Characterisation of the Tensile Bonding Strength of Ti-6Al-4V Hybrid Parts Made by Sheet Metal Forming and Laser Beam Melting

Abstract

The individualisation of product features in mass production is a current trend in the industry. To cope with this challenge of product variety in high volume, one approach is the combination of conventional manufacturing processes with additive manufacturing technologies. By combining sheet metal forming and laser beam melting (LBM), the advantages of both technologies can be exploited. Sheet metal forming enables the production of parts in high numbers and short cycle times with reproducible accuracy, whereas laser beam melting offers the opportunity of a high degree of geometric freedom with the possibility of individualisation and material efficiency. This approach opens up the design of hybrid parts, which consist of a sheet metal body and an additively manufactured functional element. In order to create a suitable design of hybrid parts, a thorough understanding of the interface between the formed sheet metal and the additively manufactured element is of importance. Therefore, in this work, the bonding strength of hybrid parts made of Ti-6Al-4V under tensile load is investigated. The manufacturing process of the hybrid parts consists of three subsequent steps. First, the additively manufactured element is built directly on a sheet metal material by LBM. Afterwards, the hybrid parts are heat-treated. Subsequently, the forming operation is realised by bending. Due to the low formability of Ti-6Al-4V, the bending process is conducted at an elevated temperature. This work focuses on the influence of sheet thickness, bending parameters and heat treatment temperatures on the tensile bonding strength. Since the forming operation is taken into account, a special specimen geometry is presented, which allows bending and testing of the tensile bonding strength. To link mechanical properties to the failure behaviour of hybrid parts, hardness measurements are conducted.