Influence of T4 Heat Treatment on Tribological Behavior of Za27 Alloy Under Lubricated Sliding Condition

Abstract

The effects of heat treatment on the microstructure, hardness, tensile properties, and tribological behavior of ZA27 alloy were examined. The alloys were prepared by conventional melting and casting route. The heat treatment of samples included the heating up to 370°C for 3 or 5 h, quenching in water, and natural aging. Lubricated sliding wear test were conducted on as-cast and heat-treated ZA27 samples using block-on-disc machine. The friction and wear behavior of alloys were tested in contact with steel discs using combinations of three levels of load (10, 30, and 50 N) and three levels of linear sliding speeds (0.26, 0.50, and 1.00 m/s). To determine the wear mechanisms, the worn surfaces of the samples were examined by scanning electron microscopy (SEM). The heat treatment resulted in reduction in the hardness and tensile strength but increase in elongation. The heat-treated alloy samples attained improved tribological behavior over the as-cast ones, under all combinations of sliding speeds and contact loads. The rate of improvement increased with duration of solutionizing process before quenching in water. Obtained tribological results were related to the effects of heat treatment on microstructure changes of alloy.

Influence of heat treatment on the microstructure and wear behavior of end-chill cast Zn–27Al alloys with different copper content

“…Furthermore, Prasad [13] reported that the presence of various phases with different thermal characteristics and mechanical properties in the structure of non-homogeneous as-cast alloys results in creation of residual stresses on a microscale. Based on this fact, Miroslav et al [2] concluded that obtained uniformity after heat treatment relieves the residual stresses and enhances the wear characteristics.…”

“…Some of the attractive properties of these alloys are lower density, excellent castability, good machinability, excellent corrosion resistance in a variety of environments and superior wear properties [1][2][3][4][5]. Desirable characteristics and low manufacturing cost of these alloys enable them to be considered as competing materials for cast metals such as high strength aluminum alloys, cast iron, copper alloys and brass.…”

“…One of the possible measures for overcoming this problem is applying a suitable heat treatment. Accordingly, several heat treatment procedures have been suggested by authors, which mainly involve solutionizing with subsequent water quenching and artificial aging [2,14].…”

“…Babic et al [1,2] studied the effects of heat treatment, involving solution treatment at temperature of 370°C for 3 and 5 h followed by quenching in water, on tribological behavior of ZA27 alloys. They reported that higher wear resistance of the heat-treated alloys over as-cast ones is attributed to the finer and more uniform distributed microconstituents.…”

“…To the best of our knowledge, most of published papers have focused on the aging characteristics of conventional zinc-aluminum alloys [1,2]. However, little effort has been made to investigate the microstructural changes and phase transformation during slow cooling process.…”