Overview
The objective of this proposal was to develop and validate a robust and reliable ring-rolling-only route for manufacturing IN718 alloy near-net-shaped rotating aero-engine disk components, RORC (e.g. low-pressure turbine disks). The material and mechanical response of the RORC must comply with the current microstructural and mechanical requirements demanded for close-die forged disks with an economical advantage (more efficient use of raw material and lower manufacturing costs). The proposal represents the collaborative effort of an experienced company specialised in ring-rolling of superalloys and a technological research centre with great competence in thermo-mechanical processes analysis and modelling.
Development of an advanced predictive RR modelling tool is a pre-requisite for the success of the proposal; laboratory experiments were performed for developing a predictive constitutive description of the behaviour of the alloy in conditions reproducing actual RR operation sequences. From the industrial part, full-size rings were produced by rolling alone and tested back-to back with geometrically similar close-die forged (CDF) rings as demonstrators of the competitiveness of the new process route. The results of the project also highlighted the limits of the current RR technology and provide with clues for its further improvement.
Funding
Results
Executive Summary:
The objective of this project was to develop and validate a robust and reliable ring-rolling-only route for manufacturing IN718 alloy near-net-shaped rotating aero-engine disk components, RORC (e.g., low-pressure turbine disks). The material and mechanical response of the RORC should comply with the current microstructural and mechanical requirements demanded for close-die forged disks with an economical advantage (more efficient use of raw material and lower manufacturing costs). The project represents the collaborative effort of an experienced company specialised in ring-rolling of superalloys, Forgital (Italy), and a technological research centre, Ceit-IK4 (Spain), with great competence in thermo-mechanical processes analysis and modelling. The project responds to a Clean Sky Call for Proposals, Integrated Technology Demonstrator SAGE 3, contract nº 32597. The 36-month project started the 1st March 2013.
Development of an advanced predictive ring-rolling modelling tool was a pre-requisite for the success of the project; laboratory experiments were to be performed for developing a predictive constitutive description of the behaviour of the alloy in conditions reproducing actual ring-rolling operation sequences. From the industrial part, 5 full-size rings have been produced by rolling alone and tested back-to back with geometrically similar close-die forged (CDF) rings, as demonstrators of the competitiveness of the new process route. The results of the project highlight the potential and limits of the current ring-rolling technology and provide clues for its further improvement.
The main final result is to have demonstrated mastering of processing of IN718 turbine disks by ring-rolling alone with properties, if not yet similar, comparable to those of disks obtained by using the current manufacturing technology (close-die forging) and with significant economic advantages. Another result from the project is the development of new know-how and new engineering knowledge valid for suggesting design modifications of current mills capable of rolling valid disks well beyond the capabilities of the current largest available mills; this issue will be critical in order to cope with the requirements of future large-diameter turbo-engines according to current trends.