A literary study has been made to find parameters affecting dephosphorization of stainless steel. Ways to lower phosphorus content without major loss of chromium in order to decrease the production costs of Sandvik AB’s stainless steel. The study was conducted with respect to oxidizing dephosphorization and parameters affecting dephosphorization are carbon and chromium content, temperature and slag properties. It was revealed that higher carbon content and basicity is beneficial to the dephosphorization process. However, the choice of temperature, chromium content and flux were dependant on which way dephosphorization was approached. A method of refining chromium in slag using an electric arc furnace (EAF) was also discovered. This made it possible to extract 97% of all chromium in slag. The conclusions are that in order for Sandvik to successfully remove phosphorus, scrap metal with higher carbon content should be used, together with a basic CaO slag with constituents of e g Li2O3 and CaF2. A deslagging step can be added to the argon oxygen decarburizer (AOD) process in order to remove the phosphorus bound to the slag, before decarburization.

Corrosion is a global problem which leads to both economicalct on the environment as well as other negative social and ethical aspects. Sodra Cell Monsteras, one of the largest producer of pulp in the world, suffers from corrosion problems in their evaporation plant. Problems with corrosion can be handled with an effective material selection process, where suitable materials for specific conditions is discovered. The purpose with this report is to investigate the evaporation plant at Sodra Cell and its specific conditions, including environment and temperature. Also to investigate different types of corrosions common in pulp mills and how these can be prevented, as well as how materials behave under corrosive circumstances. The information is later to be used in a detailed material selection process, which is handled in this report but also should work as a foundation for Sodra Cell Monsteras for future material selections. The material selection process in this report is performed according to Ashby's method, with CES Edupack as a supporting tool. The duplex steels, especially EN 1.4485 and EN 1.4362, showed to be the best suitable materials. However, to do a fair judgment and to choose one material, one should do a complete cost efficiency analysis, as well as decide a specific required pitting resistance equivalent number (PREN). / Korrosion ar ett globalt problem som leder till både ekonomiska förluster, negativ miljöpåverkan samt andra negativa sociala och etiska aspekter. Södra Cell Mönsterås, en av världens största producenter av pappersmassa, har problem med korrosion i sin indunstningsanläggning. Korrosionsproblem kan lösas genom att ha en effektiv materialvalsprocess där rätt material för specifika förhållanden och ändamål används. Syftet med den här rapporten är att undersöka vilka specifika förhållanden som råder i Södra Cells indunstningsanläggning, däribland miljö och temperatur. Men även att undersöka vilka olika korrosionstyper som vanligen förekommer i massaindustrin, hur dessa kan förhindras samt hur olika material beter sig under korrosiva förhållanden. Informationen ska kunna användas som underlag i en utförlig materialvalsprocess, som även hanteras i denna rapport men kan även fungera som en grund för Södra Cell Mönsterås framtida materialval. Materialvalsprocessen i denna rapport är utförd enligt Ashbys metod, med CES Edupack som ett hjälpmedel. Det visar sig att Duplexa stål, speciellt EN 1.4485 samt EN 1.4362 är material som lämpar sig bäst för användning i den korrosiva miljön i indunstningsanläggningen. För att kunna göra en rättvis bedömning och välja ut ett av dessa material, bör en fullständig kostnadsanalys utföras, samt att det bör klargöras vilket specifikt värde för "pitting resistance equivalence number" (PREN) som krävs.

Powder metallurgy is a growing field with much potential. The core purpose and problem in this work is attempting to describe and understand what and how metal powder properties impact powder flowability. Several powder flow experiments have been performed on eight different metal powders with varying size and of material types to examine correlations and seeing what parameters are important for a well flowing metal powder. Experiments performed consists of hall flow, tap density, angle of repose and a more complex Rheometer analysis. The results found display plenty correlations between different experiments with some deviations as expected due to the nature of occurring errors. The results are all displayed in tables comparing the different metal powders for all experiments. The powder with the best flowability (highly free flowing) scored best across all experiments and tests indicating all tests as significant. A well and free flowing powder is characterized by low values in cohesion, angle of repose, specific energy, etc. / Pulvermetallurgi är en växande industri med stor potential. Syftet samt problemet med detta arbete är att försöka beskriva och förstå vilka pulveregenskaper som är betydande för flödet och hur dessa egenskaper påverkar hur pulvret flödar. Flera olika experiment har utförts på åtta olika metallpulver, av varierande sorter material och pulverstorlek, har utförts för att undersöka samband och se vilka pulveregenskaper som är viktiga för ett metallpulver ska ha eftertraktade flödesegenskaper. Utförda experiment består av Hall flöde, tappdensitet, rasvinkel (angle of repose) samt en mer komplex Rheometer analys. Resultaten visar många samband mellan olika experiment och metallpulver med en del avvikelser som väntat på grund av flertalet felkällor. Resultaten för alla pulver och experiment uppvisas i stapelgrafer för enkel överblick och jämförelse. Metallpulvret som påvisade bäst flödesegenskaper (fritt flödande pulver) rankades som bästa pulver i varje experiment vilket indikerar att alla experiment är relevanta. Ett väl flödande metallpulver indikeras av låga värden på kohesion, rasvinkel, specifik energi osv.

Materials research in the aerospace industry is, among other things, focused on reducing the weight and increasing the life of components. Materials with high strength and long lifespan are therefore examined. A205 is an aluminium alloy with promising properties and the work in this thesis aims to gain an increased understanding of fatigue properties for the material in question. This has been done by studying how fatigue cracks are initiated and grow relative to the current microstructure. Four specimens of A205 have been tomographed before and after the initiation of a fatigue crack. The tomography imaging is performed with high resolution so that the microstructure can be studied. Using the tomography images, the crack has been characterised in three dimensions regarding initiation and propagation and its relation to the microstructure. Furthermore, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) have been used to study the fracture surfaces of the specimens and to determine the chemical composition of different precipitates and phases to further deepen the understanding of fatigue properties for the alloy. Correlation technique based on tomography images, so-called digital volume correlation (DVC), enables examination of small displacements and strains in the structure of the specimens, which provides an understanding of the plastic zone size at the tip of the fatigue crack. The thesis discusses how the experimental methods can be combined and provide an increased understanding of the initiation and propagation of the fatigue crack in A205. Results is related to previous research and in combination with experimental study this can develop the general understanding of the aluminium alloy A205. Fractography analysis shows that the crack is initiated by TiAl3 in two out of four specimens. To summarize, the results of the study indicate that defects highly influence the initiation of the cracks compared to propagation that are less sensitive. Crack propagation are controlled by stress intensity, low stress intensity promotes transgranular propagation and high stress intensity promotes intergranular propagation. / Materialforskning inom flygindustrin är bland annat inriktad på att minska vikten och öka livslängden på komponenter. Till följd av detta undersöks material med hög hållfasthet och lång livslängd. A205 är en aluminiumlegering med lovande egenskaper och arbetet i detta examensarbete syftar till att få en ökad förståelse för det aktuella materialets utmattningsegenskaper. Detta har gjorts genom att studera hur utmattningssprickor initieras och tillväxer relativt den aktuella mikrostrukturen.    Fyra prover av A205 har tomograferats innan och efter initiering av en utmattningsspricka. Tomografiavbildningen görs med hög upplösning så att mikrostrukturen kan studeras. Med hjälp av tomografibilderna har sprickan karakteriserats i tre dimensioner avseende initiering och propagering och dess relation till mikrostrukturen. Vidare har svepelektronmikroskopi (SEM) och energidispersiv röntgenspektroskopi (EDS) använts för att studera provernas brottytor samt för bestämning av den kemiska sammansättningen hos olika utskiljningar och faser för att ytterligare fördjupa förståelsen för legeringens egenskaper. Korrelationsteknik baserad på tomografiavbildningar, s.k. digital volume correlation (DVC), möjliggör undersökning av små förskjutningar och töjningar i provstavarnas struktur, vilket ger förståelse för den plastiska zonstorleken vid utmattningssprickans spets. Examensarbetet diskuterar hur de experimentella metoderna kan kombineras och ge en ökad förståelse för utmattningssprickans initiering och propagering i A205.    Resultaten har tagits fram och relaterats till tidigare forskning och den experimentella studien kan utveckla den allmänna förståelsen för aluminiumlegeringen A205. Fraktografi analys visar att titanaluminid (TiAl3) initierar sprickan i två utav fyra undersökta prover. Sammanfattningsvis indikerar resultaten från studien att propageringen utav sprickan inte är påverkad utav defekter på sättet initiering är, utan är kontrollerad av spänningsintensitet. Låg spänningsintensitet främjar transgranulär propagering och hög spänningsintensitet främjar intergranulär propagering.

The usage of cobalt (Co) as binder phase material in cemented carbides has been questioned becauseof the potential health hazards associated with cobalt particle inhalation. Cobalt is used because ofits excellent adhesive and wetting properties, combined with adequate mechanical properties. Thepurpose of this work is to investigate the mechanical properties of Fe-Ni bulk alloys and WC-Cocemented carbides using Integrated Computational Materials Engineering (ICME) methods com-bined with FEM data. The report investigates the mechanical properties of several bulk alloys inthe Fe-Ni system as a function of void size and fraction. FEM indentation and FEM fracture datais interpolated and used to model the hardnessHand fracture toughnessKIc. A precipitationhardening model based on the Ashby-Orowan’s equation is implemented to predict the e↵ect on theyield strength from precipitated particles. A model for solid solution hardening is also implemented.Existing models are used to simulate the properties of WC-Co cemented carbides together with thesolid solution hardening model. Results show that the simulated properties of the Fe-Ni bulk alloysare comparable to those of cobalt. However, the results could not be confirmed due to a lack ofexperimental data. The properties of WC-Co cemented carbides are in reasonable agreement withexisting experimental data, with an average deviation of the hardness by 11.5% and of the fracturetoughness by 24.8%. The conclusions are that experimental data for di↵erent Fe-Ni bulk alloys isneeded to verify the presented models and that it is possible to accurately model the properties ofcemented carbides. / Anv¨andandet av kobolt (Co) som bindefas-material i h°ardmetall har blivit ifr°agasatt som en f¨oljdav av de potentiella h¨alsoriskerna associerade med inhalering av koboltpartiklar. Kobolt anv¨ands p°agrund av dess utm¨arkta vidh¨aftande och v¨atande egenskaper, kombinerat med tillr¨ackliga mekaniskaegenskaper. Syftet med detta arbete ¨ar att unders¨oka de mekaniska egenskaperna hos Fe-Ni bulklegeringarochWC-Co h°ardmetall genom att anv¨anda Integrated Computational Materials Engineering(ICME) metoder kombinerat med FEM-data. Rapporten unders¨oker de mekaniska egenskapernahos flera bulklegeringar i Fe-Ni systemet. FEM-indentering och FEM-fraktur data interpoleras ochanv¨ands f¨or att modellera h°ardheten H och brottsegheten KIc. En modell f¨or utskiljningsh¨ardningbaserad p°a Ashby-Orowans ekvation implementeras f¨or att f¨oruts¨aga e↵ekten p°a brottgr¨ansen av utskiljdapartiklar. ¨Aven en modell f¨or l¨osningsh¨ardning implementeras. Existerande modeller anv¨andsf¨or att simulera egenskaperna hos WC-Co h°ardmetall tillsammans med modellen f¨or l¨osningsh¨ardning.Resultaten visar att de simulerade egenskaperna hos Fe-Ni bulklegeringar ¨ar j¨amf¨orbara medde f¨or kobolt. Dock kan de inte bekr¨aftas p°a grund av avsaknad av experimentell data. Egenskapernahos WC-Co h°ardmetall st¨ammer rimligt ¨overens med existerande experimentell data, meden genomsnittlig avvikelse av h°ardheten med 11.5% och av brottsegheten med 24.8%. Slutsatserna¨ar att det beh¨ovs experimentell data f¨or Fe-Ni bulklegeringar f¨or att kunna verifiera modellernasnoggrannhet och att det ¨ar m¨ojligt att f¨oruts¨aga egenskaperna hos h°ardmetall.

Ceramic Foam Filters (CFFs) are widely used to filter solid particles and inclusions from molten metal in metal production, particularly in the aluminum industry. In general, the molten metal is poured on the top of a ceramic foam filter until it reaches a certain height, also known as metal head or gravity head. This is done to build the required pressure to prime the filter media and to initiate filtration. To predict the required metal head, it is necessary to obtain the Darcy and non-Darcy permeability coefficients of the filter. The coefficients vary upon filter type. Here, it is common to classify CFFs based on grades or pore per inches (PPI). These CFFs range from10 to100 PPI and their properties vary in everything from cell and window size to strut size. The 80-100 PPI CFFs are generally not practical for use by industry, since the priming of the filters by a gravitational force requires an excessive metal head. However, recently a new method has been developed to prime such filters by using electromagnetic Lorentz forces. This allows the filters to be primed at a low metal head. To continue the research work, it was deemed necessary to measure the pressure gradients of single and stack of commercial alumina ceramic foam filters and to obtain the permeability characteristics. Therefore, efforts have been made to validate the previously obtained results, to improve the permeametry experimental setup, and to obtain Darcy and non-Darcy permeability coefficients of single 30, 50, and 80 PPI filters and stacks of filters. Furthermore, the experimentally obtained pressure gradients were analyzed and compered to the mathematically and analytically estimated pressure gradients. The studies showed that, in permeametry experiments, the sample sealing procedure plays an important role for an accurate estimation of the permeability constants. An inadequate sealing or an un-sealed sample results in an underestimation of the pressure drop, which causes a considerable error in the obtained Darcy and non-Darcy permeability coefficients. Meanwhile, the results from the single filter experiments showed that the permeability values of the similar PPI filters are not identical. However, the stacks of three identical filters gave substantially the same measured pressure drop values and roughly the same Darcy and non-Darcy coefficients as for the single filters. The permeability coefficients of the filters are believed to be best defined and calculated by using the Forchheimer equation. The well-known and widely used Ergun and Dietrich equations cannot correctly predict the pressure drop unless a correction factor is introduced. The accuracy of the mathematically estimated pressure drop, using COMSOL Multiphysics® 5.1, found to be dependent on the drag term used in the Brinkman-Forchheimer equation.  Unacceptable error, as high as 84 to 89 percent for the 30, 50 and 80 PPI single filters, compared to the experimentally obtained pressure gradient values were observed when the literature defined Brinkman-Forchheimer drag term was used. However, when the same second order drag term (containing the non-Darcy coefficient) as defined in the Forchheimer equation was used, the predicted pressure gradient profiles satisfactorily agreed with the experiment data with as little as 0.3 to 5.5 percent deviations for the 30, 50 and 80 PPI single filters. / <p>QC 20160226</p>

Currently, at Sandvik Materials Technology, slag from the AOD is primarily utilized in ladle treatment of steel. This project has evaluated three synthetic slag formers for ladle treatment. The evaluation has been conducted by measuring how the total oxygen contents and amount of non-metallic inclusions change when using the three syntethic slag formers. The result from these measurements has then been compared to how the total oxygen content and amount of non-metallic inclusions change when using the slag from the AOD. The amount of slag in the ladle has, furthermore, been measured in two ways. By the use of mass balance, and by physically measuring the slag height in the ladle. The results from these two methods of measuring the slag amount has been compared. Lastly, a correlation between the total oxygen content and detected amount of non-metallic inclusions has been evaluated. The results show that the three synthetic slag formers provides a cleaner steel with regards to total oxygen content and amount of non-metallic inclusions in comparison to the slag from the AOD. There is a good conformance between measuring the amount of slag by mass balance compared to physically measure it. Lastly, it can be determined that there is no correlation between the total oxygen contents and the detected amount of non-metallic inclusions in the steel. / Vid Sandvik Materials Technology i Sandviken används i nuläget huvudsakligen AOD-slagg vid skänkugnsbehandling. Detta projekt har utvärderat tre syntetiska slaggbildare för skänkugnen. Utvärderingen har gjorts genom att mäta hur väl de tre syntetiska slaggbildarna renar stålet med avseende på den totala syrehalten och mängden icke-metalliska inneslutningar under skänkugnsbehandling. Resultatet från de tre syntetiska slaggbildarna har därefter jämförts med hur väl AOD-slaggen renar stålet. Vidare har slagghöjden i skänken mätts på två sätt. Både genom massbalans med hjälp av slaggsammansättning och genom att fysiskt mäta slagghöjden. Resultatet från dessa två metoder har jämförts. Dessutom har en korrelation mellan den totala syrehalten och den detekterade mängden icke-metalliska inneslutningar undersökts. Resultaten visar att de tre syntetiska slaggbildarna renar stålet bättre jämfört med AOD-slaggen. Det finns en bra överrensstämmelse mellan att mäta slagghöjden med hjälp av massbalans jämfört med att mäta slagghöjden fysiskt. Slutligen kan det konstateras att det ej finns en korrelation mellan den totala syrehalten och den detekterade mängden icke-metalliska inneslutningar.

The impending change of processes at SSAB Oxelösund due to the HYBRIT project, where the blast furnace and LD converter are to be replaced with an EAF will have a significant impact on the manufacturing of steel in Oxelösund. One issue that will arise is the nitrogen content in the steel. Sources claim that the nitrogen content in steel from an EAF route is substantially larger, 60-70 ppm, than in steel from a blast furnace and LD converter route, which have a nitrogen content of around 25 ppm. Therefore, the nitrogen removal capabilities of SSAB Oxelösund’s vacuum tank degasser were to be examined. Industrial trials were performed where the amount of slag during vacuum treatment was lowered. The intention was that half the amount of slag removed prior to vacuum treatment and later completely slag free. This was performed in an attempt to increase the effective reaction area, where nitrogen removal occurs. Due to some practical problems with the steel mill, the industrial trial were unfortunately cut short. Consequently, only trials with half the amount of slag were performed and compared to existing process data for standard praxis. Also, nitrogen removal calculations based on the industrial data were performed. A parameter representing the overall reaction rate, which is dependent on effective reaction area was obtained, validated and subsequently applied to a future case scenario. The results indicate that the reduction in slag amount does have the desired effect, increasing the said area and increasing the rate of nitrogen removal. However, the sample size is not nearly sufficient enough to determine this definitively. The conclusions reached were that the facility does have the possibility to decrease the increased nitrogen content down to reasonable levels, around 20-30 ppm. Albeit, an increase in vacuum treatment time is probably required. Another conclusion was that surface active elements, such as oxygen and sulphur greatly reduce the nitrogen removal. Therefore, efforts should be taken to remove these elements prior to vacuum treatment. In addition, it was established that the effective reaction area is of great importance for a successful nitrogen removal. Therefore, actions to maximise this area should be taken. Finally, it was stated that further research is necessary in order to fully understand nitrogen contamination prevention- and removal techniques / Förändringar till följd av HYBRIT projektet kommer påverka SSAB Oxelösunds stålverk. Masugn och LD konverter skall ersättas med ljusbågsugns teknologi. Ett problem till följd av detta är kvävehalter i stålet. Enligt litteraturen är kvävehalterna betydligt högre i stål tappat från en ljusbågsugn. Med kvävehalter runt 60-70 ppm jämfört med stål tappat från en LD konverter som har kvävehalter kring 25 ppm. Därför krävdes en undersökning kring kvävereningpotentialen för SSAB Oxelösunds vakuum tank avgasare. Industriella experiment med minskad slaggmängd jämfört med standard praxis blev utförda. Detta utfördes med tanken att minskad slaggmängd skulle ge en större effektiv reaktionsarea. Intentionen var att utföra försök först med halverad slaggmängd följt av slaggfria försök. Dock, på grund av produktions praktiska problem vid verket blev försöken avbrutna. Som en följd av detta blev bara försök med halverad slaggmängd utförda och jämförda med processdata från standard praxis. Kvävereningsberäkningar på historisk processdata utfördes. En parameter som representerade genomsnittlig reaktionshastighet, vilken beror på den effektiva reaktionsarea blev erhållen, validerad och senare applicerad på ett hypotetiskt framtida scenario. Resultaten indikerar att minskad slaggmängd har en positiv inverkan på den effektiva reaktions arean och till följd av detta även en positiv inverkan på kväverening. Dock är för få försök utförda för att kunna fastställa detta. De slutsatser som dras är att vakuum anläggningen vid SSAB Oxelösund har möjligheten att, med förlängd vakuumbehandlingstid, rena de ökade kvävehalter till nivåer runt 20-30 ppm. Ytterligare slutsatser var att ytaktiva element, såsom syre och svavel, i stålet har en stor negativ påverkan för kväverening. Samt att den effektiva reaktionsarean är av stor betydelse för kväverening. Därför bör ansträngningar tas för att minska koncentrationen av ytaktiva element samt att försöka göra den effektiva reaktionsarean så stor som möjligt. Slutligen fastställdes det att ytterligare studier är nödvändiga för att öka kunskapen kring förebyggande tekniker och reningstekniker för kväveföroreningar i stål.

The effect of gas stirring in the ladle furnace on inclusion content in austenitic and duplex stainless steel has been investigated at Sandvik Materials Technology AB. The effect was mainly investigated by varying duration of stirring time and intensity of stirring. Any effect on inclusion content was determined by examining total oxygen content before and after the ladle treatment, along with mapping the chemical composition, size and size distribution of the inclusions. Any effect on slag composition was also determined. The effect of gas stirring was measured on a number of heats with continuous sampling during normal production. Data regarding oxygen content during the ladle refining process and the duration of the processes was used to determine a quantifiable relationship between stirring time, stirring intensity and resulting change in oxygen content. The result of the investigation was recommendations regarding the use of varied stirring intensities and duration of gas stirring for achieving negative net loss in oxygen content before and after ladle treatment.

Metallic materials play important roles in providing electrical, thermal, and mechanical functions in electronic devices and systems. The understanding of the electrical-thermal-mechanical interaction caused by the passage of electric current with high density is important to improve the performance and reliability of electronic assembly and packaging. The electromechanical interaction on the deformation behavior of copper and tin is studied in this work. The electromechanical response of Cu strips was studied by passing a DC electric current. The electric resistance linearly increased with time before the occurrence of electric fusing. The electrothermal interaction led to the buckling of the Cu strips with the maximum deflection increasing with the increase of the electric current density. The total strain was found to be proportional to the square of the electric current density. A power law relation was used to describe the dependence of the time-to-fusing on the electric current density. Using the nanoindentation technique, the effect of electric current on the indentation deformation of copper and tin was studied. The reduced contact modulus of copper and tin decreased with increasing the electric current density. With the passage of a DC electric current, the indentation hardness of copper increased slightly with increasing electric current density. With the passage of an AC electric current, the indentation hardness of copper decreased with increasing the indentation deformation. With the passage of a DC electric current, the indentation hardness of tin decreased with increasing the indentation load, showing the normal indentation size effect. Both the limit of infinite depth and the characteristic length were dependent on the electric current density. Using the tensile creep technique, the creep deformation of pure tin was studied with the passage of a DC electric current. The steady state creep rate increased with the increase in temperature, tensile stress and electrical current density. For the same tensile stress and the same chamber temperature, the steady state creep rate increased linearly with the square of the electric current density. The electric current density has no significant effect on the stress exponent and activation energy of the tensile creep of tin for the experimental conditions.