海上某平台弯头开裂失效分析OA

In order to explore the root cause of cracking failure of F51 duplex stainless steel pipeline el-bow on an offshore platform,a comprehensive analysis was carried out from two aspects of material quality and service environment by means of field condition investigation,macroscopic morphology observation of fracture,microscopic morphology analysis of fracture,micro-area composition detec-tion of scanning electron microscope energy spectrum(EDS),chemical composition analysis and mi-crostructure characterization of pipeline materials.The results show that the crack originates from the inner wall of the elbow and extends to the outer surface.There are large-sized and irregular non-me-tallic inclusions in the area near the inner wall of the material,which become the core cause of crack initiation.Combined with the characteristics of service conditions,it is confirmed that the failure mode is high cycle fatigue cracking.The cracking failure mechanism of the F51 duplex stainless steel elbow is high cycle fatigue.The large-size irregular non-metallic inclusions near the inner surface are the main causes of crack initiation and ultimate failure,which provides a key reference for subsequent pipeline material screening,manufacturing quality control and service maintenance.the characteris-tics of service conditions,it is confirmed that the failure mode is high cycle fatigue cracking.The cracking failure mechanism of F51 duplex stainless steel elbow is high cycle fatigue.The large-size ir-regular non-metallic inclusions near the inner surface are the main causes of crack initiation and ulti-mate failure,which provides a key reference for subsequent pipeline material screening,manufactur-ing quality control and service maintenance.