Iron production in the Qin state during the late Warring States period: a cost-efficient technological system

This paper presents the technical characterisation by metallography and slag inclusion analysis of 43 iron artefacts from Qin civilian burials in the Guanzhong Plain, dated to the late Warring States period (around 3rd c. BC). Analysing these results with previously published data, we identify correlations among artefact functions, materials and manufacturing techniques, which indicate the existence of a complex and cost-efficient technological system. It is argued that a cast iron-based iron production industry was established in the Qin state to supply the civilian needs no later than the late Warring States period. Both casting and forging were used to shape iron objects, each requiring specific types of iron as raw material. Annealing and fining (Chaogang) techniques were applied to reduce the hardness of cast iron, as well as to convert cast iron into soft iron and steel. Along with other technical innovations such as the controlled cooling of mould-casting and various heat-treatment methods, the Qin state established a much more complex, diversified and cost-effective technological system of iron making, which facilitated the state to provide low-cost iron products for civilian use, as well as high-quality iron tools for state-owned workshops.

Automated summary

This paper characterizes 43 iron artefacts from Qin civilian burials in the Guanzhong Plain, dating back to the late Warring States period, through metallography and slag inclusion analysis. By analyzing these results with previous data, correlations among artefact functions, materials, and manufacturing techniques are identified, suggesting the existence of a complex and cost-efficient technological system. The study argues that a cast iron-based iron production industry was established in the Qin state no later than the late Warring States period to meet civilian needs.