Wear 267 (2009) 2116–2121 Contents lists available at ScienceDirect Wear journal homepage: www.elsevier.com/locate/wear Abrasive wear study of white cast iron with different solidification rates J.J. Coronado a,b,∗ , A. Sinatora a a Surface Phenomena Laboratory, Department of Mechanical Engineering, University of Sao Paulo, Sao Paulo, Brazil b Mechanical Engineering School, Universidad del Valle, Cali, Colombia article info Article history: Received 23 September 2008 Received in revised form 19 June 2009 Accepted 5 August 2009 Available online 13 August 2009 Keywords: Solidification rate Abrasive wear White cast iron Austenitic matrix Martensitic matrix abstract The abrasive wear resistance of white cast iron was studied. The iron was solidified using two solidifi- cation rates of 1.5 and 15 ◦ C/s. Mass loss was evaluated with tests of the type pin on abrasive disc using alumina of different sizes. Two matrices were tested: one predominantly austenitic and the other pre- dominantly martensitic, containing M 3 C carbides. Samples with cooling rate of 15 ◦ C/s showed higher hardness and more refined microstructure compared with those solidified at 1.5 ◦ C/s. During the test, the movement of successive abrasives gave rise to the strain hardening of the austenite phase, leading to the attainment of similar levels of surface hardness, which explains why the wear rate showed no dif- ference compared to the austenite samples with different solidification rates. For the austenitic matrix the wear rate seems to depend on the hardness of the worn surface and not on the hardness of the material without deformation. The austenitic samples showed cracking and fracture of M 3 C carbides. For the predominantly martensitic matrix, the wear rate was higher at the solidification rate of 1.5 ◦ C/s, for grain size of 66 and 93 m. Higher abrasive sizes were found to produce greater penetration and strain hardening of austenitic matrices. However, martensitic iron produces more microcutting, increasing the wear rate of the material. The analysis of the worn surface by scanning electron microscopy indicated abrasive wear mechanisms such as: microcutting, microfatigue and microploughing. Yet, for the iron of austenitic matrix, the microploughing mechanism was more severe. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Solidification of cast iron consists of nucleation and growing process of different phases, such as: austenite, graphite and cemen- tite. The solidification of hypoeutectic cast iron usually begins with austenite dendrite formation, when it undergoes super-cooling in relation to the liquid temperature of the considered alloy [1]. With the increase of the cooling rate, for example, by the use of perma- nent mold or with the addition of alloy elements, carbides stabilize, and white cast iron is formed in detriment of gray cast iron that is thermodynamically more stable. The modification of the matrix in order to increase the matrix hardness can be achieved through heat treatment to transform the austenite into martensite. The metal–metal contact in austenitic steels with high manganese leads to hardening due to surface deformation, producing an increase in hardness [2]. White cast irons have great employment in the manufacture of extrusion nozzles, for the coating of cement mixers, rolling cylin- ders and in mining industry, because of their high abrasive wear ∗ Corresponding author at: Surface Phenomena Laboratory, Department of Mechanical Engineering, University of Sao Paulo, Sao Paulo, SP, Brazil. Tel.: +55 11 30919870; fax: +55 11 38142424. E-mail address: johnjairocoronado@yahoo.com (J.J. Coronado). resistance. Abrasive wear can be classified as: two-body abrasive wear (pin on abrasive disc), which occurs when the abrasive parti- cles are fixed on the second body that slides on another scratched or removing material; and the three body abrasive wear (rubber- wheel test), which occurs when the abrasive particles are free between two surfaces [3]. Zum Gahr [4] studied white cast iron in a range of 7–45% of primary and eutectic carbides and found a relation between the matrix structure and abrasive wear. Gundlach and Parks [5] found lower wear rates of austenitic iron, compared to martensitic iron, using alumina and silicon carbides as abrasive. Sinatora et al. [6] studied the effect of the percentage of retained austenite in the abrasive wear rate of white cast iron with 13% of chromium and 2% of carbon using the test pin against sandpaper. They found a reduction in the wear rate, with an increase in the percentage of austenite. Fang [7] proposed that the behaviour of austenitic and martensitic matrices depend on the proportion Cr/C, the austenitic matrix would have better performance than the martensitic matrix when the Cr/C proportion is greater than 5. In this paper the effects of different solidification rates (1.5 and 15 ◦ C/s) in the abrasive wear resistance on white cast iron with M 3 C carbides, with two different matrices was studied, being one of these matrices predominantly austenitic and the other predominantly martensitic using alumina of different sizes as abrasive. 0043-1648/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.wear.2009.08.010