Mechanical response of TiAl6V4 lattice structures manufactured by selective laser melting in quasistatic and dynamic compression tests

S Merkt,J Bültmann,M Brandt,C Hinke,Y M Xie

doi:10.2351/1.4898835

Abstract

This paper focusses on the investigation of the mechanical properties of lattice structures manufactured by selective laser melting using contour-hatch scan strategy. The motivation for this research is the systematic investigation of the elastic and plastic deformation of TiAl6V4 at different strain rates. To investigate the influence of the strain rate on the mechanical response (e.g., energy absorption) of TiAl6V4 structures, compression tests on TiAl6V4-lattice structures with different strain rates are carried out to determine the mechanical response from the resulting stress-strain curves. Results are compared to the mechanical response of stainless steel lattice structures (316L). It is shown that heat-treated TiAl6V4 specimens have a larger breaking strain and a lower drop of stress after failure initiation. Main finding is that TiAl6V4 lattice structures show brittle behavior and low energy absorption capabilities compared to the ductile behaving 316L lattice structures. For larger strain rates, ultimate tensile strength of TiAl6V4 structures is more than 20% higher compared to lower strain rates due to cold work hardening.

Highlights

AND MOTIVATIONGlobal trends like mass customization and resource efficiency lead to a rising demand of individual products highly adapted to the needs of the customer.1 To fulfill these customer needs, flexible manufacturing technologies, such as Additive Manufacturing, are required that allow the almost unlimited adaption of the products functionalities to these specific demands.2 Layer by layer the most complex products can be manufactured with no need for tools or molds
Lattice structures manufactured from TiAl6V4 powder by selective laser melting (SLM) show brittle failure mechanism during compression test
Even a sharp drop to zero-stress can be observed due to brittle fractures across the lattice structure and struts losing their connection to the structure

Summary

INTRODUCTION

Global trends like mass customization and resource efficiency lead to a rising demand of individual products highly adapted to the needs of the customer. To fulfill these customer needs, flexible manufacturing technologies, such as Additive Manufacturing, are required that allow the almost unlimited adaption of the products functionalities to these specific demands. Layer by layer the most complex products can be manufactured with no need for tools or molds. The substrate plate is lowered by one layer, a rubber or brush is depositing powder onto the last layer and the powder is melted again to represent the parts geometry (see Fig. 1) These steps are repeated until almost 100% dense parts with serial-identical properties are manufactured with the selective laser melting (SLM) process directly from the 3D-CAD model.. Topology optimization is one design approach to save weight while functionally adapting the product design to predefined load cases.7 These different relations between piece cost and product complexity offer a unique capability for Additive Manufacturing to manufacture innovative products perfectly adapted to the specific technological requirements through the integration of lattice structures (see Fig. 2 right) Topology optimization is one design approach to save weight while functionally adapting the product design to predefined load cases. These different relations between piece cost and product complexity offer a unique capability for Additive Manufacturing to manufacture innovative products perfectly adapted to the specific technological requirements through the integration of lattice structures (see Fig. 2 right)

STATE-OF-THE-ART

RESULTS AND DISCUSSION

CONCLUSION AND OUTLOOK