History of metallurgy in China

Metallurgy in China has a long history, with the earliest metal objects in China dating back to around 3,000 BC. The majority of early metal items found in China come from the North-Western Region (mainly Gansu and Qinghai, 青海). China was the earliest civilization to use the blast furnace and produce cast iron.

Copper Archaeological evidence indicates that the earliest metal objects in China were made in the late fourth millennium BC. Copper was generally the earliest metal to be used by humanity, and was used in China since at least 3000 BC.

Early metal-using communities have been found at the Qijia and Siba sites in Gansu. The metal knives and axes recovered in Qijia apparently point to some interactions with Siberian and Central Asian cultures, in particular with the Seima-Turbino complex, or the Afanasievo culture. Archeological evidence points to plausible early contact between the Qijia culture and Central Asia. Similar sites have been found in Xinjiang in the west and Shandong, Liaoning and Inner Mongolia in the east and north. The Central Plain sites associated with the Erlitou culture also contain early metalworks. Copper manufacturing, more complex than jade working, gradually appeared in the Yangshao period (5000–3000 BC). Jiangzhai is the only place where copper artifacts were found in the Banpo culture. Archaeologists have found remains of copper metallurgy in various cultures from the late fourth to the early third millennium BC. These include the copper-smelting remains and copper artifacts of the Hongshan culture (4700–2900 BC) and copper slag at the Yuanwozhen site. This indicates that inhabitants of the Yellow River valley had already learned how to make copper artifacts by the later Yangshao period. The Qijia culture (c. 2500–1900 BC) of Qinghai, Gansu, and western Shaanxi produced copper and bronze utilitarian items and gold, copper, and bronze ornaments. The earliest metalwork in this region are found at a Majiayao (c. 3100–2700 BC) site at Linjia, Dongxiang, Gansu, where they are mixed with work apparently from the Zongri culture (宗日, c. 3600–2050 BC) and later Machang (c. 2300–2000 BC), Qijia (c. 2050–1915 BC), and Siba cultures (c. 2000–1600 BC). At Dengjiawan, in the Shijiahe site complex in Hubei, some pieces of copper were discovered; they are the earliest copper objects discovered in southern China. The Linjia site (林家遺址, Línjiā yízhǐ) has the earliest evidence for bronze in China, dating to c. 3000 BC.

Bronze

Bronze technology was imported to China from the steppes. The oldest bronze object found in China was a knife found at a Majiayao culture site in Dongxiang, Gansu, and dated to 2900–2740 BC. Further copper and bronze objects have been found at Machang-period sites in Gansu. Metallurgy spread to the middle and lower Yellow River region in the late 3rd millennium BC. Contacts between the Afanasievo culture and the Majiayao culture and the Qijia culture have been considered for the transmission of bronze technology. From around 2000 BC, cast bronze objects such as the socketed spear with single side hook were imported and adapted from the Seima-Turbino culture. The Erlitou culture (c. 1900 – 1500 BC), Shang dynasty (c. 1600 – 1046 BC) and Sanxingdui culture (c. 1250 – 1046 BC) of early China used bronze vessels for rituals (see Chinese ritual bronzes) as well as farming implements and weapons. By 1500 BC, excellent bronzes were being made in China in large quantities, partly as a display of status, and as many as 200 large pieces were buried with their owner for use in the afterlife, as in the Tomb of Fu Hao, a Shang queen. In the tomb of the first Qin Emperor and multiple Warring States period tombs, extremely sharp swords and other weapons were found, coated with chromium oxide, which made the weapons rust resistant. The layer of chromium oxide used on these swords was 10 to 15 micrometers and left them in pristine condition to this day. Chromium was first scientifically attested in the 18th century. The beginning of new breakthroughs in metallurgy occurred towards the Yangzi River's south in China's southeastern region in the Warring States period such as gilt-bronze swords.

Section-mold casting There are two types of bronze smelting techniques in early China, namely the section mold process and the lost-wax process. The earliest bronze ware found in China is the bronze knife (F20: 18) unearthed at the Majiayao in Linjia, Dongxiang, Gansu, and dated to about 3000 BC. This bronze knife uses the section mold process, which is spliced by two molds. The section mold process is a commonly used bronze casting method in the Shang dynasty, that is, the mud is selected, and after selecting, filtration, showering, deposition and other procedures, the mud is cooled to a moderate hardness as a backup, and then the mud is made according to the shape of the vessel to be made. There are two types of molds, which is inner mold and outer mold. The inner mold is only the shape of the bronze ware, without decoration; the outer model should consider the division of the bronze ware after casting in the future, that is, the block during the production of the clay model, and also engrave the inscriptions and inscriptions of the bronze ware decoration on the clay model. After the clay mold are done, put it in a cool place to dry in the shade, and then put it into the furnace for roasting. After the mold are heated, they become pottery molds unearthed during modern archaeological discoveries. After the pottery mold is fired, do not rush out of the furnace. After the copper furnace has liquefied the required copper, the pottery mold that still has residual temperature is taken out and poured. In this way, the temperature difference between the copper liquid and the pottery mold is not large, and the pottery mold is not easy to burst. The quality of the finished product is relatively high. After the copper liquid is poured, remove the pottery molds and molds according to the blocks they were made. If they can't be removed, they can be broken with a hammer. The bronze will come out, and after grinding, it is the finished product.

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