第一夫人

鑄鐵(cast iron)

鐵的合金，含碳2～4%，還含有數量不等的矽、錳、硫、磷。鑄鐵是在高爐內還原鐵礦石生產的，放出鐵水澆注冷卻成錠，稱為生鐵。鑄鐵與熟鐵不同，不能鍛造，只能鑄造成型，性脆、抗拉強度低，但產品價廉。鑄鐵有較高的抗壓強度，以致成為首要的結構金屬。18～19世紀時，鑄鐵是比熟鐵較為便宜的工程材料。20世紀建築業以鋼取代鑄鐵，但在工業中仍有許多用途，如汽車發動機缸體、農業機械和機器零件、管道、凹形器皿、火爐、熔爐等。按照斷面顏色，鑄鐵有灰口或白口之分。灰口鐵含矽較高，硬度較低，比白口鐵加工效能好。白口鐵和灰口鐵均較脆。18世紀，在法國發展了白口鑄鐵經長時間加熱處理生產可鍛鑄鐵。1948年在美國和英國發明瞭在鑄造狀態下就有延伸性的鑄鐵。這類韌性鑄鐵，現已形成重要的金屬體系，廣泛用於齒輪、模具、汽車曲軸和許多其他機械零件。

English version：

cast iron

Alloy of iron that contains 2-4% carbon,along with silicon,manganese,and impurities. It is made by reducing iron ore in a blast furnace (cast iron is chemically the same as blast-furnace iron) and casting the liquid iron into ingots called pigs. Pig iron is remelted,along with scrap and alloying elements,in cupola furnaces and recast into molds for a variety of products. In the 18th-19th century,cast iron was a cheaper engineering material than wrought iron (not requiring intensive refining and hammering). It is more brittle and lacks tensile strength. Its compressive (load-bearing) strength made it the first important structural metal. In the 20th century,steel replaced it as a construction material,but cast iron still has industrial applications in automobile engine blocks,agricultural and machine parts,pipes,hollowware,stoves,and furnaces. Most cast iron is either so-called gray iron or white iron,the colors shown by fracture; gray iron contains more silicon and is less hard and more machinable than white iron. Both are brittle,but malleable cast iron (produced by prolonged heat treating),first made in 18th-century France,was developed into an industrial product in the U.S. (see Seth Boyden). Cast iron that is ductile as cast was invented in 1948. The latter now constitutes a major family of metals,widely used for gears,dies,automobile crankshafts,and many other machine parts.