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High-chromium white cast iron contains chromium carbides that provideexcellent wear resistance, but also cause poor fracture properties. Heat treatments areapplied in an attempt to decrease the angularity of the eutectic carbides and to improve thetoughness of the matrix by intentionally creating a high fraction of retained austenite,while minimizing the formation of secondary carbides. It is found that the austenitisingtemperature hardly affects the carbide morphology. However a large effect is found on theshape and size of the secondary carbides formed and on the relative fractions of austeniteand martensite. Measurements are performed with an instrumented drop-weight impacttower on Charpy-like specimens containing electric-discharge-machined notches. Resultsshow that austenitising at high temperature (1100 °C) leads to a significantly larger totalfracture energy compared to the as-cast condition. However, the energy absorbed at crackinitiation and the KIc value seem not to be affected. SEM observations of the fracturesurfaces clearly indicate that the crack propagates along the interfaces of or through theeutectic carbides. A ductile fracture appearance is found around secondary carbides.