Laser based manufacturing of titanium aluminides

Silja‐Katharina Rittinghaus ,Janett Schmelzer,Veronica Rocio Molina Ramirez,Andreas Vogelpoth,U Hecht

doi:10.1051/matecconf/202032108001

Abstract

Lightweight titanium aluminides (TiAl, ρ = 3.9 – 4.1 g/cm3) gain in importance as high temperature structural material. The known properties like high strength and creep resistance combined with high corrosion and wear are of continuous interest for turbomachinery applications like low pressure turbine blades. Additive manufacturing (AM) provides the possibility for near-net-shape production of functional complex parts and can contribute to reduce consumption and costs of material, tooling and finishing. The typical high brittleness and oxygen affinity of TiAl cause special requirements for processing this material with AM. In this work, recent progress in Additive Manufacturing of the TiAl alloys of the nominal compositions Ti-43.5Al-4Nb-1Mo-0.1B (at.-percent, TNM™-B1), Ti-48Al-2Cr-2Nb (at.-percent, GE4822) and Ti-45Al-2Nb-2Mn-0.8B (at.-percent, 4522XDTM) is presented. Microstructures resulting from both Laser Powder Bed Fusion (LPBF) and Direct Laser Deposition (DED) are compared with respect to the characteristics of the manufacturing processes. Hardness measurements according to Vickers are performed, and pressure strength tests are performed on selected samples. The crack-free additive manufacturing of complex geometries made of TiAl is demonstrated as well as an approach for manufacturing hybrid parts combining DED and LPBF.

Highlights

Lightweight intermetallic TiAl-based alloys can compete with Ni-based alloys in temperature ranges up to 800°C
The known properties like high strength and creep resistance combined with high corrosion and wear are of continuous interest for turbomachinery applications like low pressure turbine blades
The crack-free additive manufacturing of complex geometries made of TiAl is demonstrated as well as an approach for manufacturing hybrid parts combining Direct Laser Deposition (DED) and Laser Powder Bed Fusion (LPBF)

Summary

Introduction

Lightweight intermetallic TiAl-based alloys can compete with Ni-based alloys in temperature ranges up to 800°C. Starting with General Electric introducing GE4822 as a structural material for GEnx-engine blades [12] and Rolls Royce using cast 4522XDTM for a number aero‐engine components e.g. compressor stator vanes, blades and LP turbine blades [13], MTU Aero Engines developed an alloy called TNMTM. Manufactured by forging, it is in use since 2016, e.g. in the Pratt&Whitney PW1100G fan engine [14]. The manufacturing of test material is performed to compare the procedures and test for transferability and compatibility within the γ-TiAl system especially regarding aspects of hybrid manufacturing

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