ITV Instituto Tecnologico Vale

Ribeirão Preto, Brazil

ITV Instituto Tecnologico Vale

Ribeirão Preto, Brazil
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Pereira J.I.,University of Sao Paulo | Machado P.C.,University of Sao Paulo | Machado P.C.,Federal University of Pará | Penagos J.J.,University of Sao Paulo | And 3 more authors.
Wear | Year: 2017

This work characterizes the wear behavior of pearlitic SAG Mill liner material for in-service and laboratory worn samples. The abrasion tests (Dry Sand/Rubber Wheel Abrasion Test – DSRW) were carried out on samples removed from the undeformed region of the same liner – applying different normal loads (from 22 N to 380 N). The electron microscopy techniques (FEG-SEM, FIB-SEM) were used to characterize the microstructural and wear micromechanisms. A cross sections analysis of both samples highlighted the presence of a deformed layer. The hardness of the original microstructure (undeformed pearlite) was 360 HV10, however, this work shows that the typical operational conditions in the mining process increased the hardness in a sub-superficial layer up to 580 HV10. The thickness of the deformed layer was determined to be approximately 300 µm and 3 µm in-service and laboratory worn samples, respectively. The in-service worn samples showed scratches and micro-indentations along the surface. For the laboratory tests, the predominant wear mechanisms were micro-cutting with and without micro-ploughing and micro-indentation. It was shown that the normal load in the laboratory abrasion tests did not significantly affect the deformed layer formation. For the various normal loads applied, the thickness of deformed layer remained practically constant, around 3 µm. On the other hand, regarding wear mechanisms, a change in the normal load affected the indentations/cutting ratio: for lower loads micro-indentations prevailed whereas increased loads (above 130 N) indicated the presence of micro-cutting. Therefore, on the basis of these observations, it was possible to conclude that the DSRW represented a suitable alternative to simulate the abrasion component occurring in liners for SAG Mills once a higher load was applied (200 N to 280 N). © 2017 Elsevier B.V.


Franco L.A.,University of Sao Paulo | Sinatora A.,University of Sao Paulo | Sinatora A.,ITV Instituto Tecnologico Vale
Wear | Year: 2017

Material removal factor, fab, is defined by ZumGahr as “the ratio of volume of wear debris to the volume of wear groove produced”. It appears in the literature within the context of abrasive wear, usually as a possible indication of prevailing mechanisms such as plowing, wedge formation and cutting. Microcracking, an important mechanism in the abrasion of brittle material such as highly hardened steels and ceramics, was not considered in this work. Measurements of cross section areas in scratch tests – groove and pile up – are essential for fab calculation. This paper presents a short review of the literature in that sense. It also covers scratch testing of gray cast iron (GCI) and AISI 1070 steel specimens, both with macro hardness close to 200 HV30kgf. Laboratory tests were performed under constant loads selected from 20 to 200 mN, dry interface. Geometric parameters of the scratches were measured with an optical interferometry profilometer and an SEM was used for image analysis. Clear correlations between scratch width (or depth) and applied load were observed, but that was not the case with calculated fab values. Image analysis confirmed the presence of different abrasion mechanisms at the same scratch shedding light on the difficulties encountered when measuring groove and pile-up areas. © 2017 Elsevier B.V.

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