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从宏观断口形貌、金相显微组织、化学成分等方面分析了球墨铸铁管卡脆断的原因。脆断管卡断口存在大面积白口组织是其脆断的直接原因。金相分析表明,珠光体含量和游离渗碳体含量越多,管卡的脆性越严重。本文进一步分析了各种化学元素对铸态球墨铸铁组织的影响,结合工艺过程的仔细调查,确定Cr、Mn含量高是球墨铸铁管卡脆断的主要原因,并给出稳定球墨铸铁管卡质量的措施。
The causes of brittle fracture of ductile iron pipe were analyzed from macroscopic fracture morphology, metallographic microstructure and chemical composition. The existence of a large area of white fissure in the fracture of brittle broken tube is the direct reason of brittle fracture. Metallographic analysis showed that the more pearlite content and free cementite content, the more serious the fragility of the tube card. In this paper, the influence of various chemical elements on the microstructure of as-cast nodular cast iron was further analyzed. With the careful investigation of the technological process, it was determined that the high content of Cr and Mn was the main reason for the brittle fracture of ductile iron pipe. The measure.