Assessment of Dislocation Density by Various Techniques in Cold Rolled 1050 Aluminum Alloy

This study examines the evolution of dislocation density in cold rolled 1050 Al alloy. Various techniques such as numerical approaches, indentation techniques, X-ray diffraction line profile analysis, and electron backscattering diffraction were employed for the characterization of the deformed state. These methods allowed us to determine the nature of the evolution of the dislocation substructure during cold rolling. The investigated material was subjected to thickness reductions varying from 5% to 47%, which resulted in a continuous increase in hardness while the estimated dislocation density showed a tendency towards a less intense increase after a ~30% straining level. The numerical approaches employed, such as the Kubin–Estrin and a modified version of this model, are capable of ensuring a reasonable estimation of dislocation density at low and moderate deformation levels (~5–30%), while the discrepancy between the measured and simulated data is negligible when the material has been exposed to more severe rolling reductions.

Joining of Sheets with Tubes by Electrohydraulic Forming

Electrohydraulic forming is a high-speed process, which is based on a force transmission by a working media. In this process, shock waves transmit the punching force in a very short period of time. These shock waves are applied to accelerate the workpiece towards a passive die. Besides forming and embossing of sheets and tubes, joining of sheets with tubes is enabled as a novel application presented in this contribution. Thereby, the tube is embedded temporarily in the die as a functional part. By accelerating the sheet towards the tube end, the joint is formed. This study deals with the question of how this joint is formed in sense of process kinematics and material flow. Therefore, the loading energy, the distance of sheet and tube as well as the sheet thickness was varied and the influence of these parameters and geometric conditions of the tube on the process and resulting joints was observed. Joining of EN AW-1050 aluminum alloy sheets to EN AW-6060 aluminum alloy tubes was performed. These joints were analyzed by microsections and head tension tests. The investigations introduce the new joining process regarding its process behavior and show first joining results.

Effects of process parameters on tensile strength of friction stir welded Al-Cu double-layer sheets

In this paper, friction stir welding (FSW) process was used to join double-layer sheets of pure copper and 1050 aluminum alloy produced by explosive welding (EXW). The double-layer sheets were arranged side by side to perform friction stir butt-welding. In this regard, rotary FSW tools with different geometries were used at rotational speeds of 800 and 1250 rpm and linear speeds of 8, 12, and 20 mm min‑1, in one and two number of passes. According to the results, the sample welded by a conical tool with a rotational speed of 800 rpm and a linear speed of 12 mm min‑1 in one pass offered the highest tensile strength, which was approximately equivalent to the 84% of the strength of the raw double-layer sheet. In addition, applying the second FSW pass and using a threaded tool from the aluminum side had negative effects on the tensile strength. The microstructural evaluation showed the presence of more intermetallic phases including Al4Cu9, AlCu, and Al2Cu in the sample welded by the threaded tool from the aluminum side in two number of passes, which was the responsible of the lower tensile strength and the higher microhardness.

Dissimilar Metals Laser Welding between DP1000 Steel and Aluminum Alloy 1050

The welding of dissimilar metals was carried out using a pulsed Nd: YAG laser to join DP1000 steel and an aluminum alloy 1050 H111. Two sheets of each metal, with 30 × 14 × 1 mm3, were lap welded, since butt welding proved to be nearly impossible due to the huge thermal conductivity differences and melting temperature differences of these materials. The aim of this research was to find the optimal laser welding parameters based on the mechanical and microstructure investigations. Thus, the welded samples were then subjected to tensile testing to evaluate the quality of the joining operation. The best set of welding parameters was replicated, and the welding joint obtained using these proper parameters was carefully analyzed using optical and scanning electron microscopes. Despite the predicted difficulties of welding two distinct metals, good quality welded joints were achieved. Additionally, some samples performed satisfactorily well in the mechanical tests, reaching tensile strengths close to the original 1050 aluminum alloy.