ISSN:
1662-8985
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Currently new continuous casting processes such as thin slab caster or strip casting areindustrialized or under developing in the world steel makers. In these casting processes, cooling rateafter solidification becomes much faster compared with thick slab caster, and hot rolling millconnected directly with casting machine tends to be installed. The present study was conducted toinvestigate variations of austenitic grain size and micro segregation with cooling rate aftersolidification and also direct hot deformation conditions in austenite immediately after solidificationin HSLA steels. HSLA steels were 0.15%C-0.25%Si-1.50%Mn, 0.028%Nb and0.028%Nb-0.015%Ti with the same basic compositions. A hot working simulator ofTHERMECMASTER-Z was used, and the center part of tensile specimen set up in this machinewas partially or fully levitation-melted by induction heating under argon gas atmosphere. Aftermelting, specimens were cooled at cooling rate from 0.4K/s to 40K/s, and this range coveredcooling rates after solidification in heavy thick slab caster and strip casting. Direct hot tensilestraining in austenite after solidification was conducted at strain rates from 1.4×10-3s-1 to 2.6s-1,corresponding to an extracting speed in a respective caster. The increase of cooling rate refinedcontinuously as cast austenitic grain size, and it was enhanced in micro alloyed steels. Microsegregation such as Mn was improved by faster cooling. Direct straining after solidificationmarkedly refined austenitic grain size through dynamic or static recrystallization occurringdepending on strain rate
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.15-17.726.pdf
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