Influence of titanium on hot ductility of as cast steels

Effect of High Temperature Deformation on the Hot Ductility of Nb Microalloyed Steel

“…[80) On the contrary, for Ti and S, the tensile specimens must be tested directly after in situ melting and solidification to ensure dissolution of the TiN particles and MnS inclusions. [49, [80][81][82] Provided these precautions are taken, precipitate sÏze and distribution in the tensile specimens foliows closely that found near the surface of the continuously cast slabs. [9,78] However, even in situ casting of the tensile specimens is not ideal, as smali castings in general produce neither the exact segregation patterns experienced near the surface of conventionaliy cast strand nor the columnar grain structure that is often present and which may be directly responsible for the ease of crack propagation during straightening.…”

“…The beneficial effect of Ti depends on the cooling rate. Abushosha et al [81] observed that for a Nb-containing steel, Ti improved the hot ductility in the temperature range 800-1000°C only when the cooling rate was slow enough, i.e. 25 Kmin-I .…”

Effects of Titanium Addition on Precipitate and Microstructural Control in C-Mn Microalloyed Steels.

“…With typical N and Al contents such as those of the steels investigated, AlN is not likely to precipitate. 3,9,10) Finally, the thermal treatment stage performed by austenitising at 920°C, quenching and tempering only affects the less stable carbides and nitrides. Here, factors concerned with phase coalescence and non-equilibrium generation of new constituents assume greater importance but their study is beyond the scope of the present investigation.…”

“…Alternatively, transformation controlled cracking can occur due to formation of thin films of soft ferrite, promoting strain localisation at grain boundaries. [8][9][10][11] Microalloying with Ti is a well known method to reduce hot cracking susceptibility and a large number of papers were published on its effects in microalloyed steels. It is now established that Ti, being a powerful nitride former, acts by removing most of the N from solid solution at very high temperatures, thus preventing subsequent grain boundary embrittlement to occur due to formation of nitrides with other microalloying elements.…”

“…It is now established that Ti, being a powerful nitride former, acts by removing most of the N from solid solution at very high temperatures, thus preventing subsequent grain boundary embrittlement to occur due to formation of nitrides with other microalloying elements. 1,5,10,11) A debate was raised in literature on optimal Ti : N ratio as a function of other alloying elements and on the actual mechanisms acting in reducing hot cracking susceptibility. 8,9,11,12) It is now widely accepted that optimal Ti : N ratio should lie on the hyperstoichiometric side, at values ranging from 4 to 10, depending on actual steel composition.…”