Work hardening in cone crusher liners

Övrigt konferensbidrag, 2003

Cone crushers are used in the aggregates and mining industries to crush rock material. A computer program was previously developed in order to predict the geometry of a worn cone crusher. In that model there was some discrepancy between predicted and measured geometry. The liners in rock crushers are made of manganese steel, a material known for its capability of work hardening. It is widely used in abrasive wear applications. It has been assumed that there is a variation in obtained hardness in a worn crusher liner; that higher crushing pressure would yield higher hardness, and consequently a lower wear rate in relation to the pressure. Such a variation would explain the discrepancy in the computer model. Hardness tests performed in this study reveal that this is not the case. The same hardness is measured regardless of where on the mantle the test is made or what rock material is used. Increased hardness is observed to a depth of about 1.5 mm. If the measured hardness is extrapolated to the surface, the obtained surface hardness is about 500 HV1. Microstructural analysis confirms the hardness tests. Slip lines generated by plastic deformation near the surface are clearly visible up to depths of 1-2 mm. The absence of variation in measured hardness leads to the conclusion that it is not the work hardening effect that causes the discrepancy in the wear model. Possible reasons are non-linear dependency between pressure and wear, dependency between particle size and wear rate, inaccuracy in the flow model, or tangential stresses near the surface, caused by frictional forces.