Stress Corrosion Cracking Observation in API G-105 Grade Drill Pipe Steel at 125-175℃ in CO_2 Containing Environment

摘要

Stress Corrosion Cracking (SCC) susceptibility of an API G-105 grade drill pipe steel was studied at different temperatures from 25-175℃ in CO_2 containing solution using slow strain rate test in connection with a high temperature/high pressure autoclave. Corrosion film formation and its morphology on the steel surface were investigated using X-ray diffraction (XRD), and scanning electron microscopy (SEM). Results showed occurrence of SCC at temperatures 125-175℃ and increasing temperature increased the loss of ductility; also, the depth and size of the cracks increased with temperature. SEM studies showed formation of a rhombohedric crystalline film on the surface at temperatures 100℃ and above while this layer was not formed at temperatures 75℃ and below. XRD analysis demonstrated formation of siderite on the surface.