Modern bearing steels need to have good mechanical properties as well as sufficient corrosion resistance in order to be considered for an application in advanced aircraft engines. The desired material properties can be reached by low pressure carburizing. High alloyed steels tend to form carbides during carburizing because of their high content of carbide forming elements. Especially the formation of chromium rich M7C3-carbides in the highly carburized case has a negative influence on the corrosion resistance of the material. In this diploma thesis the low pressure carburizing behaviour of the new presumptive case hardened bearing steels C4+Nil, C5+Nil and C6+Nil was investigated. For this purpose, five carburizing trials were conducted with different process temperatures and different numbers and lengths of boost and diffusion cycles. The aim of this work was to establish adequate process parameters for the low pressure carburizing treatment of the alloys C4+Nil, C5+Nil and C6+Nil, which allow to create a hard and wear resistant surface layer, but without strong chromium carbide precipitations that could lead to a significant decrease in the materials corrosion resistance.