Effect of Ti de-oxidation on solidification and post-solidification microstructure in low carbon high manganese steel
2007 (English)In: ISIJ International, ISSN 0915-1559, Vol. 47, no 9, 1255-1264 p.Article in journal (Refereed) Published
This paper investigates the effect of de-oxidation inclusions on micro-structure in low-carbon steels. Low carbon (0.07 wt%), high Mn (0.9 wt%) steel in a Al2O3 or MgO crucible was deoxidized by adding either aluminum (0.05 wt%) or titanium (0.05, 0.03 or 0.015 wt%) in a 400 g-scale vacuum furnace, and cast in a Cu mold at cooling rates between 2.0-6.0 K/s. The oxide inclusions were identified as Al2O3 (1-3 mu m) in the Al-killed steel and Ti-Al-(Mg)-O (0.3-0.5 mu m) in the Ti-killed steel. Oxide inclusion sizes in all the Ti-killed steels were smaller and inclusion densities higher than those in the Al-killed steel. Solidification structure, defined as the density of primary dendrite arms within a defined region was finer with increasing inclusion density and as a result, the solidification structure of the Ti-killed steel was finer than that of the Al-killed steel. A Confocal Scanning Laser Microscope (CSLM) and a Differential Scanning Calorimeter (DSC) were used to study the differences in solid state micro-structural evolution between the Ti-killed, Al-killed and the non de-oxidized samples. The growth of austenite grains were studied under isothermal conditions and it was found that both grain-boundary mobility and final grain size were lower in the Ti-killed sample than for the others. With regards to austenite decomposition, during continuous cooling from a comparable austenite grain structure, the resulting austenite decomposition structure was finer for the Ti-killed sample due to a higher Widmanstatten lath density due to precipitation at particles in addition to grain boundaries.
Place, publisher, year, edition, pages
2007. Vol. 47, no 9, 1255-1264 p.
low-carbon steel, de-oxidation, aluminum, titanium, inclusion, solidification microstructure, confocal-laser-scanning-microscopy, phase transformation, grain growth
Metallurgy and Metallic Materials
IdentifiersURN: urn:nbn:se:kth:diva-37049DOI: 10.2355/isijinternational.47.1255ISI: 000249743100003ScopusID: 2-s2.0-36148989989OAI: oai:DiVA.org:kth-37049DiVA: diva2:431911