一、前言作为时代进步产物之一的超纯钢(Ultra-Clean),其钢中磷、硫及其他夹杂物的含量是相当低的。一般,普碳钢的磷、硫均<0.050％;优质钢的磷、硫均<0.040％;高级优质钢的磷、硫均<0.030％;而超纯钢的磷、硫却要求<0.02％,有的甚至低到0.005％。就其他夹杂物而言,超纯钢的夹 I. INTRODUCTION Ultra-Clean steel (Ultra-Clean), one of the products of the times, has relatively low content of phosphorus, sulfur and other inclusions in steel. Generally, the phosphorus and sulfur of the general carbon steel are all less than 0.050%; the phosphorus and sulfur of the high quality steel are all less than 0.040%; the phosphorus and sulfur of the high quality steel are all less than 0.030% , Some even as low as 0.005%. In terms of other inclusions, ultra-pure steel folder