Twin-Web Turbine Discs: Part 2 — Fabrication and Processing

Abstract

The first part of this paper shows that the implementation of twin-web (hollow) discs can lead to an 8–30% decrease in mass or to a cyclic life increase of up to 300%, depending on the size of the disc and the operating conditions. The second part of this paper describes the results of the development of approaches for the manufacturing and processing of twin-web discs, both with the help of additive and traditional manufacturing methods. Several hollow discs with a closed cavity and a slot in the hub are made from the heat-resistant nickel alloy EI698P with the help of additive manufacturing (AM) and hot isostatic pressing (HIP), respectively. Various welding methods are considered for the production of the twin-web discs. The effect of post-processing on the characteristics of the materials is investigated in specimens that were produced with AM methods. Special attention is paid to the surface treatment methods that should be used for discs manufactured by AM methods. The “printed” discs were controlled using radiographic, ultrasonic, fluorescent penetrant, and eddy current methods, and they were examined using computed tomography. As a result, this paper shows that different approaches can be used for the manufacturing and processing of twin-web discs.