PURPOSE: To allow the σ-phase of a two-phase stainless steel contg. a specified percentage of Cr, Ni and Mo to disappear by solubilization by heating the steel to a specified temp.
CONSTITUTION: A two-phase stainless steel contg. 20W28% Cr, 4W10% Ni and 0.5W5.0% Mo is heated to 1,100W1,300°C. By this heating the σ-phase is redissolved in the austenite, and simultaneously the microsegregation of Cr and Mo promoting the growth of σ-phase is allowed to disappear. In addition, the area of the ferrite grain boundaries is reduced. The steel may contain ≤ about 0.10% C, ≤ about 2.0% Si, ≤ about 4% Mn, ≤ about 0.04% P, ≤ about 0.03% S, ≤ about 2% Cu, ≤ about 3.0% N, ≤ about 1% W, ≤ about 1% V, ≤ about 1% Ti, ≤ about 1% Nb, and other trace constituents.
MATSUURA MASASHI
MAEHARA YASUHIRO
