Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Effects of Nitride-Oxide Particles on Solidified Structure inFe-20mass%Cr Alloy Deoxidised with Ti/M (M = Zr or Ce)
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
Visa övriga samt affilieringar
2010 (Engelska)Rapport (Övrigt vetenskapligt)
Abstract [en]

The ratio of equiaxed grains on a cross section and average grain sizein Fe-20mass% Cr alloy deoxidised with Ti/M (M = Zr or Ce) were studiedas function of nitrogen content and particle characteristics such as sizedistribution, morphology and composition. Fe-20mass%Cr alloys weremelted at 1600ºC, deoxidised, cooled to 1400ºC followed by waterquenching. The particles were investigated on a surface of film filter afterelectrolytic extraction of metal samples with 10%AA electrolyte. It wasfound that the number of particles increases with increasing the N content.The as-cast solidification structure and grain size were clearly affected bythe number of oxide and oxide-nitride particles in Ti/Zr experiments. Theeffect in the Ti-Ce case was almost undetectable.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH , 2010. , s. 40
Serie
KTH/MSE ; 10:13
Nyckelord [en]
Fe-Cr alloy; Ti, Zr and Ce deoxidation, grain size distribution
Nationell ämneskategori
Metallurgi och metalliska material
Identifikatorer
URN: urn:nbn:se:kth:diva-13327OAI: oai:DiVA.org:kth-13327DiVA, id: diva2:323684
Anmärkning
QC20100611Tillgänglig från: 2010-06-11 Skapad: 2010-06-11 Senast uppdaterad: 2010-06-11Bibliografiskt granskad
Ingår i avhandling
1. Inclusions and/or Particles Engineering for Grain Refining Purposes in Ferritic Fe-20mass%Cr alloys
Öppna denna publikation i ny flik eller fönster >>Inclusions and/or Particles Engineering for Grain Refining Purposes in Ferritic Fe-20mass%Cr alloys
2010 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Compared to more common used austenitic stainless steels, ferritic stainless steels contain very low amounts of the expensive alloying element Ni. In addition, they have good corrosion properties, but are sometimes suffering from poor weldability and bad mechanical properties. This is mainly due to the presence of large grains after casting and large grain growth during heat treatment or welding. Processes for reducing the grain size (grain refining) of metal alloys are widely known and proven before to be suitable for many alloys. A successful grain refining process can increase the strength of an alloy without decreasing the ductility. This can be achieved by different methods, such as rolling or cooling. In this work, the focus has been on studying the aspect from a metallurgist point of view, to analyse the possibilities to create small particles in the liquid stage to enhance the solidification. The focus has been on oxide and nitride formation for nucleation of smaller grains during solidification.

This study was made by forming particles, develop the analysis methods and thereafter to study the effect of particles on the structure of a ferritic stainless steel. The particles were formed by additions of Ti, Ce and Zr in to a liquid Fe-20mass% Cr alloy containing different amounts of oxygen and nitrogen. The electrolytic extraction technique was used to achieve a good understanding of the reaction processes and the particles size, number, composition and morphology. The grain sizes and the particles were then studied in as-cast samples as well as in specimens heat treated for 60 minutes at 1200, 1300 and 1400°C in a Confocal Scanning Laser Microscope (CSLM). Also, based on Scanning Electron Microscope (SEM) determinations and Thermo-Calc calculations, the precipitated particles were divided as primary and secondary particles. Thereafter, the grain refining potential was studied for each of these types.

In this work, particles engineering by using small particles have been proven suitable for the Fe-20mass% Cr ferritic stainless steel alloys. Although the work has been based on small-scale samples and experiments, the results show good tendencies with respect to grain refining as well as a clear relationship between the particles in the steels and the microstructures. It was found that Ti-Ce additions in Fe-20mass% Cr alloys resulted in complex oxides including Ti, Ce and Cr. These oxides were observed to have high agglomeration tendencies and therefore to form larger particles or clusters. The grain refining potential on the solidification structure was insignificant, despite a relatively large amount of particles. However, Ti-Zr additions in Fe- 20mass% Cr alloys on the other hand resulted in primary precipitated particles such as ZrO2 and ZrO2+ZrN. Furthermore, ZrN nucleated ferrite during solidification, which lead to a clearly observed grain refining effect. This effect was also increased with an increased number of particles. The amount of particles (primary and secondary) was also found to increase with an increased amount of nitrogen. Secondary particles (mostly TiN) were precipitated near grain boundaries, which lead to a location based pinning effect of the grain growth during heat treatment at 1200 °C. This pinning effect was increased by an increased nitrogen content and thereby an increased number of particles. Finally, the pinning effect was clearly reduced during heat treatment at 1400 °C.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH, 2010. s. x, 55
Nyckelord
Inclusions, Particles, Grain size, High Cr, Ferritic, Grain refining, Solidification, Pinning effect, Stainless steel, Oxides, Nitrides
Nationell ämneskategori
Metallurgi och metalliska material
Identifikatorer
urn:nbn:se:kth:diva-13012 (URN)978-91-7415-599-0 (ISBN)
Disputation
2010-05-20, F3, Lindstedtsvägen 26, KTH, Stockholm, 13:00 (Engelska)
Opponent
Handledare
Anmärkning
QC20100524Tillgänglig från: 2010-05-24 Skapad: 2010-05-24 Senast uppdaterad: 2011-09-19Bibliografiskt granskad

Open Access i DiVA

fulltext(9775 kB)293 nedladdningar
Filinformation
Filnamn FULLTEXT01.pdfFilstorlek 9775 kBChecksumma SHA-512
097da7a4df96a10bf2bf7c5c363011666d39094342b8b2d58f0e8b9645e05f3df2949ca34e56e8083ca9ca6ba7fdedd3e65aa7397695614c01f598203cc60326
Typ fulltextMimetyp application/pdf

Sök vidare i DiVA

Av författaren/redaktören
Janis, JesperNakajima, KeijiKarasev, AndreyJonsson, StefanJönsson, Pär
Av organisationen
Tillämpad processmetallurgi
Metallurgi och metalliska material

Sök vidare utanför DiVA

GoogleGoogle Scholar
Totalt: 293 nedladdningar
Antalet nedladdningar är summan av nedladdningar för alla fulltexter. Det kan inkludera t.ex tidigare versioner som nu inte längre är tillgängliga.

urn-nbn

Altmetricpoäng

urn-nbn
Totalt: 289 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf