A STEEL CONTAINING PHOSPHOROUS WITH EXCELLENT IMPACT TOUGHNESS AND HIGH STRENGTH

摘要

The present invention relates to steel containing phosphorous having high strength and toughness and, more specifically, to a new type of phosphorous-containing steel which overcomes a traditional concept in which brittleness can be induced when phosphorous is plentifully contained in steel. According to an embodiment of the present invention, the phosphorous-containing steel includes greater than 0.3 and less than or equal to 0.6 wt% of C; 0.5-3.0 wt% of Mn; 0.05-0.3 wt% of P; 0.0005-0.01 wt% of B; 0.05-0.5 wt% of Mo; 0.05-0.5 wt% of La; less than or equal to 0.01 wt% of N; and the rest consisting of Fe and unavoidable impurities. The phosphorous-containing steel has an organization in which a surface area fraction of martensite is above 80%.