| 1. |
- Hansén, Thorbjörn, et al.
(författare)
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On the assessment of macro inclusions in stainless steels using ultrasonic technique.
- 2004
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Determination of the inclusion size distribution in clean steels is a difficult task since the inclusion content is very low. This is even more pronounced for inclusions in the size range between 20-100 microns. Depending on the steel application the inclusions might cause fatigue failure or rupture. The use of light optical methods for the assessment of macro or semi macro inclusions in such steel grades is not beneficial since finding sufficient number of inclusions for statistical calculations, is a very time consuming process. The application of ultrasonics with immersed scanning high frequency transducers has proven to be an excellent tool for this purpose. This technique is now used as a standard tool by a producer of ball bearing steels. However, for stainless steels there are limitations of the ultrasonic technique. In this study examination of different stainless steel grades has been done and it clearly shows that the austenitic crystal structure attenuates the sound wave to such an extent that the inclusions detected are hidden behind the background noise. This is more or less independent of the grain size. The overall result is that Ultrasonic examination for the assessment of macro and semi macro inclusions is a reasonable method for stainless steel grades with other structure than austenitic.
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| 2. |
- Ipek, Nulifer, et al.
(författare)
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Electrolytic pickling of duplex stainless steel
- 2005
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Ingår i: Materials and corrosion - Werkstoffe und Korrosion. - : Wiley. - 0947-5117 .- 1521-4176. ; 56:8, s. 521-532
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Tidskriftsartikel (refereegranskat)abstract
- Pickling of duplex stainless steels has proved to be much more difficult than that of standard austenitic grades. Electrolytic pre-pickling is shown to be a key process towards facilitating the pickling process for material annealed both in the production-line and in laboratory experiments. The mechanism for the neutral electrolytic process on duplex 2205 and austenitic 316 steels has been examined and the oxide scale found to become thinner as a function of electrolytic pickling time. Spallation or peeling of the oxide induced by gas evolution did not play a decisive role. A maximum of about 20% of the current supplied to the oxidised steel surface goes to dissolution reactions whereas about 80% of the current was consumed in oxygen gas production. This makes the current utilisation very poor, particularly against the background of reports that in indirect electrolytic pickling only about 30% of the total current, supplied to the process, actually goes into the strip. A parametric study was therefore carried out to determine whether adjustment of process variables could improve the current utilisation.
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| 3. |
- Nordqvist, Annie, et al.
(författare)
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Characterization of metal droplets sampled during top lance blowing
- 2006
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Ingår i: Sohn International Symposium Advanced Processing of Metals and Materials. - WARRENDALE : MINERALS, METALS & MATERIALS SOC. ; , s. 351-362
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Konferensbidrag (refereegranskat)abstract
- Laboratory trials were performed in an induction furnace to study droplet formation during lance blowing. Compressed air was blown on a molten iron bath consisting of iron alloyed with carbon and silicon. Steel droplets were collected using a specially designed sampler. The average steel droplet composition and the oxide layer thickness were determined using scanning electron microscopy combined with energy dispersed spectroscopy. In addition, the concentration gradient of elements was deter-mined using a microprobe. It should be noted that a special technique had to be developed in order to prepare the droplet sample. The size distribution and composition of the droplets was also determined using the microprobe. It was found that the carbon content in the droplets was lower than the carbon content in the bulk.
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| 4. |
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| 5. |
- Ternstedt, Patrik, 1979-, et al.
(författare)
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Methods to Determine Characteristics of AOD-Converter Decarburization-Slags
- 2020
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- Argon Oxygen Decarburization (AOD) converter slags are known to consist of both liquid and solid phases, but limited information on the slag characteristics has been published in the open literature. Therefore, a new methodology to study the characteristics of slag samples taken from the AOD converter process during production was developed based on petrography. The results show that the preparations of the slag samples using the borax method are suitable to use when determining the chemical composition of AOD slag samples using the X-ray fluorescence (XRF) method. The results also showed that both the light optical microscopy (LOM) method and a method combining scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) can be used to characterize the slag samples and that the correlation between the methods was found to be good. This means that it is possible to use the faster LOM method instead of the more complicated SEM-EDS method to characterize AOD slag samples. Finally, the results show that the difference between calculated values based on stoichiometry and measured data for Ca and Cr in AOD slags are 11.7 mass% and 11.3 mass%, respectively. This is considered to be a good agreement for industrial samples.
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