The influence of nickel content on the structure parameters and magnetic properties of austenitic ductile iron castings

Abstract

Ductile austenitic cast irons are a series of cast irons, which typically contain nickel in the range of 18–36% weight. Its addition in an amount higher than 18 wt% allows the austenitic metallic matrix to be obtained in castings. Consequently, the material has relatively good mechanical properties with elongation exceeding 40% and can operate in a wide temperature range from 77 to 1123 K. Despite its wide range of excellent mechanical properties and corrosion resistance, the important area of magnetic properties of austenitic ductile iron is still largely unknown. Therefore, the main aim of this study was to show the role of nickel and chromium content in shaping the magnetic properties and correlate it with the structural and microstructural features such as chemical order, lattice parameters distribution of graphite nodules and primary austenitic dendrite structure including the microsegregation process. In this context, austenitic ductile iron with the addition of 21, 25, 28, and 35 wt% of nickel with and without the addition of chromium at the level of 2.5 wt% was investigated. Material characterization was carried out utilizing optical and scanning electron microscopy, including electron backscatter diffraction, high-energy synchrotron X-ray radiation, and magnetic properties using vibrating sample magnetometer (VSM). The investigation of the magnetic properties revealed that the nickel content strongly influences the magnetic characteristic of the analysed ductile cast iron, contributing to a better understanding of its potential uses in various industrial applications.