石油套管缺陷形成原因分析
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摘要
采用金相显微镜、扫描电镜和能谱仪对石油套管制造过程中形成的缺陷进行了分析,并对缺陷的形成原因进行了探讨。结果表明:钢管分层、内表面鼓包缺陷以及螺纹表面麻坑缺陷是管坯中大型夹杂物导致的,其中分层和内表面鼓包缺陷中的夹杂物来源于钢水,夹杂物在浸入式水口中聚集长大后被钢流冲刷到钢液中;螺纹表面麻坑缺陷的夹杂物来源于钢液中的结晶器保护渣。钢管外折缺陷是由于管坯表面存在皮下裂纹,在轧制过程中遗传到钢管中形成的。提高钢水的洁净度、减少结晶器保护渣的卷入、控制铸坯表面的皮下裂纹是控制石油套管缺陷的关键。
The defects formed in the oil casing manufacturing process were analyzed by means of metallographic microscope, scanning electron microscope and energy spectrometer, and the causes of defects were discussed. The results show that the lamination defects, internal surface bulging defects and thread surface pit defects are caused by the large inclusions in the tube billet and the inclusions in lamination and bulging defects come from molten steel and it is gathered and grown in the submerged entry nozzle, then it is washed into molten steel by steel flow; the inclusions in pit defects on the surface of thread are derived from entrapped mold flux. The folding defect of steel tube is caused by the subsurface crack of billet inherited into steel tube during rolling. Improving the cleanliness of molten steel, reducing the entrappment of mold flux and eliminating the subsurface cracks on the billet surface are the keys to control the defects of oil casing.
The defects formed in the oil casing manufacturing process were analyzed by means of metallographic microscope, scanning electron microscope and energy spectrometer, and the causes of defects were discussed. The results show that the lamination defects, internal surface bulging defects and thread surface pit defects are caused by the large inclusions in the tube billet and the inclusions in lamination and bulging defects come from molten steel and it is gathered and grown in the submerged entry nozzle, then it is washed into molten steel by steel flow; the inclusions in pit defects on the surface of thread are derived from entrapped mold flux. The folding defect of steel tube is caused by the subsurface crack of billet inherited into steel tube during rolling. Improving the cleanliness of molten steel, reducing the entrappment of mold flux and eliminating the subsurface cracks on the billet surface are the keys to control the defects of oil casing.
引文
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