The friction surfacing process of two deposited layers on two deposition surface conditions, i.e., a smooth interface and a rough interface, was investigated. The control parameter of the deposition process was the rod feed rate with the use of a conventional milling machine. Analyzes of the surface characterization and microstructural characterization along the produced deposits were performed. The interface strength of the substrate/deposit1 (smooth) and deposit1/deposit2 (rough) was evaluated by bending tests and the micro-hardness profile along the transverse section of the substrate/deposit1 and deposit1/deposit2. The bending tests revealed the presence of smalls delaminations with no evidence of fracture at the rough deposit1/deposit2 interface (D1/D2) with less predominance in the deposition condition 3B. This suggests that the combination of the travel speed of 5.5 mm/s and an increase in the consumable rod feed rate of (≥5.5 mm/s) increases the adhesive strength of the two produced interfaces.

The aim of this work was to produce deposits of AA6351-T6, reinforced with alumina (Al₂O₃) particles, over a substrate of AA5052-H32 through friction surfacing. AA6351-T6 consumable rods were drilled with one and two holes, which were filled with Al₂O₃ particles posteriorly. To perform the deposition, a conventional KONE KFE-3/BR milling machine was used. The results showed that Al₂O₃ particles increase the hardness values of the produced deposits when compared to those without particle addition. The coatings presented a fine equiaxed grain size distribution, once the grain refinement was nearly 48% lower than the as-received material. Moreover, deposit regions that showed finer grain boundaries also showed a higher volume fraction, which can be related to the particle stimulated phenomenon. Electron backscatter diffraction results showed the occurrence of low angle grain boundary substructures and lattice rotation, indicating that the material undergoes dynamic recrystallization during friction surfacing.

In this paper the fatigue damage accumulation under block program loading is investigated. Alternative flexion bending fatigue tests with a single change in stress amplitude are performed at room temperature for step-down sequence with two-step and threestep loading. The fatigue strength of aluminum 7050-T7451 alloy under block loading is investigated through comparison between the remaining cycles and consumed cycles ratios. The experimental results from the blocks loading fatigue tests are compared with the predictions using Miner’ss rule. It is shown that, two-step the fatigue strength is enhanced for smaller consumed fatigue loading and the cumulative fatigue damage calculated in accordance with the LDR, for three-step the fatigue strength occurs to a higher number of consume fatigue loading and the LDR rule trend to underestimate the fatigue life and the accumulative damage becomes higher than unity