Overview
Development of new aeronautic engine technologies is led by the requirements in term of noise and fuel consumption reduction. The working temperatures in these new engines for materials such as Inconel 718DA are currently borderlines. Hence, the development of new engine generations, including higher temperatures will certainly impose the replacement of Inconel 718DA by other superalloys for some HPT and LPT disks.
Within that context, Aubert & Duval has worked to propose a new innovative superalloy named AD730™. The superalloy had been designed to be an alternative to the U720Li, which is a γ/γ’superalloy know as been very difficult to forge and which is expansive. The AD730™ patented composition makes of this alloy, a very promising substitution solution to classical U720Li alloy. First, AD730™ raw material cost is lower than that of U720Li. This alloy is less prone to segregation and its composition more suitable for scrap recycling. One remarkable property of AD730™ is its improved workability. This property permits a significant reduction of the number of heatings for billet conversion. The conversion process which can be applied improves also the ultrasonic inspectability compared to U720Li. Finally, this alloy can be closed die forged under a classical hydraulic press, avoiding the use of expansive isothermal presses.
Within CESAME project, Aubert & Duval demonstrated that AD730™ LPT disks can be produced with similar mechanical properties compared to U720Li similar parts, but at a significantly lower economical and environmental cost. This R&D program, divided into 6 work packages, concerned the melting process, the conversion process, the closed die forging process and heat treatment process cost optimisation. Aubert & Duval aimed through the project to create a new 100% European made processing route for high temperature engine disks allowing cost and energy savings, compared to the classical U720Li processing route.
Funding
Results
Executive Summary:
The CESAME project has shown that the new European superalloy, AD730TM, is a suitable alternative to replace the classical U720Li alloy regards manufacturing process cost and properties. Mechanical properties and ultrasonic inspectability obtained on AD730TM parts were found similar and even higher than those obtained on U720Li parts. During the project, technical and cost saving optimizations of AD730TM process were performed. It was demonstrated that the use of larger ingots up to 25’’ diameter was possible with AD730TM alloy without any detrimental effect on mechanical properties. This new manufacturing route was a step forward to reduce the AD730TM manufacturing cost regards U720Li. CESAME project achieved to demonstrate that the new European superalloy, AD730TM, responds to the requirements of the aeronautic engine market in term of energy and cost saving.
To make full use of the results of the project, Aubert & Duval was eager to disseminate the results from this project as widely as possible and to maximise the commercial impact of the results through a strategic exploitation plan. The CESAME project gave a strong comparison of AD730 properties versus U720Li properties which were published on scientific publications in order to share with the scientific community the knowledge learnt. Presentation of paper at Superalloys 2016 conference was planned.