Journal of Archaeological Science 47 (2014) 53e63 Contents lists available at ScienceDirect Journal of Archaeological Science journal homepage: http://www.elsevier.com/locate/jas A view of iron and steel making technology in the Yan region during the Warring States period and the Han dynasty: scientific study of iron objects excavated from Dongheishan site, Hebei province, China Haifeng Liu a,*, Jianli Chen b, Jianjun Mei a, Jinbiao Jia c, Lei Shi c a Institute of Historical Metallurgy and Materials, University of Science and Technology Beijing, Haidian District, Beijing 100083, China b School of Archaeology and Museology, Peking University, Haidian District, Beijing 100871, China c Hebei Provincial Institute of Culture Relics, China article info abstract Article history: Iron objects excavated from the Dongheishan site provided a chance to systematically study the iron and Received 9 January 2013 steel making technology during the Warring States period and the Han dynasty in the Yan region, north Received in revised form China. According to the results of radiocarbon dating, metallographic and slag inclusions analysis, it was 30 March 2014 found that they were made of cast iron or cast iron subsequently processed into steel, and most Accepted 1 April 2014 radiocarbon dates of iron artefacts were consistent with the determination from their archaeological Available online xxx context. The technology in this region was as advanced as the Central Plain China, and it was probably a previously unknown centre of technological innovation during this period. Meanwhile, the results Keywords: Iron objects analysis showed that the local craftsmen used different types of iron and steel and different technologies to The Warring States period and the Han produce different types of objects. dynasty Ó 2014 Elsevier Ltd. All rights reserved. Dongheishan site The Yan region China 1. Introduction Hebei province. Here, not only iron objects but also iron-casting works were found near the imperial palace (Hebei Provincial From 475 BCE to 220 CE China experienced three important Institute of Culture Relics (1996)). Besides iron objects, casting periods: the Warring States period (475 BCEe221 BCE), the Qin moulds made from irondwhich could be used repeatedly e were dynasty (221 BCEe206 BCE) and the Han dynasty (206 BCEe220 found in the Shouwangfeng site, Xinglong county, Hebei province CE). During this period a technological system of cast iron and (Zheng, 1956: 1). Among these objects, 14 agricultural implements steelmaking was established and consolidated, while iron and steel and 21 weapons from the Yanxiadu site were analysed (Beijing products came to be used in many areas of China (Bai, 2005:116; University of Iron and Steel Technology (1975): 4; Li et al., 1996: Han and Ko, 2007: 440; Wagner, 2008: 115). 881). The results show that all agricultural implements were made The Yan state was one of the seven big states in the Warring of cast iron and some had experienced a decarburization process- States period, extending from the Taihang Mountain in the west to ing. The weapons were made of cast iron or steel. The steel, which the north part of Korean Peninsula in the east, and from the Liao was made from both cast iron and bloomery iron, was very River in the Northeast to the Qi state in the southeast and to the different from the iron used to make agricultural implements. Zhao state in the southwest. Up to the present, about 2800 iron The Qin and Han dynasties mark the beginning of Imperial objects from 38 sites or tombs were found within the Yan state’s China and established many of the institutions that would define territory, and they may therefore be defined as Yan-state iron ob- the period. For instance, in 117 BCE Emperor Wu-di introduced a jects. The most important excavation took place at the Yanxiadu state monopoly on the salt and iron industries, the policy set iron site, the capital of the Yan state which is now located in Yi county, and steel production on a course towards industrialization and standardization throughout China. A large number of state’s monopoly-run ironworks have been located, and several have been excavated; meanwhile, lots of iron objects have been excavated * Corresponding author. from Han-period settlements, tombs and ironworks (Li, 1994: 158; E-mail addresses: [email protected], [email protected] (H. Liu). Han and Ko, 2007: 502; Wagner, 2008: 198). At this time, the Yan http://dx.doi.org/10.1016/j.jas.2014.04.001 0305-4403/Ó 2014 Elsevier Ltd. All rights reserved. 54 H. Liu et al. / Journal of Archaeological Science 47 (2014) 53e63 Fig. 1. The location of the Dongheishan site and the Yan state. region was divided into several provinces or states, including the spectrometry radiocarbon dating (AMS-14C dating), optical micro- northern part of the Zhongshan state, which also had a state’s scopy, and scanning electron microscopy (SEM) with energy monopoly-run ironwork. The Zhongshan ironwork has not yet been dispersive spectrometry (EDS). located, but is the apparent source of the considerable quantity of iron objects unearthed in the Mancheng tomb (Institute of Archaeology, Chinese Academy of Social Sciences, 1980). Twenty- 2. Background of the site and iron artefacts six iron objects from the Mancheng tomb were analysed (Beijing University of Iron and Steel Technology, 1980: 369; Tsinghua The Dongheishan site, located in Xushui county, Hebei province, University, 1980: 388). The results concluded that most were China, roughly 120 km southwest of Beijing city (Fig. 1), was made of cast iron and steel; the steel had been converted from cast excavated by the Hebei Provincial Institute of Culture Relics in iron via a decarburization processing and had been quenched to 2006. The excavations uncovered a long period of occupation, from improve mechanical performance. Meanwhile, scholars (Beijing the late Warring States period to the Qing dynasty, with rich as- University of Iron and Steel Technology (1980): 369) have stated semblages of pottery, porcelain, bronze, and iron artefacts, and that objects from the Mancheng tomb appear to be a primitive form other materials. Finds dating to the period from the late Warring of Bailian steel (hundred refining steel). In addition, bloomery iron States period into the Han dynasty were deemed to be the most objects were also found in the Dabaotai tomb in Beijing (Beijing important. Because the site was located on the south boundary of University of Iron and Steel Technology (1989): 125), which the Yan state e facing the Zhao state directly e and only 30 km proved that bloomery iron was still in use, though they only south of the capital, it is considered to be an important military occupied 6% among all the iron objects. stronghold of the state in the late Warring States period (Jia et al., Past research has answered many questions about the iron in- 2007). In the Han dynasty, the site was a more residential area dustry of the Warring States period and the Han dynasty. However, belonging to the Zhongshan state. the use of iron artefacts and the development of iron and steel 175 iron objects were excavated, with 137 of those from layers making technology during this period in the Yan region need dating to the late Warring States period or the Han dynasty. Among further research. The large quantity of iron objects excavated from them, 26% are agricultural implements, 23% belong to other im- the Dongheishan site in Xushui county, Hebei province, provide an plements, and 18% are weapons (Table 1, Fig. 2). 66 iron objects opportunity to carry out fresh research. The present study of the were analysed, of which 51 were excavated from the layers of the Dongheishan iron objects will characterize their chronology, late Warring States and the Han dynasty, in order to investigate microstructure, and chemistry through the use of accelerator mass local iron and steel making technology of this period. H. Liu et al. / Journal of Archaeological Science 47 (2014) 53e63 55 Table 1 The iron objects excavated from the Dongheishan site. Types Late Warring Early Western Mid-late Eastern Han Tang-Song Jin-Yuan Ming-Qing Age Total States period Han dynasty Western dynasty period period period uncertain Han dynasty Agricultural Unearthed number 4 13 19 6 1 1 1 45 implement Sampled number 2 4 6 4 16 Other implement Unearthed number 2 13 11 10 2 1 2 41 Sampled number 4 7 1 1 1 2 16 Weapon Unearthed number 1 7 9 6 2 5 1 31 Sampled number 3 4 2 1 10 Other kinds Unearthed number 2 9 12 13 9 4 9 58 Sampled number 1 3 4 6 6 1 3 24 Total Unearthed number 9 42 51 35 12 12 1 13 175 Sampled number 3 14 21 13 6 3 1 5 66 Fig. 2. Selected iron objects from the Dongheishan site. 3. Experiments and results one standard deviation, and background is 43,000 years. Calibrated dates were determined using the software Oxcal v3.10. The radio- 3.1. Radiocarbon dating carbon dates and calibrated dates of objects from the site are shown in Table 2. Artefacts are often assigned a date via their archaeological context, but it is necessary to consider that many objects may have 3.2. Metallographic and SEM-EDS analysis been deposited only after a long use life. By employing AMS-14C dating on iron objects, a date of manufacture can be established Using metallographic and SEM-EDS analysis to reveal the with confidence (Craddock et al., 2002: 717). In order to compare metallographic and slag inclusion structure as well as chemical the radiocarbon dates of iron objects with contextually determined composition of artefacts can help to understand the materials and dates, we chose 15 samples which have high concentrations of technologies used in the past.