Effects of precipitated phases on the magnetic properties of 2304 duplex stainless steel

The effects of precipitated phases on the magnetic properties of 2304 duplex stainless steel (UNS S32304) were investigated. For this purpose, various artificial aging treatments were carried out at different temperatures (700, 800, and 900 centigrade) and times (20, 30, 60 120 min). The microstructural evaluations were performed by optical and scanning electron microscopy (SEM) equipped with energy-dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD) method. In order to assess the magnetic properties, hysteresis loop was determined using the vibrating-sample magnetometer (VSM) method. The results showed that the aging treatment produces precipitates such as carbides chromium (M23C6), Cr2N chromium nitride, sigma phase and the secondary austenite in the ferrite/austenite interface that grows in to the ferrite grains and decreases the magnetic compound of the microstructure. The ferrite volume fraction decreases from 92.5% to 68.1% by increasing of the aging transformation intensity (ATI). This phenomenon drastically damages the magnetic properties. The saturation magnetization of the steel decreases from 123 emu/g to 91 emu/g with increasing of ATI. The lowest level of MS and highest aging transformation intensity occurred at the aging temperature of 800 degrees C for 120 min.