Formation of Microgrooving on C110 Casing Steel After Sulfide Stress Cracking Test

NACE TM0177 is a commonly used materials qualification standard specifying how sulfide stress cracking (SSC) tests must be conducted and interpreted to verify the suitability of material application in sour service. This standard specifies through the so-called method A test (a tensile uniaxial environmental cracking test) that a material could be considered acceptable for sour service as long as no failure is evidenced after 720 h of exposure, and no initiation of environmental cracking is observed on the reduced length of the specimen after macrographic observations. After cross-sectional observations, so-called “microgrooves” can sometimes be evidenced on the surfaces of nonfailed specimens. Such features can hardly be interpreted as SSC crack initiation sites considering their shape and depth. Experience, however, shows that the formation of these microgrooves appears to be dependent on test conditions and type of load. This paper presents the results of investigations on the parameters influencing the microgroove formation on C110 steel after the method A uniaxial tensile SSC test. Test parameters influencing the groove formation are studied, and the results suggest that grooving is not SSC initiation for the testing conditions used in this work.