Effect of Cryogenic Soaking Duration on the Crystallographic Structure and Corrosion Resistance of ASTM A36 Steel

This study investigates the influence of cryogenic soaking duration on the crystallographic characteristics and corrosion resistance of ASTM A36 structural steel. Specimens were immersed in liquid nitrogen at −196°C for 0, 12, 36, and 60 hours. Crystallographic analysis was conducted using X-ray diffraction (XRD), while electrochemical corrosion behavior was assessed through Tafel polarization in 3.5% NaCl solution using an Autolab PGstat. Key parameters evaluated included crystallite size, microstrain, dislocation density, corrosion rate, and material degradation. The results showed that soaking up to 36 hours significantly refined the microstructure, as indicated by reduced crystallite size and increased dislocation density and microstrain. These changes were associated with improved corrosion resistance. Notably, the most substantial decrease in corrosion rate and degradation percentage occurred at 60 hours, indicating superior electrochemical performance. However, 36 hours was identified as the optimal soaking time to achieve a balance between crystallographic stability and corrosion protection. This work confirms that cryogenic soaking duration is a critical variable in optimizing both the microstructural and electrochemical performance of ASTM A36 steel. The integration of XRD and electrochemical analysis provides a comprehensive understanding of the underlying mechanisms, offering strategic insights for enhancing the durability of structural steels in aggressive environments.