| At present, the domestic development of anti-corrosion oil casing is based largely onseamless steel pipe that has a series of problems such as the uneven wall thickness of the tube,the poor quality of inner wall, and so on. Electric Resistance Weld (ERW) welding steel piperelying on excellent quality replaces the seamless pipe in more and more fields.The properties of weld zone are hindering the application of ERW casing in oil pipe field.Compared with the traditional heat treatment processing of weld zone,“ERW+hot stretchreducing+full body heat treatment†introduces mechanical high temperature rolling techniqueinto ERW welded pipe to get the high quality of weld zone and can meet the requirements ofanti-sulfur oil casing.The chemical composition of anti-sulfu oil casing was designed and the five differentkinds of tested steel was achieved by vacuum induction furnace. The process of welding wassimulated and the welding temperature and extrusion deformation degree was determined byadopting Gleeble-3500machine. The effects of deformation temperature, deformation degreeand “hot tension reducing+tempering treatment†on the microstructure and properties oftested steel was also studied. Finally, groove corrosion experiment and H2S corrosionexperiment for weld zone of ERW pipe under different processing was peformed.Results show that the mechanical properties of80ksi steel grade sulfur resistance ERWcasing meet the requirements of API standards for L80steel grade, which shows good strengthand toughness matching, low residual stress and groove corrosion sensitivity. At the same time,hydrogen sulfide corrosion resistance performance of the weld zone and base metal that wastested using four point bending method in A solution according to NACE StandardTM0177-2005and loaded85%and90%of nominal yield strength. After720hours, no crackappears in the weld zone or base metal, which can meet the oil and gas fields with H2S. |
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