There are currently no internationally standardized procedures for determining the fracture appearance transition temperature FATT50. Brittle fracture surface fractions (in %) of broken impact test pieces from ferritic steel are compared. A unified methodology, recently developed within the German Steel Institute VDEh, allows a more reproducible determination of the FATT values. The result is the new Stahl-Eisen-Prüfblatt (test specification for iron and steel) SEP 1670 which may be the basis for global standardization of this test methodology. Diagram for determining characteristic values from the compensation curves is presented. The SEP 1670 applies to forged steels in particular according to SEW 555. A Windows-based FATT-determination software was developed as a supplement to this test specification.