PURPOSE: To improve ductility, toughness, and strength at very low temp. after subjected to Nb3-forming heat treatment by specifying respective contents of C, Si, Mn, P, S, Ni, Cr, Mo, and Nb and the total content of Sn, Sb, and As.
CONSTITUTION: The title high-Mn nonmagnetic steel has a composition consisting of, by weight, ≤0.1% C, 0.1-2% Si, 14-30% Mn, ≤0.025% P, ≤0.015% S, 3-12% Ni, 12-20% Cr, 0.1-3% Mo, ≤0.2% Nb, 0.05-0.25% N, ≤0.02%, in total, of Sn, Sb, and As, and the balance Fe and further satisfying Ni+0.5Mn+30C+30N >(4/3)×(Cr+Mo+1.5Si-4) and (Nb%)/(C%)=2-4. The above steel has superior very low temp. characteristics (strength, ductility, and toughness) even if subjected to Nb3Sb-forming heat treatment after or without cold working.
KAJI HARUO
TONE SHOJI
IKEDA SOICHI
