Effects of Si alloying and T6 treatment on mechanical properties and wear resistance of ZA27 alloys

Abstract

To improve the mechanical properties and wear resistance of ZA27 alloy, Si was introduced to the alloy, and the effect of Si alloying and T6 heat treatment on the microstructure, mechanical properties and wear resistance was investigated. The results show that with 0.55% Si, the microstructure of the alloy can be refined effectively, which leads to the increase of hardness. But the tensile strength and elongation decrease because Si undermines the integrity of the matrix. On the other hand, the dendrites are transformed into a desired α+η+(α+η) mixture with T6 heat treatment, which introduces a remarkable increase to the elongation and hardness of the alloy. The wear resistance of the ZA27 alloy with Si alloying is significantly better than that of the ZA27 alloy without Si. With the increase of Si addition, the wear resistance of the alloy firstly increases and then decreases. In the alloy without Si alloying, severe plastic deformation and large delamination were observed on the worn surface of the alloy. However, with the increase of Si, the main wear mechanism transformed to abrasive wear gradually. In addition, the T6 treatment can further improve the wear resistance of the alloy with Si alloying.

Keywords

• ZA27 alloy; Si alloying; mechanical properties; wear resistance