Austenite stainless steel and its manufacturing methods

Abstract

The invention relates to a non-austenite steel suitable for use as a material for the outer shells of vehicles, structural parts and similar parts, and a method for producing such steel. In a design, a non-austenite steel consisting, in percentage by mass (% by mass), of 0.005% to 0.03% C, of ​​0.1% to 1% Si, of 0.1% to 2% Mn, of 6% to 9% Ni, of 16% to 19% Cr, of 0.2% or less N, and the remainder being Fe and unavoidable impurities. With the symbol for the total thickness of the steel material being t, the value of the average grain size d in the thickness range from l / 4t to 3 / 4t is equal to or greater than 5 μm, the ASP value calculated according to Formula (1) below is in the range from 10 to 25, the value calculated according to Formula (2) below is equal to or greater than 435, and the value calculated according to Formula (3) below is equal to or greater than 6,000. (l)t 551 - 462*([C]+[N]) - 9.2*[Si] - 8.1*[Μη] - 13.7*[Cr] - 29*{[Nib [Cu]) - 18.5+[Mo] - 68*([Nb]+[V]); (2): (1600* [NI) + (700 / ) + (4*ASP) - (20*[NĨJ) -4- 100; (3): YS*EL - 500*([NÍ]+[Cr]); In Formulas (1), (2), and (3), [C], [N], [Si], [M], [CrJ], [Ni], [Cu], [Mo], [Nb], and [V] are the percentage by mass (° / o mass) of the respective elements, YS is the melting limit (MPa), and EL is the elongation (%).