Effect of trace elements on the pinhole fatigue-resistance of gasoline Al-Si piston alloy

摘要

Trace elements, i.e., Cu, Ni, Zr and V are added into Al-Si piston alloy to optimize the phase structure. Micro-structures and fatigue performances are discussed. The stress state of pinhole inner-surface is investigated by finite element method (FEM). The comparative tests of original piston alloy and modified piston alloy are conducted on a specialized piston fatigue setup under the same condition as a real engine, and then the fracture analyses are addressed to discuss the relevant mechanisms. Results show the content and size of primary Si particles are restrained after the addition of trace elements. The ultimate tensile strength (UTS) and high cycle (HC) fatigue strength of modified piston alloys under high temperature are increased obviously. The increase of intermetallics and decrease of primary Si are the main reasons.