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.

Inom fordonsindustrin arbetas det kontinuerligt med att utveckla mer miljövänliga och ekonomiska produkter. Genom att undersöka material och förbättra utmattningshållfastigheten på befintliga material kan växellådor bli mer kompakta, ekonomiska och starkare samtliga parter. Syftet och målet med detta arbete är att få en generell förståelse för icke-metalliska inneslutningar och hur de påverkar ett materials utmattningshållfasthet, samt att ge förslag på förbättringar till den nuvarande materialspecifikationen. Genom tester på ultraljud kan en klar skillnad mellan storleken på defekter ses mellan stål tillverkade med olika processer. Genom undersökande av tidigare utförda tester på roterande böj kan en ökning av utmattningshållfastigheten på 37.5% ses mellan ett götgjutet stål och ett stränggjutet. Vid studerande av internationella och Europeiska standarder kan korrigeringar till den nuvarande materialspecifikationen föreslås. / <p>Arbetet är censurerat.</p>

One of the greatest challenges of human today is to provide the continuous and sustainable energy supply to the worldwide society. This shall be done while minimizing all the negative consequences of the operation(s) to the environment and its living habitants including human beings, taking from the whole life cycle perspective. In this thesis work new solutions for treatment biomass and waste are analyzed.   Based on the fundamental research on the conversion of various materials (biomass: straw pellets, wood pellets; and waste: plastic waste, ASR residues after pyrolysis), converted by means of different systems (pyrolysis in a fluidized bed reactor, gasification in a fixed-bed reactor using highly preheated agents) it is recommended to classify materials against their charring properties under pyrolysis, in order to find the best destination for a given type of fuel.    Based on phenomenological research it was found that one of the important effects, affecting performance of downdraft gasifiers, is the pressure drop through the bed and grate. It affects, directly, the velocity profile, temperature distribution and of the height of the bed, especially for the grate with restricted passage surface, although it was not investigated in literature. The lower grate porosity, the higher conversion of fuel and heating value of gas is produced. However, the stability of the process is disturbed; therefore reducing the grate porosity below 20% is not recommended, unless the system is designed to overtake the consequences of the rising pressure inside the reactor. This work proposed the method for prediction of a total pressure drop through the fixed-bed downdraft gasifier equipped with a grate of certain porosity with an uncertainty of prediction ±7.10.     Three systems have been proposed; one for the treatment of automotive shredder residue (ASR), one for the treatment of plastic waste (polyolefins) and one for biomass (wood/straw pellets). Pyrolysis is an attractive mean of conversion of non-charring materials (like plastic waste) into valuable hydrocarbons feedstock. It gives directly 15-30% gaseous olefins while the residue consisting of naphtha-like feedstock has to be reformed/upgraded to olefins or other chemicals (e.g. gasoline generation) using available petrochemical technologies. Pyrolysis of complex waste mixture such as ASR is an attractive waste pretreatment method before applying any further treatments, whereby useful products are generated (gaseous and liquid fuel) and char, rich in precious metals. The solid residues are meant for further treatment for energy and metals recovery. Gasification is a complementary method for handling pyrolysis residues. However, metals can be removed before gasification. Pyrolysis of charring materials, like biomass, is a very important step in thermo-chemical conversion. However, the char being approximately 25%wt. contains still very high caloric value of about 30MJ/kg. This in connection with the High Temperature Steam Gasification process is a very promising technology for biomass treatment, especially, above 900oC. This enhances the heat transfer towards the sample and accelerates kinetics of the gasification. This, in turn, improves the conversion of carbon to gas, increases the yield of the producer gas and reduces tar content. At higher steam to fuel ratio the process increases the yield of hydrogen, making it suitable for second-generation biofuels synthesis, whereas at lower steam to fuel ratio (S/F&lt;2) the generated gas is of high calorific value making it suitable for power generation in a combined cycle. / <p>QC 20110607</p>

This thesis is about the design of the gating system and selection of proper alloy for defects free (grate bar) casting. The gating system plays an important role in casting manufacturing process. The gating system has different elements like pouring cup, sprue, well, runner, riser, and ingates. The function of the gating system is to provide molten metal to the mould cavity through different gating system elements.  Casting is a metal shaping process which is used to produce a cast component. The casting process depends upon the material, type of pattern, mould and various techniques like sand casting, investment casting, die casting, squeeze casting and lost foam casting. The sand mould casting process is used in this report. The casting process is used for making small to large cast parts, complicated shapes, and precision parts, etc. Making a casting without defects is an important requirement for its strength. The effective and efficient design of the gating system is necessary for making defects free castings. There are various defects like shrinkage cavity, porosity, pinholes, blowholes and incomplete filling that may occur in sand casting. The simulation software like Magma Soft and Nova Flow Solid are used to predict the possible defects in the casting. The uses of the simulation improve product quality and increase productivity. It also helps to reduce the rejection rate by identifying and controlling defects. This work is done at AB Bruzaholms Bruk as part of master thesis work at Jönköping University, Sweden. The company provides all the necessary data for simulation purposes. The design of the gating system is finalized as per company requirements and needs. The research questions that have been answered in this report based on the following points. 1) What does zero-defect mean? 2) Which is the best design among the ones that are prepared and simulated? 3) Which is the best alloy combination for casting parts that give defects free casting and better fluidity and filling?

No description available.

Gas turbines are widely used in industry for power generation and as a power source at "hard to reach" locations where other possibilities for electrical supply are insufficient. There is a strong need for greener energy, considering the effect that pollution has had on global warming, and we need to come up with ways of producing cleaner electricity. A way to achieve this is by increasing the combustion temperature in gas turbines. This increases the demand on the high temperature performance of the materials used e.g. superalloys in the turbine. These high combustion temperatures can lead to detrimental degradation of critical components. These components are commonly subjected to cyclic loading of different types e.g. combined with dwell-times and overloads at elevated temperatures, which influence the crack growth. Dwell-times have shown to accelerate crack growth and change the cracking behaviour in both Inconel 718 and Haynes 282. Overloads at the beginning of the dwell-time cycle have shown to retard the dwell time effect on crack growth in Inconel 718. To understand these effects more microstructural investigations are needed. The work presented in this licentiate thesis was conducted under the umbrella of the research program Turbo Power; "High temperature fatigue crack propagation in nickel-based superalloys", concentrating on fatigue crack growth mechanisms in superalloys during dwell-times, which have shown to have a devastating effect on the crack propagation behaviour. Mechanical testing was performed under operation-like conditions in order to achieve representative microstructures and material data for the subsequent microstructural work. The microstructures were microscopically investigated in a scanning electron microscope (SEM) using electron channeling contrast imaging (ECCI) as well as using light optical microscopy. The outcome of this work has shown that there is a significant increase in crack growth rate when dwell-times are introduced at the maximum load (0% overload) in the fatigue cycle. With the introduction of a dwell-time there is also a shift from transgranular to intergranular crack growth for both Inconel 718 and Haynes 282. When an overload is applied prior to the dwell-time, the crack growth rate decreases with increasing overload levels in Inconel 718. At high temperature crack growth in Inconel 718 took place as intergranular crack growth along grain boundaries due to oxidation and the creation of nanometric voids. Another observed growth mechanism was crack advance along phase boundaries with subsequent severe oxidation of the phase. This thesis comprises two parts. The first giving an introduction to the field of superalloys and the acting microstructural mechanisms that influence fatigue during dwell times. The second part consists of two appended papers, which report the work completed so far in the project.

The most common way of producing steel worldwide is with the continuous casting process, where a strand of steel is continuously cast. Further optimization of this process requires data from measurements, measurements which must take place in a hostile high-temperature and corrosive environment such as liquid steel. At Swerim, a Continuous Casting Simulator has been constructed to replicate the flow conditions in the process. A eutectic bismuth-tin alloy with properties similar to steel is used instead to make measurements in liquid metal possible. In this report pressure, velocity and vibration measurements were made using multiple sensors under different flow conditions.

In this work, the influence of different cooling rates (5, 20, 50 and 100 °C/s) on the microstructure and mechanical properties of Laser Metal Wire Deposited (LMwD) Ti-6Al-4V was investigated, this was done using a thermal-mechanical physical simulation system (Gleeble 3800, DSI). Two different soak times above β transus (held at 1100 °C), 5 and 40 s, were used and after cooling to 150 °C, the samples were tensile tested. The samples were characterized with optical microscopy (OM) and scanning electron microscopy (SEM) and hardness testing. The results were then compared, both with each other and with two reference samples, that were only heated to 150 °C and then tensile tested. It was found that for the lowest cooling rate, 5 °C/s, the microstructure had transformed from a basketweave α microstructure to a colony α microstructure in the center of the specimen waist where heating was most efficient. Ultimate tensile strength (UTS) was found to be in the range of 858 – 977 MPa, with the highest average being recorded for the reference samples, similar results were noted for the strain, with a range of  ⁓5 – 14 %, where the highest recorded average was for the reference samples. However, the extensometer used was not optimized for this kind of test, therefore percent reduction of area (RA) measurements were performed. The RA measurements produced a significantly different result than that obtained from the testing, a large scatter in the ductility was found, possibly due to thermal instability that occurred during testing. Overall, the microstructure appears to be relatively stable over the cooling range of 20 - 100 °C/s, no major differences were observed, the microstructure consisted of a homogeneous basketweave α microstructure, with little to no change in the measured average α lath thickness.

De ökande kraven på kvalité från kunder och ett allt strängare regelverk från myndigheter gällande miljön, har lett till att Ovako Sweden AB Hällefors har planer på att introducera polymer (Aquatensid) som nytt kylmedel i sin Induktionshärdningslinje. Detta för att minska risken för sprickbildning i materialet till följd av för stora spänningar, samtidigt som vattnet byts ut mot ett resultatmässigt bättre alternativ. Tidigare studier med lovande resultat har utförts inom området och detta arbete inriktar sig på att finna en balanserad koncentrationshalt av polymer i blandning med vatten som kan passa för hela Ovakos seghärdade sortiment.Tester har skett på två av de vanligaste stålsorterna (Ovako 356 och Ovako 495) dessa har gemensamt att de är relativt höglegerade stål i Ovakos sortiment. Stålsorterna har härdats i en kammarugn vid höga temperaturer och sedan kylts under omröring i ett bad av vattenblandad polymer vid varierande koncentrationer. Noggrann fysikalisk provning innefattande hårdhetsprofiler i Vickers, mikroskopering i ljusmikroskop och Svepelektronmikroskop (SEM). Detta för att se om eventuella skillnader i strukturen uppkommit, som kan ge tendenser till sprickuppkomst och försämrad härdbarhet. Resultaten av testerna visar att för stålsort 495B kan jämna hårdhetsintervall uppnås över de olika koncentrationerna, men att man får en större variation då man kyler 356D.