In this article, the effect of the volume content and distribution of non-metallic inclusions on the fracture toughness of a quenched and tempered 42CrMo4 steel is investigated. The investigations focused on the material behavior in the ductile-brittle transition range. To this end, fracture toughness tests were performed on 42CrMo4 with different inclusion characteristics. These were achieved by metal melt treatment with functional filter materials. The results showed a significant effect of both volume content and distribution of the non-metallic inclusions. The transition to brittle material behavior was accompanied by a decreasing fracture toughness as well as low scatter of the test data.
EXTENDED ABSTRACT