During the production of steel in the LD converter the refractory lining is exposed to high temperature emulsion of steel, slag and gas. It protects the steel body of the vessel to come in contact with the molten steel.The main purpose of this work was to observe the temperature distribution profile in converter refractory lining which is very important to understand the life of the refractory lining of the LD converter.In this study, a three dimensional (3D) heat transfer model for the refractory lining of converter was developed. The lining of the refractory material was considered as magnesite brick for inner lining, dolomite for intermediate lining and steel shell as outer part. In order to do the numerical modeling, the CFD software Ansys Fluent 13.0 was used. After considering the proper dimensions, meshing, properties of the lining material and boundary conditions, the modeling in Ansys was performed in two stages. In the first stage, the modeling was performed by assuming that the converter is already heated and the inside temperature of the furnace is 1923K and the outside temperature of the steel body is 300K. In the second stage, the temperature change of the molten steel, slag and the gas was considered as function of blowing time and slag height based on theories from different references. Firstly, the three dimensional (3D) heat transfer model was used for the refractory lining of the converter to show transient heat flow through the lining at different times. Secondly, 3D modeling results from fluent 13.0 was used to develop temperature distribution profile through the lining at different height for different time steps and at different positions with time and also along the converter height from the bottom to top. It has been noticed that refractories in the lining in contact with steel and slag must be of good quality for the reduction of wear cost and downtime and therefore the reduction of refractory cost per ton of steel production.

Stainless steel, an alloy of iron and chromium, is renowned for its corrosion resistance, strength, ductility and durability. Phosphorus in stainless steel production is considered an impurity due to its detrimental impact on the material's properties, for example, increased brittleness and decreased corrosion resistance. Due to this reason, the amount of phosphorus in the stainless steel must be controlled. Currently, dephosphorization is not applied in stainless steel production using the EAF and AOD pathway, since chromium is oxidized simultaneously along with phosphorus. This thesis explores whether phosphorus refinement is theoretically possible for stainless steel production and evaluates its feasibility from both economic and environmental perspectives. The aim is to offer valuable insights and potentially enhance stainless steel manufacturing processes. The goal of this thesis is achieved through conducting a literature study, a theoretical study using the software Thermo-Calc, interviewing various steel industries and a study visit to Outokumpu in Avesta where an empirical experiment is carried out. The results of this thesis show that dephosphorization is theoretically possible for stainless steel production when varying the temperature, CaO content, gas quantity, and argon quantity. However, regardless of the dephosphorization degree, high amounts of chromium oxidize to the slag. The chromium losses increase production costs and environmental impacts. Therefore, it is not feasible from an economic and environmental standpoint. / Rostfritt stål, en legering av järn och krom, är känt för sin korrosionsbeständighet, styrka och duktilitet. Fosfor i rostfritt stål tillverkning betraktas som en förorening på grund av dess negativa inverkan på materialets egenskaper. Fosfor bidrar till exempel med ökad sprödhet och minskad korrosionsbeständighet. På grund av detta måste mängden fosfor kontrolleras under tillverkningen. I dagsläget utför man inte fosforraffinering vid tillverkning av rostfritt stål i ljusbågsugn och AOD konverter eftersom krom oxideras samtidigt med fosfor, som är ett dyrt och värdefullt material.Detta projekt syftar till att undersöka om fosforraffinering är teoretiskt möjligt för tillverkning av rostfritt stål, samt undersöka dess genomförbarhet ur både ett ekonomiskt och miljömässigt perspektiv. Målen med detta projekt uppnås genom att genomföra en litteraturstudie, termodynamiska beräkningar med programvaran Thermo-Calc, intervjuer med olika stålindustrier och ett studiebesök till Outokumpu i Avesta där även ett empirisk experiment utförs. Resultatet visar att fosforraffinering är teoretiskt möjligt vid tillverkning av rostfritt stål när varierande temperaturer, kalk mängder, gas mängder och argon mängder testas i Thermo-Calc. Höga halter krom oxideras till slaggen oavsett graden av fosforraffinering. Dessa kromförluster ökar produktionskostnaderna och medför en negativ miljöpåverkan. Sammanfattningsvis så är fosforraffinering inte genomförbart ur ett ekonomiskt och miljömässigt perspektiv.

Monitoring the non-metallic inclusions formed in steels is of the utmost importance. In fact, inclusions, depending on their type, can affect both the properties of the steel and its processing. Once the most problematic inclusions have been detected, solutions can be found and applied to counter the arising issues. One such solution is the addition of calcium during ladle treatment to modify the inclusions shapes and avoid the precipitation of problematic inclusions. The focus was put on the detection, analysis and calcium addition countermeasure of inclusions. No clear conclusion could be drawn as to the effects of calcium addition on the inclusions, due to the very high zirconium content of the inclusions. A high zirconium content has a significant impact on the thermodynamics governing inclusion formation and prevents reliable analysis of the results. After discussion with the company, it has been found that the zirconium is not present in the steel grade but instead originates from the samplers that were used. / Övervakning av icke-metalliska inneslutningar som bildas i stål är av yttersta vikt. Faktum är att inneslutningar, beroende på typ, kan påverka både stålets egenskaper och dess bearbetning. När de mest problematiska inneslutningarna har upptäckts kan lösningar hittas och tillämpas för att motverka de uppkomna problemen. En sådan lösning är att tillsätta kalcium under skänkbehandlingen för att ändra inneslutningarnas form och undvika utfällning av problematiska inneslutningar. Fokus låg på detektering, analys och kalciumtillsats som motåtgärd för inneslutningar. Ingen tydlig slutsats kunde dras om effekterna av kalciumtillsats på inneslutningarna, på grund av inneslutningarnas mycket höga zirkoniuminnehåll. En hög zirkoniumhalt har en betydande inverkan på den termodynamik som styr bildandet av inneslutningar och förhindrar en tillförlitlig analys av resultaten. Efter diskussion med företaget har det visat sig att zirkoniumet inte finns i stålsorten utan istället härrör från de provtagare som användes.

The current thesis focuses on the deformation behaviour and strain distribution in the microstructure of ductile iron during tensile loading. Utilizing Digital Image Correlation (DIC) and in-situ tensile test under optical microscope, a method was developed to measure high resolution strain in microstructural constitutes. In this method, a pit etching procedure was applied to generate a random speckle pattern for DIC measurement. The method was validated by benchmarking the measured properties with the material’s standard properties. Using DIC, strain maps in the microstructure of the ductile iron were measured, which showed a high level of heterogeneity even during elastic deformation. The early micro-cracks were initiated around graphite particles, where the highest amount of local strain was detected. Local strain at the onset of the micro-cracks were measured. It was observed that the micro-cracks were initiated above a threshold strain level, but with a large variation in the overall strain. A continuum Finite Element (FE) model containing a physical length scale was developed to predict strain on the microstructure of ductile iron. The materials parameters for this model were calculated by optimization, utilizing Ramberg-Osgood equation. For benchmarking, the predicted strain maps were compared to the strain maps measured by DIC, both qualitatively and quantitatively. The DIC and simulation strain maps conformed to a large extent resulting in the validation of the model in micro-scale level. Furthermore, the results obtained from the in-situ tensile test were compared to a FE-model which compromised cohesive elements to enable cracking. The stress-strain curve prediction of the FE simulation showed a good agreement with the stress-strain curve that was measured from the experiment. The cohesive model was able to accurately capture the main trends of microscale deformation such as localized elastic and plastic deformation and micro-crack initiation and propagation.

A steel slitting process is simulated using FEM (Finite Element Method) in order to see potential defects along the edge in a steel sheet after it has been cut. The model's results were compared to microscope images of the steel sheet in order to verify accuracy. The purpose is conceptual and to find a model that successfully simulates a steel cutting process and (hopefully) how the edge depends on different parameters. The model developed seems to achieve this task, and a more thorough calibration of the model could result in (more) optimal parameters for the machine to use.

Additive manufacturing has developed radical through the years. Sandvik has invested in the area by building a center specific for additive manufacturing. Due to problems with the material- and product properties and high production costs no products have been used with additive manufacturing method. These aspects have improved over the years and therefore the master thesis was made with an objective: to compare two different produced blades with focus on the aspects of material- and product properties and production costs. One of the blades was produced through additive manufacturing (AM) and the other blade was produced in today’s production at Sandvik Coromant in Gimo. If the blade can be produced through AM there is a possibility to lower the production costs and improve the degree of design freedom. The material that will be used is SS2230 (50CrV4) which are used in conventionally produced blades and 1.2709 which are used in AM produced blades.   The investigation consisted of five different tests (flow rate, pressure force, vibration, fatigue and keyhole wear) and a study on production aspects with focus on value stream mapping, investments and production costs. The main objective in the result was to compare each test between the two different produced blades, not to investigate the optimal value. Therefore, was the test designed to have continuity with as small deviation as possible between the tests. This resulted in choosing values which were not optimal for the blades but focused on continuity and deviation.   The coolant channels flow rate improved with 35% on the AM produced blades but pressure force, fatigue and keyhole wear resistance did not deviate much from conventionally produced blades. Fatigue tests were made twice with two different inserts because the result from the first test differentiated too much from the expected results on both blades. Production costs will be higher with AM but on a long-term may an investment improve the degree of design freedom on a product and a possibility to produce towards costumer (just in time). This will need an expensive investment with a bigger perspective on the timeframe. The value of the product may increase but the production costs will increase too.

Industrial gas turbines are often used as a mechanical drive for pumps and compressors or in power generation as an electric power supply. The gas turbine has for many years been a popular engine due to its flexibility with respect to different types of fuel and due to a design, that enables a high power-to-weight ratio. A simplified description of a gas turbine is that the engine consists of a cold and hot section. The turbo compressor section belongs to cold section and the combustion chamber together with the turbine section belongs to the hot section. In the hot section of a gas turbine, the condition is extremely severe because of an aggressive environment characterized by high temperatures, increased temperature gradients, high pressure and centrifugal forces resulting in large stresses on individual components together with an oxidizing and corroding atmosphere. Materials used in the high temperature section (hot gas path) of a modern gas turbine are different types of superalloys, as single crystal, directionally solidified or polycrystalline alloys, depending on temperature and load conditions. In the first turbine stage, temperature is very high due to exposure to the combustion gas. To handle the problem with creep, single crystal superalloys are often used in this section. In the second row of turbine blades, the temperature of the gas is lower and polycrystalline superalloys are typically used. IN-792 is a cast polycrystalline superalloy with high strength, good resistance to hot corrosion and a cheaper option than single crystals. In the hot section of gas turbine, IN-792 is a suitable material for components such as turbine blades and vans where a complex load condition, high temperature and severe environment prevails. Due to startup and shutdown of the gas turbine engine during service, the components in the hot section are exposed to cyclic load and temperature. This will generate mechanical and thermal fatigue damage in gas turbine components. Steady state temperature gradient arises by the cooling system acting at cold spots during service to introduce tensile stress, which indirectly gives rise to creep damage in the component. This work includes tree studies of deformation and damage mechanisms of superalloy IN-792. The first study is made on test bars exposed to thermomechanical fatigue in laboratory environment, the second and the third study is made on turbine blades used during service. In the second study, the machines are placed off-shore and exposed to marine environment. In the third study the machine is landbased and exposed to an industrial environment. In the second study, the deformation and damage mechanisms are compared between the turbine blades used during service and the test bars exposed to thermomechanical fatigue testing in the first study.

Examensarbetet har utförts under våren 2017 vid Bergsskolan i Filipstad, i samarbete med voestalpine Precision Strip i Munkfors. Att producera så kostnadseffektivt som möjligt likväl att minimera material som kasseras är något företag idag ser som självklart. På samma gång som detta efterlevs bör även kundnöjdheten maximeras. Utrymmet att göra fel har minskat vilket leder till en ständig strävan att undvika att produkter med oönskade defekter går ut till kund. För att nå detta måste företaget ha en förståelse för vilka mekanismer som påverkar vilka defekter. Syftet med det här arbetet är att dokumentera bandstålets processteg, från råmaterial till halvfabrikat. På så vis kan arbetets mål uppnås, det vill säga att hitta vilka möjliga orsaker som kan påverka bandstålets rakhet, specifikt den så kallade kortkrokigheten. Det finns två typer av rakhet, långkrok och kortkrok. Den som ställer till med problem vid beläggning och slipning av bandstål är den så kallade kortkroken. Därmed är det detta som voestalpine Precision Strip önskat hjälp med att kartlägga. Materialet som studerats var tre olika band av samma stålsort (UHB 20C), dessa var alla tänkta att gå vidare till beläggningen. För att bandet ska kunna beläggas måste materialet vara helt rakt, toleransen är +/- 33 µm, vilket många gånger innebär att bandet ser rakt ut trots en rakhetsavvikelse. Finns en avvikelse går det inte att färdigställa produkten utifrån kundspecifikation och materialet används då till annan slutprodukt, eller i värsta fall skrotas. För att kartlägga vilka mekanismer som bandstålet utsattes för användes den teoretiska ansatsen ”de sju förbättringsverktygen”, en teori utvecklad i Japan som är användbar då kvalitetsförbättringar efterfrågas. Arbetet börjades med litteraturstudier, det var svårt att hitta studier och annan litteratur som behandlar ämnet kortkrok i allmänhet och kortkrok i kallvalsat bandstål i synnerhet. Förutom litteratur erhölls en del information av personal på voestalpine Precision Strip i Munkfors. Det gjordes inga intervjuer utan enbart samtal med personal på plats i Munkfors. Dessa samtal ledde till ökad förståelse för vad problemet innebär och ett orsak-verkan-diagram gjordes. Fem möjliga orsaker till kortkrok vid kallvalsning av stål identifierades. Utifrån detta ritades ett flödesschema över hela processen upp. De fem möjliga orsakerna som studerades närmre var ·        tvärprofil ·        reduktionen i tre olika valsverk ·        kontaktlängd och valsmaterial i valsverken ·        rullsaxen som kantskär och slittar materialet ·        den mänskliga faktorn. Utifrån detta arbete kunde flera alternativa svar på problemet till varför kortkrok uppstår identifieras. Det kan vara stickserien i valsverk 311, bomberingen som var sliten/icke-sliten i valsverk 322, kontaktlängden i valsverk 345, materialet i arbetsvalsen i valsverk 311 eller rullsaxen. Ett antal orsaker som kan påverka att kortkrok uppkommer är överhuvudtaget inte är studerade. Till exempel värmebehandling, friktion och smörjmedel. I arbetet framkom en orsak som mest trolig till varför kortkroken uppstår, rullsaxen. Att rullsaxen påverkat kortkrokens uppkomst kan bero på den mänskliga faktorn likväl som att det kan bero på att den är felkonstruerad för just detta ändamål. I dagsläget saknas exakta rutiner för hur arbetsprocessen vid rullsaxen utförs, vilket inneburit att de som arbetar vid maskinen gör samma sak men på olika vis. Slutresultatet kan ha påverkats av vilken person som arbetat vid valsen. Det finns en möjlighet att voestalpine Precision Strip kan vinna på att ha detaljerade inställningsscheman så det är möjligt att utesluta att slutresultatet påverkas av vem som arbetar vid maskinen. / This thesis has been carried out during the spring of 2017 at Bergsskolan in Filipstad, in cooperation with voestalpine Precision Strip in Munkfors. The demands to produce as cost-effectively as possible is increasing as well as demands to minimize the amount of discarded materials and at the same time maximize customer satisfaction. To achieve this, the company must have an understanding for the mechanisms that influence the defects. The purpose of the thesis is to document the production steps of the strip steel process, from raw materials to processed steel. Doing that the goal can be achieved, i.e. to find the parameters that influence the strip steel's straightness, specifically the so-called camber. There are two types of straightness which causes problems and the important one in this thesis is the so-called camber. The material studied was three different strips of the same steel (UHB20C) which were all supposed to move on to the department CCB (Coated Coater Blades). But to proceed, the material must be perfectly straight. The tolerance is as small as +/-33 microns, which often means that the strip looks straight even when there is a straightness deviation. If so, the material may be used in a different application and occasionally it will be scrapped. To identify the mechanisms the strip steel was exposed to, the theoretical approach “the seven QC-tools", was used. This is a theory usable when quality improvements are demanded. The work begun with literature studies, however, it was very difficult to find studies and other literature that discussed camber in cold-rolled strip steel. In addition to literature some information was obtained through conversations with the staff in Munkfors. This led to better understanding about the problem. Afterwards it was time to draw a chart over the causes effecting the camber. Five parameters were identified as important and was chosen for closer looking. The parameters studied more closely were: ·        transverse profile ·        reductions done in the three different rolling mills ·        contact length and materials in the work roll ·        slitter scorer (the machine that slits the material) ·        human influence Then a flow chart of the entire process was drawn up. There are several alternative answers to the problem this paper is trying to solve. The answer could be among the parameters studied but it may as well be found among causes not studied. For example friction, lubricants or the heat treatment the material is exposed to. Due to all measurements done in this study there is one parameter most likely to be the cause of camber, the slitter scorer seems to influence the material straightness most of all. Though it is not cleared why the slitter scorer affects the camber more than the other production steps. It could be caused by human influence, it is a machine where very small mistakes, probably unconscious, can lead to big consequences. It may also be due to malfunction of the machine. Rolling is a craft which means that the person working at the rolling mill, and the other machines in the production process, has a big influence on final outcome. Voestalpine Precision Strip could probably gain a lot by having detailed setting schedules and measuring instruments that would help the staff doing the exact same thing every time. Hopefully the outcome would not fluctuate as much as it does in the current situation. / <p>Presentationen har redan ägt rum, i juni 2017 på Bergsskolan i Filipstad</p>

The vehicles industry is facing increasing demands for fuel efficiency and cost reduction due to environmental legislation, sustainability and customer demands. Therefore, there is a great need to develop and produce lightweight components by using materials and processes that offer higher specific strength and/or design optimization. Semi‐solid aluminium casting offers design freedom and castings with lower shrinkage and gas entrapment defects compared to high pressure die castings. The lack of understanding of microstructure and defect formation, and design data, for semi‐solid castings is a barrier for foundries and designers in the vehicles industry to use semi‐solid castings. In this study, the effect of two grain refiners on slurry formation and surface segregation of semi‐solid Al‐7Si‐0.3Mg castings produced by the Rheometal™ process was evaluated. The influence of grain refinement on primary α‐Al grain size, shape factor and solid fraction was analysed in addition to the solute content of the surface segregation layer. The influence of magnesium on the formation of intermetallic phases during solidification and the heat treatment response of Al‐7Si‐Mg semi‐solid castings was investigated. The magnesium content was varied from 0.3 to 0.6wt.% and the semi-solid castings were analysed in the T5 and T6 conditions. Energy dispersive spectroscopy was used to identify the intermetallic phases formed during solidification. Tensile testing was performed and the results were correlated to the magnesium and silicon concentration measured in the interior of the α‐Al globules formed during slurry preparation. The results suggest that the addition of grain refiner decreases the solid fraction obtained in the Rheometal™ process. However, no significant effect was observed on the α‐Al grain size and shape factor. A good correlation was obtained between the magnesium concentration in the interior of the α‐Al globules formed during slurry preparation and the offset yield strength for all alloys. The low magnesium solubility in α‐Al at temperatures in the solidification range of the Al‐7Si‐Mg alloys is suggested to be the reason for the low hardening response for the T5 heat treatment compared to the T6 condition.

Used lead-acid batteries are the main raw material in secondary lead production. Technologicalprogress in the car industry, have raised concerns regarding the lead-acid battery’s leading positionas electrochemical storage system in the future. However, the lead-acid battery industry isadvancing with innovations, such as hybrid and micro-hybrid vehicles, and is believed to have acontinued important role in the rechargeable battery market. Lead is one of the most investigatedmetal due to concerns from society regarding the negative effect on human health and theenvironment. Consequently, that has led to tighter controls and regulations of the lead processingindustry which, in turn, has led to technological improvement concerning design and operation ofthe lead processing plants. Used lead-acid batteries have a complex composition with a variety ofcomponents made of lead (i.e., metallic, oxide or sulphate) and non-lead materials (plastics andelectrolyte). Traditionally, battery recycling is done without separating those components.However, to optimise the use of resources and decrease the environmental impact of secondarylead production, a pre-treatment step to the batteries recycling is desired. The pre-treatment iscomprised of breaking the batteries and separation of the battery components. The aim of the present thesis, was to study the components of a used lead-acid battery, which willbe the outgoing material of a future plastic separation plant at Boliden Bergsöe, and their effect onthe process. Furthermore, the study aimed at investigating the possibilities to adjust the feedcomposition for further process optimisation and improvement of the process quality in terms ofenergy usages and environmental impact. This was done by characterise, through qualitative andquantitative composition and mass distribution, the fractions in a used lead-acid car battery. Four lead-acid car batteries were provided for dismantling to study mass distribution, and toliberate the components for further analysis. The analytical techniques used in this study werequalitative and quantitative (Rietveld) XRD analysis, SEM-EDS and TGA. The result showed thatoverestimated amount of battery separators (PE) has been used at production planning in energyandemission calculations, which can cause financial losses due to overpaid emission tax. The pastefraction showed a large variation in mass between the studied batteries and consists mostly ofPbSO4. Large variation in the paste mass may cause uneven sulphur emission from smelter.Consequently, this reinforces the need for implementation of the separation of the battery feed fora better control of the paste addition to the smelter. When PE decomposes in the shaft furnace the remaining ash will mainly consist of silica, whichwill affect the sulphur uptake in the shaft furnace. The large content of silica leads to a lower energycontribution to the process; however, a lower content of hydrocarbons leads to lower CO2emissions. If a desulphurisation of the pastes would be implemented, it is believed to affect theprocess through a decreased need of coke and iron. A reduced usage of coke and iron would lowerthe production costs and lead to decreased CO2 emissions. A desulphurisation will also decreasethe lead sulphate content in the feed, thus lead to better control of the sulphur emissions. This study provides additional support and further insight into composition and mass distributionof the components in a lead-acid battery. Furthermore, the study indicates possible impact of thefuture separation on the new feed properties and on the subsequent processing.