Vilma Ratia

Impact-abrasion wear of wear-resistant steels at perpendicular and tilted angles

Earth moving and processing machinery has to withstand heavy wear caused by impacts and scratching by the soil. Especially, the edges are subjected to heavy wear. To simulate these conditions, impeller–tumbler impact-abrasion wear testing equipment was used to determine the wear resistance of four steel grades at perpendicular and tilted sample angles. The angles were selected to simulate the loading conditions. Natural granite rock was used as abrasive. The amount of wear was clearly smaller in the harder materials. The significance of hardness was quite similar at both sample angles in the steady-state wear of wear-resistant steels. On the initial state wear, hardness had a slightly greater effect at the perpendicular angle due to more severe wear in sample edges already at the beginning of the test. Overall, the largest differences in wear were observed in the sample edges. At the perpendicular sample angle, the sample edges were much more rounded. Some small differences were observed in the surface formations due to dissimilar movement of the abrasive. Deformed surfaces and fractured lips indicated that wear occurred mainly by the deformation of material followed by the removal of the deformed areas through impacts. In addition, scratches and dents were observed. It was found that larger sized abrasives caused higher mass loss than abrasives of similar mass but smaller size. Moreover, same amount of abrasive particles in each test reduces the scatter of the results.

Effect of Multiple Impacts on the Deformation of Wear-Resistant Steels

More durable materials enable reducing the downtime and maintenance costs by decreasing the number of replaced core components in various industrial applications. In this study, the behavior of three wear-resistant quenched martensitic steel grades and the S355 structural steel was examined in controlled impact conditions. The materials’ impact behavior was investigated by several methods including residual stress measurements and electron backscatter diffraction. For all studied materials, the size and depth of the impact marks correlate via a logarithmic function to the number of impacts mostly due to work hardening. The underlying deformation behavior of the material depends on the mechanical properties and microstructure of the material. At high impact counts, softer martensitic steel was found to behave differently when compared to the other tested materials as it underwent severe changes in its microstructure and exhibited marked hardening.