Effect of abrasive particle size on slurry abrasion resistance of austenitic and martensitic steels

The effects of the abrasive particle size and the pH-value of the aqueous solution on the abrasive wear resistance of H-13 steel and Hadfield steel were investigated. Abrasive wear tests, using a wet rubber wheel abrasion tester, were carried out applying abrasive sizes in the range of 0.15-2.40 mm. The pH values of the aqueous solution ranged from 5.5 to 12.8. The microstructure of each material was characterized with optical microscopy. The wear surfaces and the wear particles (debris) were analyzed by scanning electron microscopy (SEM). The macro- and microhardness were measured before and after the wear tests using a Vickers hardness tester. The surface topography of the wear scars was examined by a non-contact 3D profiler in order to measure the depth of the abrasive penetrations. The results demonstrated that Hadfield steel is more wear resistant than H-13 steel for all pH-values and all abrasive particle sizes used in the tests. Moreover, the micro-hardness of the wear scar surface of the Hadfield steel increased significantly with the size of the abrasive grain, while this increase was lower for the H-13 steel. The greater work-hardening of the austenitic Hadfield steels was considered to be responsible for this higher wear resistance in comparison with the martensitic H-13 steel. For both materials the loss of mass increased linearly up to a critical abrasive particle size (CPS); this CPS, the mass loss continued to increase but with a lower gradient. An explicit effect of the steel matrix on the mass loss behavior as a function of the abrasive grain size was not observed. The less acidic aqueous solution resulted in lower mass losses for both materials and for all abrasive grain sizes. This effect was greater for the two smaller abrasive grain sizes. For higher pH-values, lower depths of penetration of the abrasive particles were observed. The analysis of the wear particles in all test conditions displayed continuous and discontinuous chips for the H-13 steel but only discontinuous chips for the Hadfield steel,. For both materials two abrasive wear micromechanisms were determined: microcutting and microploughing. Finally, the results presented in this work suggest that the wear performance analysis of Hadfield steel, to be used in an abrasive environment, should consider the effects of the pH value of the aqueous solution and the abrasive particle size. (C) 2017 Elsevier B.V. All rights reserved.