Objectives and content: In order to compete with the US manufacturers, the European gas turbine industry is bound to continue improving its technical capabilities in terms of achieving higher efficiencies & safety standards & of complying with future environmental legislation. In direct response to this challenge this RTD programme aims at the introduction of the bi-metallic disk technology in land based power turbines & aero-engines. Although the focus of the programme is on gas turbine disks the technology will be generic in that it provides manufacturing routes & verified lifing model for the design of bonded bi-metallic components subjected to variable loading conditions. The concept of the bi-metallic gas turbine disk enables the differing mechanical property requirements of hub region (tensile strength & low cycle fatigue resistance) & rim region (creep & high cycle fatigue resistance) of the disk to be reconciled in a single disk structure as opposed to the mono-alloy disk. Therefore bi-metallic gas turbine disks offer considerable advantages over their mono-alloy counterparts in terms of higher temperature & larger size capabilities, allowing substantial power & efficiency gains, & reduced emissions. Today, the main limitation for the introduction of high integrity bi-metallic disks is the manufacturing technology.
Objectives of the proposed project are:
- to develop that manufacturing technology, demonstrating the ability of existing joining & post-manufacturing heat treatment routes for realising the desired bi-metallic disk structures & to engineer these further based on reliability & economy considerations;
- to set up validated qualification & NDT inspection procedures for bi-metallic disks;
- to validate, by means of disk spin testing, a lifing method for bi-metallic disks that is being developed by BE97-4296 BI-METAL project. Validated procedures are necessary because of the safety critical nature of disks
The manufacturing technology will be developed for two applications:
- bi-metallic disks for land based power gas turbines where the goal is to achieve a temperature capability of 50 to 200ÐC in excess of that of mono-alloy disks, & larger disk diameters;
- bi-metallic radial wheels for aero-engines where the objective is to realise larger dimensions & temperature capability of 150ÐC in excess of that of current mono-alloy wheels. The approach selected to achieve the project goals is as follows. The in-service requirements of disks and wheels will be extensively analysed so as to enable the selection of materials with adequate properties for the hub rim & joint. The conditions for the chosen joining routes, HlP-assisted diffusion bonding with or without forge enhancement, & for the post joining heat-treatments that are necessary to optimise the parent material & joint microstructures will be determined during a series of manufacturing trial experiments. This will be followed by mechanical screening & qualification testing aimed at identifying the optimum manufacturing parameters & combinations of materials/material grades. The most promising manufacturing route will be selected & optimised for the ultimate production of nine full scale disks (three disks/ wheels per each of three selected material/ material grade combinations).
These disks will be used:
- for the qualification testing of the production route & for mechanical testing to provide input data into the life prediction method being developed by the BE97-4296 BI-METAL &;
- for spin testing, aimed at validating the life prediction method.
NDT techniques that are valued the most promising for inspecting the likely critical defects in the bi-metallic joints will be tested both on manufacturing trial specimens without and with artificial defects for validation purposes, & subsequently applied to the full scale disks. The MANDATE consortium of 6 partners and 7 associated partners from 6 European countries consists of 2 major European gas turbine manufacturers as end users, 4 component manufacturers and 7 research institutes, all with a wide and complementary experience in the work areas concerned. The large number of industrial participants reflects the strategic importance and the potential cost savings of the bi-metallic gas turbine disk technology. BE97-4650
Funding SchemeCSC - Cost-sharing contracts
63770 Les Ancizes
SK10 2SG Macclesfield
1755 ZG Petten
GU14 0LX Farnborough - Hampshire