9th ECCC European Continuous Casting Conference – ECCC 2017

The In-Situ Material Characterization–Bending (IMC-B) test is a new laboratory method to evaluate the susceptibility of steel towards transverse crack formation in the continuous casting process. Samples are cast under near process conditions, cooled to bending temperature in a controlled way and finally bent in a 3-point bending test with a deflection of only a few millimeters, according to the conditions in the straightening area of a continuous casting machine. The maximum tensile strain is as well limited to only a few percent and both the re-crystallization as the deformation induced precipitation/phase transformation are suppressed. Surface oxidation is permitted and the initiation of defects at the surface along austenite grain boundaries is thus promoted. First result proved the correspondence of the characteristic of defects with those formed in the cc process and the significance of the results regarding the influence of bending temperature and alloying content. This work deals with the results of bending experiments on Al-killed medium carbon steel at temperatures of between 1100°C and 650°C. The thermal sequence is derived from slab casting conditions. The results prove the existence of a pronounced temperature range of low ductility at between 1000°C and 850°C. At the most critical temperatures a tensile strain of only 1.5 % is sufficient in order to form first transversal cracks. The number is increasing significantly at higher strains up to 6.5 %. The results are finally interpreted by precipitation kinetics. In future the results will mainly be used to verify quality functions for process models.