Failure mode and hot ductility of Ti-bearing steel in the brittle zone

The hot ductility of Ti-bearing steel was studied by theoretical calculation and a thermal 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 the interdendritic region. At a temperature of 1300 degrees C, large TiN particles have little effect on the hot ductility. In the temperature range from 1000 degrees C to 900 degrees C, the Reduction of Area (R. A) declined rapidly from 81.77% to 31.77%, with the size of particles decreasing from 5 to 20 nm and quantity increasing from 1.2 inds/mu m(2) to 354 inds/mu m(2), respectively. In the temperature range from 900 degrees C to 850 degrees C, R. A decreased from 31.77% to 30.12% with the ferric films gradually thickening. The critical stress, 63.58 MPa, was equal to tensile strength at 912 degrees C. Intergranular fracture occurred easily with higher critical stress below 912 degrees C.