Journal of Materials Processing Technology 142 (2003) 762–766 The effect of precipitation-hardening conditions on wear behaviours at 2024 aluminium wrought alloy Hülya Kaçar ∗ , Enver Atik, Cevdet Meriç Mechanical Engineering Department, Engineering Faculty, Celal Bayar University, 45140 Manisa, Turkey Received 2 September 2002; received in revised form 20 March 2003; accepted 30 April 2003 Abstract In this study, wear behaviours of 2024 aluminium wrought alloy were investigated in different tribological conditions based on its ageing conditions. For this purpose, the alloy aged in five different temperatures and periods (at room temperature for 1 week, at 120 ◦ C for 24 h, at 150 ◦ C for 18 h, at 160 ◦ C for 16 h, at 200 ◦ C for 2 h) was worn in pin-on disc model wear test apparatus using different abrasive grit size (5, 11, 18 and 30 m SiC papers). Furthermore, the effects of different sliding speeds (0.078, 0.156, 0.208 and 0.338 m s -1 ) and loads (6.45, 9, 9.3 and 11 N) on wear resistance were also examined. It was measured amounts of mass loss and examined worn surfaces. The mass loss of the specimens increased with load and the abrasive grit size. © 2003 Published by Elsevier B.V. Keywords: 2024 Aluminium wrought alloy; Abrasive wear; Precipitation hardening 1. Introduction The use of aluminium alloys in industry is increasing ow- ing to their high strength/density ratios and other advan- tage properties. Precipitation strengthening is applied to the some aluminium alloys. Precipitation strengthening is one of the most important hardening methods used to increase strength in aluminium alloys. In this treatment, the second phase is precipitated within matrix phase. The hardness and strength values increase as a result of precipitation of a new precipitate due to period and heat from supersaturated solid solution [1,2]. Alloy 2024 is an aluminium alloy containing copper, mag- nesium, manganese and some minor alloying elements. It is fabricated mainly by hot extrusion and hot rolling. It has the highest hardness value between aluminium alloys. Elastic- ity modulus and strength value of 2024 aluminium wrought alloy are high. It is used in engineering applications such as aeroplane constructions, orthopaedic soles, rivet and pulling wheels. One of the most important properties of 2024 alu- minium alloy is that the treatment of solid solution is not so critical [3,4]. This alloy can be aged naturally or artificially [5–9]. 2024 Aluminium wrought alloy has Mg. So its pro- duction is made by special methods. The formability of the this alloy is very good. Its corrosion strength is lower than ∗ Corresponding author. E-mail address: hulya.kacar@bayer.edu.tr (H. Kaçar). other aluminium alloys. Physical and mechanical properties of 2024 aluminium wrought alloy are very good [4,10]. In 2024 aluminium wrought alloy that is used in this study, element that provides precipitate is copper. The prin- cipal precipitation-hardening reactions, however, are those of the ternary aluminium–copper–magnesium system. The commercially important alloys contain copper as major addi- tion, and the phase reactions which occur are those between an aluminium solid solution and the intermetallic phases CuAl 2 and CuMgAl 2 . Precipitation hardening at high ratios of copper to magnesium is achieved in the sequence GP zones through a coherent phase (θ ′ ) to CuAl 2 (θ). Precipi- tation hardening at lower ratios of copper to magnesium is achieved in the sequence GP zones through a coherent phase to CuMgAl 2 . This intermetallic precipitates are incoherent with main structure and it affects mechanical and physical properties of the material [5,11–14]. The most important reason for the damage and conse- quently failure of machine parts is wear [15,16]. Technically speaking, according to DIN 50320 and ASTM G40-93 stan- dards, wear is unwanted surface damage as a result of sep- aration of small pieces from the material surface due to the interaction of other materials such as liquid, solid or gas. The mechanism of wear means the physical and chemical processes that occur during wear. The term of abrasive wear is the removal of pieces from one of the two rubbing bodies. The abrasive wear occurs in devices moving in touch with various abrasives [16]. 0924-0136/$ – see front matter © 2003 Published by Elsevier B.V. doi:10.1016/S0924-0136(03)00642-3