Investigation on the axial distribution of micron inclusions and their influence on mechanical properties in a wind power spindle

Abstract A detailed anatomical analysis of a large wind power spindle has revealed that the presence of micron inclusions concentrated in the core of spindle, leading to fracture failure of the spindle after quenching treatment. This study established that the chemical composition, metallographic structure, and grain size exhibited minimal variation along the axial distribution of the spindle, resulting in slightly influence on the mechanical properties. Further studies showed that the inclusions primarily consisted of Al 2 O 3 , TiN, and MnS–Al 2 O 3 composite inclusions. Using image recognition software, the axial distribution of these micron inclusions was analyzed, revealing a pattern where inclusion density was higher at both ends of the spindle than in the middle section. Finally, the relationship between the number of micron inclusions and mechanical properties was explored, revealing that tensile strength initially increased with the number before declining, while elongation consistently decreased. It’s worth noting that the Al 2 O 3 inclusions tended to gather together as the number increased, resulting in a negative influence on both tensile strength and elongation.