Search

This paper presents the archaeometallurgical study of iron objects unearthed from the Niejiagou bone workshop dated between late Warring States period to the end of Qin dynasty. Through metallographic study and slag inclusion analysis, all analysed samples were confirmed to be made from cast iron as raw material, with the exception of NJG-34, which production technique cannot be positively confirmed. To convert cast iron into soft iron or steel, both annealing for decarburisation and fining techniques were applied, with the preference of annealing technique for the majority of the iron tool. The extremely fine-grained soft iron/steel microstructure, which was rarely observed in past research, represents a highly developed annealing technique with possible independent normalising operation adopted to reduce the grain size. Such a decarburisation method creates materials with exceptionally high quality, while the cost is also much higher compared to the finning process. Additionally, two iron objects with unique slag inclusions in terms of their morphology and compositional data were found, which possibly represent a new decarburisation method unknown to current research yet. Overall, this site displayed a unique technological choice on cast iron decarburisation methods, which can be argued to be the result of unlimited production cost considering this site was state controlled and served the Qin royalty. [ABSTRACT FROM AUTHOR]