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Next gEneration loW pressure TurbinE Airfoils by aM

Periodic Reporting for period 2 - NEWTEAM (Next gEneration loW pressure TurbinE Airfoils by aM)

Reporting period: 2020-05-01 to 2022-01-31

The aim of NEWTEAM project was to develop and assess alloys by Powder Bed Additive Manufacturing (PB-AM) processes, with the goal to apply them on next generation of low pressure turbine (LPT) blades production.
To achieve this target 6 objectives were identified, as listed and discussed in the following:

- NEWTEAM 1 Objective was to develop an enhanced Ti-48Al-2Cr-2Nb alloy optimized for Electron Beam Melting (EBM) both in terms of chemical composition modification as well as fine tuning of post processing like Hot Isostatic Pressing (HIP) and Heat Treatments (HT) specifically for manufacturing LPT blades.

- NEWTEAM 2 Objective was to increase the portfolio of Nickel-base superalloys production processed by Laser Beam Melting (LBM) for high temperature applications to be employed for LPT blades.

- NEWTEAM 3 Objective was to define, through at least NADCAP certified tests, material properties characterization for 3 alloys (1 Ti-48-2-2 based + 2 Ni-base)

- NEWTEAM 4 Objective was to realize LPT representative blades via both EBM and LBM exploiting the alloys certified in the Objective 3.

- NEWTEAM 5 Objective was to provide an enhanced process simulation tool for EBM process.

- NEWTEAM 6 Objective was to avoid the needs of machining of the Ni- base alloys produced by LBM defining a best-practice approach in terms of surface finishing thus allowing to have more degrees of freedom in terms of complex shape design and production.

NEWTEAM project, as a part of the CS2 program, aims at giving an important contribution to the economic and social raise of the EU aviation sector and, as a larger result to a general economic growth. In particular, the extension of the use of Additive Manufacturing for producing strategical components like turbine blades can have a very positive impact in view of its inherent efficient use of raw materials and energy. Both blade designs proposed have high potential for lightweightning of this type of components: the TiAl blade due to the use of a material with very high specific properties; the Ni superalloys blade due to their hollow design. This benefit would impact markedly on fuel consumption and would defitnitively provide environmental benefits.
The NEWTEAM project has achieved the development of a modified Ti-48Al-2Cr-2Nb alloy fabricated Electron Beam Melting. The post processing, involving both Hot Isostatic Pressing (HIP) and subsequent Heat Treatment (HT), was tailored for this new chemical composition, thus optimizing the material microstructure. Industrially transferable parameters were defined both for EBM, HIP and HT in view of future exploitations.

The NEWTEAM project has also expanded the portfolio of Ni-based superalloys that can be processed via Laser Beam Melting (LBM). Two difficult to weld Ni superalloys were LPBF processed. With ad hoc tailored post processing recipes, integrity levels respecting TM limits were achieved. In this case, a coupling of shot peening, specific Stress Relief (SR) and HIPsteps was necessary. A newly conceived definition of the Fully Heat Treatment (FHT) for these alloys was carried out to fine tune the microstructural features.

The chemical and mechanical properties of all the alloys developed were characterized using to TM approved procedures and laboratories; data were gathered and compared to literature and to TM reference values. Further to this the microstructural and property stability upon prolonged exposure to high temperature was also assessed.

The NEWTEAM project has fabricated demonstrators with real scale geometries typical of LPT blades using both TiAl alloys (both reference alloy and the two new chemical compositions) and the two Ni-superalloys. For Ni-based blades, unconventional hollow blade geometry was developed and successfully fabricated via LPBF and post processed using both Ni-superalloys studied. The estimated TRL achieved with such development is 3.

The NEWTEAM project has applied an advanced process simulation tool to EBM process, adapting it to Titanium Aluminides properties and key-features. Thermal distribution was derived with this tool and through decoupled microstructural models it was possible to estimate Al-loss variation in EBM printed parts when process parameters were changed.

The NEWTEAM project has tailored shot peening procedures for surface finishing the Ni-based superalloys. Although further improvements on achievable finishing levels are needed, the developed method was applied directly on hollow LPT blade demonstrator, giving promising results especially in terms of residual stresses state introduced on LPBF manufactured surfaces.

The NEWTEAM partners have identified the results generated by the project and their potential for exploitation. These are reported in the public D4.4. final PEDR.
NEWTEAM has developed three materials oriented to the PB-AM technologies.
To follow the today aero-engine market needs, an exploitation of high performance materials is required. The introduction of advanced alloys capable to withstand higher operational temperature and/or capable to exhibit higher performances at a given temperature is an never-ending focus of the material research. Additionally, to couple the new materials with advanced manufacturing systems, such as PB-AM, will allow to produce complex geometry components and to reduce their overall buy-to-fly ratio.
Outcome of the NEWTEAM project could be transferred not only on LPT blades production, but also to other aero components that can be optimized and produced by AM PBF in a convenient way.
The introduction of more AM generated parts is of major importance, in the current aeronautical engines sector, in order to reduce the final aircraft weight and to improve the overall engine efficiency.

Today, supporting the European Union aviation means to support an important sector that creates economic growth and wealth, as well, and provides highly skilled jobs. This is particularly relevant in view of the consequences of the current pandemic Covid-19 crisis and of the war in the East of Europe. These two events have led economic constraints for the aeronautic sector, uncertainties on future investments and developments and have further raised the energy cost affair. Furthermore, the dramatic crisis of raw materials supply chain makes even more critical the use of materials like those used within the NEWTEAM project, that include chemical elements that are critical either/both in economic or/and in supply risk terms. For instance, the cost of Ni is daily fluctuating and Ni-products are facing today unpredictable delivery delays. Therefore, the extension of the use of Additive Manufacturing for producing strategical components like turbine blades can have a very positive impact in view of its inherent efficient use of raw materials and energy.
NEWTEAM PBF process