bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy Absorption Behaviour of Austenitic and Duplex Stainless Steels in a Crash Box Geometry
Authors: Ratte Evelin , Leonhardt Sven , Bleck Wolfgang , Franzen Markus , Urban Peter
Published: December 2016

The improvement of the passive safety plays an important role in the development of new steels for automotive parts. At the same time aspects of weight reduction as well as the industrial feasibility have to be considered. Powered by these objectives, the development and application of new steel concepts for various purposes is promoted. For the present investigation especially weight reduction combined with an improvement of the passive safety are emphasised. As example one representative part of the body structure, the crash box, is considered. At the moment different steel grades (dual phase‐, TRIP‐and HSLA‐steels) as well as fibre reinforced materials are applied. New materials for this special purpose have to exhibit outstanding formability, a high capacity to absorb energy during a possible crash and should be cost effective compared to already existing material concepts. During this project different grades of austenitic stainless steels with varying stability were compared to duplex stainless steels and a TRIP grade with regard to their possible application as crash‐box material. The austenitic grades show excellent gradual formability according to their strength level. All of them exhibit an extraordinary strain hardening behaviour. The duplex grades show a lower formability but on a much higher yield level.

Besides the determination of classical material data such as uni‐ and multi‐axial flow curves, dynamic tensile tests and forming tests for the determination of forming limit curves were performed. The material data were used in the simulation of a drop tower test which is commonly used to evaluate the performance of different materials in car components. The results were then evaluated with regard to the absorbed energy, the folding behaviour and the resulting forces.
Ti/Al Interaction and Austenite Grain Control in Crankshaft Manufacturing with 38MnSiVS5 Steel
Authors: Medina Sebastián F. , Chapa Modesto
Published: December 2016

38MnSiVS5 steel is similar to 38MnVS6 steel (EN), the difference being the addition of a small Ti content. Typical Ti and Al contents in the chemical composition of 38MnSiVS5 steel are Ti=0.020 and Al=0.035 mass%. Both elements combine easily with nitrogen, especially Ti, and it has been observed that relatively high Al levels are harmful for austenite grain size control at reheating temperatures. In this work 38MnSiVS5 steel is used to manufacture a large number of castings, varying only the Ti and Al contents and obtaining ingots with a different Ti/Al ratio in each case. The results show that abnormal growth of the austenitic grain occurs irrespective of the Ti and Al contents, due fundamentally to the partial dissolution and coarsening of TiN precipitates. However, the steels with high Al contents present worse behaviour due to the formation of a second type of precipitates, namely AIN, which quickly dissolve between 1000 and 1100°C, causing a drastic decline in local pinning forces that gives rise to more pronounced abnormal growth of the affected grains.
Deformation Induced Martensite Formation and its Effect on Transformation Induced Plasticity (TRIP)
Authors: Weiß Andreas , Gutte Heiner , Scheller Piotr R.
Published: December 2016

The knowledge of the stress‐ and deformation‐induced martensite formation in metastable austenitic steels including the formation temperatures and amounts formed is of considerable importance for the understanding of the transformation induced plasticity. For this purpose a stress‐temperature‐transformation (STT) and a deformation‐temperature‐transformation (DTT) diagram have been developed for the steel X5CrNi 18 10 (1.4301, AISI 304). It is shown that the Md‐temperature for γ→∊, ∊→α', γ→∊→α’ and γ→α’ martensite formation is defined by two stress‐temperature curves which show a different temperature dependence. They specify the beginning and the end of the deformation‐induced martensite formation in the range of uniform elongation. The intersection point defines the corresponding Md‐temperature. The stress difference which results from the stresses for the end and the beginning of the martensite formation shows positive values below the Md‐temperature. It defines the amount of martensite being formed. When the Mdγ→∊ temperature is reached and the formation of the first deformation‐induced amount of ∊‐martensite appears, an anomalous temperature dependence of the maximum uniform elongation starts. The highest values of the maximum uniform elongation are registered for the tested steel in the immediate vicinity of the Mdγ→α' or the Mdγ→∊→α' temperature ‐ similar as in other metastable austenitic CrNi steels. At this temperature the highest amount of deformation‐induced ∊‐phase exists. The transformation plasticity in the test steel is considerably caused by the deformation‐induced ∊ and α’ martensite formation. Using the new evaluation method, the increase of plasticity ΔA (TRIP‐effect) and strength ΔR can be quantified.
On the Algorithmic Implementation of a Material Model Accounting for the Effects of Martensitic Transformation
Authors: Antretter Thomas , Fischer Franz Dieter , Cailletaud Georges , Ortner Balder
Published: December 2016

The formulation and numerical implementation of a material model with as little phenomenological input as possible requires a thorough investigation of the physical relationships relevant for the material under consideration. In the present case the focus is on the correct description of the TRIP (Transformation Induced Plasticity) effect and its interpretation in terms of a transformation surface concept similar to the well‐known yield surface approach used in classical plasticity. Some general aspects of the thermodynamics of martensitic transformation along with a general idea of the topology of a transformation surface in stress space are presented and cast into equations suitable for the implementation into a finite element program. A normality rule for the transformation strain rate can be derived in analogy to the well established procedures of flow plasticity. The notion of a transformation hardening is introduced, collectively characterizing the mechanisms inhibiting transformation. They can be quantified based on the data from dilatometer tests. In contrast to earlier models of this group of authors [1], the algorithm at hand allows to keep track of the evolution of each single variant thus providing detailed insights into the variant selection mechanisms for various load levels and loading directions.
Mechanism Study on the Formation of Liquid Calcium Aluminate Inclusion from MgO‐Al2O3 Spinel
Authors: Kang YoungJo , Li Fan , Morita Kazuki , Sichen Du
Published: December 2016

A study on the formation mechanism of liquid calcium aluminate inclusions from MgO‐Al2O3 spinel was carried out. It was found that spinel reacted with dissolved Ca in liquid steel forming liquid calcium aluminate phase. Stability calculations showed good agreement with the experimental result. According to the thermodynamic calculation, liquid calcium aluminate inclusions would form from spinel even at very low level of dissolved Ca content at 1873 K. At lower temperatures, the compound CaO‐2Al2O3 was found to be the stable phase at the spinelmetal interface. Potential sources of dissolved Ca during ladle processes were also discussed.
Low Temperature Formation of Iron Carbide from Iron Oxide with CO‐H2 Gas Mixtures
Authors: Conejo Alberto N. , Estrada Raul S.
Published: December 2016

Commercially pure iron oxide in the form of fine particles were reacted with CO‐H2 gas mixtures at ambient pressure (≍ 0.8 atm) in the temperature range 573 to 1073K. Reduction to metallic iron was carried out with pure hydrogen. The rate of formation of iron carbide was measured by recording the weight change with a thermogravimetric apparatus. The results obtained indicate that for each gas phase composition a maximum rate was observed, at apparently the same temperature. These maxima in the rate occur at a lower temperature than those reported in previous investigations. A dissociative adsorption model, based on the reduction of CO with hydrogen was developed which qualitatively describes the observed results.
Size Change due to Anisotropic Dilation Behaviour of a Low Alloy SAE 5120 Steel
Authors: Hunkel Martin , Frerichs Friedhelm , Prinz Christian , Surm Holger , Hoffmann Franz , Zoch Hans‐Werner
Published: December 2016

A conventional hot rolled, low alloy carburizing steel (C: 0.21 wt.‐%; Cr: 1.08 wt.%; Mn: 1.36 wt.%) has been investigated in terms of inhomogeneous phase transformations and anisotropic size changes during heating to austenitizing temperature and during slow cooling from austenitizing temperature to room temperature. A detailed study was executed on dilatometer specimens. The results were compared with the size changes of shafts with similar heat treatment. Ferrite nucleated first at selected chain‐like positions and a pronounced ferrite/pearlite rodlike structure was formed. After reaustenitizing the rodlike structure appeared exactly at the same position. At intermediate transformation stages broad regions were still untransformed while other regions had an advanced transformation state. Dilatometer specimens with different orientations to the former rolling direction of the bar had different changes in length, which indicates an anisotropic size change. Cylindrical shafts showed a similar macroscopic size change like the small dilatometer specimens. For the dilatometer specimens as well as for the shafts the absolute valuese of the size change depended on the initial microstructure.
Estimation of the Transient Surface Temperature, Heat Flux and Effective Heat Transfer Coefficient of a Slab in an Industrial Reheating Furnace by using an Inverse Method
Authors: Wikström Patrik , Blasiak Wlodzimierz , Berntsson Fredrik
Published: December 2016

In the steel industry it is of great importance to be able to control the surface temperature and heating or cooling rates during heat treatment processes. In this paper, a steel slab is heated up to 1300°C in an industrial reheating furnace and the temperature data are recorded during the reheating process. The transient local surface temperature, heat flux and effective heat transfer coefficient of the steel slab ares calculated using a model for inverse heat conduction. The calculated surface temperatures are compared with the temperatures achieved by using a model of the heating process with the help of the software STEELTEMP® 2D. The results obtained show very good agreement and suggest that the inverse method can be applied to similar high temperature applications with very good accuracy.
Preliminary Investigation of Mathematical Modeling of Stainless Steelmaking in an AOD Converter: Mathematical Model of the Process
Authors: Zhu Hong‐Li , Wei Ji‐He , Shi Guo‐Min , Shu Jie‐Hui , Jiang Qing‐Yuan , Chi He‐Bing
Published: December 2016

Mathematical modeling of stainless steelmaking in an AOD (argon‐oxygen decarburisation) converter with side and top combined blowing has been preliminarily investigated. The actual situations of the side and top combined blowing AOD process were analysed. A mathematical model for the whole refining process of stainless steel has been proposed and developed. The model is based on the assumption that one part of the oxygen blown through a top lance reacts with CO escaping from the bath, another part of the oxygen oxidizes the elements in the molten steel droplets splashed by the oxygen jet, and the remaining oxygen penetrates and dissolves into the molten steel through the pit stroked by the jet. All the oxygen entering into the bath oxidizes C, Cr, Si, and Mn dissolved in the steel and also the Fe of the steel melt, but the FeO generated is also an oxidant of C, Cr, Si, and Mn in the steel. During the process, all possible oxidation‐reduction reactions occur simultaneously and reach their equilibria, respectively their combined equilibrium, in competition at the liquid/bubble and liquid/slag interfaces. In the simple side blowing after the top blowing operation is finished, the possible reactions take place simultaneously and reach a combined equilibrium in competition at the liquid/bubble interfaces. The overall decarburization rate in the refining process is the sum of the contributions of both the top and side blowing processes. It is also assumed that at high carbon concentrations, the oxidation rates of elements are mainly dependent upon the supplied oxygen rate, and at low carbon contents, the rate of decarburisation is primarily related to the mass transfer of carbon from the molten steel bulk to the interface. It is further assumed that the non‐reacting oxygen blown into the bath does not accumulate in the steel and will escape from the bath and react with CO in the atmosphere above the bath. The study presents calculations of the refining rate and the mass and heat balances of the system for the whole process. Additionally, the influences of the operating factors, including addition of slag materials, scrap, and alloy agents, the non‐isothermal conditions, the changes in the amounts of metal and slag during the whole refining process, and others have all been considered.
Reduction Behaviour of Wüstite Doped with MgO
Authors: Bahgat Mohamed , Halim Khaled S. Abdel , Nasr Mahmoud I. , El‐Geassy Abdel Hady A.
Published: December 2016

Compacts made from pure wüstite and compacts doped with 2% MgO were annealed at 1000°C for 3 hrs in 50%CO‐CO2 gas mixtures. The annealed samples were isothermally reduced at 800‐1100°C in H2 gas. Selected samples were isothermally reduced at 1000°C with pure CO and 50%H2‐CO gas mixture to investigate the effect of gas composition on the reduction processes. The oxygen weight loss resulting from the reduction of the samples was recorded as a function of time. X‐ray diffraction (XRD), scanning electron microscopy (SEM), optical microscopy and porosity measurements were used to characterize the annealed and reduced samples. Magnesio‐wüstite (MgO·FeO) phase was formed during the annealing of MgO doped wüstite. The MgO·FeO in turn decreased the porosity of the annealed doped samples compared to pure wüstite compacts. The influence of temperature, gas composition and MgO content on the reduction behaviour and the morphology of the annealed samples was investigated. The values of the apparent activation energy were calculated from Arrhenius plots and correlated with the reduction mechanism. The reduction rate increased with reaction temperature. In doped compacts, the MgO·FeO phase was not completely reduced both at lower reduction temperature (800°C) and during reduction with pure CO. From the activation energy values, the initial reaction stage was controlled by the combined effect of chemical reaction and gas diffusion while solid state diffusion controlled the final stage of reduction. Morphologically, metallic iron was formed in different shape structures under the effect of MgO addition and reduction conditions.
Effect of Size Parameters of Mix Ingredients on the Porosity and Reduction Characteristics of Sinter
Authors: Bhagat Ram P. , Chattoraj Uday S. , Goswami Manik C. , Singh Deo P. , Sil Samir K.
Published: December 2016

The paper aims to describe the effect of size parameters of the mix ingredients on the tumbler index, porosity and reduction properties of sinter. These parameters are important factors for the furnace performance when the sinter is fed as burden material Understandably, the fines generated inside the furnace in the stack zone or during reduction affect the permeability of the stack zone, which results in a decrease in driving rate and CO utilisation. Pot sintering studies were carried out using hematite ore mix from typical mines in India. The sinter basicity (CaO/SiO2) and MgO content in the sinter were kept at 2.1 and 1.5% respectively. The effect of the size parameters of the mix ingredients, namely size of coke, size of ore fines and that of limestone, on the porosity and quality parameters of sinter was investigated. The studies have shown that reducibility of sinter was well correlated with the proportion of micro‐pores out of total pores available in the sinter. Micro‐porosity of the sinter samples and their reducibility increased with decrease in the size range of coke breeze. Sintering of ore fines with reduced size, also, increased the sinter micro‐porosity. Besides, the average pore radius and density of the sinter sample and consequently the sinter reducibility increased with decreasing ore size. When the size of flux was narrowed down to –3+0.5 mm from –3 mm, the reduction degradation index value declined from 26.8% to 25.6% with marginal decrease in sinter reducibility. Moreover, the speed of sintering increased as well.
Modelling of Stress State, Centre Consolidation and Roll Force in Billet Rolling
Authors: Lundberg Sven‐Erik , Överstam Henrik
Published: December 2016

Roll pressure models have been derived from theoretical studies, FEM simulations and experimental investigations. A model developed from slip line field theory has been shown to fit well to the experimental results. The Finite Element simulations overestimated the pressure function. This is a common problem in hot rolling experiments, since the problem of measuring the correct rolling temperature makes the estimation of the yield strength very difficult. The difference between the FE calculations and the experimental measurements is a measure for the error in the experimental temperature measurements rather than for the accuracy of the Finite Element Method.

Traditional modelling has not been an appropriate tool to evaluate the material flow in the centre of the billet. In spite of the fact that the entire stress state can be modelled by slip line field theory, the slip lines which determine the stress state in the centre coincide for actual geometries only in one single point. Thus the strain increments are known only in that single point. Since a material element passes that point instantaneously, it is not possible to find any finite strains in the centre by integrating any incremental function. By FEM, strain modelling is simple and the possibility to consolidate a porous bloom or ingot core can be determined.

FE modelling requires an entirely new approach to the modelling problem. It is not reasonable to use FEM to evaluate only the temperature distribution for the use in roll force models from the previous century. Instead, a fully thermomechanically coupled FE model is suggested. However, the calculation time is still far too long to be used for on‐line control purposes. For this application hybrid modelling can be a solution, where off‐line FE models are combined with empirical modelling, and simplified models can be used for the process control.
Mild Oxidative Wear Behaviour of Plain Carbon Dual‐Phase Steel
Authors: Abouei V. , Saghafian H. , Kheirandish Sh. , Ranjbar Kh.
Published: December 2016

In order to explore the tribological potential of the dual phase (DP) steel as wear resistant material, the wear and friction characteristics of this steel, which consists of hard martensite island embedded in a ductile ferrite matrix, were investigated and compared with those observed in plain carbon normalized (N) steel with the same composition of 0.2 wt pct carbon. Dry sliding wear tests were carried out using a pin‐on‐disk wear testing machine at normal loads of 21.3, 28.5, 35.7 and 42.6 N and at a constant sliding velocity of 1.20 m/s. The analysis of surface and wear debris of the tested specimens showed that wear mechanism was mainly mild oxidative. The friction and wear rate of the DP steel and N steel were explained with respect to microstructure and the wear mechanism.
Laboratory Investigations on Copper‐alloyed Interstitial Free Steel – Part III: Ageing Behaviour
Authors: Rana Radhakanta , Bleck Wolfgang , Singh Shiv Brat , Mohanty Omkar Nath
Published: December 2016

An attempt has been made in this investigation to develop high strength interstitial free steel with about 463 MPa yield strength and 577 MPa tensile strength by adopting a new approach. The concept lies in the addition of 1.18 wt.% copper to conventional interstitial free steels and employing a post annealing ageing treatment to achieve copper precipitation hardening. Ageing response has been studied under various processing conditions. Advantages, drawbacks and possible scheme of application of this new steel have been addressed.
Equlibrium between Liquid Fe‐Ti‐O Slags and Metallic Iron
Authors: Eriksen Jan Martin , Robles Eloy Crespo , Rosenqvist Terkel
Published: December 2016

The compositions of Fe‐Ti‐O melts in equilibrium with molten iron have been determined by melting mixtures of TiO2, metallic iron and various additions of either Fe2O3 or metallic titanium in a high‐frequency induction furnace. The furnace had a vertically segmented water‐cooled copper crucible which enabled the mixture to be melted with vigorous stirring inside a freeze‐lining of about 1 mm thickness. The slag compositions were found to form a curved line in the ternary diagram FeTiO3 – TiO2 – Ti2O3 with its highest TiO2 content slightly higher than the pseudobrookite (M3O5) composition FeTi2O5 ‐ Ti3O5. The slags were examined by X‐ray diffraction and microprobe analyses. For all slags the main phase was pseudobrookite (M3O5) solid solution with some rutile or Magnéli phase (TinO2n‐1). The most iron‐rich and the most titanium‐rich slags contained also some FeTiO3, respectively Ti2O3 phase. A melting point diagram is suggested with a eutectic groove running between the M3O5 phase and the TiO2 or Magnéli phase from about 1665°C for the iron‐free to the less than 1500°C for the titanium‐free slags.
High Strength Stainless Austenitic CrMnN steels ‐ Part III: Electronic Properties
Authors: Shanina B.D. , Gavriljuk V.G. , Berns H.
Published: December 2016

Some results of ab initio calculations and experimental studies of the C, N and C+N effect on the electron structure of austenitic CrMn steels are presented. It is shown that the total electron energy per atom decreases due to alloying in the sequence of carbon→nitrogen→carbon+nitrogen, which suggests a corresponding increase in the thermodynamic stability of the austenite. Alloying with nitrogen and nitrogen+carbon increases the density of electron states at the Fermi level in comparison with interstitial‐free and carbon‐alloyed steel. Measurements of conduction electron spin resonance (CESR) allow separating the contributions from free electrons which are responsible for the metallic character of interatomic bonds and from localized electrons involved in the covalent bonds. It is shown that, in contrast to carbon, nitrogen enhances the metallic character of atomic interactions with a maximum of the concentration of free electrons at some critical content of nitrogen (about 2 at.%). The combined alloying with carbon+nitrogen leads to two effects: (i) a larger concentration of free electrons and (ii) a shift of the critical content of interstitials towards higher values. The obtained results of the theoretical and experimental studies of the electron structure were used as a physical background for the development of super‐high–strength stainless austenitic steels.
A Study of Surface Deformation during Wire‐Rod Rolling of High Speed Steels using Experimental and Computational Techniques
Authors: Nordén Kristina , Jonsson Stefan
Published: December 2016

The evolution of surface defects during shape rolling of high‐speed steel billets is studied using longitudinal surface defects prepared by machining and welding. The reduction of the defects during rolling in a production mill is compared to the total area reduction of the billets. Samples are collected after pass 4, 6, 8, 14, 19 and the final pass, 28, representing the finished 5.5mm wire. By inspecting the cross sections, the rotation of the billets from pass to pass is evaluated. Results from FE simulations on solid billets are compared to the experimental results. Generally, simulations predict less reduction than observed experimentally. In most cases cracks reduce most effectively followed by carbon steel welds and stainless steel welds.
Neural Networks Analysis of Steel Plate Processing Augmented by Multi‐objective Genetic Algorithms
Authors: Pettersson F. , Chakraborti N. , Singh S.B.
Published: December 2016

An earlier neural network analysis of processing of steel plates through hot rolling was subjected to a further refined analysis through some flexible neural networks that evolved using a multi‐objective predator‐prey genetic algorithm. The original data set expressing the Yield Strength and Ultimate Tensile Strength of the rolled slabs in terms of a total of 108 process variables were subjected to a systematic pruning through this evolutionary approach, till the nitrogen content of the steel emerged as the most significant input variable. A theoretical explanation is provided for this slightly unexpected result.
Duplex Stainless Steels ‐ a Review after DSS ‘07 held in Grado
Authors: Charles Jacques
Published: December 2016

Duplex stainless have always been an exiting area of interest for researchers, stainless steel producers, fabricators and end users. They present very diversified technical challenges and simultaneously attractive in‐service properties at excellent cost/properties ratios, particularly in critical markets including oil and gas, chemical industry, pulp and paper industry, water systems, desalination plants, pollution control equipments, chemical tankers, etc. This explains why although they still remain a marginal production in the stainless steel business (less than 1%) dedicated international conferences have been organised since about 25 years. The purpose of this paper is to present a review of the 100 scientific contributions presented during the latest international duplex stainless steel conference witch took place in Grado, Italy, on 18‐20 June 2007. The main topics concerned microstructure and mechanical properties, weldability, corrosion resistance and in‐service properties. The “standard” duplex stainless steels, i.e. the 2304, 2205, and the family of 2507 (Cu,W, ...) grades were confirmed as very valuable grades with outstanding performances proven in more than 20 years successful in‐service applications. New grades including the so‐called lean duplex dedicated to volume oriented markets (possible replacement of 304/316 grades) and some “niche” grades dedicated to very specific markets were presented. It was pointed out that the duplex grades start to be well established products particularly suitable for corrosion resistance applications. They show a two‐digit yearly growth thanks to the production of new grades and production ranges (coils and bars) targeting the replacement of the more costly 300 series including 304 but also rusty carbon steel in e.g. structural application.
Weldability Aspects of a Newly Developed Duplex Stainless Steel LDX 2101
Authors: Westin Elin M. , Brolund Bengt , Hertzman Staffan
Published: December 2016

Duplex grades have, due to balanced chemical compositions of both filler and base metals, a weldability that allows for successful welding using a majority of the technically relevant techniques of today. In order to fulfil the performance requirements several aspects must be considered. In the heat affected zone (HAZ) the austenite reformation must be reasonably high and in the weld metal the microstructure must be stable so that e.g. high productivity welding and multi‐pass welding are possible, without precipitation of detrimental phases in previous passes. This paper addresses the effect of alloying elements and thermal cycles on phase balance in the high temperature HAZ (HTHAZ) of the newly developed lean duplex grade LDX 2101 (EN 1.4162, UNS S32101). Bead‐on‐plate welds and simulated weld structures have been produced and investigated using metallography, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results are analysed using the thermodynamic database Thermo‐Calc and a model for phase transformation based on a paraequilibrium assumption for ferrite‐austenite transformation. In the temperature region outside the paraequilibrium domain, growth controlled by diffusion of substitutional elements was considered. The analysis follows a model by Cahn regarding grain boundary nucleated growth and the Hillert‐Engberg model on kinetics of spherical and planar growth.
Characterization of the Microstructure, Crystallographic Texture and Segregation of an As‐cast Duplex Stainless Steel Slab
Authors: Herrera Clara , Ponge Dirk , Raabe Dierk
Published: December 2016

The microstructure of a duplex stainless steel slab 1.4362 produced by continuous casting has been investigated by optical microscopy, scanning electron microscopy, EBSD and EDS. The slab showed different macrostructures through the thickness. The macrostructure can be divided into 3 types: fine equiaxed, columnar and coarse equiaxed grains. In all three regions, the volume fraction of each phase austenite and delta‐ferrite is close to 50% and the hardness is very similar for both. The austenite has Kurdjumov‐Sachs or Nishiyama‐Wassermann relationship with the delta‐ferrite. The slab does not show a strong segregation profile through the thickness. The delta‐ferrite is enriched in Cr and Mo, while austenite is enriched in Ni and Mn.
High Temperature Materials Based on the Intermetallic Compound NiAl Reinforced by Refractory Metals for Advanced Energy Conversion Technologies
Authors: Frommeyer Georg , Rablbauer Ralf
Published: December 2016

Advanced NiAl‐based high temperature materials are developed and characterized for structural applications in energy conversion systems. The intermetallic compound NiAl with B2 superlattice structure exhibits superior physical and high temperature mechanical properties, and excellent oxidation resistance. Disadvantages of polycrystalline pure NiAl are the lack in plasticity and fracture toughness at room temperature and insufficient high temperature strength at temperatures above 800 °C. The refractory metals Cr, Mo, and Re form with NiAl quasi‐binary eutectic systems which enable to produce metal fibres reinforced NiAl‐based alloys in the as‐cast condition and by performing directional solidification. These in‐situ composites show fine‐grained and thermally stable microstructures possessing high temperature strength, superior creep resistance and sufficient room temperature ductility.
Analysis of Material and Energy Consumption of Corex C3000
Authors: Wang Nan , Xie Xuemei , Zou Zongshu , Guo Li , Xu Wanren , Zhou Yusheng
Published: December 2016

The first Corex C3000 unit has been built at Baoshan Iron and Steel Corporation, China, and some improvements compared with C2000 have been made. On the basis of material and heat balances, an analysis of material and energy consumption in the Corex C3000 smelting reduction process was conducted and the calculated consumption of lump ore and pellets, coal rate, oxygen consumption are compared with the target values of C3000. Regarding the heat balance calculation, the main factors affecting the energy consumption of C3000 are analysed, and the effective utilization of the sensible heat of top gas and molten slag, as well as the calorific heat of the export gas can be considered to realize lower energy consumption. In addition, the effects of metallization in the reduction shaft and oxidation degree of the gas produced in the melter‐gasifier on the Corex performance are discussed.
Physical Modelling of Inclusion Behaviour in Secondary Refining with Argon Blowing
Authors: Zheng Shu‐gou , Zhu Miao‐yong
Published: December 2016

The effects of gas blowing time and flow rate on inclusion removal in a ladle were quantitatively investigated. A physical model was developed where emulsion drops simulate the collision and aggregation of inclusions in steel. The results show that most of the inclusions can be removed within eight minutes at lower gas flow rates, whereas sixteen minutes are needed with larger gas flow rates. All the inclusions which had the possibility to be removed almost disappeared from the system in twenty‐eight minutes. Both the high and the low gas flow rates seemed to be efficient for inclusion removal, which was explained based on discussing the mechanism of inclusion removal by bubbles. In addition, it was found that the inclusion removal was in exponential relationship with gas blowing time.
Microstructure, Mechanical Properties, and Abrasive Wear Behaviour of Si‐Mn‐Cr‐B Cast Steel as a Function of Carbon Concentration
Authors: Fu Hanguang , Kuang Jiacai , Wang Lintao
Published: December 2016

The microstructures, mechanical properties and abrasive wear behaviour of five kinds of Si‐Mn‐Cr‐B cast steels were studied. The steels investigated contained X wt.% C with X= 0.15, 0.25, 0.35, 0.45, 0.55, 2.5 wt.% Si, 2.5 wt.% Mn, 0.5 wt.% Cr, 0.004 wt.%B . The results showed that the Ac1temperatures increased and Ac3 and Ms temperatures decreased with increasing carbon concentration. From the continuous cooling transformation (CCT) curves, it was discovered that the incubation period of pearlitic transformation was prolonged and the transformation curves of pearlite and bainite were separated significantly with rising carbon concentration. At lower carbon concentration, the normalized structure of Si‐Mn‐Cr‐B cast steel consisted mainly of granular bainite and M‐A islands. The normalized microstructures of the cast steel changed from granular bainite gradually to needle‐like bainite, upper bainite, and lower bainite with rising carbon concentration. The tensile strength and hardness of Si‐Mn‐Cr‐B cast steel increased and impact and fracture toughness decreased with increasing carbon content. The wear testing results showed that the wear resistance of Si‐Mn‐Cr‐B cast steel improved with higher carbon content but was obviously unchanged beyond the carbon concentration of 0.45%. The best balance of properties of Si‐Mn‐Cr‐B cast steel is obtained at the carbon concentration range of 0.35 ‐ 0.45%C.
Influence of Microalloying Elements (Nb, V, Ti) on Yield Strength in Bainitic Steels
Authors: Rancel L. , Gómez M. , Medina S.F.
Published: December 2016

In order to study the influence of microalloying elements in bainitic high strength steels, seven steels with different contents of V, Ti, Nb and N were investigated. The steel 35 CrMo 4 (C=0.38; Mn=0.82; Si= 0.25; Cr=0.83; Mo=0.17, all in wt.%) was used as reference steel. CCT diagrams were determined by dilatometric tests at different cooling rates, and the maximum and minimum cooling rates for bainite formation were determined. With regard to tensile tests, the presence of precipitates in the bainitic microstructure contributed to raising their yield strength, as was found by comparing the results for all the steels with the reference steel which did not contain microalloying elements. The yield strength can be predicted by an Orowan expression.
A Physical Based Method to Predict Spread and Shape during Flat Rolling for Real‐Time Application
Authors: Dixon Andrew E. , Daniel Yuen W. Y.
Published: December 2016

A physical based method is developed that gives real‐time solutions for the transverse variations, across the strip width, for the strip stresses and strains during rolling. From this the strip spread and downstream shape defect are predicted for a given variation in the thickness reduction across the width. The method implicitly couples the downstream residual stresses of the strip under tension, due to non‐uniform strip elongations or shape, to the stress field within the roll gap. The case of a parabolic variation in thickness reduction across the strip width is investigated with the sensitivity of shape defect with the non‐uniform reduction predicted, for various strip thicknesses and widths. These results are shown to be consistent with previously published experimental results. The model is therefore useful in predicting the limits of thickness profile change during rolling before shape defects are formed. Furthermore, being an analytical method the prediction of spread and shape defects can be made in real‐time with a minimum of computational cost. The spread model is then coupled to a roll stack deflection model so that the non‐uniform thickness reduction is also calculated for a set of rolling conditions. The full model solution is calculated within several seconds on a PC, making it possible for real‐time application.
Correlation between the KIc, the HRc and the Charpy V‐Notch Test Results for H11/H13 Hot‐work Tool Steels at Room Temperature
Authors: Leskovšek Vojteh
Published: December 2016

This investigation was conducted to determine whether there are correlations between CVN, HRc and KIc test results at room temperature for AISI H11/H13 hot‐work tool steels that could be developed to a tool for materials engineers and the structural designers. The results showed that such correlations do exist for electro‐slag‐remelted (ESR) and conventional AISI H11 hot‐work tool steel. Static KIc values were correlated with the results of standard CVN impact tests and the obtained hardness values at room temperature. Furthermore, the results show that the correlation can also be used to calculate KIc values from standard CVN impact tests and the respective Rockwell‐C hardness for AISI H13 tool steel. In general, the results of this investigation show that the correlation between the values for KIc, CVN and HRc can be used to estimate the KIc values from the CVN test results and the Rockwell‐C hardness.
Mental Health and Military‐Connected Students on Campus: Culture, Challenges, and Success
Authors: Bonar Ted C.
Published: December 2016

This chapter provides an overview of common challenges faced by military‐connected students on university campuses. The characteristics, culture, and experiences of service members and veterans are described through vignettes based on military‐connected students.
International Student Mental Health
Authors: Prieto‐Welch Susan L.
Published: December 2016

This chapter describes the mental health status of international students in institutions of higher education, unique challenges these students face and their impact on mental health, and suggestions for ways to address these challenges.
Anticipating the Future of Mental Health Needs on Campus
Authors: Bonfiglio Robert A.
Published: December 2016

The provision of college mental health services is undergoing a dynamic evolution. The ability of mental health practitioners and administrators to balance multiple and sometimes opposing trends may determine the future course of mental health services in higher education.
Lightning occurrence data observed with lightning location systems of electric power companies in Japan: 2009–2013
Authors: Shindo Takatoshi , Motoyama Hideki , Miki Toru , Saito Mikihisa , Matsueda Akiyori , Honma Noriyasu , Hida Tomohito , Shinjo Kazuo , Hayashi Kiyotaka , Awazu Hayato , Makabe Katsuhisa , Fujikawa Masato , Kurihara Satoshi , Sato Masashi
Published: December 2016

Nine electric power companies in Japan have been collecting lightning data with lightning location systems. Five years of the lightning data (2009–2013) are summarized and analyzed in this paper. The recent annual number of lightning flashes of which the current is more than 10 kA in Japan is around 1 million. The variations of lightning occurrence characteristics by areas, seasons, and so on, are clarified. Meteorological conditions that may affect lightning occurrence are also discussed. Furthermore, we show that there is a clear correlation between the number of lightning strikes and the outage rate of transmission lines. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
A measurement method for atmospheric ion mobilities based on cylindrical electrodes in direct current corona discharge
Authors: Zou Zhilong , Cui Xiang , Lu Tiebing , Bian Xingming
Published: December 2016

Ion mobility is one of fundamental parameters to describe the motion of ions in an electric field and a significant quantity to calculate the ionized field and ion current density of ultrahigh‐voltage direct current (UHVDC) power lines. This paper presents a measurement method for atmospheric ion mobilities in a DC corona discharge. An apparatus with coaxial cylindrical electrodes is designed and utilized. A vibrating electric field meter is employed to measure the ionized field of the electrode. Experimental results show that under atmospheric conditions, the average positive and negative ion mobilities are 1.76 × 10−4 and 1.88 × 10−4m2·V−1·s−1, respectively. The proposed method is compared with previous works of others. The impact of fluctuations of the measured ionized field and ion current density on the results of ion mobilities is also analyzed. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
A novel approach for detecting broken rotor bar around rated rotating speed using frequency component and clustering
Authors: Nakamura Hisahide , Pandarakone Shrinathan Esakimuthu , Mizuno Yukio
Published: December 2016

Induction motor plays an important part in many industrial processes. Detection of motor faults in the early stages improves process productivity, minimizes motor damage, and reduces repair costs. In this paper, a new method is proposed to detect broken rotor bars in a cage induction motor around the rated rotating speed. In this method, first, a frequency analysis is performed according to rotor bar's conditions and the characteristic frequency components are extracted. Further, a two‐step diagnosis method based on self‐organizing map, which is one of the classification methods, is proposed. Finally, the effectiveness of the proposed diagnosis method is verified by performing some experiments. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Physical constitution adjustment for a human body model used in motion capture data analysis
Authors: Miura Takeshi , Kaiga Takaaki , Shibata Takeshi , Tajima Katsubumi , Tamamoto Hideo
Published: December 2016

This paper proposes a method to adjust the physical constitution of a human body model used in motion capture data analysis. A physical constitution is adjusted so as to accurately classify motion capture data based on the difference in motion characteristics. The adjustment process is modeled as an optimization problem and solved numerically. Analysis results suggest the effectiveness of the proposed method and the point to which attention should be paid. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Pre and post-entry resource needs for international entrepreneurs: The role of government and industry networks
Authors: Chang Frances Y M , Jack Robert , Webster Cynthia M
Published: December 2016

This paper identifies the resource needs of international entrepreneurs and examines the role of government and industry networks as providers of resource opportunities deemed essential by international entrepreneurs for international growth. Unique resource challenges confront international entrepreneurs in their pursuit of international markets. Our qualitative study of Australian entrepreneurs in the health industry reveals that international entrepreneurs emphasise information, knowledge and relational resources as crucial for international market entry. Although government networks provide essential resources at the planning and pre-entry stage of internationalisation, at the postentry stage industry networks offer more relevant resource opportunities. Both networks, however, fall short of expectations in affording knowledge and relational resources that are instrumental in entering international markets.
Faith in the God who Resurrects: The Theocentric Faith of Hebrews
Authors: Easter Matthew C.
Published: December 2016

This article investigates the object of faith in the Epistle to the Hebrews, and argues that the object of faith is God and not Jesus. God is the object of faith in Hebrews because God is the one who holds the power of resurrection, the eschatological hope of both the faithful one par excellence (Jesus) and those who follow him. The author of Hebrews expects his persecuted community to place their faith in God in hope of being raised with Jesus, the resurrected faithful one who also placed his faith in God.
Contingent technocracy: bureaucratic independence in developing countries
Authors: Teodoro Manuel P. , Pitcher M. Anne
Published: December 2016

This study investigates the effects of formal bureaucratic independence under varying democratic conditions. Conventional accounts predict that greater formal independence of technocratic agencies facilitates policy implementation, but those claims rest on observations of industrialised, high-income countries that are also established democracies. On the basis of research in developing countries, we argue that the effects of agency independence depend on the political context in which the agency operates. Our empirical subjects are privatisation agencies and their efforts to privatise state-owned enterprises in Africa. We predict that greater independence leads to more thorough privatisation under authoritarian regimes, but that the effect of independence declines as a country becomes more democratic. Using an original data set, we examine the relationship between formal agency independence and privatisation in Africa from 1990 to 2007. Our results modify the conventional wisdom on bureaucratic independence and culminate in a more nuanced theory of “contingent technocracy”.
Educating Missions. Teachers and Catechists in Southern Tanganyika, 1890s and 1940s
Authors: Hölzl Richard
Published: December 2016

This article concentrates on Catholic mission teachers in Southern Tanzania from the 1890s to the 1940s, their role and agency in founding and developing the early education system of Tanzania. African mission teachers are an underrated group of actors in colonial settings. Being placed between colonized and colonizers, between conversion and civilising mission, between colonial rule and African demands for emancipation, between church and government and at the heart of local society, their agency was crucial to forming African Christianity, to social change and to a newly emerging class of educated Africans. This liminal position also rendered them almost invisible for historiography, since the colonial archive rarely gave credit to their vital role and European missionary propaganda tended to present them as examples of successful mission work, rather than as self-reliant missionary activists. The article circumscribes the framework of colonial education policies and missionary strategies, it recovers the teachers’ active role in the colonial education system as well as in missionary evangelization. Finally, it contrasts teachers’ self-representation with the official image conveyed in missionary media.
Negotiated and Mediated Lives: Bolivian teachers, New Zealand missionaries and the Bolivian Indian Mission, 1908–1932
Authors: Morrison Hugh
Published: December 2016

This article places missionary education squarely at the centre of any consideration of European expansion in the modern era. It focuses more specifically on the place of local teachers in Bolivia and their relationship with one evangelical Protestant mission, the Bolivian Indian Mission, which originated in New Zealand in the early 1900s. It takes a non-metropole and a “multi-sited” approach to missions and education. It argues that what we know about Bolivian teachers was mediated through the missionary voice and that these teachers negotiated their lives within a particular missionary space, in which there operated a number of intersecting influences from other sites within the wider imperial or Western network. It aims to both reclaim the identities of Bolivian teachers (focusing on teachers’ identity and function) and to reflect critically on intrinsic methodological and conceptual issues (emphasizing the nature of sources, missionary discourse, the resulting status of Bolivian teachers, and Bolivian agency).