Chen Q.,Jiangxi University of Science and Technology |
Xu L.,Tianjin Iron and Steel Group |
Qiu S.,Tianjin Iron and Steel Group |
Lai C.,Jiangxi University of Science and Technology |
And 3 more authors.
Jinshu Rechuli/Heat Treatment of Metals
Based on the hot ductility curves at 600-1350°C tested by Gleeble-3800 thermal stress-strain simulation machine for Q235B-2B steel sized to 230 mm × 1800 mm cast slab, the third brittle zone of the cast slab is between 750-1000°C, the low plasticity temperature range is wide. Lots of MnS precipitation and some composite precipitates of MnS and BN were found at the grain boundary by scanning electron microscope and composition analysis by SEM and EDS. Crack sensitivity of the boron microalloyed steel is relatively high, because of boron segregation at grain boundaries and precipitation of second phase particles and lead to the grain boundary embrittlement. Combined the thermodynamics analysis, reducing the nitrogen content can reduce the precipitation of second phase particles, and improve steel hot ductility. Source