Kornwachstum und Rekristallisationsverhalten von HSLA-Stählen

This master thesis was performed in cooperation of the Montanuniversität of Leoben and the voestalpine and examines the effects of the combination of microalloying elements (aluminium, niobium and titanium) on the grain growth and recrystallization behaviour in HSLA-steels. A reference alloy (23MnNiCrMo5-4) served as a basis. In this reference, firstly the titanium-content was varied and secondly the aluminium-content was varied. The austenitic grain growth was investigated by annealing treatment and subsequent metallographic grain boundary etching. The grain size was evaluated using the line-segment-method according to DIN EN ISO 643, with several recordings being evaluated over the cross section. The mean grain diameter was calculated from this. It was found that the mean grain size decreases with increasing titanium content and the variation of the aluminium content has hardly any influence on the mean grain size. The recrystallization behaviour was determined by means of double deformation test. The result showed that the recrystallization is accelerated with increasing titanium content and the recrystallized fraction increases with increasing titanium content. In addition, a further acceleration of the recrystallization, as well as an increase in the recrystallized fraction, were observed when the austenitizing temperature was reduced.