HIGH-STRENGTH FERRITE STAINLESS STEEL HAVING EXCELLENT FORMABILITY AND METHOD FOR MANUFACTURING THEREOF

A high-strength, high-formability ferritic stainless steel and a manufacturing method thereof are disclosed. The high-strength ferritic stainless steel with excellent formability includes 0.001 to 0.3 wt% of C, 0.001 to 0.3 wt% of N, 0.01 to 1.0 wt% of Si, 0.1 to 3.0 wt% of Mn, 10 to 15 wt% of Cr, 0 to 0.03 wt% of P, 0 to 1.0 wt% of Ni, 0 to 1.0 wt% of Cu, 0.01 to 1.0 wt% of Ti, 0 to 1.0 wt% of Al, with the remainder including Fe and inevitable impurities. The phase diagram calculation shows that the γ Vol. fraction at 1200℃ is at least 15%, the average grain size of cold-rolled annealed material below 2.0 t is 15 μm or less, yield strength is at least 240 MPa, tensile strength is at least 400 MPa, elongation is at least 25%, and the plastic strain ratio represented by the R45 value is 1.5 or higher. Equation (1): γ Vol. fraction at 1200℃ >= 15%. Therefore, through grain refinement, ferritic stainless steel with improved strength and formability can be obtained. 중량 %로, C: 0.001 ~ 0.3%, N: 0.001 ~ 0.3%, Si: 0.01 ~ 1.0%, Mn: 0.1 ~ 3.0%, Cr: 10 ~ 15%, P: 0 ~ 0.03%, Ni: 0 ~ 1.0%, Cu: 0~1.0%, Ti: 0.01 ~ 1.0%, Al: 0 ~ 1.0% 를 포함하고, 잔부는 Fe 및 불가피한 불순물을 포함하며, 상태도상 계산된 1200℃에서의 γ Vol. fraction이 15% 이상이고, 2.0t 이하 냉연소둔재의 평균 결정립 크기가 15㎛ 이하인 동시에, 항복강도는 240MPa 이상이면서 인장강도는 400MPa 이상이고, 연신율은 25% 이상을 만족하며, 소성이방성을 나타내는 R45도 값이 1.5 이상인 고강도 고성형 페라이트계 스테인리스강 및 이의 제조방법을 나타낸다. 식 (1): γ Vol. fraction at 1200℃ ≥ 15%