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Assessment of Segregation in Hot Tear Cracks
Author(s) -
Preßlinger Hubert,
Ilie Sergiu,
Fluch Judith,
Reisinger Peter
Publication year - 2008
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.200806222
Subject(s) - materials science , metallurgy , niobium , casting , carbon fibers , slab , composite material , titanium , geology , geophysics , composite number
In solidified slabs different types of segregations such as crystal segregation (micro segregation), centre segregation (macro segregation) and hot tear segregation (HTS) may occur. The present paper examines the segregation behaviour of different elements in hot tear cracks depending on the carbon content. The aim of this work is to determine the segregation factors in the hot tear cracks filled with residual melt and compare with micro and macro segregation. Within the scope of this examination, a microanalytical assessment was made of eight slab samples with different steel grades each showing different types of hot tear cracks that had been healed up by an inflow of residual melt. The hot tear cracks are located outside the primary dendrites in the dendritic interstices, parallel or transversal to the direction of casting. Segregation in the cracks healed up by residual melt depends on the carbon content and will become more pronounced as the carbon content increases. The intensity of segregation for the various elements in the hot tear cracks (hot tear crack segregation) is between that of crystal segregation and centre segregation. The thickness of the segregated zone in the hot tear crack area is 30 ‐ 50 μm. Apart from an enrichment of the alloying elements manganese, silicon and chromium, the healed up hot tear cracks also contain secondary precipitates of sulphides and niobium‐titanium‐carbonitrides. Towards the slab centre, the latter can cause, among other things, the development of niobium‐titanium‐carbonitrides (Nb 1‐x , Ti x )(C 1‐y , N y ) networks in the primary dendritic interstices.