Properties of the Inconel 713 Alloy Within the High Temperature Brittleness Range

Nickel-based alloys are widely used in industries such as the aircraft industry, chemicals, power generation, and others. Their stable mechanical properties in combination with high resistance to aggressive environments at high temperatures make these materials suitable for the production of components of devices and machines intended for operation in extremely difficult conditions, e.g. in aircraft engines. This paper presents the results of thermal and mechanical tests performed on precision castings made of the Inconel 713C alloy and intended for use in the production of low pressure turbine blades. The tests enabled the determination of the nil strength temperature (NST), the nil ductility temperature (NDT), and the ductility recovery temperature (DRT) of the material tested. Based on the values obtained, the high temperature brittleness range (HTBR) and the hot cracking resistance index were determined. Metallographic examinations were conducted in order to describe the cracking mechanisms. It was found that the main cracking mechanism was the partial melting of grains and subsequently the rupture of a thin liquid film along crystal boundaries as a result of deformation during crystallisation. Another cracking mechanism identified was the DDC (Ductility Dip Cracking) mechanism. The results obtained provide a basis for improving precision casting processes for aircraft components and constitute guidelines for designers, engineers, and casting technologists.