The use of new high-strength steels with good plasticity in automobiles offers a remarkable potential for improvements in the area of weight reduction with simultaneous improvement in crash-safety. For the steel industry, this trend to highly-alloyed, high-strength steels means a considerable potential for metallurgical research. Continuous casting in particular appears to be a big challenge for such steels. The focus of the investigations documented in the present doctor thesis is: production routes, high temperature properties, crack behaviour, non-metallic inclusions and segregation effects in new light-weight steels with induced plasticity (transformation induced plasticity - TRIP - and twinning induced plasticity - TWIP - steels). It is possible to investigate these topics using thermodynamic calculation software packages and certain laboratory trials. The high-temperature properties and the crack susceptibility of new steel grades are tested with the SSCT (submerged split chill tensile) test. Metallografic work and a new method for the determination of steel cleanness are important parts of the work too. Knowledge of the high-temperature mechanical properties, the crack sensitivity and the non-metallic inclusions provides an important basis for the development of industrial-scale production processes for these new steel grades using the continuous casting process.