en گروه سطح پوشش و خوردگی Surface Coatings and Corrosion Research Paper Research Paper <div style="text-align: justify;">In this paper, the effects of solutioning and various aging heat treatment processes on the microstructure, the hardness and electrochemical properties of a duplex stainless steel (DSS) were studied. The evaluation of the microstructure and phase compositions were carried out by the optical microscopy (OM) and the X-ray diffraction (XRD), respectively. Electrochemical behaviors of specimens were evaluated by both potentiodynamic polarization and electrochemical impedance spectra (EIS) tests at temperatures of 25 and 60 &ordm;C. The obtained results showed that the solutioning heat treatment increased corrosion rates with respect to the blank specimen. The aging process at 490 &ordm;C for 20 hrs increased the volume percent of the carbide phase to the highest value (25.1%) which resulted in an increase of the hardness value to 170 VHN. The specimen which was aged at 540 &ordm;C for 10 hrs with the Cr₇C₃ size of 22.8 &micro;m, exhibited the higher corrosion resistance at both temperatures of 25 and 60 &ordm;C with respect to other aged specimens. In addition, the temperature of 60 &ordm;C promoted the anodic reactions in 3.5 wt% NaCl solution which decreased impedance modulus values significantly. Consequently, the carbide size was more effective parameter than the carbide content in predicting electrochemical behaviors of such alloys.&nbsp;</div> Duplex Stainless Steel,Heat Treatment,Aging,Microstructure,Electrochemical Behaviors,Hardness 91 101 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-2315-1&slc_lang=en&sid=1 M. Azadi mahbub.azadi@gmail.com 180031947532846009662 180031947532846009662 Yes Faculty of Materials and Metallurgical Engineering, Semnan University, Semnan, Iran M. Ferdosi mortezaferdos@gmail.com 180031947532846009663 180031947532846009663 No Faculty of Materials and Metallurgical Engineering, Semnan University, Semnan, Iran H. Shahin m_azadi2@yahoo.com 180031947532846009664 180031947532846009664 No Faculty of Materials and Metallurgical Engineering, Semnan University, Semnan, Iran