SANS-study of the nano-defects in a NiCrMoV wheel of the axial compressor of a heavy duty gas turbine

A wheel for nuclear/traditional energy applications is considered for the study of nano-defects by small angle neutron scattering (SANS). The constitutive material is a NiCrMoV steel with reference to the ASTM A 471 (type 2) norms. Measurements were performed using the SANS instrument of the Budapest Neutron Centre, at specific positions on the disc where the residual stresses in the lattice have also been analysed by neutron diffraction. The data obtained testify that the material has a low concentration of nano-defects when after thermal treatment compared with steels in which an intense formation of precipitates is usually induced.