Hydrogen Permeation Behaviors of X80 Steel and Weld Joint Under Cathodic Polarization
CHEN Xu1,2, HE Chuan1, ZHANG Wei1,3, WANG Fuming2, LI Xiaogang2
1. School of Petroleum Engineering, Liaoning Shihua University, Fushun 113001, Liaoning Province, China;2. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China;3. China Huanqiu Contracting and Engineering Corporation Liaoning Subcompany, Fushun 113001, Liaoning Province, China
Abstract：Absorption of hydrogen in steel could lead to the loss of mechanical properties. The electrochemistry hydrogen permeation technology was used to study the hydrogen permeation of the X80 steel base metal and weld joint in Yingtan soil simulation solution under cathodic polarization potentials. The morphologies were observed by optical microscopy after hydrogen permeation experiments. The results show that the behavior of hydrogen diffusion in X80 steel depended on both the cathodic polarization potential and the microstructure. The hydrogen concentration and traps in X80 steel base metal and weld both increased with the cathodic potential moving negatively, which indicated hydrogen induced cracking(HIC) sensitivity increased. The HIC sensitivity of weld joint was higher than that of base metal. The hydrogen evolution reaction kinetics was different between base metal and weld when the cathodic potential was higher than-1000mV(SCE). The hydrogen bubble burst on the weld surface because of hydrogen pressure inside the metal exceeding the plastic limit. However, hydrogen concentration kept increasing in base metal when the cathodic potential reached-1200mV (SCE). The inhibition of acicular ferrite and pearlite on hydrogen diffusion in base meal was greater than coarse bainite in HAZ and proeutectoid ferrite in fusion line.