Post-Machining Deformations of Thin-Walled Elements Made of EN AW-2024 T351 Aluminum Alloy as Regards the Mechanical Properties of the Applied, Rolled Semi-Finished Products

The paper presents an evaluation of post-machining deformations of thin-walled elements as regards the mechanical properties of the applied, rolled semi-finished products. Nowadays, wrought aluminum alloys, supplied primarily in the form of rolled plates, are widely applied in the production of thin-walled integral parts. Considering the high requirements for materials, especially in the aviation sector, it is important to be aware of their mechanical properties and for semi-finished products delivered after plastic working to take into account the so-called “technological history” concerning, inter alia, the direction of rolling. The study focused on determining the influence of the ratio of the tension direction to the rolling direction on the selected mechanical properties of the EN AW-2024 T351 aluminum alloy depending on the sample thickness and its relation to the deformation of thin-walled parts. Based on the obtained results, it was found that the sample thickness and the ratio of the tension direction to the rolling direction affected the mechanical properties of the selected aluminum alloy, which in turn translated into post-machining deformations. Summarizing, the textured surface layer had a significant impact on the mentioned deformation. Greater deformations were noted for samples made of a semi-finished product with a thickness of 5 mm in comparison to 12 mm. It was the result of the influence of the surface layer, which at lower thickness had a higher percentage of contents than in thicker samples.

Finite Element Method for Ship Composite-Based on Aluminum

The structure and construction of ships made of aluminum alloy, generally of the type of wrought aluminum alloy, when experiencing fatigue failure caused by cracking of the ship structure, is a serious problem. Judging from the ‘weaknesses’ of aluminum material for ships, this chapter will explain the use of alternative materials for ship building, namely aluminum-based composite material which is an aluminum alloy AlSi10Mg (b) ship building material based on the European Nation (EN) Aluminum Casting (AC) - 43,100, with silicon carbide (SiC) reinforcement which has been treated with an optimum composition of 15%, so that the composite material is written with EN AC-43100 (AlSi10Mg (b) + SiC * / 15p. Composite ship model using ANSYS (ANalysis SYStem) software to determine the distribution of stress. The overall result of the voltage distribution has a value that does not exceed the allowable stress (sigma 0.2) and has a factor of safety above the minimum allowable limit, so it is safe to use. The reduction in plate thickness on the EN AC-43100 (AlSi10Mg (b)) + SiC * /15p composite vessel is significant enough to reduce the ship’s weight, so it will increase the speed of the ship.

On the extraordinary low quench sensitivity of an AlZnMg alloy

The scope of this work was to investigate the quench sensitivity of a high-purity wrought aluminum alloy Al6Zn0.75 Mg (in this work called 7003pure). This is compared to a similar alloy with the additions of Fe, Si, and Zr at a sum less than 0.3 at.% (in this work called 7003Fe,Si,Zr). Differential scanning calorimetry (DSC) was used for an in situ analysis of quench induced precipitation in a wide range of cooling rates varying between 0.0003 and 3 K/s. In 7003pure, three main precipitation reactions were observed during cooling, a medium temperature reaction with a distinct double peak between 325 and 175 °C and a very low temperature reaction starting at about 100 °C. An additional high temperature reaction related to the precipitation of Mg2Si starting at 425 °C has been observed for 7003Fe,Si,Zr. In terms of hardness after natural as well as artificial aging, alloy 7003pure shows a very low quench sensitivity. Hardness values on the saturation level of about 120 HV1 are seen down to cooling rates of 0.003 K/s. The as-quenched hardness (5 min of natural aging) shows a maximum at a cooling rate of 0.003 K/s, while slower and faster cooling results in a lower hardness. In terms of hardness after aging, 0.003 K/s could be defined as the technological critical cooling rate, which is much higher for 7003Fe,Si,Zr (0.3–1 K/s). The physical critical cooling rates for the suppression of any precipitation during cooling were found to be about 10 K/s for both variants.

EFFECT OF PRE-HEATING ON THE MECHANICAL PROPERTIES OF FRICTION STIR WELDING FOR 6061 ALUMINUM ALLOY

Friction stir welding (FSW) process is a solid-state joining invented via the Welding Institute in 1991 at a great rate emerging as an application by fusion welding for joining different alloys. The wrought aluminum alloy 6061 is heat treatable and possesses a high corrosion resistance. This alloy has been used in a wide range of applications, like arenas gymnasiums and trains bodies. Aluminum alloy 6061 cannot be easily welded by the conventional fusion welding process because of the cracks that make the mechanical of welding joint very weak. In FSW, many parameters effect on its welding process. In the present research, the pre-heating effect on the aluminum 6061 sheet at 100°C and 150°C was studied. This heat has to be given for obtaining a defect-free as well as quality joint. Result manifested that the welding without pre-heating the parent metal at a (1120 r.p.m) rotational speed and a (30 mm/min) welding speed gave the best result of the ultimate tensile strength (236 N/mm2).

Multi-Spot Ultrasonic Welding of Aluminum to Steel Sheets: Process and Fracture Analysis

Ultrasonic metal welding is an energy-efficient, fast and clean joining technology without the need of additional filler materials. Single spot ultrasonic metal welding of aluminum to steel sheets using automotive materials has already been investigated. Up to now, further studies to close the gap to application-relevant multi-metal structures with multiple weld spots generated are still missed. In this work, two different spot arrangements are presented, each consisting of two weld spots, joined 0.9 mm thick sheets of wrought aluminum alloy AA6005A-T4 with 1 mm sheets of galvannealed (galvanized and annealed) dual-phase steel HCT980X. An anvil equipped with variable additional clamping punches was used for the first time. The tensile shear forces reached 4076 ± 277 N for parallel connection and 3888 ± 308 N for series connection. Temperature measurements by thermocouples at the interface and through thermal imaging presented peak temperatures above 400 °C at the multi-metal interface. Microscopic investigations of fractured surfaces identified the Zn layer of the steel sheets as the strength-limiting factor. Energy-dispersive X-ray spectroscopy (EDX) indicated intermetallic phases of Fe and Zn in the border areas of the weld spots as well as the separation of the zinc layer from the steel within these areas.