Comparison of Hot Ductility Behavior of microAlloyed Steels with Different B-, Cr-, Ni- and Ti-content

The continuous casting process requires permanent investigation and innovative improvements due to its large application in steel production. A good hot ductility behavior is essential to avoid the formation of defects during slab casting. The behavior of two low alloyed steels, with different compositions in B-, Cr-, Ni- and Ti-content, was compared to understand the features that might bring improvements in hot ductility, and consequently reduce the occurrence of defects. The first alloy investigated presents a low content of all elements and the second has a composition with a higher fraction of the alloying elements referred to. Hot tensile tests after in situ melting of the samples were performed to reveal the hot ductility behavior of the each microalloyed steel. The results of final reduction of area showed a much better ductility of the second steel, alloyed with higher B, Cr, Ni and Ti-content, in comparison to the first. Initial microstructure analysis was performed as a means of better evaluating the effects of the temperatures and strain rate applied in both steels. Furthermore, precipitation kinetics of both steels were calculated using the MatCalc software, determining the expected mean radius, number density and phase fraction of the predicted precipitates. Possible reasons for the changes seen experimentally are discussed based on both, simulations and microstructure analysis.