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The failure analysis of a martensitic stainless steel (CA-15M) roll manufactured by centrif-ugal casting and used in cast glass rolling was carried out by means of traditional charac-terization techniques (optical metallography, SEM, EDX microanalysis, tensile testing andXRD). The roll was in the as-cast condition and its microstructure featured large proportionof dferrite (between 20% and 27%) in a martensitic ( a 0 ) matrix, with the d/ a 0 interfaces pre-senting an intergranular network of M 23 C 6 carbides. The crack propagation began in theinternal surface of the roll, with d/ a 0 intergranular and transgranular cleavage in the ‘‘equi-axed region’’ of the casting, progressing to d/ a 0 intergranular ductile fracture in the ‘‘colum-nar’’ and ‘‘chilled regions’’. Tensile thermal stresses in the internal surface of the rollassociated with microstructural embrittlement (network of interfacial carbide and micro-porosities) are thought to be the main causes for the premature failure of the roll. Finally,materials selection was performed to replace the CA-15M stainless steel with another classof stainless steel for centrifugal casting. 2013 Elsevier Ltd. All rights reserved. |
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