Influence of ageing time on microstructure, hardness and corrosion of UNS Zeron 100 super duplex stainless steel

The present study is to investigate the influence of ageing time on the microstructure, hardness and corrosion properties of UNS Zeron 100 super duplex stainless steel. The material was solution treated at 1050°C and water quenched, further the ageing has been carried out at 850°C for 30, 60 and 90 minutes. Hardness test and corrosion test were carried out for both solution treated as well as aged specimens for different ageing period. Results of hardness test indicate an increase in hardness as the ageing period increases. Corrosion test results showed good resistance to corrosion as the ageing time increases. Changes in mechanical properties were observed due to sigma phase formation. Scanning electron microscope (SEM) analysis showed the sigma phase precipitation in duplex stainless steel. EDX analysis shows the consumption of ferrite and formation of chromium which indicates the formation of sigma phase. Optical image analysis showed the increment of sigma phase as the ageing time is increased.