The beneficial effect of B on the hot ductility of 20CrMnTi steel with 0.05% Sn wasinvestigated. The results show that there is a trough in the hot ductility-temperaturecurve. With the increase in the B content, the trough shifts to a lower temperature andbecomes shallow, and the hot brittle range becomes narrow. In addition, B greatlyenhancing the hot ductility was due mainly to its suppressing the Sn segregation,retarding the austenite/ferrite deformation, accelerating the onset of dynamicrecrystallization (DRX) and promoting the intragranular nucleation of ferrite. Moreover,in the present case, adding 92 ppm B can nucleation of ferrite. Moreover, in the presentcase, adding 92 ppm B can obtain the best effect in improving the hot ductility of20CrMnTi steel with 0.05% Sn.

The hot ductility of Ti-bearing steel was studied by theoretical calculation and athermal simulation experiment. Meanwhile, microsegregation and precipitates were analyzed.The results showed that the S, P and O elements were enriched at the grain boundaries,while the hot ductility was deteriorated by inclusions of (Fe, Mn, Si, Al)(S,O) in theinterdendritic region. At a temperature of 1300 °C, large TiN particles have little effecton the hot ductility. In the temperature range from 1000 °C to 900 °C, the Reduction ofArea (R.A) declined rapidly from 81.77%to 31.77%, with the size of particles decreasing from 5 to 20 nm and quantity increasingfrom 1.2 inds/μm2 to 354 inds/μm2,respectively. In the temperature range from 900 °C to 850 °C,R.A decreased from 31.77% to 30.12%with the ferric films gradually thickening. The critical stress, 63.58 MPa, was equal totensile strength at 912 °C. Intergranular fracture occurred easily with higher criticalstress below 912 °C.