Influence of Modification and Casting Technology on Structure of IN-713C Superalloy Castings

Abstract

The paper presents the results concerning impact of modification (volume and surface techniques), pouring temperature and mould temperature on stereological parameters of macrostructure in IN713C castings made using post-production scrap. The ability to adjust the grain size is one of the main issues in the manufacturing of different nickel superalloy castings used in aircraft engines. By increasing the grain size one can increase the mechanical properties, like diffusion creep resistance, in higher temperatures. The fine grained castings. on the other hand, have higher mechanical properties in lower temperatures and higher resistance to thermal fatigue. The test moulds used in this study, supplied by Pratt and Whitney Rzeszow, are ordinarily used to cast the samples for tensile stress testing. Volume modification was carried out using the patented filter containing cobalt aluminate. The macrostructure was described using the number of grains per mm 2 , mean grain surface area and shape index. Obtained results show strong relationship between the modification technique, pouring temperature and grain size. There was no significant impact of mould temperature on macrostructure.

Creep Behaviour of Modified Mar-247 Superalloy

“…Modification mixture contained cobalt aluminate CoAl 2 O 4 which gave it characteristically blue colour, hence the naming "blue" and "white". Moulds were prepared according to procedures of combined volume and surface modification with double filtration [16][17][18].…”

“…In case of the turbine blades, the good understanding of cracking in creep conditions allows for proper selection of materials, modification and heat treatment procedures and thus obtain optimal material characteristics such as microstructure and mechanical properties. Some of the methods of structure refinement are the surface [11][12][13], volume [14][15][16] and combined surface and volume modification techniques [17,18]. This processes allow for obtaining grains of various dimensions, orientation and distribution.…”

Microstructural Investigations of Cracks in Turbine Wheels in Car Engine Turbochargers

“…As far as the internal combustion engines in the private cars are concerned, nickel base superalloys offer the best combination of the mechanical properties, corrosion resistance and creep with their price [1]. Considering the whole family of the polycrystalline nickel base superalloys, MAR M246 and Inconel 713C are most commonly applied.…”