Institute of Fundamental Technological Research

An influence of the chemical composition, porosity and ageing on mechanical behaviour of light, multifunctional aluminium alloys (AlSi8Cu3 and AlSi7MgCu0.5) subjected to creep and low cycle fatigue (LCF) was investigated. The materials were tested to verify their applicability as the cylinder heads in car engines. During creep tests, a strain response of the materials was observed under a range of the step-increased stresses and different temperatures. The LCF tests were carried out under strain control in three blocks of 100 cycles each with a constant strain amplitude. The results of creep and LCF tests were analysed with regard to chemical composition, type of porosity and ageing of the materials tested. An influence of porosity on the creep resistance and lifetime was considered. The results of the LCF tests were compared for the materials in the as-received state and after ageing. An experimental evaluation of cyclic behaviour because of the LCF was carried out to check whether the hardening or softening effects can be observed in the materials. Taking into account the various history of loading, a stress response of the materials was investigated.

creep, cylinder heads, fatigue, light alloys