Analysis of a martensitic stainless steel that failed due to the presence of coarse carbides

A set of martensitic stainless steel cutting blades failed in use when installed in a meat mill for preparing sausages. Failure analysis was conducted on the cutting blades. Results indicate that the failure of the whole set was caused by the fracture of one blade by fatigue, whereas the others failed by impact from the debris generated from the first one. The metallographic analysis shows that the microstructure of the first blade was that of a martensitic matrix in which coarse M23C6 carbides were present, yielding to a hard but brittle material.