Research On A Novel High Performance Aluminum Alloy For Automobile Piston

Aluminum alloys are widely used in industrial production due to a series of advantages such as small density,high specific strength,rich resources,and high recyclability,thus being taken as the preferred materials for automotive lightweight.With the awareness of energy conservation and environmental protection is growing,the automotive engine is developing toward the direction of low consumption and high energy.Pistons are one of the main parts of the engine.With the improvement of the performance requirements for the engine,the performance requirements for the pistons are getting higher and higher correspondingly.The cast Al-Si alloys are widely used in piston parts due to their excellent performance.During the using process,it is found that the strength of Al-Si alloys at high temperature(300°C)are significantly reduced,resulting in performance reducing of Al-Si alloy pistons and affecting overall performance of automotive engine.According to this problem,the study is to research a novel Al-Si piston alloy with good properties at high and room temperatures,having far-reaching engineering application significance.In this paper,taking the Al-Si-Cu-Mg-Ni alloy as the research object,the effects of alloying elements,heat treatment process and modification treatment process were investigated to gain a novel Al-Si piston alloy with good properties at high and room temperatures.The specific research contents can be concluded as follows:(1)Based on some trademark Al-Si piston alloys,the compositions of alloys were redesigned.According to the principle of alloying to change the contents of Cu and Ni,the Al-Si-Cu-Mg-Ni ingots were prepared by gravimetric casting method.By means of studying the effects of different contents of Cu and Ni on the microstructure and mechanical properties of the alloy,a novel Al-Si piston alloy with good properties at high and room temperatures was obtained.(2)The heat treatment process of new prepared Al-Si piston alloy material was investigated.Based on the strengthening mechanism of heat treatment on aluminum alloy,the solution treatment and aging treatment processes of alloys were established.Through the analysis of microstructure and mechanical properties of alloys,it was concluded that the optimum heat treatment process was 510°C×6h solution(water quenching)+ 185°C×6h aging(T6).(3)The modification treatment process of new prepared Al-Si piston alloy material was investigated.Based on the principle of eutectic Si metamorphism,the influence of Sr metamorphism on the microstructure and mechanical properties of alloys was analyzed,and it was concluded that the optimum adding contact of Sr element was 0.06wt%.Through the above research work,a novel eutectic Al-Si alloy for automotive pistons with excellent performance(?b,300?=128MPa)at high temperature and relatively good performance(?b=305MPa)at room temperature was obtained,providing significant guidance for piston production.