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N80热轧无缝钢管在轧后矫直过程中发生断裂。利用光学显微镜、SEM及EPMA等方法对管的断裂形态、显微组织及微区成分等进行分析。结果表明,钢管矫直断裂的主要原因为钢管显微组织中存在呈带状分布的硬脆马氏体。马氏体的产生是由于钢管在精轧段冷却不均,局部冷却强度过大所致。在轧制N80热轧无缝钢管制品时,尽量保持在600℃左右终轧,可有效减轻钢管的带状组织;严格控制精轧冷却环节,避免管件在强冷区滞留,可避免生成硬脆的马氏体。
N80 hot-rolled seamless steel pipe in the post-rolling straightening process occurred fracture. The fracture morphology, microstructure and micro-zone composition of the tube were analyzed by optical microscope, SEM and EPMA. The results show that the main reason for the straightening and rupturing of the steel pipe is the presence of strip-shaped brittle martensite in the microstructure of the steel pipe. The production of martensite is due to uneven cooling of the pipe in the finish rolling zone, local cooling intensity is too large. In rolling N80 hot-rolled seamless steel pipe products, try to keep at about 600 ℃ finishing, steel pipe can effectively reduce the banded organization; strict control of the finishing rolling cooling section, to avoid pipe retention in the strong cold zone, to avoid the formation of hard and brittle Of martensite.