Solution Treatment Effect on Tensile, Impact and Fracture Behaviour of Trace Zr Added Al\u201312Si\u20131Mg\u20131Cu Piston Alloy

Md Salim Kaiser

doi:10.1007/s40033-017-0140-5

Abstract

The effects of T6 solution treatment on tensile, impact and fracture properties of cast Al–12Si–1Mg–1Cu piston alloys with trace of zirconium were investigated. Cast alloys were given precipitation strengthening treatment having a sequence of homogenizing, solutionizing, quenching and ageing. Both cast and solutionized samples are isochronally aged for 90 min at different temperatures up to 300 °C. Tensile and impact properties of the differently processed alloys have been studied to understand the precipitation strengthening of the alloys. Fractograpy of the alloys were observed to understand the mode of fracture. It is observed that the improvement in tensile properties in the aged alloys through heat treatment is mainly attributed to the formation of the Al2Cu and Mg2Si precipitates within the Al matrix. Solution treatment improves the tensile strength for the reason that during solution treatment some alloying elements are re-dissolved to produce a solute-rich solid solution. Impact energy decreases with ageing temperature due to formation of GP zones, β′ and β precipitates. The fractography shows large and small dimple structure and broken or cracked primary Si, particles. Microstructure study of alloys revealed that the solution treatment improved distribution of silicon grains. The addition of Zr produces an improvement in the tensile properties as a result of its grain refining action and grain coarsening resistance in the matrix at a higher temperature.

Highlights

Al–Si is a 4xxx series alloy, which is basically non-heat treatable
Solution treatment involves keeping the alloy on temperature higher than solvus temperature but less than liquidus temperature for a period of time to get homogeneous one phase of the solid solution, where the solute atoms are dissolved completely in the solution
In the early stage of ageing, fine and profuse GP zones homogeneously distribute in the matrix and their effects on strengthening are significant

Summary

Introduction

Al–Si is a 4xxx series alloy, which is basically non-heat treatable. Usually, magnesium and copper are added to achieve the age hardening properties [1]. When Zr is added to aluminum alloys, formation of Al3Zr phase is usually much finer and coherent with the matrix. The cast and solutionized alloys were subjected to isochronal ageing for 90 min at different temperatures up to 300 °C.

Results

Conclusion