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

Abstract

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.