Evaluation of hydrogen-Induced cracking resistance of the In625 laser coating system on a C-Mn steel substrate

Abstract The corrosion of C-Mn steels in the presence of hydrogen sulfide (H2S) represents a significant challenge to oil production and natural gas treatment facilities. The failure mechanism induced by hydrogen-induced cracking (HIC) in a Inconel 625 coating / C-Mn steel has not been extensively investigated in the past. In the present work, an API 5CT steel was coated with In625 alloy using laser cladding and the HIC resistance of different regions, such as the coating surface, the substrate and HAZ, were evaluated. SEM observations illustrated that all HIC cracks were formed at the hard HAZ after 96h of exposure. No HIC cracks were observed in the substrate and the In625 coating after the same exposure duration. Pitting was recorded in the substrate caused by non-metallic inclusion dissolving.

摘要 碳锰钢（C-Mn steels）在硫化氢（hydrogen sulfide, H₂S）环境中的腐蚀问题，对石油开采与天然气处理设施构成了显著挑战。此前针对因科奈尔625（Inconel 625）涂层/碳锰钢体系的氢致开裂（hydrogen-induced cracking, HIC）诱导失效机制，尚未开展广泛深入的研究。
本研究采用激光熔覆（laser cladding）技术，在API 5CT钢表面制备了因科奈尔625合金涂层，并对涂层表面、基体以及热影响区（heat-affected zone, HAZ）等不同区域的抗氢致开裂性能进行了评估。扫描电子显微镜（scanning electron microscope, SEM）观测结果显示，经过96小时的腐蚀暴露后，所有氢致开裂裂纹均形成于硬度较高的热影响区内；相同暴露时长下，基体与因科奈尔625涂层中均未观测到氢致开裂裂纹。此外，观测到基体中因非金属夹杂物溶解引发了点蚀现象。