nodular iron(Since 1948 spheroidal graphitic cast iron, better known as S.G. iron or nodular iron, and in the U. S.A. as ductile iron, has been developed as a constructional material which can compete with steel castings or forgings for many stressed components. 自 1948 年以来，球墨铸铁就以" S.G. 铁"或"球铁"著称，在美国则称之为"延性铁"。这种铸铁作为结构材料获得了发展，在诸多承受应力的零部件制造领域，它可与铸钢件或锻钢件相媲美。)
