Reheat treatments for two HSLA steels, a forged Al-Nb-containing steel (Steel-1) and an as-rolled Nb-containing steel (Steel-2), were carried out for one to three hours at temperatures between 1090 and 1250°C which were selected by the precipitates’ dissolution temperatures predicted by Thermo-Calc and DICTRA. Steel-1 contains continuous segregation bands with segregation spacing of 65 ± 10 µm, whereas Steel-2 contains discontinuous segregation bands with spacing of 35 ± 10 µm. Uniform grain size distributions occurred in Steel-1 for all reheat temperatures whereas abnormally large grains were observed in Steel-2 when reheating at 1090°C. A mechanism for grain size development in materials with continuous and discontinuous segregation bands based on austenite nucleation and growth and precipitate pinning in the segregation band is proposed.
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