Influence of grain structure and slip planarity on fatigue crack growth in low alloying artificially aged 2xxx aluminium alloys

Abstract

The fatigue crack growth behaviour under constant amplitude loading of three low alloying artificially aged 2xxx aluminium alloys with distinct microstructures is analysed. Fatigue crack growth tests show a correlation between fatigue performance and the occurrence of crack closure. Fractography and fracture surface measurements show that rougher surfaces give higher closure levels suggesting a dominating influence of roughness induced crack closure in these alloys. The relationship between the crack path and the microstructure, i.e. grain structure and slip planarity, is assessed semi-quantitatively. A criterion to evaluate the propensity for slip band formation is derived and reasonable correlation is found between the fatigue fracture behaviour of the three alloys and this criterion.

Predicting grain refinement by cold severe plastic deformation in alloys using volume averaged dislocation generation

“…Tensile tests were performed using an 8800 series Instron machine at a constant strain rate of 0.001 s -1 . Selected processing and microstructure data on the Al-Mg-(Cu)-Mn, Al-Cu-Mg and Al-Li-Cu-Mg alloys was reported before [38,39,40]. From the tensile test data K A (as defined in Section 3.2) was determined from the flow stress between 0.01 and 0.05 plastic strain.…”

A model for co-clusters and their strengthening in Al–Cu–Mg based alloys: a comparison with experimental data

“…Al-Cu-Mg alloys, which are the topic of the present work, are widely used in structural aerospace applications due to their good combination of specific strength and damage tolerance [7]. Age hardening of Al-Cu-Mg alloys with composition in the (α+S) phase field occurs in two distinct stages separated by a constant hardness plateau, see Fig.…”

Al–Mg–Cu based alloys and pure Al processed by high pressure torsion: The influence of alloying additions on strengthening

“…In these applications they derive their strength mostly from solution strengthening and strain hardening [13]. The Al-Mg-Cu alloys with higher Cu content (>2.5wt%) that are being studied in this work are applied predominantly in the aeronautical industry due to their in-service strength, which is due primarily to precipitation hardening [14,15,16,17], combined with good damage tolerance properties [18]. Recent development in these types of alloys has seen the introduction alloys with Li at relatively low levels (<2wt.…”