Within these investigations, a combined welding process consisting of inductive preheating and a single layer GMA-laser hybrid welding process was developed. High-strength fine-grained steels with grades of 460 up to 690 N/mm² in a thickness range from 10 to 20 mm were welded in one operation. By means of inductive preheating, the cooling period as well as the microstructure and mechanical properties were influenced. Furthermore, cold and hot cracking of the weld metal and the HAZ was affected. The weld qualities were classified using visual inspection, x-ray inspection and metallographic analyses of cross-sections according to ISO 13919 and ISO 12932. The welded seams reached the normative regulations of quality level B. The effect of various preheating temperatures on the cooling down periods and the mechanical properties were shown using temperature measurements, hardness measurements, as well as tensile tests and Charpy impact tests. For a deeper process understanding, the experimental investigations were accompanied by numerical simulations of the inductive preheating and the GMA-laser hybrid welding. A good agreement between measurements and calculations could be reached.