Porosity in Medical Drills Caused by Fractured Carbides – A Review

Abstract Just as 10 years ago, an examination of drills used in human medicine revealed cracks in the microstructure which can be attributed to fractured carbides. The drills are made of corrosion-resistant chromium steels with special carbides which are of the composition (Cr,Fe) 23 C 6 and (Cr,Fe) 7 C 3 (e. g. material no. 1.4125 or 1.4112). The cracks occur in the coarser carbides during the forming of the drills. It was considered problematic that the cracks are filled with contaminants which cannot be fully removed in the cleaning process. One of the drills examined for this study also contained MnS inclusions which is consistent with a “rust and acidresistant steel / free-machining steel” (e. g. material no. 1.4005).