Grain size reduction in the 713C nickel superalloy as a result of heat treatment

The paper presents metallographic test results for the 713C nickel superalloy after heat treatment and crystallographic orientation analysis performed with the EBSD method. The 713C alloy was subjected to annealing in the temperature of 950 ºC for 30 hours followed by aircooling. As a result of the applied heat treatment the local grain size reduction in the alloy was observed. It has been found that in the primary grains the new subgrains of different crystallographic orientation are created. Between the new grains and the primary grains the boundaries of high angle appear. Orientation change in the micro-areas is closely related to the carbides rebuilding and volume diffusion of elements dissolved in the γ - γ’ alloy matrix and the (NbTi)C carbides.