Tehnički Glasnik (Jan 2017)
Effect of heat treatment parameters on the mechanical properties and microstructure of aluminium bronze
Abstract
Aluminium bronzes are used for their combination of high strength, excellent corrosion and wear resistance. This paper presents the research of heat treatment parameters of two different chemical compositions of aluminium bronze (Cu-Al-Fe- Ni alloy) on microstructure and mechanical properties. The heat treatment employed in this research were solutionizing and tempering. The solution treatment was carried out at a temperature of 950 °C and the duration in the range of two hours. Similarly, tempering was carried out at 300 °C and 400 °C, wherein the duration was maintained at two hours. The heat treated samples were subjected to the cold water quenching in order to bring them to an ambient temperature. Metallographic studies were performed on samples in order to determine the changes in the microstructure of the hardened bronze, on the metallographic microscope OLYMPUS GX51 with a digital image analysis and the scanning electron microscope TESCAN VEGA 5136MM with EDX along with the digital recording on the computer. Moreover, the Glow Discharge Spectroscopy-GDS was done to determine the chemical composition of the samples. The results of the chemical composition for the aluminium bronze AK2 were: Cu- 78,37%; Al- 10,52%; Fe- 4,44%; Ni- 5,16% and for AK3 alloy: Cu- 78,95%, Al- 10,97%; Fe- 4,16%; Ni- 4,8%. The behavior of the alloy has been assessed in terms of the influence of the temperature and duration of the heat treatment on the microstructural and mechanical properties of the samples. The hardness of samples was measured by using a Vickers hardness tester at an applied load of one kg. The samples were polished metallographically prior to their hardness measurement and an average of three observations has been considered. The hardness of the AK2 alloy increased from 320 HV1 to 425 HV1 after quenching and to 500 HV1 after tempering on 300 °C or 540 on 400 °C. The hardness of the AK3 alloy increased from 300 HV1 to 400 HV1 after quenching and to 475 HV1 after tempering on 300 °C or 470 on 400 °C.
