Mechanical properties and corrosion resistance of SA508-4 low carbon alloy steel

Abstract

The mechanical properties and corrosion resistance of SA508-4Ni-Cr-Mo low carbon alloy steel are elucidated using tensile testing, Charpy impact testing, fracture surface analysis and in-situ electrochemical noise (EN) technique. The metallographic structures are characterized by metallographic microscope combining with transmission electron microscope (TEM), and the fracture morphology is characterized by scanning electron microscope (SEM). The intercritical heat treatment (IHT) is introduced to heat the SA508-4 steel. The experimental observations reveal that the metallographic structure of SA508-4 steel is fine and uniform after different heat treatment, with martensite and lower bainite structures. The strength and toughness of SA508-4Ni-Cr-Mo are confirmed higher than that of SA508-3Mn-Ni-Mo steel used for reactor pressure vessels (RPV) at present. The IHT decreases the yield strength and toughness. EN results show that the noise resistance of SA508-4 steel decreased with the elevated temperature from 27 to 250°C, illustrating the passivity degradation of SA508-4 induced by the elevated temperature. © The Electrochemical Society of Japan, All rights reserved.