(Faculty of Engineering, Department of Industrial Engineering, Stellenbosch University, 2016) Rzyankina, E.; Pytel, M.; Mahomed, N.; Nowotnik, A.
An investigation of the microstructure and mechanical properties for heat treated directionally cast
rods, produced from the nickel-based superalloy, CMSX-4, is presented. The rods were cast
using the Bridgman method for manufacturing single crystal structures. The microstructure of the
cast rods consists of γ and γ' precipitates. This microsegregation has a negative effect on the
microstructure and, hence, the mechanical properties of the castings. The solution heat treatment
of the second generation, single crystal Ni-base superalloy, CMSX-4, is known to dissolve the
eutectic γ and γ' region. This requires temperatures up to 1316°C and approximately 45 hours
total time. These high temperatures and long processing times result in high costs. The aim of
this study is to investigate the effect of the heat treatment protocol on the extent of improvement of
quality of single crystal castings, as a basis for determining cost feasibility in practice.