Current Production Status of Alloy 718 Turbine Disks in China

Abstract

For the past few years the production of high quality alloy 7 18 turbine disks has made great strides in China. A closer working arrangement with research laboratories in universities and steel plants has resulted in higher quality components which are comparable to those produced in other countries. The main technology studies which led to the production of quality alloy 718 disks were: (a) effects of Mg on segregation, (b) influence of inclusion control on mechanical properties, and (c) effect of grain size. The mechanical and structural results from a current production turbine disk are presented in this paper. Introduction Early in the assessment of turbine disk technology, it was recognized and agreed on that a cooperative effect between university research and factory manufacturing technologies was necessary to produce high quality turbine disk components. The three technical areas that seemed to be the most important for successful production of turbine disks were: 1. Better understanding of the role that Mg plays in countering the effects of detrimental trace elements in raw materials but also, Mg’s influence on the mechanical properties. 2. The influence of inclusions and stringers which form large amounts of MC and TIN particles. 3. The role of grain size and phases on the mechanical properties. This paper describes some of the research results in these three areas which have been successfully transferred to industry and incorporated into production of alloy 7 18 turbine disks. Materials and Experimental Procedure Eleven experimental heats of alloy 718 with varying of magnesium (Group A, Heat 1, 2, 3, 4 and Group B, Heat 42, 44), carbon (Group C, Heat 5, 6 7) separately and addition of magnesium and carbon simultaneously (Group D, Heat 8, 9) were melted in 50 Kg VIM furnace. Two production heats (Group E and F) were VIM + VAR melted for 406 mm diameter ingots. Chemical composition and alloy designation are listed in Table I. Superalloy 718-Metallurgy and Applications Edited by E.A. Loria The Minerals, Metals & Materials Society, 1989