Phase transformation and cooling curves of the mild steel influenced by previous hot rolling

摘要

Rods from mild steel S235JR were intensively rolled in the laboratory continuous mill. Specifically defined temperatureof phase transformation Ar was determined from the free cooling curves measured by the temperature scanner.The Ar value increased from 763 to 786 °C with rolling temperature descending from 1 200 to 800 °C. The value ofAr = 730 °C was obtained at free cooling of the non-deformed rod of the same diameter 9,8 mm from heating temperature1 000 °C. The obtained results were compared with continuous cooling transformation (CCT) and deformationcontinuous cooling transformation (DCCT) diagrams based on the dilatometric tests.