WXCS shear viscosity was determined in a capillary rheometer (Rheoplast®), showing an inverse linear temperature dependence, decreasing by a factor larger than 3 when the temperature changed from 100 to 120 °C, with a pseudoplastic flow described by the power law (n: 0.25-0.40), consistency index (32607 - 6695 Pa.s) and specific mechanical energy (124 - 75 J/g). The extensional viscosity was always higher than the shear viscosity, where increasing the strain rate and temperature enlarged the Trouton number (25-145). Complete WXCS transformation under real process conditions was achieved with a 30% w/w moisture content and 100 °C, which induced full granular integrity loss and crystalline structure destruction. The results confirmed a potential utilization for this new starch to obtain extruded-type food products or to serve as a biothickening agent.

A comprehensive method for modeling and simulating ion exchange chromatography of complex mixtures

In recent years, many biological-based products have been developed, representing a significant fraction of income in the pharmaceutical market. Ion exchange chromatography is an important downstream step for the purification of target recombinant proteins present in clarified cell extracts, together with many other unknown impurities. This work develops a robust approach to model and simulate the purification of untagged heterologous proteins, so that the improved conditions to carry out an ion exchange chromatography are identified in a rational basis prior to the real purification run itself. Purification of the pneumococcal surface protein A (PspA4Pro) was used as a case study. This protein is produced by recombinant Escherichia coli and is a candidate for the manufacture of improved pneumococcal vaccines. The developed method combined experimental and computational procedures. Different anion exchange operating conditions were mapped in order to gather a broad range of representative experimental data. The equilibrium dispersive and the steric mass action equations were used to model and simulate the process. A training strategy to fit the model and separately describe the elution profiles of PspA4Pro and other proteins of the cell extract was applied. Based on the simulation results, a reduced ionic strength was applied for PspA4Pro elution, leading to increases of 14.9% and 11.5% for PspA4Pro recovery and purity, respectively, compared to the original elution profile. These results showed the potential of this method, which could be further applied to improve the performance of ion exchange chromatography in the purification of other target proteins under real process conditions.

Scale-Up Strategies of Jet Loop Reactors for the Intensification of Mass Transfer Limited Reactions

For the purpose of the intensification of an industrial-scale gas-liquid process, the implementation in an alternative reactor concept is investigated at Hamburg University of Technology (TUHH) in cooperation with Ehrfeld Mikrotechnik GmbH. Existing process operation data from a bubble column hint at a mass transfer limitation of the gas-liquid reaction. In the project, a jet loop reactor (JLR) is chosen to increase the specific interfacial area between gas and liquid, and thus increase mass transfer, while keeping the reactor system mechanically simple and low-maintenance. For the investigation, a laboratory scale reactor has been designed on the basis of an existing industrial scale process and scaled according to a pilot scale reactor available at TUHH. For scaling, geometric similarity is desired, while specific energy dissipation rate and volumetric gas input are kept constant for the chosen scale-up strategy. Between the two different scales, the reactors are successfully characterised in a water-air system with regards to the important mass transfer, among other parameters. A pressure- and chemical-resistant twin of the laboratory-scale reactor is provided to the project partner for trials under real process conditions with the original material system. The presented work shows that the JLR concept can be transferred sufficiently well between different scales when suitable parameters are chosen, and offers a wide operating window. The investigations aim to provide a basis for a future scale-up of the chemical process in the JLR system to the industrial scale.

A Materials Science-Based Approach to Finite Element Simulation of Warm-Forming of Al-Mg-Zn Alloys

Warm deep-drawing of pre-aged (under-aged) blanks of 7xxx series aluminum alloys (Al-Zn-Mg) at moderate temperatures of roughly 120–230°C is a promising route for producing parts with considerable geometrical complexity, good paint bake hardening response, and, thus, excellent final mechanical properties. Furthermore, oil-based lubricants can be used, eliminating the need for elaborate cleaning routines. However, finite element (FE) simulation of the process is challenging: time-temperature regimes during coupon testing for material cards should closely follow the real conditions in the press because the material undergoes significant changes at warm-forming temperatures, such as recovery and precipitation/coarsening/reversion of hardening phases. When convective heating is used for Nakajima or tensile testing, heating rates are usually too low to adequately represent real process conditions (where inductive or contact heating may be used). Here we present a method for establishing FE material cards and calibrating the GISSMO damage model using miniaturized tensile specimens for a dilatometer with inductive heating. The simulations are compared with warm deep-drawing experiments of pre-aged 7xxx and good agreement of minimum draw temperature for two alloys is achieved. The findings are discussed with regards to transmission electron microscopy investigations and final mechanical properties published earlier. It was found that warm-forming is suitable to produce complex 7xxx parts with high final strength. Conditions in the press can be represented by using miniaturized tensile specimens and inductive heating for calibration of material cards/damage models.

Reduction of Acid Iron Ore Pellets under Simulated Wall and Center Conditions in a Blast Furnace Shaft

The operational conditions, including temperature and gas composition, vary along the radial position in a blast furnace. Nevertheless, very few studies can be found in the literature that discuss how the reduction behavior of the ferrous burden varies along the radial position. In this study, the effect of the radial charging position on the reducibility of acid iron ore pellets was investigated using a laboratory-scale, high-temperature furnace in CO-CO2-N2 and CO-CO2-H2-H2O-N2 atmospheres up to 1100 °C. The experimental conditions were accumulated based on earlier measurements from a multi-point vertical probing campaign that was performed for a center-working European blast furnace. The main finding of this study is that the pellet reduction proceeded faster under simulated blast furnace conditions resembling those in the center area, compared to the wall area, because of a higher share of CO and H2 in the gas. Therefore, the pellet charging position affects its reduction path in a blast furnace. Additionally, it was shown that the presence of H2 and H2O in the reducing gas enhanced the progress of reduction reactions significantly and enhanced the formation of cracks slightly, both of which are desirable in blast furnace operation. The reducibility data attained in this study are important in understanding how temperature and gas composition is connected to the reduction degree under realistic process conditions.