This report is about continuous temperature measurements of pig-iron at tapping from blast furnace 2 in Oxelösund, SSAB. Nowadays the temperature is only checked once at every tapping. The purpose of this project is to see if the process stability increases by continuously knowing the temperature and to compare the costs of this new technique with the technique used today. Possible savings due to less consumption of coke/coal if the silicon amount and the temperature are closer to their aim values will be regarded and if as little steam consumption as possible are used. The process stability can be divided into different sub goals. The ordinary measuring techniques were investigated as a part of the main goal; such as the ordinary measured temperature, the pig-iron and slag samples. The new continuous temperature measuring technique was compared with the ordinary temperature measurement and investigations of the life length were done. How representative the pig-iron and slag samples are, when taking them at the time they are today, are also looked into. The continuous measured temperature showed around 0,37 % higher temperature than the ordinary measured temperature. The pig-iron and slag samples should be taken as they are today, for mainly safety aspects. By using continuous temperature measurement, some of the sub goals can be achieved for a more stable process. The economy on the other hand has shown that large savings can be done by using this continuous temperature method due to a more stable process. This is mainly because of a decrease in steam usage in the experimental period. By regarding only the material of the methods the continuous temperature equipment is a bit more expensive, but the savings are much larger so the continuous temperature method is beneficial. With time this method could probably improve the process stability even more since the operators will deal with the information and the probe better.

The mechanical properties of components made by PM steels are normally inferior to those made by alternative processes. One of the main reasons is that a large amount of pores are present in sintered components. The other main reason is that the alloying elements, particularly Ni, are not uniformly distributed after conventional sintering procedures.  This work is aimed at a better understanding of the influence of alloying additions on mechanical properties and homogeneity of the microstructure. The experimental work has been carried out in two trials. Trial 1 was performed to investigate mechanical properties of Distaloy powders (commercial grades) and second trial to examine influence of alloying additions on homogeneity of microstructure.  For trial 1, as-sintered and heat treated specimens were produced by mixing commercial powders with two different carbon levels. Whereas, alloying elements were admixed to base iron powder for producing  sintered specimens for trial 2. Mechanical properties including dimensional changes, micro-hardness, tensile strength and impact resistance were measured. Distribution of alloying elements was studied using LOM and SEM-EDS analysis. The results obtained show that additions of alloying elements enhance the mechanical properties. Moreover, interaction of C with Cu and Ni as well as interaction between Cu and Ni have a deceive role in determining final properties of the components. The metallographic investigation indicated that major reasons of heterogeneous microstructure are slow diffusion of Ni in Fe matrix and interaction of other alloying elements with Ni.  The results of trial 2 showed that addition of Mo and Cu to Ni-containing PM steels improves the distribution of Ni in Fe matrix. Mo results in improved uniformity of microstructure by lowering the chemical potential of carbon. In Ni and Cu containing alloys, the interaction between Ni and Cu is responsible for enhanced distribution of Ni. However, the improved Ni distribution is achieved at the expense of non-uniform distribution of Cu. In Ni-containing PM steels, improved microstructure homogenization can be attained by increasing Ni-Cu interaction, lowering the surface energy of Ni-Cu liquid and decreasing the chemical potential of carbon.

This study aims on characterization of non-metallic inclusions (oxides and sulfides) in steel with and without Calcium treatment. In this paper, the three-dimensional (3-D) investigation method of inclusions on film filter after Electrolytic Extraction (EE) of steel samples is applied on two different steel grades (280, 316L). Image analysis of non-metallic inclusions is carried out on Scanning Electron Microscope (SEM) images following with inclusion characteristic analysis. Steel samples with calcium treatment in the production process and reference samples was investigated and compared in density, size and composition. It shows that higher magnification and larger inclusion size correspond to more accurate result. With restriction of equipment and measurement, 2μm is the smallest size could be measured in ×500 magnification within 5% error. The comparison of distribution of inclusions varies with different zones: center has the largest size with least number of NMI; surface has the smallest size with largest number of NM; middle part has the median properties. In 316L steel, Ca treatment increases the number of oxides inclusions significantly; the content of Ca and Si in oxides inclusions is also increased. Two shapes of oxides inclusions, oval and elongated ones, are found with Ca treatment. In 280 steel, the total amount of NMI decreases slightly with Ca treatment; CaS is found in spherical inclusions; Because of earlier formation of larger size spherical inclusions, higher Ca content is found than that in smaller size spherical inclusions.

The procurement of ores and metals necessitates consideration of the sustainability of both the productand of the producer. Current trends in procurement practices move toward assuring the lowestenvironmental, social and economic impacts feasible. In order to ensure a high level of sustainability inthe raw materials acquired, the practices and methods of the producers must be evaluated. To this enddifferent assessment models may be used. This report aims to, through an investigation ofcontemporary assessment models; develop an assessment model which facilitates the sustainableprocurement of ores and metals with a reduced need for compliance from the assessed parties. Theevaluation is carried out based on the triple bottom line (TBL) definition of sustainability and considersthe practices and needs of the ores and metals industry. A number of desirable traits were found in themodels evaluated. A design for a novel assessment model is proposed for scoring ore and metalproducers. The proposed model features recommendations for weighing methods and specifications forimpact indicators, measurement methods, and grading methods. / Malm- och metallindustri arbetar allt mer med hållbar utveckling. Detta kräver metoder för attsäkerställa att potentiella underleverantörer använder sig av procedurer och strategier som anses sundaur ett hållbarhetsperspektiv. För att undersöka detta finns etablerade bedömningsmodeller. Syftet meddenna rapport är att utvärdera dessa modeller för få en grund på vilken en ny modell, anpassad förmalm- och metallindustrin, kan utformas. Denna nya modell utformas för att minska krav av storaeftergifter från de aktörer som undersöks. Utvärderingen baseras på ”triple bottom line” -definitionenav hållbar utveckling och tar hänsyn till behoven som finns i industrin, och de metoder som redananvänds. Arbetet resulterade i att ett antal egenskaper som är önskvärda för en bedömningsmodellidentifierades. Med dessa egenskaper i beaktande utformades en ny bedömningsmodell medrekommendationer för viktning av betyg och specifikationer för mätpunkter, mätmetoder, ochbetygsmodeller.

The carburizing atmosphere during the case hardening process contains a large proportion of hydrogen. Due to the rapid diffusion of hydrogen a high amount of hydrogen can be absorbed by the carburizing component. The amount of absorbed hydrogen is dependent on some factors such as for example the carburizing time and component dimensions. Hydrogen diffused in material can then cause hydrogen embrittlement and in some cases cause cracking under a static load. This hydrogen must therefore be removed. High amounts of hydrogen diffuse out spontaneously at room temperature. Tempering accelerates the process. The aim of this study was to experimentally measure the amount of absorbed hydrogen after case hardening and hydrogen content after storage at room temperature and also after tempering. The effect of the enriching gas in carburizing furnace on hydrogen absorption was investigated in this study. Three steel grades with different content of alloying elements were used in this investigation. Steel samples were case hardened by gas carburizing and tempering. The hydrogen content analyses included the measurement of hydrogen content before case hardening, after case hardening and after tempering using Leco-RHEN602. Based on the results in this study it was concluded that all steel grades used in this investigation absorb hydrogen during case hardening by gas carburizing. A major part of the absorbed hydrogen is then released by effusion after being stored at room temperature and during tempering. Around 50% of the absorbed hydrogen content during gas carburizing is due to the presence of the enriching gas in the carburizing atmosphere. Around 50 % of hydrogen diffuses out of the steel specimens after one day. It is likely that all of free diffusible) hydrogen has diffused out of the specimens of two steel grades after one week at room temperature or after tempering. / Vid sätthärdning består den uppkolande atmosfären till stor del av vätgas och p.g.a. vätets snabba diffusion kan stora mängder av väte absorberas i komponenten. Halten av absorberade väte beror bl.a. på sätthärdningstid och komponentens dimensioner. Väte i materialet kan sedan leda till sprickbildning vid statisk belastning. Detta väte måste därför avlägsnas. En stor del av väte diffunderar ut spontant vid rumstemperatur. Vid anlöpning går processen fortare. Syftet med denna studie var att experimentellt mäta halten av väte som absorberas under sätthärdning, samt efter att metallen har lagrats i luft vid rumstemperatur. Dessutom mättes vätehalten efter anlöpning. Dessutom undersöktes effekten av ugnsatmosfärens tillsatsgas på mängden absorberad väte efter uppkolning. Tre olika höghållfasta och låg legerade stål sorter sätthärdades genom gas uppkolning. Mängden väte analyserades innan sätthärdning, efter sätthärdning, efter lagring i rumstemperatur och efter anlöpning med hjälp av Leco-RHEN602. Enligt resultaten i denna studie, absorberar alla av de tre undersökta stålsorterna väte under sätthärdning. En stor del av det absorberade vätet diffunderar ut efter att stålet har lagrats i luft vid rumstemperatur och under anlöpning. Omkring 50 % av den absorberade vätehalten under uppkolningen är på grund av reaktionen med tillsatsgasen i ugnsatmosfären. Omkring 50 % av vätet diffunderar ut ur proverna efter en dag. Möjligen all fritt (diffunderbart) väte har diffunderat ut ur proverna i två av stålsorterna efter en vecka i rumstemperatur eller efter anlöpning.

The purpose of this master thesis was to evaluate variations in solidification and cooling rate in compacted graphite iron prototype cylinder blocks and for each position relate this to the microstructure and also relate the microstructure to mechanical properties. This has been done to increase the knowledge to predict mechanical properties in cast iron components. There were three sample categories; reference-, tensile test- and thermocouple samples. The investigation included analysis of cooling curves, SinterCast parameters, image analysis, measured hardness and tensile strength. Thermocouples of type N were used at interesting positions for observation of the cooling behaviour and the image analysis was carried out by the software Axio Vision SE64 by Carl Zeiss GmbH. The hardness was measured according to Brinell HBW 5/750 and tensile testing was performed according to standard SS-EN ISO 6892-1:2009. It is concluded that the microstructure depend on many parameters, one of them is the position in the cylinder block. A relation between solidification time and the microstructure features; secondary dendrite arm spacing and eutectic cell size was observed. Because of dissimilarity in microstructure between the tensile test samples and thermocouple samples it is believed that the thermocouples have contributed with a cooling and/or nucleation effect. Considering the mechanical properties there is not solely the nodularity, eutectic cell size or secondary dendrite arm spacing that are the controlling microstructure feature, more research needs to be made.

No description available.

The purpose of this thesis has been to evaluate the use of a swirl blade in the uphill teeming process through plant trials. Two series of trials were carried out at Scana Steel Stavanger AS. In the trials a divergent entrance nozzle with a 62° outlet angle were used when casting duplex stainless steel on a base plate with two 6.2 tons ingots. All molds were burned onto the ingots; leading to problems with emptying the ingots from the molds and severe damages on the molds. To get a better insight during the casting and understand why the molds were burned onto the ingots; during the second series of trials one mold on each base plate were filmed in the beginning of the casting process. Evaluation of the castings indicated that splashing on the mold wall at an initial stage was one reason for the mold burned onto the ingot. Further, material samples were collected to evaluate the non-metallic inclusion composition and distribution with SEM when casting with a swirl blade compared to when casting without. The area percentage of the inclusions in the samples was 1% and 2% for samples casted with and without swirl blade respectively with d=2.8 mm. The inclusion size also varied for samples casted with and without swirl blade; 98% of the inclusions were in the size range of 0-10 μm when casted with and in the size range 0-20 μm when casted without swirl blade. / Syftet med denna uppsats har varit att utvärdera användningen av swirlblad i götgjutningsprocessen. Två serier med försök har utförts på Scana Steel Stavanger AS. I försöken användes en inloppssten med 62°-vinklat utlopp, där duplexa rostfria stål göts på stigplan med två 6,2 tons kokiller. Alla kokiller brände fast på göten, vilket ledde till svårigheter vid urtag av göten samt skador på kokillerna. För att få en bättre förståelse av varför kokillerna brände fast, filmades ett göt på vardera stigplan under den andra försöksserien. Utvärdering av försöken indikerar att en anledning till att kokillerna brände fast på göten var att det stänkte upp stål på kokillväggen i ett tidigt stadium. Vidare har materialprover samlats in för att utvärdera sammansättningen samt utspridningen av icke-metalliska inneslutningar i SEM då göt gjutits med swirlblad jämfört med utan. Area procenten i proverna var 1% och 2% då proverna gjutits med respektive utan swirlblad, med d=2.8 mm. Även storleken på inneslutningarna i prover som gjutits med och utan swirlblad skiljde sig åt, 98% av inneslutningarna var i storleksintervallet 0-10 μm för prover gjutna med swirlblad medan de som gjutits utan var i storleksintervallet 0-20 μm. / JK24053

The IronArc process is a novel process for a more sustainable production of liquid pig iron using electricity for heating and hydrocarbons for reduction. This thesis aims to facilitate its use by investigating possible refractory solutions and the gas blowing in the process which is done by a plasma generator. The process involves a slag with a high FeO content of 90 wt % and gangue content of approximately 5 wt % SiO2 and 5 wt % CaO. The interaction between such a slag and refractories of MgO, Al2O3, Cr2O3, SiC, ASZ,and C was investigated by high temperature experiments at 1700 K and by thermodynamic calculations in Thermo-calc and FactSage. In the high temperature experiments it was found that all of the studied refractory materials experienced signicant wear after 3 h, but the MgO-Al2O3 spinel refractories were the least affected. The thermodynamic calculations show fair agreement to the experiments, with the exception for the Cr2O3-spinel refractory which performed much worse than predicted by thermodynamic equilibrium calculations. It was concluded that the thermodynamic equilibrium calculations in Thermo-calc and Factsage can be used as an indicator for the stability of a refractory material, but with varying accuracy depending on the quality of the data in the database used. Since industrial refractory materials are not viable as refractory for the IronArc process a freeze-lining approach was evaluated by using CFD in ANSYS Fluent. The flow of a slag was simulated through two different designs of slag runner to investigate how well a freeze-lining protects the walls in a region with rapid flow and the cooling required to form and maintain said freeze-lining. It was found that the enthalpy porosity model in ANSYS Fluent in combination with the RSM turbulence model accurately predicts the thickness of a freeze lining when validated against experiments in the CaCl2-H2O system. For optimal protection of the refractory walls the reactor and runner should be designed to minimize the movement close to the walls as high near-wall turbulence will reduce the thickness and stability of the freeze-lining, leading to greater cooling requirements to maintain afreeze-lining. The IronArc process uses a plasma generator to supply heat to the reactor using electricity. By blowing gas and hydrocarbons through an electric arc, superheated gas is formed which when injected into the reactor provides both stirring and heating for the process. To study the behavior of the injected gas a simulation model was developed in OpenFOAM. The model for simulating gas blowing was tested in both incompressible and compressible simulations in the air-water system which were veried against an experimental study in the air-water system and found good agreement. The simulations of the plasma generator blowing were done in the compressible model to account for the high temperature and pressure present in the IronArc process. It was found that the stability of the gas blowing is dependent on the Froude number where low values cause an unstable and pulsating plume and higher values produce a more stable jet. It was also found that the empirical equation for penetration length is only valid for gas blowing with suciently high Froude numbers to produce a jetting behavior. It was found that the transition from pulsating to steady jetting in the IronArc system occurred around Froude numbers of 300 and higher values further increased the stability of the jet. For gas blowing below the transition region, the penetration length of the unstable and pulsating jet will be severely underpredicted by the empirical equation. This behavior must be considered when designing the gas blowing system for the IronArc process as the gas penetration length will signicantly influence the stirring in the reactor. Additionally, a pulsating and unstable jet produces large bubbles which risk coming in contact with the refractory walls which in previous studies has been shown to be very detrimental to the refractory lifetime. A decrease of the inlet diameter for the gas blowing increases the Froude number and the stability of the jet. By implementing the proposed refractory protection by freeze-lining and the small changes to the plasma generator inlet diameter the IronArc process can be developed into a promising industrial process capable of producing liquid pig iron in a more sustainable way. / Sammanfattning IronArc processen är en nytänkande metod för att producera flytande råjärn på ett mer hållbart sätt genom att använda elektricitet för uppvärmning och kolväten för reduktion. Denna avhandling ämnar att utvärdera möjliga metoder för att skydda infordingen i processen och undersöka gasblåsningen i processesen som görs med en plasma generator.   Ett av huvudstegen av IronArc processen är tillverkningen av en slagg med upp till 90 vikts % järnoxid samt 5 vikts % kiseldioxid och 5 vikts % kalciumoxid från gångarten. Interaktionen mellan en sådan slagg och olika infodringar baserade på MgO, Al2O3, Cr2O3, SiC, ASZ, och C undersöktes i högtemperaturexperiment vid 1700 K samt med termodynamiska beräknar i Thermo-calc och FactSage. Experimenten visade att alla de undersökta infodringsmaterialen bröts ned under de 3 timmar de var i kontakt med slaggen, men de två MgO-Al2O3 spinel baserade infodringarna visade högst motståndskraft mot slitaget. De termodynamiska beräkningarna överrensstämde bra med de experimentella resultaten för alla infodringsmaterial förutom den kromoxid baserade infodringen som bröts ned fullständigt trots att de termodynamiska beräkningarna påvisade viss stabilitet. Slutsatsen är att inget av de studerade infodringsmaterialen är bra anpassat för IronArc processen men att metoden som användes för de termodynamiska beräkningarna i Thermo-calc och FactSage kan användas för att ge en indikation om stabiliteten för olika infodringsmaterial i kontakt med slagg. Dock så kommer resultaten av de termodynamiska beräkningarna vara beroende av kvalitén av databasen som används för beräkningen.   Eftersom infodringsmaterialen inte kunde motstå slitaget från slaggen undersöktes en dynamisk infodring för slaggrännan i IronArc processen. Detta gjordes genom att simulera flödet och stelningen av slagg i flödesberäkningar i ANSYS Fluent i två olika typer av slaggrännor. Studien visade att enthalpy-porosity modellen för stelning samt RSM modellen för turbulens kunde förutspå stelningsförloppet i slaggrännan samt beskriva hur väl den dynamiska infodringen skyddar väggen och vilken kyleffekt som krävs för att bibehålla den. Denna modell validerades mot experimentella studier i CaCl2-H2O systemet med god överrensstämmelse. För optimalt skydd av väggarna i IronArc processen borde reaktorn och slaggrännan utformas så att flödet nära väggarna minimeras då ett turbulent flöde nära väggen är negativt för stabiliteten och tjockleken hos den dynamiska infodringen.   IronArc proceesen använder sig av en plasmagenerator för att förse processen med värme via elektricitet. Genom att blåsa gas och kolväten genom en ljusbåge värms gasblandningen och trycks in i reaktorn  vilket ger både värme och omrörning till processen. För att undersöka hur den varma gasen beter sig i reaktorn utvecklades en simuleringsmodell i OpenFOAM. Modellen utformades som både inkompressibel och kompressibel för blåsning av luft i vatten och jämfördes med experiment där gas blåstes i vatten. De båda modellerna överrensstämde bra med de experimentella resultaten och kunde därför användas för att studera gasflödet i IronArc processen. För simuleringen av IronArc processen valdes den kompressibla versionen av simuleringen då den tar hänsyn till de höga temperaturer och tryck som uppstår i reaktorn.   Simuleringarna visade att den inblåsta gasen kan ge en stabil gas-jet om Froude-talet för inblåset är tillräckligt högt. Om Froude-talet för gasblåsningen är för lågt så kommer gasen pulsera på ett instablit sätt och skapa stora bubblor som kommer i kontakt med infodringsmaterialet, vilket tidigare har påvisats orsaka ökat slitage på infodringsmaterialet. För IronArc processen krävdes ett Froude tal på ca 300 eller högre för att skapa en stabil jet av gas, där högre värden vidare ökar gas-jettens stabilitet. Studien visade också att den empiriska ekvationen som används för att beräkna penetrationslängden vid gasblåsning endast är korrekt om gasen är en stabil jet. Om ekvationen används för att beräkna penetrationslängden för gasblåsning med mindre än det krävda Froude talet kommer penetrationslängden kraftigt underskattas vilket kan medföra att fel beslut tas när en process utformas. Genom att minska diametern på dysan som används för gasblåsningen ökas Froude-talet och därmed stabiliteten av gasjetten, vilket gör den mer förutsägbar och bättre för processen.   För att vidare utveckla IronArc processen så bör den undersökta dynamiska infodringen samt de föreslagna modifieringarna till gasblåsningen användas. Då kan en lovande industriell process utformas som har möjlighet att producera flytande råjärn på ett mer hållbart sätt.    Keywords: IronArc, infodringsslitage, plasmagenerator, dynamisk infodring

This study has focused on determining the heat flows in a production blast furnace hearth. This part of the blast furnace is exposed to high temperatures. In order to increase the campaign length of the lining an improved knowledge of heat flows are necessary. Thus, it has been studied both experimentally and numerically by heat transfer modeling. Measurements of outer surface temperatures in the lower part of a production blast furnace were carried out. In the experimental study, relations were established between lining temperatures and outer surface temperatures. These relations were used as boundary conditions in a mathematical model, in which the temperature profiles in the hearth lining are calculated. The predictions show that the corner between the wall and the bottom is the most sensitive part of the hearth. Furthermore, the predictions show that no studied part of the lining had an inner temperature higher than the critical temperature 1150°C, where the iron melt can be in contact with the lining. / QC 20101124