摘要
通过试验研究，对碎块状石墨的结晶、生长机制及其影响因素进行了更深入的探讨。结果认为，碎块状石墨在共晶凝固即将开始前先于奥氏体枝晶析出；石墨与奥氏体之间的松散偶合是碎块状石墨形成的原因。为防止这种缺陷，提出了共晶凝固（它反映着热影响因素）开始时的冷却速度（ｄＴ／ｄτ）ＥＵ的具体数值；另外，还必须限制反偏析元素Ｓｉ、Ｎｉ、Ｃｕ的含量。
The first part of the paper reviewed the literature concerned,a structure defect,chunky graphite,commoly occurring in the ductile iron castings with heavy sections has been presented.The second part,based on experiments,the crystallization of chunky graphite,the mechanism of its growth and the influencing factors were discussed in detail.It is considered that the chunky graphite precipitates prior to the austenite dendrite soon before the eutectic solidification growing in the form of eutectic grain.The in compact coupling between the graphite and austenite is the reason for the formation of chunky graphite.To present this defect,the specific data is given about the cooling rate(dT/dτ) eu at the begining of eutectic solidification which showes thermal effects.In addition,the content of inverse segregation elements(Si,Ni,Cu)must be limited.
出处
《铸造》
CAS
CSCD
北大核心
1997年第11期10-17,共8页
Foundry
