PROCEEDINGS OF THE 2003 INTERNATIONAL SYMPOSIUM ON LIQUID METALS JOURNAL OF MATERIALS SCIENCE 39 (2 0 0 4 ) 7259 – 7267 A simple transient numerical model for heat transfer and shape evolution during the production of rings by centrifugal spray deposition R. M. WARD, M. D. BARRATT, M. H. JACOBS, Z. ZHANG, A. L. DOWSON IRC in Materials Processing, University of Birmingham, Birmingham, B15 2TT, UK E-mail: r.m.ward@bham.ac.uk Centrifugal spray deposition, the atomisation of a liquid metal by centrifugal force and the subsequent collection of the atomised droplets on a reciprocating collector, is currently being developed for the production of high performance Fe, Ni and Ti based ring-shaped components for use in aerospace and gas turbine containment applications. The process combines the technical, economic and metallurgical benefits of more conventional gas-assisted spray forming techniques with the advantage that it can easily operate under vacuum, reducing potential problems from gas entrapment and thermally induced porosity. In order to aid process development, understanding and optimisation, a transient numerical heat and mass transfer model has been developed that is capable of predicting the evolution of the deposit temperature distribution during spraying. The model has been validated experimentally using thermocouple measurements obtained during the production of 35 kg (340 mm diameter) IN718 rings and qualitative correlations have been observed between the predicted data and the type/distribution of porosity and second phase precipitates in the deposit. The model is currently being further developed and integrated with droplet size distribution and cooling models to provide a better insight into the physics and operational parameters which control deposit shape and microstructure. C  2004 Kluwer Academic Publishers 1. Introduction Centrifugal Spray Deposition (CSD) converts liquid metal into a near net-shaped preform via centrifu- gal atomisation and deposition, and offers unique opportunities for producing both powders and axi- symmetric ring shaped components, for example for use in aerospace and gas turbine containment applications. Metal is melted in a crucible and poured through a nozzle onto a rapidly rotating disk. At the edge of the disk it is atomised to form a spray that travels out- wards onto a substrate where it solidifies to form a fine-grained solid deposit. The process combines the cost and metallurgical benefits of conventional gas as- sisted spray forming operations with the additional ad- vantage that the process can operate under vacuum or reduced pressure. Thus the costs of gas delivery, storage and recycling are reduced, and potential metallurgical problems deriving from gas entrapment are virtually eliminated. More details are available in [1]. Rings of IN718 have been succesfully produced by CSD (Fig. 1) and ring-rolled to produce properties equivalent to those achieved by conventional routes [2]. Whilst considerable effort has been directed world- wide at modelling spray forming, much of the focus has been on gas-assisted deposition techniques such as Osprey TM . A good fundamental understanding of gas-assisted deposition processes has evolved from this (e.g. [3–5]), and droplet based deposition models have started to emerge linking microstructure to the state of the spray at the point of impact [6]. Less atten- tion has been directed at the CSD process, and where work has been undertaken it has tended to be concen- trated on the atomisation process itself and on under- standing the liquid metal flow on the disc up to the point of atomisation. The principal aim of the current modelling work was to extend these studies so as to provide a predictive tool which would aid process un- derstanding, and facilitate the selection and optimisa- tion of the key operational parameters which influence microstructure and shape evolution during deposition. On this basis it was decided to focus mainly on the macroscopic and thermal aspects of deposition, recog- nising that (subject to slight modifications) droplet cooling and impact models developed for the Osprey process are becoming increasingly well established and transferable, and that work on modelling the fluid dy- namic aspects of centrifugal atomisation is continuing elsewhere. 0022–2461 C  2004 Kluwer Academic Publishers 7259