Untersuchung unterschiedlicher Einflussfaktoren auf die Heißrissbildung von Kohlenstoffstählen

For the evaluation of the hot tearing sensitivity of continuous casting steels some criteria are based on the definition of a critical strain. An approach from literature considers the brittle temperature range and the strain rate for the calculation of a critical strain. The former mainly depends on the microsegregation during solidification. In this thesis results from literature have been compared with results from calculations using a microsegregation model with respect to characteristic temperatures in the mushy zone. Furthermore, experiments under laboratory conditions (Submerged Split Tensile-Test) have been made in order to investigate the hot tearing sensitivity depending on the carbon content at various strains and strain rates. The results of these experiments are compared to calculated critical strains. The results show that critical strains for 0.08 and 0.12 wt.-% carbon steels (1.3 %Mn, 0.3 %Si, 0.004 %P, and 0.005 %S) are considerably lower than calculated values. Furthermore, it has been found that strains, induced by shrinkage and thermal contraction in peritectic steels, are high enough to initialise hot tearing.