• Journal of Conservation Science
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• v.34 no.1
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• pp.39-50
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• 2018

This study replicated traditional smelting methods to produce iron blooms from sand iron. The metallurgical properties of the slag and the iron blooms were analyzed. The sand iron materials used in the smelting experiments, which were based on ancient documents, were collected from Gyeong-Ju and Pohang. Analysis by WD-XRF and XRD showed that Gyeong-Ju's sand iron contains a high-titanium, with magnetite, and Pohang's sand iron contains a low-titanium, which magnetite and ilmenite were mixed. Analysis of the slag with XRD, and the micro-structure with metal microscopes and SEM-EDS, confirmed that the major compounds in the slag of the Gyeong-Ju's sand iron were fayalite and $w\ddot{u}stite$, and those in the slag of the Pohang's sand iron were titanomagnetite and fayalite. The differences in the main constituents were confirmed according to the Ti quantity. Finally, we observed the microstructures of the iron blooms. In the case of the iron bloom produced from Gyeong-Ju's sand iron, the outside was found to be dominantly a pearlite of eutectoid steel, while the inside was a hypo-eutectoid steel where ferrite and pearlite were mixed together. While, the major component of the iron bloom produced from Pohang's sand iron was ferrite, which is almost like pure iron. However, there were many impurities inside the iron blooms. Therefore, this experiment confirmed that making ironware required a process that involved removing internal impurities, refining, and welding. It will be an important data to identify the characteristics of iron by-products and the site through traditional iron-making experiments under various conditions.

• Journal of Conservation Science
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• v.17 s.17
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• pp.57-64
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• 2005

In the course of examining the micro structure of Iron chisel and Iron arrowhead, a relics of the 16th or 17th of Chosun Dynasty unearthed at near Gangsun-tower, Chengpyeong temple. Collected un-eroded samples from the relics were looked into the metallic structure through optical metallography. Non-metallic inclusions were-analysed by SEM and EDS. The micro structure examination and SEM-SDS analysis revealed that Iron chisel and Iron arrowhead had been produced from the sponge iron close to pure iron made by low temperature reducing in a solid and then the surface carbon content was increased by carburizing treatment. It was also found that Iron chisel had been hardened through the repetitive processes of quench hardening and heat treatment, after increasing carbon content to a certain level. Up to now, there have been a number of studies in the domestic academia which were studied mainly on the structure of metallic relics in the period of the Three Kingdoms or before. Although this research was limited in type and number of the relics, it turned out to be interesting in that it revealed the 16th or 17th century way of processing iron, even in fragments. It is thought to be fruitful that iron had been made even in the Chosun Dynasty from the sponge iron.

• KOMUNHWA
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• no.56
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• pp.147-180
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• 2000

This study has been investigated to use base research data of archaeology and conservation science for cultural properties about iron artifacts from Kimhae Yangdong-Ri tombs as metallurgical research. 1. Iron artifacts from Kimhae Yangdong-Ri tombs had be

• Korean Journal of Heritage: History & Science
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• v.53 no.1
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• pp.168-183
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• 2020

Efforts had been made to eliminate the brittleness unique to cast ironware from 5 BC up until the time that cast ironware became widely used. One of the techniques used to this end was to produce the cast ironware in one kiln and then anneal it in another kiln. This technique condensed or removed the carbon in the structure to eliminate the brittleness of cast ironware and enable forging. To clarify the nature of this technique, this study examined cast ironware made of malleable cast iron, which manifests the characteristics of the annealing technique for cast ironware excavated on the Korean peninsula, based on current steelmaking technology and research results from China and Japan. Results confirmed that all cast ironware made of malleable cast iron had been imported into Korea until the Proto-Three Kingdoms Period. Also, since the Chiljido (Seven-Branched Sword), which is housed at the Ishigami Shrine in Japan, appears to have been produced in the Korean peninsula, it is determined that Baekje in the 4^th century must have possessed such an annealing technique. At that time, however, iron was produced mainly with an iron bloom, and a large amount of forged iron was produced with a steel bloom smelted from an iron bloom. In addition, most of the cast ironware that was used previously, except for cast iron hoes, had been replaced by forged ironware. In other words, this annealing technique was not used frequently until the Three Kingdoms Period. However, it spread broadly during the Unified Silla Period in so much as it was identified in the Jangan-ri remains, which represented the regional hub of iron production and distribution.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.475-499
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• 2023

To infer the provenance of raw iron materials utilized in iron production at the archaeological sites in Gyeongsang province, petrographic and geochemical analyses were conducted for smelting samples and major iron ores sourced from ore deposits. The smelting samples excavated from various iron archaeological sites were classified into different types according to their refining processes, such as iron bloom, iron bloom slag, pig iron, pig iron slag, forging iron flake, smithery iron, iron flake, and arrowhead. These samples exhibited discernable differences in their mineralogical components and texture. The enrichments of major elements such as aluminum and calcium in silicate minerals of the residual slags and the high contents of trace elements such as nickel and copper in some iron-making relics reflect the characteristics of raw iron ores, and thus can be regarded as potential indicators for inferring the provenance of source materials. In particular, the compositional ranges of Pb-Sr isotope ratios for the iron smelting samples were classified into three categories: 1) those exhibiting similar ratios to those of the raw iron ores, 2) those enriched in strontium isotope ratio, and 3) those enriched in both lead and strontium isotope ratios. The observed distinct Pb-Sr isotope characteristics in the iron smelting samples suggest the potential contribution of specific additives being introduced during the high-temperature refining process. These results provide a new perspective on the interpretation of the provenance study of the iron archaeological samples in Gyeongsang province, particularly in terms of the potential contribution of additives on the refining process.

• Journal of Conservation Science
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• v.18 s.18
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• pp.33-50
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• 2006

Around Yeongsan river basin, there are Yeongkwang Gundong, Muan Inpyeong Tombs, Muu Gusan-ri Tombs and Hampyeong Guksan remain from which a lot of iron artifacts were excavated. Among them, 6 iron artifacts were chosen, and their microstructures were analyzed. As a result, Iron artifacts were produced sponge iron by the low temperature reduction process and a part of microstructure have the possibility that steel made by decarburizing. And also, by tempering the parts which need high strength, the iron artifacts had high strength and by distributing the weakness of the tempered structure to the nearby untempered parts, their breaking was prevented and they had the durability. These skills were used then. Especially these skills were found to be used in the 2nd century by high skilled people because an iron axe excavated at Yeongkwang Gundong of 2nd century by the historical record showed that the skill was used. Also microstructures were found to show the possibility that the iron technology was inherited to the late 5th century. When producing iron artifacts made of sponge iron containing small amount of carbon, that was made by the production process repeating molding, carburizing, heat treatment and hammering.

• Journal of Conservation Science
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• v.29 no.4
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• pp.367-378
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• 2013

Microstructures and nonmetallic inclusions of five forged iron axes and one cast iron axe were analyzed. The axes were excavated from the Proto-Three Kingdom Period site located in Yangchon, Gimpo. The forging objects were made of almost pure iron and low carbon steel, and only one among five were quenched after its figuration. Malleable cast iron structures showing on the casting suggest that the decarbonized casting method were applied. According to the results of nonmetallic inclusion analysis, the axes were produced by hammering the iron bloom which was attained with low-temperature -solid-reduction-method. Showing higher Fe content over $SiO_2$, it is assumed that the re-collecting rate of Fe was low because of the insufficient forging temperature and the impurities were included during the smelting process. It is assumed that the lime was used as a preparation because of detecting high Ca contents.

• Journal of Conservation Science
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• v.30 no.4
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• pp.335-343
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• 2014

This study classified the result of non-metallic inclusion analysis and result of microstructure investigation on the ironware excavated in the Baekje region into Han River, Geum River, and Yeongsan River to estimate the iron making temperature and study the characteristics of regional and temporal characteristics of the heat treatment technology and steel making technology. Regardless of era, bloom iron and sponge iron are judged to be the major method for making as a directreduction process in all three regions. The result of the reinterpretation of the non-metallic inclusion by the oxide ternary constitutional diagram suggest that the temperature inside of the furnace is estimated to be between $1,100{\sim}1,300^{\circ}C$ while making the steel. The magnetic iron ores are the major raw material of steel ore and irons with high $TiO_2$ are estimated to use iron sands. Ironware with $CaO/SiO_2$ rate higher than 0.4% are considered to have artificially added the flux of calcareous materials. It was found that the iron making method is the solid caburizing-steel which caburizes low-carbon steels by the CO gas and $CO_2$ gas created when heating the forging furnace with charcoal. Also, the ironware manufacturers in the Baekje during 3rd century recognized the heat treatment technology as they performed carburizing process and quenching to intentionally increase the strength of necessary parts.

• Journal of Conservation Science
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• v.34 no.6
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• pp.581-593
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• 2018

Studies on ancient iron production technologies still have challenges to overcome, although there have been many results that have enabled us to understand these old technologies. The purpose of this study is to propose a suitable temperature condition for smelting experiments. The target for reconstruction is a smelting-smithing process in the ancient Jungwon area, and the experiment was designed on the basis of published research, such as archaeological evidence. Experiment A was performed at a low temperature to produce low-carbon iron, while Experiment B was conducted at a relatively high temperature to synthesize high-carbon iron. In addition, the low-carbon iron proved to be suitable for the smithing process. Moreover, aspects such as the microstructure and chemical composition of the slag and the surface condition of the furnace wall showed that the low-temperature smelting process was closer to the ancient method. It is important to mention the premise that the reconstruction of ancient technology can be achieved when the results of an experiment replicate the conditions of a real site. The results show that direct smelting, which produces low-carbon iron bloom under a low-temperature condition, should be the subject of smelting experiments concerning the iron production technologies of the ancient Jungwon area.

• Korean Journal of Heritage: History & Science
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• v.50 no.1
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• pp.4-17
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• 2017

In this research, the chemical composition of the iron artifacts from the late 6th-century to early 7thcentury Baekje remains in Gwanbuk-ri, Buyeo, specifically of the nine iron artifacts including slags, furnace walls and ingot iron excavated in the District "Na", were examined by observing their chemical compounds and microstructures. As a result, GB1 and GB6 were determined to be proto-reduction lumps whereas GB2, GB3, GB4 and GB5 were determined to be tempered slags, respectively. Also, he furnace wall GB7 were containing mullite and cristobalite, which are high temperature index minerals, The extrusion temperature was found out to be about $1200{\sim}1300^{\circ}C$, and it is most likely that the smelting temperature in the furnace was in that temperature range. GB8 ingot iron was determined to be a forged ironware. This ingot iron was an intermediary product for making ironware and its nonmetallic inclusions displayed similar microstructure and contents compared to the forged iron. Because of the existence of proto-reduction lumps and forged iron, the iron making facility located in District "Na" most likely had a small-scale iron making facility that handled iron bloom smelting and refining processes.