| 摘要 |
PURPOSE:To obtain a ferritic stainless steel for welded structure, which is excellent in toughness of a base material and a welding heat-affected zone, by optimizing the quantity of Al and Nb especially in a steel composition, stabilizing C and N, specifying the heat treatment condition, and refining the structure. CONSTITUTION:Steel which contains <=0.02 C, <=0.02 N, <=0.03 C+N, <=1.0 Si, <=1.0 Mn, <=12-30 Cr, <=4 Mo, <=0.6 Nb, <=0.5 Al, and <=0.01 0 by wt%, also satisfies 7(C+N)<=Nb<=7(C+N)+0.39 and 2N<=Al<=2N+0.46, and consists of the balance Fe and inevitable impurities is refined. As necessary, this steel is subjected to working whose draft is >=20% at a recrystallization temperature or below in the course of hot rolling, or working whose draft is >=20% is executed by cold rolling after hot rolling, or at a recrystallization temperature or below after reheating. After this hot rolling, annealing is executed at 850-1,100 deg.C. In this way, it is possible to obtain ferritic stainless steel which is excellent in cold- toughness of a base material and a welding heat-affected zone, and is suitable for a welded structure member. |
