Manufacturing techniques of armor strips excavated from Emperor Qin Shi Huang's mausoleum, China

The chemical compositions and microstructures of the armor strips excavated from the Emperor Qin Shi Huang's mausoleum were examined systematically by using optical microscopy and electron microscopy. It was found that the armor strips were made of pure copper. Based on the morphology of alpha-Cu recrystal grain and copper sulphide (Cu2S) inclusions in the armor strips, the manufacturing techniques were proposed as follows: smelting pure copper, casting a lamellar plate, forming the cast ingots into sheets through repeated cold forging combined with annealing heat treatment, and finally cutting the sheets into filaments. Furthermore, through the deformation of copper sulphide (Cu2S) inclusions in the strips, the work rate during forging was evaluated and calculated to be close to 75%.