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采用光学显微镜、扫描电镜及X射线荧光光谱仪,研究了65Mn钢冷轧带球化退火后的开平矫直过程脆断行为。结果表明:65Mn冷轧板730℃球化退火10～12h后组织没有完全球化,具有粗大渗碳体片层结构的珠光体团。开平矫直过程中粗大的渗碳体板条受轧制力发生断裂或破碎。连铸坯粗大枝晶引起局部C、Mn元素偏析,贫C、贫Mn区珠光体相变温度升高,导致高于正常相变温度形成片层结构异常粗大的珠光体。将钢液过热度调低20℃,中间包钢水温度控制在1500～1510℃,能有效抑制粗大树枝晶的形成,避免此类缺陷的产生。
The brittle fracture behavior of the cold-rolled 65Mn steel after spheroidizing annealing was studied by optical microscopy, scanning electron microscopy and X-ray fluorescence spectrometer. The results show that the microstructure of 65Mn cold-rolled steel is not completely spheroidized after being spheroidizing annealed at 730 ℃ for 10-12h, and the pearlite with coarse cementite lamella structure is formed. Kaiping straightening coarse cementite slab by the rolling force fracture or broken. The coarse dendrites in the continuous casting slab cause local C and Mn segregation, and the temperature of pearlite transformation in lean and Mn-deficient areas is increased, resulting in the formation of pearlite with abnormally large lamellar structure, which is higher than the normal transformation temperature. Reducing the superheat of the molten steel by 20 ℃ and the temperature of the molten steel in the tundish to 1500-1510 ℃ can effectively inhibit the formation of coarse dendrites and avoid the occurrence of such defects.