Twenty children were grouped in a circle round a chrome steel tower.
二十个孩子围着一座克罗米钢塔。
英语百科
Chrome steel
Chrome steel is one of a class of non stainless steels such as AISI 52100, En31, SUJ2, 100Cr6, 100C6, DIN 5401 which are used for applications such bearings, tools, drills and utensils.