ABSTRACT Optical analysis, dilatometry as well as neutron diffraction are utilised to investigate the phase transition within ductile iron both in-situ and after the heat treatment process for perferritic isothermed ductile iron (IDI). A suitable annealing temperature is chosen by calculating a phase diagram for the investigated alloy. The phase transition which happens slightly above upper intercritical temperature is followed by neutron diffraction, while dilatometry elucidates the IDI microstructure evolution for cooling rates from 40 to 0.125 K/s. The dilatometry results are visualised in a CCT diagram and further investigated with metallography. An additionally used colour etching method is basis for discussing the formation of the pearlitic/ferritic network. The presence of 2 vol.-% of ferrite was sufficient to achieve the typical IDI microstructure. Finally, the cementite phase volume fractions and crystal structure are evaluated. . The lattice constants of ferrite and cementite were independent of the formed microstructure.

中文翻译：

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铁素体等温球墨铸铁 (IDI) 的相变和显微组织研究

摘要 利用光学分析、膨胀测定法以及中子衍射来研究原位和热处理工艺后球墨铸铁内的相变，对全铁素体等温球墨铸铁 (IDI) 进行研究。通过计算所研究合金的相图来选择合适的退火温度。相变发生在略高于上临界温度时，随后是中子衍射，而膨胀法则阐明了冷却速率从 40 到 0.125 K/s 时的 IDI 微观结构演变。膨胀测量结果在 CCT 图中可视化，并用金相学进一步研究。另外使用的彩色蚀刻方法是讨论珠光体/铁素体网络形成的基础。2 卷的存在。-% 的铁素体足以实现典型的 IDI 微观结构。最后，评估渗碳体相体积分数和晶体结构。. 铁素体和渗碳体的晶格常数与形成的微观结构无关。