Thin-slab cast direct-rolling (TSCDR) has become a major process for flat-rolled production. However, the elimination of slab reheating and limited number of thermomechanical deformation passes leave fewer opportunities for austenite grain refinement, resulting in some large grains persisting in the final microstructure. In order to achieve excellent ductile to brittle transition temperature (DBTT) and drop weight tear test (DWTT) properties in thicker gauge high-strength low-alloy products, it is necessary to control austenite grain coarsening prior to the onset of thermomechanical processing. This contribution proposes a suite of methods to refine the austenite grain from both theoretical and practical perspectives, including: increasing cooling rate during casting, liquid core reduction, increasing austenite nucleation sites during the delta-ferrite to austenite phase transformation, controlling holding furnace temperature and time to avoid austenite coarsening, and producing a new alloy with two-phase pinning to arrest grain coarsening. These methodologies can not only refine austenite grain size in the slab center, but also improve the slab homogeneity.
T. Zhou et al., "Control Upstream Austenite Grain Coarsening during Thin Slab Casting Direct Rolling (TSCDR) Process," Metals 2019, vol. 9, no. 2, MDPI, Feb 2019.
The definitive version is available at https://doi.org/10.3390/met9020158
Materials Science and Engineering
Peaslee Steel Manufacturing Research Center
Keywords and Phrases
Thin-slab cast direct-rolling; Austenite grain coarsening; Grain growth control; Liquid core reduction; Secondary cooling; Two-phase pinning
International Standard Serial Number (ISSN)
Article - Journal
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01 Feb 2019