Influence of varying aluminum contents on the hot ductility of medium manganese steels

The influence of aluminum nitride (AlN) precipitation on the hot ductility of medium manganese steels was investigated using hot tensile testing, as good hot ductility is essential for continuous casting. A reasonable hot ductility is reached up to 0.04% and at 1.6% aluminum. At 0.04% only few AlN precipitates due to slow kinetics. At 1.6%, coarse AlN precipitates at high temperatures, minimally affecting hot ductility. In contrast, 0.6% aluminum leads to significant ductility loss due to AlN precipitating at γ_Fe grain boundaries. At 1% aluminum, higher nitrogen contents only slightly reduce hot ductility. Thus, hot ductility is mainly influenced by AlN precipitation from γ_Fe. SEM-EDX analysis confirmed that fine AlN at γ_Fe grain boundaries correlate with poor hot ductility.