为了提高活塞环的使用寿命,铸铁以0.025%氮合金化。方法是用棒将浸渍尿素的耐火物加入在铁水包液面下,经1～1.5分钟分解,使铁水被活性氮饱和,然后在1400℃浇注第一只筒形活塞环坯件(内径470毫米、壁厚30毫米、高400毫米)。铁水成分为3.2～3.6%C,0.6～0.9%Mn,1.3 In order to improve the service life of the piston ring, cast iron is alloyed with 0.025% nitrogen. The method comprises the following steps: adding urea-impregnated refractories into the surface of a molten metal and decomposing for 1 to 1.5 minutes to saturate molten iron with active nitrogen, then pouring a first cylindrical piston ring blank (inner diameter 470 mm , Wall thickness 30 mm, height 400 mm). The hot metal composition is 3.2 to 3.6% C, 0.6 to 0.9% Mn, 1.3