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铸铁孕育不良缺陷的形成机制及防止措施
Formation Mechanism and Prevention Measures of Inoculating Defects in Cast Iron
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- DOI:
- 作者:
- 程凤军 潘安霞 罗广思
CHENG Fengjun;PAN Anxia;LUO Guangsi
- 作者单位:
- 常州工业职业技术学院
Changzhou Vocational Institute of Industry,Changzhou 213164,China
- 关键词:
- 铸铁 组织缺陷 孕育
cast iron microstructure defect inoculation
- 摘要:
- 对高镍奥氏体球墨铸铁碎块状石墨和灰铁D型石墨的形态进行研究分析,认为铸铁孕育不良缺陷与凝固过程中奥氏体和石墨的析出时机有直接关系:当奥氏体大量析出,而石墨析出严重滞后,易形成异常组织;当石墨优先析出的倾向增大,则易形成正常组织。球墨铸铁孕育不良会使石墨析出严重滞后,奥氏体析出时机提前,从而形成碎块状石墨、spiking枝晶、反白口、白口等缺陷组织。在生产实践中,根据缺陷类型的不同,改变孕育量、孕育剂类型、孕育剂粒度、孕育方式、孕育温度或采用特殊孕育剂等强化孕育措施可有效防止缺陷的形成。The morphology of fractal graphite and D-type graphite of high nickel austenite nodular cast iron were studied.The results show that the defects are directly related to the precipitation time of austenite and graphite during solidification.When a large amount of austenite precipitates,but the graphite precipitates seriously,it is easy to form abnormal structure.When the preference of graphite precipitation increases,it is easy to form normal structure.Poor instillation of nodular cast iron will lead to a serious lag in graphite precipitation and an earlier timing of austenite precipitation,resulting in the formation of broken graphite,Spiking dendrite,antileucorrhoea,leucorrhoea and other defects.In production practice,according to the different types of defects,changing inoculating amount,inoculating agent type,inoculating agent particle size,inoculating mode,inoculating temperature or using special inoculating agent can effectively prevent the formation of defects.