X80焊管H_2S环境应力腐蚀开裂行为研究

On behavior of sulfide-stress corrosion cracking (SSCC) of X80 pipeline in H_2S environment

采用三点弯曲加载法和微电极扫描测试技术,研究了X80高强度级管线钢及其焊缝区的抗H2S环境应力腐蚀开裂(SSCC)行为。测定了焊接接头的显微硬度分布,分析了显微组织结构、力学性能及抗腐蚀性能之间的相关性。研究表明,热影响区(HAZ)对应力腐蚀开裂最为敏感,母材的纵向和横向取样对应力腐蚀敏感性影响不显著,薄壁管材比厚壁管材有较好的抗H2S环境应力腐蚀性能。HAZ晶粒粗大、硬度高,局部腐蚀倾向大,由此导致该区SSCC敏感性高。

The behavior of sulfide-stress corrosion cracking (SSCC) of X80 pipeline steel and its welding seam area is investigated by using the method of 3-point bend loading and technique of micro-electrode scanning in H2S environment. The microscopic hardness distribution of welded joint is detected. The relationship between the microstructure, mechanic performance and corrosion resistance of the welded joint are analyzed. The study shows that the heat-affected zone (HAZ) is the most sensitive position of SSCC, while the vertical and horizontal sampling of the base metal has less influence on SSCC, and the thin pipeline has better SSCC resistance than that of the thick one in H2S environment. In HAZ, crystalline particles are coarse and has high hardness and is apt to cause local corrosion, thus it is a high SSCC sensitive area.