Ferrite grain refinement in seamless pipes through intragranular nucleation on VN
2008 (English)In: 3rd International Conference on Thermomechanical Processing of Steels, TMP 2008, 2008Conference paper, Published paper (Refereed)
Abstract [en]
Mill rolling process of seamless pipe was simulated with the aim of applying grain refinement through the formation of intragranular ferrite on VN precipitated inside austenitic grains, for production of as-hot rolled microstructures, which are currently attained only by in-line normalising. Tests were performed on V+N and V+N(Ti) steels using two types of schedules with long and short transfer/heating times prior to sizing between 930-830°C. It was found that transfer/heating time between high temperature rolling and low temperature sizing could be used for precipitation of VN in austenite which in turn can nucleate intragranular ferrite grains on cooling. To facilitate the precipitation process of VN a sub-micro-addition of Ti was used which also helps to restrain austenite grain growth during piercing and pipe forming. Subsequent V(C,N) precipitation of the remaining vanadium in the ferrite contributes precipitation strengthening. Hot rolling followed by intragranular ferrite formation in 0.1%V-0.015%N-0.005%Ti steel is able to develop a fine ferritepearlite microstructure with an average ferrite grain size of 7um.
Place, publisher, year, edition, pages
2008.
Keywords [en]
Ferrite, Grain refinement, Hot rolling, Microalloying, Nucleation, Pipe manufacture, Precipitates, Titanium, Vanadium, Vanadium nitride
National Category
Materials Engineering
Identifiers
URN: urn:nbn:se:ri:diva-12986ISBN: 8885298664; 9788885298668 (print)OAI: oai:DiVA.org:ri-12986DiVA, id: diva2:973179
Conference
3rd International Conference on Thermomechanical Processing of Steels, TMP 2008, Padua, 10 September 2008 through 12 September 2008, 96573
2016-09-222016-09-22Bibliographically approved