TITAFORM - Precision Hot Forming, development of innovative hot-forming processes of aeronautical components in Ti-alloy with low buy/fly ratio: an Italian example of co-operation between academy and industry

In the paper the description of the project TITAFORM is provided. The project has been financed on the call "PON Linea 1" of the Italian government and represents an effective example of cooperation between academy and industry. The project is focused on the beta forging and hot stretch forming operations of titanium alloys. �� 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

An optimization procedure for the friction stir welding FEM model of corner fillet joints

Friction stir welding (FSW) is an energy efficient and environmentally "friendly" (no fumes, noise, or sparks) welding process, during which the sheets are welded together in a solid-state joining process. FSW is mature for simple configurations but a significant lack of knowledge is found when dealing with different designs such as T-sections, box sections and corner welds. Although the latter joint morphology has traditionally been considered unfeasible for the process, it seems to have a great potential to be used also for T-joint configurations, a recurrent design pattern in transport applications. A specific tool has been developed and a set of experimental welds has been produced with…

Reshaping End-of-Life components by sheet hydroforming: An experimental and numerical analysis

In this study, a numerical/experimental analysis is proposed to investigate the possibility of reshaping sheet metal-based End-of-Life (EoL) components using sheet Hydroforming (SHF). Returned EoL components are challenging to be reformed, they are usually characterised by high heterogeneity as there are localised thinning areas (caused by the original forming processes), and the overall formability is reduced with respect to the original flat sheet material. The reshaping route was replicated: a deep drawing process was adopted to impart a square feature; subsequently, SHF was performed. The capability of remove the deep drawn feature was analysed with varying Blank-holder force, oil press…

Effect of process parameters in Linear Friction Welding Processes of Steels

Advanced FEM modeling of friction stir welding of Ti6Al4V: Microstructural evolutions

Friction Stir Welding (FSW) is a solid state welding process patented in 1991 by TWI; initially adopted to weld aluminum alloys, is now being successfully used also for high resistant materials. Welding of titanium alloys by traditional fusion welding techniques presents several difficulties due to high material reactivity resulting in bonding with oxygen, hydrogen, and nitrogen with consequent embrittlement of the joint. In this way FSW represents a cost effective and high quality solution. The final mechanical properties of the joints are strictly connected to the microstructural evolutions, in terms of phase change, occurring during the process. In the paper a 3D FEM model of the FSW wel…

Hybrid prediction-optimization approaches for maximizing parts density in SLM of Ti6Al4V titanium alloy

AbstractIt is well known that the processing parameters of selective laser melting (SLM) highly influence mechanical and physical properties of the manufactured parts. Also, the energy density is insufficient to detect the process window for producing full dense components. In fact, parts produced with the same energy density but different combinations of parameters may present different properties even under the microstructural viewpoint. In this context, the need to assess the influence of the process parameters and to select the best parameters set able to optimize the final properties of SLM parts has been capturing the attention of both academics and practitioners. In this paper differ…

Experimental and numerical analysis on post welding formability of FSWed AZ31 magnesium alloy thin joints obtained using a "Pinless" tool configuration

The post welding formability of friction stir welded AZ31 magnesium alloy thin sheets (1.5 mm thick), obtained using a “pinless” tool configuration, was widely investigated by means of the hemispherical punch method at 350°C, with a constant crosshead speed of 0.1 mm/s. The results were compared with those obtained on the base material. It has shown that formability of the joints is lower than the one of the base material. The experimental work was supported by a numerical investigation based on FEM in order to highlight the material flow occurring during the welding process. Additionally, hemispherical punch tests were simulated starting from the calculated conditions, in terms of accumula…

Die design for aluminium thin tubes extrusion: a 2D simulation approach

Joining by forming technologies: current solutions and future trends

AbstractThe progressively more demanding needs of emissions and costs reduction in the transportation industry are pushing engineers towards the use of increasingly lightweight structures. This goal can be achieved only if dissimilar and/or new materials, including polymers and composites, are joined together to create complex structures. Conventional fusion welding processes have often been proven inadequate to this task because of the high heat input reducing the joint mechanical properties or even making the joining process impossible. Joining by forming technologies take advantage on the plastic deformation to create sound joints out of even very dissimilar materials. Over the last 25 y…

Review on mechanical joining by plastic deformation

Mechanical joining technologies are increasingly used in multi-material lightweight constructions and offer opportunities to create versatile joining processes due to their low heat input, robustness to metallurgical incompatibilities and various process variants. They can be categorised into technologies which require an auxiliary joining element, or do not require an auxiliary joining element. A typical example for a mechanical joining process with auxiliary joining element is self-piercing riveting. A wide range of processes exist which are not requiring an auxiliary joining element. This allows both point-shaped (e.g., by clinching) and line-shaped (e.g., friction stir welding) joints t…

Mechanical and Microstructural modifications induced by Friction Stir Welding and Processing on AA5754 Aluminum Alloys

ASSESSMENT OF DIMENSIONAL ACCURACY OF COLD FORGED COMPONENTS THROUGH ACCURATE MODELLING OF THE FORMING PROCESS CHAIN

Optimization of the sheet hydroforming process parameters to improve the quality of reshaped EoL components

Abstract. The reshaping of End-of-Life (EoL) components by means of sheet metal forming process has been considered largely attractive, even from the social and economic point of view. At the same time, EoL parts can be often characterized by non-uniform thicknesses or alternation of work-hardened/undeformed zones as the results of the manufacturing process. Such heterogeneity can hinder a proper reshaping of the EoL part and residual marks on the re-formed blanks can be still present at the end of the reshaping step. In a previous analysis, the authors evaluated the effectiveness of reshaping a blank with a deep drawn feature by means of the Sheet Hydroforming (SHF) process: it was demonst…

On the choice of tool material in friction stir welding of titanium alloys