Effect of Different Forms of Application of a Laser Surface Treatment on Fatigue Crack Growth of an AA6013-T4 Aluminum Alloy

Effect of laser heating on mechanical properties, residual stresses and retardation of fatigue crack growth in AA2024

“…Below the remelted layer, the heat-affected zone (BM HAZ) is present. The partial remelting of the specimen surface is often unavoidable in case of the application of LH treatment to thin aluminium sheets and was also reported by da Cunha and de Lima 16 in case of 1.6-mm-thick AA2024-T3 and by Gonçalves et al 17 in case of 1.3-mm-thick AA6013-T4.…”

“…The main mechanism of the FCG retardation due to the presence of compressive residual stresses could be attributed to the crack closure effect, which was extensively reported in the literature 28–30 . In case of compressive residual stresses introduced through LH treatment, the appearance of the crack closure effect was reported in the study of Concalves et al 17 …”

“…A particular challenge was to achieve a positive effect with lower microstructural changes due to remelting of the clad layer on the specimen surface. A similar study was conducted for AA6013‐T4 with a thickness of 1.3 mm by Gonçalves et al 17 …”

“…The main mechanism of the FCG retardation due to the presence of compressive residual stresses could be attributed to the crack closure effect, which was extensively reported in the literature. [28][29][30] In case of compressive residual stresses introduced through LH treatment, the appearance of the crack closure effect was reported in the study of Concalves et al 17 On the da/dN versus the crack length curves of specimens with LH lines (Figure 12a), several regions with sudden changes in the FCG rate are visible, which might be attributed to the crossing of areas with either compressive stresses (decrease in the FCG rate) or tensile residual stresses (increase in the FCG rate). The regions with tensile residual stresses are located in LH lines, and due to the redistribution of residual stresses during FCG, the regions can be shifted from the exact positions of the LH lines.…”

“…A particular challenge was to achieve a positive effect with lower microstructural changes due to remelting of the clad layer on the specimen surface. A similar study was conducted for AA6013-T4 with a thickness of 1.3 mm by Gonçalves et al 17 Groth et al [18][19][20][21] investigated the LH process with regard to its potential for application to AA2024-T3 M(T) 200 specimens with a thickness of 2 mm. The M(T) geometry was chosen because it mimics the load conditions of an aircraft structure more realistically.…”