High Temperature Mechanical Properties of P-Containing High Strength IF Steel

Abstract

The high temperature mechanical properties of P- contained high strength interstitial free(IF) steel were investigated using Gleeble3500 thermal simulation testing machine, in terms of zero ductility temperature(ZDT), zero strength temperature(ZST) and the relationship of tensile strength with temperature. The fractured surfaces at different tensile temperatures were characterized by means of scanning electron microscope. The phase transition temperature interval was deduced by the THERMOCALC software. The results show that the ZDT and ZST of the steel are 1420℃ and 1445℃, respectively. The brittleness temperature interval Ⅰ is from 1400℃ to the melting point, and there is no the brittleness temperature interval Ⅲ. The transverse cracks on the surface of casting blank did not occur during the straightening process. The tensile strengths decrease with the increasing temperature in the test temperature range, and which are lower than 5.3 MPa above 1300℃. The result of THERMO-CALC calculation shows that, with the specimens cooling from 500℃ to 400℃, Fe3 P precipitates out in the α-Fe matrix,which may results in cold short. The transverse cracks on the continuous casing(CC) slab could dramatically be reduced by Hot-charging Technology.