Effect of microstructure on the oxidative wear behavior of plain carbon steel

Wear 262 (2007) 1225–1231

Effect of microstructure on the oxidative wear behavior of plain carbon steel
V. Abouei ∗ , H. Saghafian, Sh. Kheirandish
Iran University of Science and Technology, Iran Received 3 June 2006; received in revised form 24 October 2006; accepted 15 November 2006 Available online 15 December 2006

Abstract According to explore the tribological potential of the dualphase (DP) steel as wear resistant material, the wear and friction characteristics of this steel, which consists of hard martensite island embedded in a ductile ferrite matrix, have been investigated and compared with those observed in plane carbon normalized (N) and hardened (H) steels with the same composition of 0.2 wt.% carbon. Dry sliding wear tests have been conducted using a pin-on-diskmachine under different normal loads of 21.3, 28.5, 35.7 and 42.6 N and at a constant sliding speed of 1.20 m/s. The analysis of surface and wear debris of specimens showed that wear mechanism was mainly mild oxidative. The friction, wear rate and wear coefficient of the steels, have been explained with respect to microstructure and the wear mechanism. © 2006 Elsevier B.V. All rights reserved.Keywords: Dual phase steel; Mild oxidative wear; Microstructure; Heat treatment

1. Introduction Dual phase (DP) steels consist of hard martensite islands embedded in a relatively soft and ductile matrix of ferrite. They have recently emerged as a potential engineering material system for automobile and other engineering application [1]. Low carbon dual phase steels have found application inmaking pipelines for transportation of mineral slurry and other wear resistant applications [2]. In a recent study they have also been found to hold good potential for use as farm implements where strength and wear resistant become of great concern [3]. The tribology of dual phase steels has not yet been investigated extensively, and only a few studies have been reported [2–9]. Tyagi et al. [4] haveshown that the duplex microstructure of the DP steel offers higher wear resistance than that observed in normalized steel. It has also been indicated that the wear resistance of dual phase steels increases with increasing volume fraction of martensite [5–8]. Sawa and Rigney [9] have found that the wear behavior of the DP steel also depends strongly on its morphology, i.e. the

shape, size,and distribution of its martensite. The work reported is a part of a detailed study on the comparative wear and friction characteristics of plain carbon dual phase (DP), normalized (N) and hardened (H) steels, using a standard pin-on-disk wear testing machine. 2. Experimental procedure Cylindrical pin samples (30 mm × 6.0 mm in diameter) of a plain carbon steel having C, 0.21 wt.%; Mn, 1.18 wt.%;Si, 0.26 wt.% and balance iron, were used for the current investigation. The specimens were heat treated using a vertical tubular furnace. The heat treatments (Table 1) carried out were (1) normalizing, involved austenitization at 950 ◦ C for 15 min followed by air cooling, (2,3,4,5) intercritical annealing, i.e. heating at 780 ◦ C for 6.5, 7.5, 9 and 20 min followed by water quenching and (6)hardening, involving austenitization at 950 ◦ C for 15 min followed by quenching in water. The resulting samples of different heat treatments are designated as N, DP1, DP2, DP3, DP4 and H, respectively. Microstructures were analyzed to determine the volume fraction of martensite in the DP steels by a point-counting method, after polishing to 4/0 grade emery paper and etching with 2% Nitalsolution. The macrohardness of all samples was measured using a Brinell hardness tester.

∗ Corresponding author at: Department of Metallurgy and Materials Engineering, Iran University of Science & Technology, Narmak 16844, Tehran, Iran. Fax: +98 21 77240480. E-mail address: abouei v@metaleng.iust.ac.ir (V. Abouei).

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