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俄罗斯高硅管线钢K52采用高硅低锰成分体系,较高的Si含量使得Mn/Si比接近1,在ERW制管时易出现焊缝冲击功偏低、水压测试前后探伤不合格等问题。本文通过冲击试验、探伤检测及水压试验检验K52焊管的焊缝质量,并采用扫描电镜及能谱分析对焊缝冲击断口、缺陷形貌及夹杂物形貌与成分进行了研究。研究表明,焊缝的冲击韧性偏低及焊缝附近裂纹的主要原因是焊接过程中产生的含硅氧化物夹杂,同时与母材的韧性及焊缝热处理工艺有关。为充分排出含硅氧化物,应在焊接过程中适当增大挤压量及焊机功率;同时考虑Si元素的影响,适当提高正火温度,确保充分消除内应力。
Russian high-silicon pipeline steel K52 adopts high-silicon and low-manganese component system, and the higher Si content makes the ratio of Mn / Si close to 1, the weld impact energy is low when ERW pipe is made, and the unqualified test before and after hydraulic pressure test . In this paper, the weld quality of K52 welded pipe was tested by impact test, flaw detection test and hydrostatic test. The impact fracture, defect morphology and inclusions morphology and composition were studied by SEM and EDS. The results show that the low impact toughness of the weld and the main reason of the crack near the weld are inclusions of silicon oxide generated in the welding process and are related to the toughness of the parent material and the heat treatment process of the weld. In order to fully discharge the silicon-containing oxide, the amount of extrusion and welding power should be appropriately increased during the welding process; meanwhile, the influence of Si element should be taken into consideration to appropriately increase the normalizing temperature to ensure that the internal stress is fully eliminated.