The use of CADI, a variant of Austempered Ductile Iron (ADI) containing free carbides, is on the increase thanks to its excellent combination of high abrasion resistance and good impact toughness, when compared to other materials with similar wear resistance.The present work focuses on the study of two CADI variants in which carbides were obtained by a combination of alloying elements and the effect of a cooper chill located in the mould.A detailed microstructural characterization of the material was made; and the content and composition of the carbides as well as their stability during the heat treatment were particularly studied. The abrasion wear resistance was evaluated by testing under the ASTM G 65 standard, and comparing the relative wear resistance of samples taken just beside the cooper chill up to locations where the chill did not affect the solidification rate. The relative wear resistance, determined by using ADI as a reference material, ranged from EϷ3 to EϷ2 for samples taken from the different locations, close and far to the chill, respectively. For samples taken from the same locations, the impact toughness ranged from 6.5 to 10 J, respectively. The results allow establishing a relationship between the solidification rate, the microstructure and the mechanical properties, thereby enabling to predict their effect on current applications.
This work studies the sliding wear behavior of PVD coated austempered ductile iron samples. The effects of the substrate surface finishing method (grinding and polishing) and coating material (CrN and TiN) on the wear behavior are evaluated. Coatings were applied in an industrial reactor. Deposition times were adjusted to obtain similar film thicknesses in both coating materials. Wear tests under dry sliding conditions were carried out with a pin-on-disc tribometer (ASTM G99). The steady-state friction coefficient and wear rate were calculated for each sample variant. The wear track of the discs was examined by using optical microscopy and stylus profilometry.The results obtained indicate that the uncoated and TiN coated samples show steady-state friction coefficients close to 0.8, while the CrN coated samples show steady-state values close to 0.4. The sliding wear tests do not produce the fracture and/or delamination of the films in any case. The specific wear rate of the CrN and TiN coated samples is close to zero, while that of the uncoated samples is higher. The wear rate of the uncoated samples is slightly higher for the ground ones. The specific wear rate of the pins (AISI 52100 bearing balls) is higher than that of the discs in all the cases. The wear rate of the pins tested against uncoated samples is higher for the ground ones. The wear rate of the pins tested against coated samples is higher for the polished and TiN coated ones.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.