碳素工具钢

• Had already produced the high quality steel in the 12th century b . c . , produced the plain tool steel of carbon in the 7th century b . c .
  西元前12世纪已生产出优质钢铁，西元前7世纪生产了碳素工具钢。
• Had already produced the high quality steel in the 12th century b . c . , produced the plain tool steel of carbon in the 7th century b . c .
  西元前12世纪已生产出优质钢铁，西元前7世纪生产了碳素工具钢。