Multiaxial Fatigue Behaviour of A356-T6

TL;DR

This study investigates the multiaxial fatigue behavior of A356-T6 aluminum alloy, revealing that endurance limits depend on maximum principal stress and detailing fracture mechanisms under various loading conditions.

Contribution

It provides new insights into the fatigue life, crack initiation, and propagation mechanisms of A356-T6 under multiaxial loading, including the negligible initiation life near 1E6 cycles.

Findings

Endurance limits are governed by maximum principal stress.

Fractography shows shear mode III propagation with multiple initiation sites.

Crack growth rates are comparable to long cracks in similar materials.

Abstract

Aluminum alloy A356-T6 was subjected to fully reversed cyclic loading under tension, torsion and combined loading. Results indicate that endurance limits are governed by maximum principal stress. Fractography demonstrates long shear mode III propagation with multiple initiation sites under torsion. Under other loadings, fracture surfaces show unique initiation sites coincidental to defects and mode I crack propagation. Using the replica technique, it has been shown that the initiation life is negligible for fatigue lives close to 1E6 cycles for combined loading. The natural crack growth rate has also been shown to be comparable to long cracks in similar materials.