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Cold metal transfer (CMT) welding process was used to join the AL6XN super-austenitic stainless steel to a nickel-based super alloy IN718. Microhardness, tensile and low cycle fatigue tests were carried out to determine the mechanical properties of the welded joint. The heat used to perform the weld decreases the microhardness in the heat affected zone (HAZ) of the IN718 material. A decrement of about 50% with respect to the base material (∼410 HV0.2) was observed, which is attributed to the microstructural transformation produced by the weld thermal cycles, inducing the partial dissolution of the γ'′ phase in the nickel matrix. In contrast, the HAZ on the AL6XN side, the microhardness tends to be similar with respect to the base material (∼203 HV0.2). In terms of the fracture energy, determined from the stress-strain plot, the welded joint decreases about 60–65% with respect to the base materials. This tendency was also observed in the case of the Charpy impact test behavior. From the low cycle fatigue test, it was observed that AL6XN material and AL6XN-IN718, performed better than the IN718 alloy, i.e. more tolerance to the strain cyclic, increasing the number of cycles to failure. A 3-D transient thermal conduction finite element model was developed to correlate the thermal history with the microstructural transformation on the HAZ and mechanical properties. The weld thermal cycles are in good agreement with the experimental measurements obtained by K-type thermocouples.

Orthogonal impact load in 6061-T651 and 7075-T651 aluminum alloys was evaluated. Clamped square plates with the dimensions of 300 × 300 × 6.35 mm were experimentally impacted at 200, 400 and 600 J with different velocities by means of a drop tower-device. Impacted force-time and -displacement curves were obtained to evaluate the absorbed energy. Also, the impact damage was evaluated in terms of the transverse displacement and overall crack length induced to the plate. Further, explicit finite element and analytical approaches were used to compare against the experimental results. Considering the absorbed energy as a direct function of the induced damage, it was observed that the 7075-T651 alloy had a better performance than 6061-T651 for the 200 J impact test. Even though both alloys had a similar response for the 400 J impact test, it was not the case at 600 J where the absorbed impact energy for the 6061-T651 alloy was higher than for the 7075-T651. The induced damage (crack length) tends to increase with the strain rate for a given impact energy level.

A dual phase (DP500/800) steel sheet (1.6 mm thickness) was evaluated by means of low cycle fatigue (LCF). The fatigue properties of the material were assessed by means of the cyclic elastic modulus determination at half-life as well as by the plastic strain amplitude measurements. Both methods show a good correlation and high reliability, however, the plastic strain amplitude approach tends to fit better to the experimental results. From a parametric analysis performed, it was observed that the plastic strain amplitude approximation could be more suitable to assess the fatigue properties for LCF of the material due to an improved correlation of the computed cyclic elastic modulus in comparison to the cyclic elastic modulus measurements at half-life. Both methods showed that, for strain amplitudes higher than εa = 0.004, the cyclic elastic modulus tends to be lower than 210 GPa, meanwhile for lower strain amplitudes, the cyclic elastic modulus tends to increase. An evaluation by X-ray Diffraction technique allowed to determine that the increment of residual equivalent strain contributes to the cyclic elastic modulus diminution.