Creep and Low Cycle Fatigue Investigations of Light Aluminium Alloys for Engine Cylinder Heads

Abstract

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 and LCF Tests of Aluminium Alloys : A. Rutecka et al.

Influences of strain rate on the low cycle fatigue behavior of gravity casting Al alloys

“…They also found that the Zr-Ti-V-containing particles of the examined material characterized by fatigue striations at the low total strain amplitude of 0.002, whereas these particles were featured by multiple cracking along with some micro-cliffs at the high total strain amplitude of 0.006. Other studies have shown that the LCF behaviors of Al-Si-Cu alloys correlated closely with total strain amplitude [4], as well as temperature [5][6][7][8]. For instance, early work by the authors has demonstrated that the total strain amplitude could play a crucial role in the LCF of Al9Si3Cu alloys, which in turn affected the fracture modes and crack paths [4].…”

“…A key issue regarding automotive cylinder heads, therefore, is the strain controlled low cycle fatigue (LCF) performance of the used material. A few experimental investigations and theoretical analyses have been conducted to promote the understanding of the strain controlled LCF mechanisms of Al-Si-Cu alloys, and some significant achievements have been made [2][3][4][5][6][7][8]. Some work has been completed on the effect of alloying elements on the cyclic deformation of Al-Si-Cu alloys during LCF.…”

Elevated temperature low cycle fatigue of a gravity casting Al–Si–Cu alloy used for engine cylinder heads

“…However, most published works on ϰ Al-Si-Cu alloys have been focused on the stress controlled high cycle fatigue (HCF) regime [3][4][5][7][8][9][10][11][12][13]15]. Only a few strain controlled LCF studies are available on Al-Si-Cu alloys [14,[17][18][19][20]. For example, early research by Ovono Ovono et al [17] revealed that the fatigue life of a cast Al-Si-Cu alloy was connected with the density of intermetallic compounds and the volume fraction of pores.…”

Effects of Temperature on the Evolution of Yield Surface and Stress Asymmetry in A356–T7 Cast Aluminium Alloy

“…Ma et al [20] observed a similar compression-tension peak stress asymmetry in poly crystalline copper and ascribed this difference to differential constraints in tension and compression induced by inhomogeneous deformations between the different phases in the material. Several studies have been reported on the peak stress asymmetry observed in various aluminium alloys under cyclic loading [21][22][23].…”